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Sample records for absorbs microwave power

  1. Effect of specific absorbed power on microwave sintering of 3YSZ ceramics

    Science.gov (United States)

    Bykov, Yu V.; Egorov, S. V.; Eremeev, A. G.; Plotnikov, I. V.; Rybakov, K. I.; Sorokin, A. A.; Kholoptsev, V. V.

    2017-07-01

    Samples of 3 % yttria-stabilized zirconia (3YSZ) ceramics have been sintered to near full density with no appreciable grain growth using an ultra-rapid microwave sintering process. The sintering experiments were carried out on a 24 GHz / 6 kW gyrotron system for microwave processing of materials with automatic process control. By varying the properties of the thermal insulation surrounding the samples it was possible to vary the microwave power required for heating. The final relative density of 3YSZ ceramic samples microwave heated at a rate of 50 °C/min to a temperature of 1400 °C without isothermal hold varied from 91.6 % when the specific absorbed microwave power was 4 W/cm3 to 99.4 % when the specific absorbed microwave power was 90 W/cm3. The specific absorbed power is therefore demonstrated to be the key parameter determining the achievable density in ultra-rapid field-assisted sintering processes.

  2. Magnetic field effects on microwave absorbing materials

    Science.gov (United States)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  3. Microwave power engineering applications

    CERN Document Server

    Okress, Ernest C

    2013-01-01

    Microwave Power Engineering, Volume 2: Applications introduces the electronics technology of microwave power and its applications. This technology emphasizes microwave electronics for direct power utilization and transmission purposes. This volume presents the accomplishments with respect to components, systems, and applications and their prevailing limitations in the light of knowledge of the microwave power technology. The applications discussed include the microwave heating and other processes of materials, which utilize the magnetron predominantly. Other applications include microwave ioni

  4. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    bandwidth below −10 dB and minimum RL decrease with increasing thickness of HCNSs/paraffin composites. Keywords. Nanomaterials; nanospheres; CVD; electric; magnetic; microwave absorption properties. 1. Introduction. In recent years, microwave absorbing materials have attracted considerable attention because it ...

  5. Synthesis and microwave absorbing properties of Cobalt ferrite

    Science.gov (United States)

    Liu, H. Y.; Li, Y. S.

    2018-01-01

    Cobalt ferrite power CoFe2O4 was synthesized through the chemical co-precipitation method. The structure, morphology and microwave absorbing properties were studied by changing raw materials, annealing temperature and experimental steps. The measurements of X-ray diffraction and scanning electron micrograph suggest that annealed CoFe2O4 sample is still a spinel structure. Moreover, the crystalline and grain sizes become large with the enhancement of annealing temperature. The measurements of microwave absorbing properties show that the reflection loss decreases continuously, and the wavelength of maximum absorption loss shift to short-wave limit as the sample thickness increases.

  6. Ultrathin microwave metamaterial absorber utilizing embedded resistors

    Science.gov (United States)

    Kim, Young Ju; Hwang, Ji Sub; Yoo, Young Joon; Khuyen, Bui Xuan; Rhee, Joo Yull; Chen, Xianfeng; Lee, YoungPak

    2017-10-01

    We numerically and experimentally studied an ultrathin and broadband perfect absorber by enhancing the bandwidth with embedded resistors into the metamaterial structure, which is easy to fabricate in order to lower the Q-factor and by using multiple resonances with the patches of different sizes. We analyze the absorption mechanism in terms of the impedance matching with the free space and through the distribution of surface current at each resonance frequency. The magnetic field, induced by the antiparallel surface currents, is formed strongly in the direction opposite to the incident electromagnetic wave, to cancel the incident wave, leading to the perfect absorption. The corresponding experimental absorption was found to be higher than 97% in 0.88-3.15 GHz. The agreement between measurement and simulation was good. The aspects of our proposed structure can be applied to future electronic devices, for example, advanced noise-suppression sheets in the microwave regime.

  7. Commercial microwave space power

    International Nuclear Information System (INIS)

    Siambis, J.; Gregorwich, W.; Walmsley, S.; Shockey, K.; Chang, K.

    1991-01-01

    This paper reports on central commercial space power, generating power via large scale solar arrays, and distributing power to satellites via docking, tethering or beamed power such as microwave or laser beams, that is being investigated as a potentially advantageous alternative to present day technology where each satellite carries its own power generating capability. The cost, size and weight for electrical power service, together with overall mission requirements and flexibility are the principal selection criteria, with the case of standard solar array panels based on the satellite, as the reference point. This paper presents and investigates a current technology design point for beamed microwave commercial space power. The design point requires that 25 kW be delivered to the user load with 30% overall system efficiency. The key elements of the design point are: An efficient rectenna at the user end; a high gain, low beam width, efficient antenna at the central space power station end, a reliable and efficient cw microwave tube. Design trades to optimize the proposed near term design point and to explore characteristics of future systems were performed. Future development for making the beamed microwave space power approach more competitive against docking and tethering are discussed

  8. Wide band cryogenic ultra-high vacuum microwave absorber

    Science.gov (United States)

    Campisi, I.E.

    1992-05-12

    An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

  9. Microwave and Pulsed Power

    Energy Technology Data Exchange (ETDEWEB)

    Freytag, E.K.

    1993-03-01

    The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. (1) We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. (2) We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. (3) We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO{sub x} from various effluent sources. (4) We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. (5) We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. (6) We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

  10. Microwave absorbing properties of activated carbon fibre polymer ...

    Indian Academy of Sciences (India)

    The reduction of electromagnetic backscatter with the use of microwave absorbing material (MAM) has important appli- cations in the field of radar and electromagnetic compatibility. (Singh et al 2006; Qiu et al 2007). Carbon .... According to the transmission-line theory (Meshram et al. 2003), the RL is related to the input ...

  11. Microwave absorbing properties of activated carbon fibre polymer ...

    Indian Academy of Sciences (India)

    absorption characteristics of the ACF composite with one containing unactivated fibres, it is found that carbon fibre activation increases the absorption of the composite. Keywords. Activated carbon fibres; microwave absorbing properties; composite materials. 1. Introduction. The reduction of electromagnetic backscatter with ...

  12. A microwave powered sensor assembly for microwave ovens

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a microwave powered sensor assembly for micro- wave ovens. The microwave powered sensor assembly comprises a microwave antenna for generating an RF antenna signal in response to microwave radiation at a predetermined excitation frequency. A dc power supply circuit...... of the microwave powered sensor assembly is operatively coupled to the RF antenna signal for extracting energy from the RF antenna signal and produce a power supply voltage. A sensor is connected to the power supply voltage and configured to measure a physical or chemical property of a food item under heating...... in a microwave oven chamber....

  13. Dendritic-metasurface-based flexible broadband microwave absorbers

    Science.gov (United States)

    Wang, Mei; Weng, Bin; Zhao, Jing; Zhao, Xiaopeng

    2017-06-01

    Based on the dendritic metasurface model, a type of flexible and lightweight microwave absorber (MA) comprising resistance film array with dendritic slot (RFADS), dielectric material, and metal plate is proposed. A broadband absorptivity of >80% is obtained both from simulation and experiment at frequency ranges of 3.0-9.2 and 3.2-9.00 GHz, respectively. And the thickness of MA is 5 mm, which is only 0.05λ _{low}, or 0.15λ _ {high}, where the λ _{low} and the λ _{high} are the beginning and the end of the working frequency. By combining this metasurface-based MA with the dendritic-resistance-film-based microwave metasurface absorber (MMA), we designed a broadband MMA. The simulations and experiments showed that this kind of MMA can absorb the radiation effectively at a wide frequency range 4.5-17.5 GHz. And the thickness of this combined MMA is 4 mm. All the structures showed their insensitivity to the incident angle (0°-40°) and the polarization of the incident wave because of their structural symmetry. In addition, the small thickness, low apparent density, and flexibility made those structures possess the advantages of being applied in microwave stealth and radar cross-section (RCS) reduction.

  14. Large-power microwave circuit device

    International Nuclear Information System (INIS)

    Suzuki, Kunio

    1987-01-01

    A 250 KW CW circulator and 1 MW CW dammy load are developed as large-power microwave circuit devices for Tristan, and they are shown to have good characteristics. The circulator has a Y-shape and consists of waveguides divided into four parts. Partition plates are provided in the waveguide connected to each port in order to divide the power into four components. A ferrite material which is high in Curie temperature and less likely to suffer from a RF loss is selected to be used in the circulator. Thin disks of this material, which is low in temperature gradient in the direction of thickness, are bonded to the surface of the waveguides with an epoxy adhesive. A magnet is provided at the top and bottom of the main portion of the circulator and the magnetic field is adjusted so that optimum characteristics are achieved. These arrangements result in good electrical and power characteristics. The dammy load of a water loading type is selected because microwave power is easily absorbed in water. A mechanically strong pipe which does not cause a large loss in microwave is mounted in a waveguide and water is passed through it to allow the power to be consumed gradually. A test up to a RF power of 750 KW shows that the temperature rise in the waveguide is 30 deg C. (Nogami, K.)

  15. Effect of Sand Base Grade and Density of Moulding Sands with Sodium Silicate on Effectiveness of Absorbing Microwaves

    Directory of Open Access Journals (Sweden)

    Stachowicz M.

    2016-09-01

    Full Text Available In the paper, presented is a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened moulding sands prepared of three kinds of high-silica base and a selected grade of sodium silicate. Measurements of power loss of microwave radiation (Pin expressed by a total of absorbed power (Pabs, output power (Pout and reflected power (Pref were carried-out on a stand of semiautomatic microwave slot line. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological and economical importance for manufacture of high-quality casting moulds and cores of various shapes and sizes. It was found that relative density influences parameters of power output and power reflected from samples of moulding sand placed in a waveguide. Absorption expressed by the parameter Pabs is not related to granularity of high-silica base: fine, medium and coarse. It was found that the semiautomatic microwave slot line supports evaluation of effectiveness of microwave absorption on the grounds of power loss measurements and enables statistic description of influence of relative density of the sandmix on penetration of electromagnetic waves in unhardened moulding sands.

  16. Microwave power transmission by satellites

    Science.gov (United States)

    Keydel, W.

    The MPTS (microwave power transmission system) is examined with regard to the problems involved, the proposed solutions, the future outlook, and the necessity for further work. The MPTS is analyzed with regard to system considerations, design considerations (power transmission, frequency selection, power generation, the spacetenna, microwave propagation problems, the rectenna, and efficiency), environmental impacts (electromagnetic compatibility and RF interference, and health and ecological effects). It is concluded that the MPTS is feasible, but that further studies are needed to optimize the system with respect to such factors as efficiency and environmental impact.

  17. Microwave metamaterial absorber based on multiple square ring structures

    Directory of Open Access Journals (Sweden)

    Weicheng Zhou

    2015-11-01

    Full Text Available In this paper, we report the design, analysis, and simulation of quintuple-band metamaterial absorber (MMA in the microwave region. The absorber is constructed of a delicate periodic patterned structures and a metallic background plane, separated by a dielectric substrate. By manipulating the periodic patterned structures, high absorption can be obtained at five specific resonance frequencies. Moreover, the significantly high absorptions of quintuple-peaks are persistent with polarization independence, and the influence of angle of incidence for both TE and TM modes was also elucidated. For explaining the absorption mechanism of proposed structures, the electric and magnetic field distributions and resistance matching principal were given. Importantly, the design idea has the ability to be extended to other frequencies, like terahertz, infrared and optical frequencies.

  18. Microwave absorbing property of a hybrid absorbent with carbonyl irons coating on the graphite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yan, Zhenqiang; Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2015-11-30

    Graphical abstract: The absorbing property could be enhanced as the CIPs coated on the graphite. - Highlights: • Absorbers filled with CIPs coating on the graphite was fabricated. • The permittivity and permeability increased as CIPs coated. • The CIP materials enhanced the electromagnetic property. • The graphite coated CIPs were effective in 2–18 GHz. - Abstract: The hybrid absorbent filled with carbonyl iron particles (CIPs) coating on the graphite was prepared using a chemical vapor decomposition (CVD) process. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. The results showed that α-Fe appeared in the super-lattice diffraction peaks in XRD graph. The composites added CIPs coating on the graphite had a higher permittivity and imaginary permeability due to the superior microwave dielectric loss and magnetic loss of the CIPs. The reflection loss (RL) result showed that composites filled with 5 vol% Fe-graphite had an excellent absorbing property in the 2–18 GHz, the minimum RL was −25.14 dB at 6 mm and −26.52 dB at 8 mm, respectively.

  19. Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yang; Xu, Yonggang, E-mail: xuyonggang221@163.com; Cai, Jun; Yuan, Liming; Zhang, Deyuan

    2015-09-01

    Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz.

  20. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    Science.gov (United States)

    Akman, O.; Kavas, H.; Baykal, A.; Toprak, M. S.; Çoruh, Ali; Aktaş, B.

    2013-02-01

    Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications.

  1. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    Energy Technology Data Exchange (ETDEWEB)

    Akman, O. [Physics Department, Gebze Institute of Technology (GYTE), 41400 Gebze-Kocaeli (Turkey); Department of Physics, Sakarya University, 54100, Sakarya (Turkey); Kavas, H. [Department of Physics Engineering, Faculty of Sciences, Istanbul Medeniyet University, 34720 Istanbul (Turkey); Baykal, A., E-mail: hbaykal@fatih.edu.tr [Department of Chemistry, Fatih University, 34500, B. Cekmece-Istanbul (Turkey); Toprak, M.S. [Functional Materials Division, KTH Royal Institute of Technology, SE-16440 Stockholm (Sweden); Yildirim Beyazit University, Department of Materials Science and Engineering, Ulus-Ankara (Turkey); Coruh, Ali [Department of Physics, Sakarya University, 54100, Sakarya (Turkey); Aktas, B., E-mail: aktas@gyte.edu.tr [Physics Department, Gebze Institute of Technology (GYTE), 41400 Gebze-Kocaeli (Turkey)

    2013-02-15

    Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications. - Highlights: Black-Right-Pointing-Pointer Ni, Co and Ni-Co alloyed coatings on PAN were successfully prepared. Black-Right-Pointing-Pointer The incorporation of magnetic nanoparticles leads to interfacial polarization. Black-Right-Pointing-Pointer The composite prepared in Ni bath at 0.5 min leads to a wider absorption bandwidth and minimum coefficient of reflection. Black-Right-Pointing-Pointer About of -42 dB, more than 99.99% of the microwave absorption.

  2. Applications of high power microwaves

    International Nuclear Information System (INIS)

    Benford, J.; Swegle, J.

    1993-01-01

    The authors address a number of applications for HPM technology. There is a strong symbiotic relationship between a developing technology and its emerging applications. New technologies can generate new applications. Conversely, applications can demand development of new technological capability. High-power microwave generating systems come with size and weight penalties and problems associated with the x-radiation and collection of the electron beam. Acceptance of these difficulties requires the identification of a set of applications for which high-power operation is either demanded or results in significant improvements in peRFormance. The authors identify the following applications, and discuss their requirements and operational issues: (1) High-energy RF acceleration; (2) Atmospheric modification (both to produce artificial ionospheric mirrors for radio waves and to save the ozone layer); (3) Radar; (4) Electronic warfare; and (5) Laser pumping. In addition, they discuss several applications requiring high average power than border on HPM, power beaming and plasma heating

  3. Microwave power engineering generation, transmission, rectification

    CERN Document Server

    Okress, Ernest C

    1968-01-01

    Microwave Power Engineering, Volume 1: Generation, Transmission, Rectification considers the components, systems, and applications and the prevailing limitations of the microwave power technology. This book contains four chapters and begins with an introduction to the basic concept and developments of microwave power technology. The second chapter deals with the development of the main classes of high-power microwave and optical frequency power generators, such as magnetrons, crossed-field amplifiers, klystrons, beam plasma amplifiers, crossed-field noise sources, triodes, lasers. The third

  4. Symmetric Absorber-Coupled Far-Infrared Microwave Kinetic Inductance Detector

    Science.gov (United States)

    U-yen, Kongpop (Inventor); Wollack, Edward J. (Inventor); Brown, Ari D. (Inventor); Stevenson, Thomas R. (Inventor); Patel, Amil A. (Inventor)

    2016-01-01

    The present invention relates to a symmetric absorber-coupled far-infrared microwave kinetic inductance detector including: a membrane having an absorber disposed thereon in a symmetric cross bar pattern; and a microstrip including a plurality of conductor microstrip lines disposed along all edges of the membrane, and separated from a ground plane by the membrane. The conducting microstrip lines are made from niobium, and the pattern is made from a superconducting material with a transition temperature below niobium, including one of aluminum, titanium nitride, or molybdenum nitride. The pattern is disposed on both a top and a bottom of the membrane, and creates a parallel-plate coupled transmission line on the membrane that acts as a half-wavelength resonator at readout frequencies. The parallel-plate coupled transmission line and the conductor microstrip lines form a stepped impedance resonator. The pattern provides identical power absorption for both horizontal and vertical polarization signals.

  5. Microwave power coupling with electron cyclotron resonance ...

    Indian Academy of Sciences (India)

    the electron, and B is the critical magnetic field. The microwave power gets ... to the partial reflection of the incident microwave power due to improper impedance matching [10]. However, this ..... LA-UR-87-126, LANL (1987). [16] F F Chen, R H Huddlestone and S L Leonard, Plasma diagnostics techniques (Academic,.

  6. Research on calorimeter for high-power microwave measurements.

    Science.gov (United States)

    Ye, Hu; Ning, Hui; Yang, Wensen; Tian, Yanmin; Xiong, Zhengfeng; Yang, Meng; Yan, Feng; Cui, Xinhong

    2015-12-01

    Based on measurement of the volume increment of polar liquid that is a result of heating by absorbed microwave energy, two types of calorimeters with coaxial capacitive probes for measurement of high-power microwave energy are designed in this paper. The first is an "inline" calorimeter, which is placed as an absorbing load at the end of the output waveguide, and the second is an "offline" calorimeter that is placed 20 cm away from the radiation horn of the high-power microwave generator. Ethanol and high density polyethylene are used as the absorbing and housing materials, respectively. Results from both simulations and a "cold test" on a 9.3 GHz klystron show that the "inline" calorimeter has a measurement range of more than 100 J and an energy absorption coefficient of 93%, while the experimental results on a 9.3 GHz relativistic backward-wave oscillator show that the device's power capacity is approximately 0.9 GW. The same experiments were also carried out for the "offline" calorimeter, and the results indicate that it can be used to eliminate the effects of the shock of the solenoid on the measurement curves and that the device has a higher power capacity of 2.5 GW. The results of the numerical simulations, the "cold tests," and the experiments show good agreement.

  7. Effect of inclusions' distribution on microwave absorbing properties of composites

    International Nuclear Information System (INIS)

    Qin, Siliang; Wang, Qingguo; Qu, Zhaoming

    2013-01-01

    Effect of inclusions' spatial distributions on the permeability and permittivity of composites is studied using the generalized Maxwell-Garnett equations. The result indicates that inclusions' orientation distribution can increase the longitudinal electromagnetic parameters. For inclusions' random and orientation distribution, single and three-layer absorbers are designed and optimized using genetic algorithm. The result shows that under a given absorbing requirement, absorber with inclusions' orientation distribution is lighter and thinner than absorber with inclusions' random distribution.

  8. The structural, magnetic and microwave properties of spherical and flake shaped carbonyl iron particles as thin multilayer microwave absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Khani, Omid, E-mail: omidkhani@mut-es.ac.ir [Department of Physics, Shahid Chamran University of Ahvaz, Ahvaz, Islamic Republic of Iran (Iran, Islamic Republic of); Shoushtari, Morteza Zargar [Department of Physics, Shahid Chamran University of Ahvaz, Ahvaz, Islamic Republic of Iran (Iran, Islamic Republic of); Ackland, Karl; Stamenov, Plamen [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2017-04-15

    An increase in microwave permeability is a prerequisite for reducing the thickness of radar absorber coatings. The aim of this paper is to increase the magnetic loss of commercial carbonyl iron particles for fabricating wideband microwave absorbers with a multilayer structure. For this purpose, carbonyl iron particles were milled and their static and dynamic magnetic properties were studied before and after milling. A distinct morphological change from spherical to flake-like particles is measured with increased milling time, whereas no distinct changes in magnetic properties are measured with increased milling time. The imaginary part of the permeability (µ'') of the milled carbonyl iron particles increased from 1.23 to 1.88 and showed a very broad peak over the entire frequency range 1–18 GHz. The experimental results were modeled using the Rousselle effective medium theory (EMT) in the Neo formulation. The theoretical predictions showed good agreement with the experimental results. Two layer absorbers were designed according to the measured microwave parameters and the multilayer design. The results revealed that a thin multilayer with a thickness of 1.75 mm can effectively absorb microwaves in both the entire X and Ku frequency bands. The results suggest that microwave absorbers with excellent absorption properties could be mass-produced, using commercial carbonyl iron particles. - Highlights: • The microwave properties of carbonyl iron particles can be controlled effectively by particles shape. • Milling process transforms the carbonyl iron particle morphology from spherical to flake-like. • No appreciable differences in the magnetic and chemical local environments were detected by means of Mossbauer spectroscopy. • The two layer design showed appropriate absorptions in a rather wide frequency range.

  9. Dielectric properties of microwave absorbing sheets produced with silicone and polyaniline

    Directory of Open Access Journals (Sweden)

    Luiza de Castro Folgueras

    2010-06-01

    Full Text Available The aim of this study was to produce sheets of microwave absorbing materials using conductive polyaniline dispersed in a silicone rubber matrix and to characterize the electromagnetic properties (absorption, transmission and reflection of electromagnetic energy; and electric permittivity and magnetic permeability of these sheets in the X-band (8 - 12 GHz. Two sheets were produced: one 2.80 mm thick and the other 4.39 mm thick. The thinner sheet absorbed incident microwave energy more efficiently, attenuating up to 88% of the incident electromagnetic energy. Also, calculations were performed in order to determine the electromagnetic parameters that optimize the absorbent properties of these sheets. These calculations showed that these materials can be combined and altered to produce absorbing materials with a wide range of absorbing characteristics.

  10. Optimization on microwave absorbing properties of carbon nanotubes and magnetic oxide composite materials

    Science.gov (United States)

    Mingdong, Chen; Huangzhong, Yu; Xiaohua, Jie; Yigang, Lu

    2018-03-01

    Based on the physical principle of interaction between electromagnetic field and the electromagnetic medium, the relationship between microwave absorbing coefficient (MAC) and the electromagnetic parameters of materials was established. With the composite materials of nickel ferrite (NiFe2O4), carbon nanotubes (CNTs) and paraffin as an example, optimization on absorbing properties of CNTs/magnetic oxide composite materials was studied at the frequency range of 2-18 GHz, and a conclusion is drawn that the MAC is the biggest at the same frequency, when the CNTs is 10 wt% in the composite materials. Through study on the relationship between complex permeability and MAC, another interesting conclusion is drawn that MAC is obviously affected by the real part of complex permeability, and increasing real part of complex permeability is beneficial for improving absorbing properties. The conclusion of this paper can provide a useful reference for the optimization research on the microwave absorbing properties of CNTs/ferrite composite materials.

  11. Absorber for microwave investigation in the open space

    Science.gov (United States)

    Kubacki, Roman; Smólski, Bogusław; Głuszewski, Wojciech; Przesmycki, Rafał; Rudyk, Karol

    2017-04-01

    In some circumstances there is a need to realize the Electromagnetic Compatibility (EMC) investigation not in the specialized anechoic chamber but in the open space. Typical absorbers used in anechoic chamber to reduce the reflected rays from walls and floor, such as ferrite plates and graphite cones, are not suitable in the open space. In the work the investigation of the flexible absorbing material intended to the liquidation of the radiation reflected from the ground has been presented. As an absorbing material the metallic-glass with graphite was elaborated. This material was additionally exposed to the ionizing radiation in the dose of 100 kGy in the radioactive gamma source. The permittivity, permeability as well as the shielding properties have been analyzed.

  12. A Field Performance Evaluation Scheme for Microwave-Absorbing Material Coatings

    Directory of Open Access Journals (Sweden)

    Shaopeng Guan

    2017-03-01

    Full Text Available Performance evaluation is an important aspect in the study of microwave-absorbing material coatings. The reflectivity of the incident wave is usually taken as the performance indicator. There have been various methods to directly or indirectly measure the reflectivity, but existing methods are mostly cumbersome and require a strict testing environment. What is more, they cannot be applied to field measurement. In this paper, we propose a scheme to achieve field performance evaluation of microwave-absorbing materials, which adopts a small H-plane sectoral horn antenna as the testing probe and a small microwave reflectometer as the indicator. When the size of the H-plane sectoral horn antenna is specially designed, the field distribution at the antenna aperture can be approximated as a plane wave similar to the far field of the microwave emitted by a radar unit. Therefore, the reflectivity can be obtained by a near-field measurement. We conducted experiments on a kind of ferrite-based microwave-absorbing material at X band (8.2–12.4 GHz to validate the scheme. The experimental results show that the reflectivity is in agreement with the reference data measured by the conventional method as a whole.

  13. Wide Bandwidth Microwave Absorbers of Ferrite-Rubber Composites with Square-Rod Structure

    Directory of Open Access Journals (Sweden)

    Kim Sung-Soo

    2016-01-01

    Full Text Available As one way of shape control for the wide bandwidth in microwave absorbers, a square-rod structure of ferrite composite is proposed. Microwave absorbance of the square-rod absorber is analyzed by the transmission line approximation which provides the reflection loss as a function of material parameters and dimension of the structure. In particular, the absorption bandwidth is greatly dependent upon the size of the square rod, which has been identified in both composites of Ni-Zn ferrite and Co2Z hexagonal ferrites. With a controlled geometry of square rod in those composites, a wide bandwidth (about 6 GHz with respect to – 20 dB reflection loss has been predicted.

  14. Microwave power coupling with electron cyclotron resonance ...

    Indian Academy of Sciences (India)

    Electron cyclotron resonance (ECR) plasma was produced at 2.45 GHz using 200 – 750 W microwave power. The plasma was produced from argon gas at a pressure of 2 × 10−4 mbar. Three water-cooled solenoid coils were used to satisfy the ECR resonant conditions inside the plasma chamber. The basic parameters of ...

  15. A chiral microwave absorbing absorbent of Fe–CoNiP coated on spirulina

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yuan, Liming [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Zhang, Deyuan [School of Mechanical Engineering and Automation, Beihang University, Beijing, 100191 (China)

    2015-11-15

    A chiral bio-absorbent of Fe–CoNiP coated on the spirulina was fabricated by the electroless and chemical vapor decomposition. The scanning electron microscopy (SEM) was used to evaluate the spirulina cells particle morphology. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The permittivity and permeability was measured by a vector network analyzer in frequency 8–18 GHz, and the reflection loss (RL) was calculated. The results showed the carbonyl iron particles (CIPs) and CoNiP were bonded to the spirulina surface, the permittivity and permeability could be enlarged as Fe films coated on the particles compared with the CoNiP spirulina, it was attributed to the excellent electromagnetic property of CIPs. The chiral Fe–CoNiP composites had a better absorbing property at 8–18 GHz than the CoNiP spirulina composite, the RL was −16.26 dB at 10.48 GHz, the absorbing band was 9.5–11.5 GHz of RL less than −10 dB, which indicated the Fe–CoNiP spirulina could be an effective absorbent used in 8–18 GHz. - Highlights: • Absorbers filled with Fe–CoNiP coating on the spirulina were fabricated. • The permittivity and permeability increased as CIPs coated. • The Fe material enhanced the electromagnetic property. • The spirulina coated Fe–CoNiP was effective in 8–18 GHz.

  16. Development of microwave absorbing materials prepared from a polymer binder including Japanese lacquer and epoxy resin

    Science.gov (United States)

    Iwamaru, T.; Katsumata, H.; Uekusa, S.; Ooyagi, H.; Ishimura, T.; Miyakoshi, T.

    Microwave absorption composites were synthesized from a poly urushiol epoxy resin (PUE) mixed with one of microwave absorbing materials; Ni-Zn ferrite, Soot, Black lead, and carbon nano tube (CNT) to investigate their microwave absorption properties. PUE binders were specially made from Japanese lacquer and epoxy resin, where Japanese lacquer has been traditionally used for bond and paint because it has excellent beauty. Japanese lacquer solidifies with oxygen contained in air's moisture, which has difficulty in making composite, but we improved Japanese lacquer's solidification properties by use of epoxy resin. We made 10 mm thickness composite samples and cut them into toroidal shape to measure permittivity, permeability, and reflection loss in frequencies ranging from 50 Hz to 20 GHz. Electric magnetic absorber's composites synthesized from a PUE binders mixed either with Soot or CNT showed significantly higher wave absorption over -27 dB than the others at frequencies around 18 GHz, although Japanese lacquer itself doesn't affect absorption. This means Japanese lacquer can be used as binder materials for microwave absorbers.

  17. Application of high power microwave vacuum electron devices

    International Nuclear Information System (INIS)

    Ding Yaogen; Liu Pukun; Zhang Zhaochuan; Wang Yong; Shen Bin

    2011-01-01

    High power microwave vacuum electron devices can work at high frequency, high peak and average power. They have been widely used in military and civil microwave electron systems, such as radar, communication,countermeasure, TV broadcast, particle accelerators, plasma heating devices of fusion, microwave sensing and microwave heating. In scientific research, high power microwave vacuum electron devices are used mainly on high energy particle accelerator and fusion research. The devices include high peak power klystron, CW and long pulse high power klystron, multi-beam klystron,and high power gyrotron. In national economy, high power microwave vacuum electron devices are used mainly on weather and navigation radar, medical and radiation accelerator, TV broadcast and communication system. The devices include high power pulse and CW klystron, extended interaction klystron, traveling wave tube (TWT), magnetron and induced output tube (IOT). The state of art, common technology problems and trends of high power microwave vacuum electron devices are introduced in this paper. (authors)

  18. STIR: Microwave Response of Carbon Nanotubes in Polymer Nanocomposite Welds

    Science.gov (United States)

    2016-01-28

    hypothesize that this is related to the transition from power absorbance to microwave power reflectance associated with high conductivity networks. The...partial microwave power reflectance and lower absorbance is observed. 4 Fig. 5: Preliminary study - FLIR imaging used to capture temperature...percolation), and microwave power reflectance (high MWCNT loadings). 2. Polymer migration across welds using MWCNT-based adhesives and microwaves

  19. An explosively driven high-power microwave pulsed power system.

    Science.gov (United States)

    Elsayed, M A; Neuber, A A; Dickens, J C; Walter, J W; Kristiansen, M; Altgilbers, L L

    2012-02-01

    The increased popularity of high power microwave systems and the various sources to drive them is the motivation behind the work to be presented. A stand-alone, self-contained explosively driven high power microwave pulsed power system has been designed, built, and tested at Texas Tech University's Center for Pulsed Power and Power Electronics. The system integrates four different sub-units that are composed of a battery driven prime power source utilizing capacitive energy storage, a dual stage helical flux compression generator as the main energy amplification device, an integrated power conditioning system with inductive energy storage including a fast opening electro-explosive switch, and a triode reflex geometry virtual cathode oscillator as the microwave radiating source. This system has displayed a measured electrical source power level of over 5 GW and peak radiated microwaves of about 200 MW. It is contained within a 15 cm diameter housing and measures 2 m in length, giving a housing volume of slightly less than 39 l. The system and its sub-components have been extensively studied, both as integrated and individual units, to further expand on components behavior and operation physics. This report will serve as a detailed design overview of each of the four subcomponents and provide detailed analysis of the overall system performance and benchmarks.

  20. X-band microwave absorbing characteristics of multicomponent composites with magnetodielectric fillers

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, Seyyed Salman Seyyed [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Stergiou, Charalampos A. [Lab. of Inorganic Materials, Centre for Research and Technology Hellas, 57001 Thermi (Greece)

    2016-12-01

    We have studied the microwave absorbing performance in the X-band (8–12.4 GHz) of epoxy composites filled with magnetic and dielectric oxides and multiwalled carbon nanotubes. To this end, pure cobalt-substituted Ba-hexaferrite and calcium titanate were synthesized with the hydrothermal method in the form of nanosized powder. Moreover, the produced powders were characterized in regard of their structural, morphological and static magnetic properties. For the electromagnetic investigation, composite samples were also prepared with various thicknesses up to 4 mm and two basic filler compositions; namely 30 wt% of BaCoFe{sub 11}O{sub 19} and 30 wt% of the mixture BaCoFe{sub 11}O{sub 19}/CaTiO{sub 3}/carbon nanotubes. The magnetic composites show strong but narrowband reflection losses up to 27.5 dB, whereas the magnetodielectric composites with maximum losses of 15.8 dB possess wider bandwidth of operation, due to improved impedance matching. Furthermore, the characteristic frequency of the maximum losses for these quarter-wavelength absorbers was verified to be in inverse proportion to the layer thickness. These findings are supported by reflectance measurements of the samples both in waveguide and free-space. - Highlights: • Single and multi-component composite absorbers with magnetodielectric fillers were synthesized. • The prepared absorbers are lightweight with 30 wt% filler content in epoxy matrix. • The microwave absorption characteristics of composites were measured by waveguide and free-space methods in the X-band. • Composites with a combination of magnetic and dielectric fillers exhibit wider reflection loss peaks. • Composite absorbers have a realistic potential as microwave absorbers in the X-band.

  1. Medical preparation container comprising microwave powered sensor assembly

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a medical preparation container which comprises a microwave powered sensor assembly. The microwave powered sensor assembly comprises a sensor configured to measure a physical property or chemical property of a medical preparation during its heating in a microwave...

  2. Electromagnetic scattering from microwave absorbers - Laboratory verification of the coupled wave theory

    Science.gov (United States)

    Gasiewski, A. J.; Jackson, D. M.

    1992-01-01

    W-band measurements of the bistatic scattering function of some common microwave absorbing structures, including periodic wedge-type and pyramid-type iron-epoxy calibration loads and flat carbon-foam 'Echosorb' samples, were made using a network analyzer interface to a focused-lens scattering range. Swept frequency measurements over the 75-100 GHz band revealed specular and Bragg reflection characteristics in the measured data.

  3. Design, preparation and microwave absorbing properties of resin matrix composites reinforced by SiC fibers with different electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haitao, E-mail: xzddlht@163.com [Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Science and Technology on Scramjet Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Cheng, Haifeng; Tian, Hao [Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-01-15

    Highlights: • SSMASs have better microwave absorbing properties in smaller thickness. • SSMASs can be realized by SiC fibers with different electrical resistivity. • Resistivity of SiC fibers can be regulated by adjusting surface characteristics. • The bandwidth of SSMASs at reflectivity below −10 dB can reach 11.6 GHz. -- Abstract: One kind of sandwich structure microwave absorbing structures (SSMASs) derived from Salisbury absorbers is reported. The impedance characteristics of SSMASs are analyzed, and the mechanisms of broadening microwave absorbing bandwidth are interpreted by Smith chart. In order to realize SSMASs, high electrical resistivity SiC fibers with Si–C–O surface layers and low electrical resistivity SiC fibers with pyrocarbon surface layers are employed and analyzed by SEM, XPS, AES and HRTEM. The conductive model of SiC fibers with pyrocarbon layers is built and electrical resistivity simulation is done. The SSMASs are fabricated by employing plain woven SiC fiber fabrics with high and low electrical resistivity as reinforcements of dielectric layers and lossy layer, respectively. The microwave absorbing properties of SSMASs are measured and compared with simulated results. The results show that the experimental and simulated results are in good agreement, the SSMASs have better wideband microwave absorbing properties, and the microwave absorbing bandwidth at reflectivity below −10 dB can reach 11.6 GHz.

  4. Expanded graphite—Phenolic resin composites based double layer microwave absorber for X-band applications

    Science.gov (United States)

    Gogoi, Jyoti Prasad; Bhattacharyya, Nidhi Saxena

    2014-11-01

    In this investigation, double layer microwave absorbers are designed and developed with paired combination of 5 wt. %, 7 wt. %, 8 wt. %, and 10 wt. % expanded graphite-novolac phenolic resin (EG-NPR) composites, in the frequency range of 8.2-12.4 GHz. The thickness and compositional combination of the two layers constituting the absorber are optimized to achieve minimum value of reflection loss (dB) and a broad microwave absorption bandwidth. Double layer combinations showing -25 dB absorption bandwidth >2 GHz and -30 dB absorption bandwidth >1 GHz are chosen for fabrication. The total thickness of the fabricated double layer microwave absorber is varied from 3 mm to 3.4 mm. Absorption bandwidths at -10 dB, -20 dB, -25 dB and -30 dB are determined for the fabricated structure. The maximum -25 dB and -30 dB absorption bandwidth of 2.47 GHz and 1.77 GHz, respectively, are observed for the double layer structure with (5 wt. %-8 wt. %) EG-NPR composites with total thickness of 3.2 mm, while -10 dB bandwidth covers the entire X-band range.

  5. Microwave absorbing materials using Ag-NiZn ferrite core-shell nanopowders as fillers

    International Nuclear Information System (INIS)

    Peng, C.-H.; Wang, H.-W.; Kan, S.-W.; Shen, M.-Z.; Wei, Y.-M.; Chen, S.-Y.

    2004-01-01

    Silver nanoparticles coated with Ni 0.5 Zn 0.5 Fe 2 O 4 spinel ferrites, forming a core-shell structure, were synthesized by utilizing hydrothermal method at different ferrite/silver ratio (ferrite/silver=6/1, 4/1, 2/1, 1/1, 1/6) and introduced into polyurethane matrix to be a microwave absorber. The complex permittivity (ε',ε'') and permeability (μ',μ'') of absorbing composite materials consisted of ferrite/silver core-shell nanopowders and polyurethane were measured in the frequency range of 2-15GHz. The reflection loss and matching frequency were calculated from measured data using theory of the absorbing wall for different ferrite/silver ratios. It was found that the matching frequency for reflection loss exceeded a satisfactory -25dB at 9.0GHz for using NiZn ferrite as a filler shifts to higher frequencies (10.9-13.7GHz) as the ferrite/silver ratio of core-shell nano-filler decreased from 6/1 to 2/1. The present result demonstrates that microwave absorbers using ferrite/silver core-shell filler can be fabricated for the applications over 9GHz, with reflection loss more than-25dB for specific frequencies, by controlling the ferrite/silver ratio of the core-shell nano-fillers in the composites

  6. Dielectric microwave absorbing material processed by impregnation of carbon fiber fabric with polyaniline

    Directory of Open Access Journals (Sweden)

    Luiza de Castro Folgueras

    2007-03-01

    Full Text Available It is a known fact that the adequate combination of components and experimental conditions may produce materials with specific requirements. This study presents the effect of carbon fiber fabric impregnation with polyaniline conducting polymer aiming at the radar absorbing material processing. The experiments consider the sample preparation with one and two impregnations. The prepared samples were evaluated by reflectivity measurements, in the frequency range of 8-12 GHz and scanning electron microscopy analyses. The correlation of the results shows that the quantity of impregnated material influences the performance of the processed microwave absorber. This study shows that the proposed experimental route provides flexible absorbers with absorption values of the incident radiation close to 87%.

  7. Enhanced microwave absorbing properties and heat resistance of carbonyl iron by electroless plating Co

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyu, E-mail: wanghongyu07010310@163.com; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-11-01

    Co coated carbonyl iron particles (Co (CI)) are fabricated through electroless plating method, and the electromagnetic microwave absorbing properties are investigated in the frequencies during 8.2–12.4 GHz. The complex permittivity of CI particles after electroless plating Co is higher than that of raw CI particles due to improvment of the polarization process. Furthermore, according to the XRD and TG results, the Co layer can enhance the heat resistance of CI particles. The bandwidth below −10 dB can reach 3.9 GHz for the Co(CI) absorbent. The results indicate that the electroless plating Co not only enhances the absorbing properties but also improves the heat resistance of CI. - Highlights: • The Co-coated carbonyl iron Co(CI) particles were prepared by electroless plating. • The electromagnetic wave absorbing properties of Co(CI) particles were studied. • The heat treatment on the absorbing property of Co(CI) particles was studied. • The Co(CI) particles have good absorbing property when compared with CI.

  8. Indium gallium arsenide microwave power transistors

    Science.gov (United States)

    Johnson, Gregory A.; Kapoor, Vik J.; Shokrani, Mohsen; Messick, Louis J.; Nguyen, Richard

    1991-01-01

    Depletion-mode InGaAs microwave power MISFETs with 1-micron gate lengths and up to 1-mm gate widths have been fabricated using an ion-implantation process. The devices employed a plasma-deposited silicon/silicon dioxide gate insulator. The dc I-V characteristics and RF power performance at 9.7 GHz are presented. The output power, power-added efficiency, and power gain as a function of input power are reported. An output power of 1.07 W with a corresponding power gain and power-added efficiency of 4.3 dB and 38 percent, respectively, was obtained. The large-gate-width devices provided over twice the previously reported output power for InGaAs MISFETs at X-band. In addition, output power stability within 1.2 percent over 24 h of continuous operation was achieved. In addition, a drain current drift of 4 percent over 10,000 sec was obtained.

  9. YIG based broad band microwave absorber: A perspective on synthesis methods

    Science.gov (United States)

    Sharma, Vinay; Saha, J.; Patnaik, S.; Kuanr, Bijoy K.

    2017-10-01

    The fabrication of a thin layer of microwave absorber that operates over a wide band of frequencies is still a challenging task. With recent advances in nanostructure synthesis techniques, considerable progress has been achieved in realizations of thin nanocomposite layer designed for full absorption of incident electromagnetic (EM) radiation covering S to K band frequencies. The primary objective of this investigation is to achieve best possible EM absorption with a wide bandwidth and attenuation >10 dB for a thin absorbing layer (few hundred of microns). Magnetic yttrium iron garnet (Y3Fe5O12; in short YIG) nanoparticles (NPs) were prepared by sol-gel (SG) as well as solid-state (SS) reaction methods to elucidate the effects of nanoscale finite size on the magnetic behavior of the particles and hence their microwave absorption capabilities. It is found that YIG prepared by these two methods are different in many ways. Magnetic properties investigated using vibrating sample magnetometry (VSM) exhibit that the coercivity (Hc) of solid-state NPs is much larger (72 Oe) than the sol-gel NPs (31 Oe). Microwave absorption properties were studied by ferromagnetic resonance (FMR) technique in field sweep mode at different fixed frequencies. A thin layer (∼300 μm) of YIG film was deposited using electrophoretic deposition (EPD) technique over a coplanar waveguide (CPW) transmission line made on copper coated RT/duroid® 5880 substrates. Temperature dependent magnetic properties were also investigated using VSM and FMR techniques. Microwave absorption properties were investigated at high temperatures (up to 300 °C) both for sol-gel and solid-state synthesized NPs and are related to skin depth of YIG films. It is observed that microwave absorption almost vanishes when the temperature reached the Néel temperature of YIG.

  10. Enhanced microwave absorbing properties of carbonyl iron-doped Ag/ordered mesoporous carbon nanocomposites

    International Nuclear Information System (INIS)

    Wu Hongjing; Wang Liuding; Wang Yiming; Guo Shaoli; Shen Zhongyuan

    2012-01-01

    Highlights: ► Ag/OMC-CI paraffin wax composites were successfully prepared. ► Reflection loss value below −10 dB at 12 GHz was obtained. ► Ag/OMC-CI showed excellent microwave absorption with respect to OMC-CI and Ag/OMC. ► This could be attributed to the enhancement of interfacial polarization. - Abstract: Microwave absorbing materials carbonyl iron (CI)-doped Ag/ordered mesoporous carbon (OMC) paraffin wax composites were prepared by colloidal deposition and impregnation methods, and their electromagnetic and microwave absorbing properties were investigated in the frequency ranging from 2 to 18 GHz. The microstructures and chemical compositions of the Ag/OMC and Ag/OMC-CI paraffin wax composites were characterized by TEM, XRD, XPS, SEM and EDS, respectively. The complex permittivity of the paraffin wax composites show dual resonance behavior, resulting from the multi-interfaces among Ag nanoparticles, OMC nanorods, CI and paraffin wax. The magnetic loss was mainly caused by natural resonance and eddy current loss, respectively. The minimum reflection loss (RL) value of Ag/OMC-CI was below −10 dB at 12 GHz, which were superior to those of OMC-CI and Ag/OMC. This phenomenon is attributed to the enhancement of dielectric polarization and magnetic loss.

  11. Development of FeCoB/Graphene Oxide based microwave absorbing materials for X-Band region

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sukanta [Integrated Test Range (ITR), Chandipur 756025 (India); Indian School of Mines, Dhanbad 826004 (India); Chandra Nayak, Ganesh, E-mail: ganeshnayak2006@gmail.com [Indian School of Mines, Dhanbad 826004 (India); Sahu, S.K. [Integrated Test Range (ITR), Chandipur 756025 (India); Oraon, Ramesh [Indian School of Mines, Dhanbad 826004 (India)

    2015-06-15

    This work explored the microwave absorption capability of Graphene Oxide and Graphene Oxide coated with FeCoB for stealth technology. Epoxy based microwave absorbing materials were prepared with 30% loading of Graphene Oxide, FeCoB alloy and Graphene Oxide coated with FeCoB. Graphene Oxide and FeCoB were synthesized by Hummer's and Co-precipitation methods, respectively. The filler particles were characterized by FESEM, XRD and Vibrating Sample Magnetometer techniques. Permittivity, permeability and reflection loss values of the composite absorbers were measured with vector network analyzer which showed a reflection loss value of −7.86 dB, at 10.72 GHz, for single layered Graphene Oxide/Epoxy based microwave absorbers which can be correlated to the absorption of about 83.97% of the incident microwave energy. Reflection loss value of FeCoB/Epoxy based microwave absorber showed −13.30 dB at 11.67 GHz, which corresponded to maximum absorption of 93.8%. However, reflection loss values of Graphene Oxide coated with FeCoB/Epoxy based single-layer absorber increased to −22.24 dB at 12.4 GHz which corresponds to an absorption of 99% of the incident microwave energy. - Highlights: • FeCoB coated Graphene Oxide (GO) was synthesized by co-precipitation method. • GO, FeCoB and GO@FeCoB based microwave absorbers were developed with Epoxy matrix. • GO and FeCoB/Epoxy absorbers showed −7.86 & −13.30 dB reflection loss, respectively. • Maximum Reflection loss of −22.24 dB was achieved with GO@FeCoB/Epoxy absorber.

  12. Effect of carbon black content on the microwave absorbing properties of CB/epoxy composites

    Directory of Open Access Journals (Sweden)

    Pourya Mehdizadeh

    2016-04-01

    Full Text Available To prevent serious electromagnetic interference, a single-layer and double layer wave-absorbing coating employing complex absorbents composed of carbon black with epoxy resin as matrix was prepared. The morphologies of carbon black /epoxy composites were characterized by scanning electron microscope  and atomic force microscope, respectively. The carbon black  particles exhibit obvious polyaromatic were characterized by X-ray diffraction. The electromagnetic parameters of carbon black  were measured in the frequency range of 8–12 GHz by transmission/reflection technology, and the electromagnetic loss mechanisms of the two particles were discussed, respectively. The microwave absorption properties of the coatings were investigated by measuring reflection loss  using arch method. The effects of carbon black  mass ratio, thickness and double-layer on the microwave absorption properties were discussed, respectively. The results showed that the higher thickness, higher ratio and double-layer of carbon black /epoxy content could make the absorption band shift towards the lower frequency range. Significantly, the wave-absorbing coating could be applied in different frequency ranges according to actual demand by controlling the content of carbon black  in composites.

  13. Microwave power for smart material actuators

    Science.gov (United States)

    Choi, Sang H.; Song, Kyo D.; Golembiewskii, Walter; Chu, Sang-Hyon; King, Glen C.

    2004-02-01

    The concept of microwave-driven smart material actuators was envisioned and developed as the best option to alleviate the complexity and weight associated with a hard-wire-networked power and control system for smart actuator arrays. The patch rectenna array was initially designed for high current output, but has undergone further development for high voltage output devices used in shape control applications. Test results show that more than 200 V of output were obtained from a 6 × 6 array at a far-field exposure (1.8 m away) with an X-band input power of 18 W. The 6 × 6 array patch rectenna was designed to theoretically generate voltages up to 540 V, but practically it has generated voltages in the range between 200 and 300 V. Testing was also performed with a thin layer composite unimorph ferroelectric driver and sensor and electro-active paper as smart actuators attached to the 6 × 6 array. Flexible dipole rectenna arrays built on thin-film-based flexible membranes are most applicable for NASA's various missions, such as microwave-driven shape controls for aircraft morphing and large, ultra-lightweight space structures. An array of dipole rectennas was designed for high voltage output by densely populating Schottky barrier diodes to drive piezoelectric or electrostrictive actuators. The dipole rectenna array will eventually be integrated with a power allocation and distribution logic circuit and microbatteries for storage of excessive power. The roadmap for the development of wireless power drivers based on the rectenna array for shape control requires the development of new membrane materials with proper dielectric constants that are suitable for dipole rectenna arrays.

  14. High power microwave hazard facing smart ammunitions

    Science.gov (United States)

    Bohl, J.

    1995-03-01

    The battle field of the present and even more the one in future will be characterized by the use of weapon systems with a high degree of electronics, computers, and sensors, designed and built to keep not only the man out of the loop. But the higher the technology used for smart weapon systems, the more these systems are endangered by numerous sources of hazard. One of those sources is the threat caused by induced or natural electromagnetic fields. These threat factors can be generated by natural, civil and military environment. In principle there are two main applications which must be considered in military applications: Firstly, weapon systems, that is, high power microwave sources as well as intelligent electromagnetic radiation systems to defeat ammunition on the battle field and secondly, the hardening of the own smart ammunition systems and missiles against the interference sources created by the different types of electromagnetic fields. This report will discuss the possible electromagnetic coupling effects on smart ammunition and missiles and their typical interference caused on the electronics and sensor level. Real time 6-DOF simulations show the flight mission which may be compromised depending on the coupled electromagnetic fields. The German MOD has established a research program where smart ammunitions with different seeker systems are investigated in respect of the coupling effects on smart ammunition caused by high power microwaves. This program considers all available resources and know how in Germany. The systems are investigated by analytical, numerical, and experimental methods with passive and activated missiles.

  15. Destruction and Dechlorination of Aroclor1254 in Real Waste Transformer Oil Using Microwave Irradiation, Microwave Absorbent and Reactive Materials

    Directory of Open Access Journals (Sweden)

    Bahram Kamarehie

    2014-09-01

    Full Text Available Background: In this research, the decomposition of Aroclor 1254, including 20 kinds of poly chlorinated biphenyls (PCBs, in real waste transformer oil in the presence of PEG1000, NaOH, zero valent iron and H2O by microwave (MW irradiation was studied. Methods: Central composites design (CCD method was carried out for experimental design. The effects of microwave power levels (200- 1000 W, reaction time (30-600 s, polyethylene glycol (PEG (1.5-7.5 g, zero valent iron powder (0.3-1.5 g, NaOH (0.3-1.5 g and H2O (0.4-2 ml were surveyed on the decomposition efficiency of PCBs. Results: The results specified that polyethylene glycol and NaOH, as reactants, greatly influenced the decomposition of PCBs. Nevertheless, zero valent iron had no effect, and H2O decreased the decomposition efficiency of PCBs. Furthermore, experimental results showed that at the optimum amounts of variables (PEG = 5.34g, NaOH= 1.17g, Fe= 0.6g, H2O= 0.8 ml, microwave power 800 w, 93% of PCBs were decomposed over the reaction duration of 6 min. Therefore, PCBs degradation efficiency without water rose up to 99.99% under the MW at 6 min. Conclusion: The results indicated that MW, PEG and NaOH were important variables on PCBs degradation from real waste transformer oil. It is therefore suggested that microwave radiation with the assistance of PEG and alkali can be introduced as a potential technology for PCBs removal from real waste PCB-contaminated oil.

  16. Enhancing the Performance of the Microwave Absorbing Materials by Using Dielectric Resonator Arrays

    Directory of Open Access Journals (Sweden)

    Omar H. Al-Zoubi

    2017-01-01

    Full Text Available We present a technique for enhancing the performance of microwave absorbing materials in terms of weight, thickness, and bandwidth. The introduced technique is based on fabricating the microwave absorbing (MA material in a structure comprised of an array of circular cylinder dielectric resonators (CDR backed by a perfect electric conductor (PEC ground plane. Numerical electromagnetic methods are employed to study the properties of the proposed MA array structures, where 3D full wave simulation using finite-element method is implemented. The obtained results show that the performance of the MA-CDR arrays significantly outperforms that of a flat layer composed of the same material and having equivalent thickness. A flat layer of MA material with thickness of 5 mm backed by perfect electric conductor (PEC shows as low as -50 dB reflection loss (RL peak and ~3 GHz 10-dB bandwidth, whereas an MA-CDR array, composed of the same MA material, of height of 4 mm can achieve as low as ~−50 dB RL peak and ~12 GHz 10-dB RL bandwidth.

  17. Preparation and Performance of Resin-based Fe Nanoparticles/Carbon Fibers Microwave Absorbing Composite Plates

    Directory of Open Access Journals (Sweden)

    ZHOU Yuan-liang

    2018-03-01

    Full Text Available A series of Fe NPs/CFs/ER nanocomposite plates were prepared by using Fe nanoparticles as microwave absorbent, the surface modification of as-prepared Fe nanoparticles was carried out by using silane coupling agents (KH-550, carbon fibers were used to enhance the reflection of electromagnetic waves inside and mechanical properties. The results show that microwave absorption of nanocomposite plates increases with increasing of mass percentage of Fe nanoparticles and carbon fibers,their gradient concentration results in resonance phenomena in specific frequency region.The microwave absorption property is anisotropic, the properties of at the vertical direction of carbon fibers towards incident wave are better than the parallel case, the minimum reflectivity peak value of the nanocomposites with 30%(mass fraction, the same as below of Fe NPs and 5.52% of CFs reaches -26.8dB at 4.9GHz with the matching thickness of 4.56mm.CFs can maintain the bending properties of nanocomposites effectively, the bending strength of the nanocomposite with 30% Fe NPs is just lower than that with 0% Fe NPs by 5.81%.

  18. Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications

    Science.gov (United States)

    Ansari, Azizurrahaman; Jaleel Akhtar, Mohammad

    2017-01-01

    The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4-12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of  -32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

  19. High-Power Microwave Transmission and Mode Conversion Program

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, Ronald J. [Univ. of Wisconsin, Madison, WI (United States)

    2015-08-14

    This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design for high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.

  20. One-dimensional carbon nanotube@barium titanate@polyaniline multiheterostructures for microwave absorbing application.

    Science.gov (United States)

    Ni, Qing-Qing; Zhu, Yao-Feng; Yu, Lu-Jun; Fu, Ya-Qin

    2015-01-01

    Multiple-phase nanocomposites filled with carbon nanotubes (CNTs) have been developed for their significant potential in microwave attenuation. The introduction of other phases onto the CNTs to achieve CNT-based heterostructures has been proposed to obtain absorbing materials with enhanced microwave absorption properties and broadband frequency due to their different loss mechanisms. The existence of polyaniline (PANI) as a coating with controllable electrical conductivity can lead to well-matched impedance. In this work, a one-dimensional CNT@BaTiO3@PANI heterostructure composite was fabricated. The fabrication processes involved coating of an acid-modified CNT with BaTiO3 (CNT@BaTiO3) through a sol-gel technique followed by combustion and the formation of CNT@BaTiO3@PANI nanohybrids by in situ polymerization of an aniline monomer in the presence of CNT@BaTiO3, using ammonium persulfate as an oxidant and HCl as a dopant. The as-synthesized CNT@BaTiO3@PANI composites with heterostructures were confirmed by various morphological and structural characterization techniques, as well as conductivity and microwave absorption properties. The measured electromagnetic parameters showed that the CNT@BaTiO3@PANI composites exhibited excellent microwave absorption properties. The minimum reflection loss of the CNT@BaTiO3@PANI composites with 20 wt % loadings in paraffin wax reached -28.9 dB (approximately 99.87% absorption) at 10.7 GHz with a thickness of 3 mm, and a frequency bandwidth less than -20 dB was achieved from 10 to 15 GHz. This work demonstrated that the CNT@BaTiO3@PANI heterostructure composite can be potentially useful in electromagnetic stealth materials, sensors, and electronic devices.

  1. Diffraction Effects in Measurements of Characteristics of High-Power Microwave Pulses with Wide-Aperture Liquid Calorimeters

    Science.gov (United States)

    Klimov, A. I.; Tot'meninov, E. M.

    2017-10-01

    Numerical nonstationary simulation of diffraction by a quasi-plane three-layer wide-aperture absorbing loads of liquid calorimeters intended for measuring the energy of high-power microwave radiation pulses is performed using the electromagnetic code KARAT with application to the S-band. It is shown that these effects can cause significant distortion of the microwave pulse shape behind the load as well as underestimation of the measured energy by 10-20%.

  2. Variable Power, Short Microwave Pulses Generation using a CW Magnetron

    Directory of Open Access Journals (Sweden)

    CIUPA, R.

    2011-05-01

    Full Text Available Fine control of microwave power radiation in medical and scientific applications is a challenging task. Since a commercial Continuous Wave (CW magnetron is the most inexpensive microwave device available today on the market, it becomes the best candidate for a microwave power generator used in medical diathermy and hyperthermia treatments or high efficiency chemical reactions using microwave reactors as well. This article presents a new method for driving a CW magnetron with short pulses, using a modified commercial Zero Voltage Switching (ZVS inverter, software driven by a custom embedded system. The microwave power generator designed with this method can be programmed for output microwave pulses down to 1% of the magnetron's power and allows microwave low frequency pulse modulation in the range of human brain electrical activity, intended for medical applications. Microwave output power continuous control is also possible with the magnetron running in the oscillating area, using a dual frequency Pulse Width Modulation (PWM, where the low frequency PWM pulse is modulating a higher resonant frequency required by the ZVS inverter's transformer. The method presented allows a continuous control of both power and energy (duty-cycle at the inverter's output.

  3. The microwave absorbing properties of ZnO/Fe3O4/paraffin composites in low frequency band

    Science.gov (United States)

    Yin, Pengfei; Deng, Yu; Zhang, Limin; Huang, Juan; Li, Huayao; Li, Youhongyu; Qi, Yali; Tao, Yu

    2018-02-01

    ZnO/Fe3O4/paraffin composites with good microwave absorption performance in low frequency band were prepared by physical blending technology. The morphology, phase structures, frequency-dependent electromagnetic and microwave absorbing properties of the composites were investigated. The results showed that the addition content of ZnO can adjust the microwave absorbing properties i.e. the position, intensity, and absorption bandwidth of composites, and the synergetic consequence of dielectric loss and magnetic loss is the main microwave absorption mechanism of the composites. The bandwidths with RL below -10 dB over different frequency ranges were obtained in the low frequency range of 0.5 ˜ 3 GHz at a thickness of 5 mm, e.g. 0.93 GHz from 1.59 to 2.52 GHz and 0.85 GHz from 1.26 to 2.11 GHz corresponding to the mass ratios of ZnO and Fe3O4 are 1:2 and 1:4, respectively. Thus, such absorbers can be applied as effective microwave absorbers in low frequency range of 0.5 ˜ 3 GHz.

  4. The magnetic and microwave absorbing properties of the as spun Nd-Fe-Co-B nanocomposites

    Science.gov (United States)

    Jun, Li; Guozhi, Xie; Peicheng, Ji; Jie, Qu; Jiangwei, Chen; Jing, Chen

    2017-12-01

    In this paper, microstructure, magnetic and microwave absorbing properties of NdxFe85-xCo4B11 nanocomposites (x = 3, 5, 7, 9) flaky-shaped particles prepared by melt spun were investigated. The analyses of XRD spectra suggest that all samples only have the single α -Fe phase. With the increase of the Nd content, the complex permittivity-frequency and permeability-frequency were increased at first, and then decreased with higher Nd content. The resin composites of 70 wt% of these nanocomposite powders showed excellent electromagnetic wave absorption properties in GHz range. A minimum reflection loss of -23.1 dB is obtained at 9.8 GHz for composite Nd9Fe76Co4B11.

  5. Theoretical Analysis and Design of Ultrathin Broadband Optically Transparent Microwave Metamaterial Absorbers

    Directory of Open Access Journals (Sweden)

    Ruixiang Deng

    2018-01-01

    Full Text Available Optically Transparent Microwave Metamaterial Absorber (OTMMA is of significant use in both civil and military field. In this paper, equivalent circuit model is adopted as springboard to navigate the design of OTMMA. The physical model and absorption mechanisms of ideal lightweight ultrathin OTMMA are comprehensively researched. Both the theoretical value of equivalent resistance and the quantitative relation between the equivalent inductance and equivalent capacitance are derived for design. Frequency-dependent characteristics of theoretical equivalent resistance are also investigated. Based on these theoretical works, an effective and controllable design approach is proposed. To validate the approach, a wideband OTMMA is designed, fabricated, analyzed and tested. The results reveal that high absorption more than 90% can be achieved in the whole 6~18 GHz band. The fabricated OTMMA also has an optical transparency up to 78% at 600 nm and is much thinner and lighter than its counterparts.

  6. Lightning control system using high power microwave FEL

    Science.gov (United States)

    Shiho, M.; Watanabe, A.; Kawasaki, S.; Ishizuka, H.; Takayama, K.; Kishiro, J.; Shindo, T.; Fujioka, T.

    1996-02-01

    A research project for developing a thunder lightning control system using an induction linac based high power microwave free electron laser (FEL) was started at JAERI. The system will produce a weakly ionized plasma rod in the atmosphere by high power microwaves and control a lightning path, away from, e.g., nuclear power stations and rocket launchers. It has been known that about 1 MW/cm 2 power density is enough for the atmospheric breakdown in the microwave region, which means that a high power microwave FEL with GW level output power is feasible for atmospheric breakdown, and accordingly is feasible for a thunder lightning control tool by making a conductive plasma channel in the atmosphere. From the microwave attenuation consideration in the atmosphere, FELs of 35 GHz (0.13 dB/km), 90 GHz (0.35 dB/km), 140 GHz (1.7 dB/km), and of 270 GHz (4.5 dB/km) are the best candidates for the system. Compared with other proposed lightning control systems using a visible or an ultraviolet laser, the system using microwave has the advantage that microwave has a smaller attenuation with rain or snow which always exists in the real atmospheric circumstances when lightning occurs. A detailed description and feasibility study of the system will be given.

  7. Water-based metamaterial absorbers for optical transparency and broadband microwave absorption

    Science.gov (United States)

    Pang, Yongqiang; Shen, Yang; Li, Yongfeng; Wang, Jiafu; Xu, Zhuo; Qu, Shaobo

    2018-04-01

    Naturally occurring water is a promising candidate for achieving broadband absorption. In this work, by virtue of the optically transparent character of the water, the water-based metamaterial absorbers (MAs) are proposed to achieve the broadband absorption at microwave frequencies and optical transparence simultaneously. For this purpose, the transparent indium tin oxide (ITO) and polymethyl methacrylate (PMMA) are chosen as the constitutive materials. The water is encapsulated between the ITO backed plate and PMMA, serving as the microwave loss as well as optically transparent material. Numerical simulations show that the broadband absorption with the efficiency over 90% in the frequency band of 6.4-30 GHz and highly optical transparency of about 85% in the visible region can be achieved and have been well demonstrated experimentally. Additionally, the proposed water-based MA displays a wide-angle absorption performance for both TE and TM waves and is also robust to the variations of the structure parameters, which is much desired in a practical application.

  8. Enhanced antioxidation and microwave absorbing properties of SiO2-coated flaky carbonyl iron particles

    Science.gov (United States)

    Zhou, Yingying; Xie, Hui; Zhou, Wancheng; Ren, Zhaowen

    2018-01-01

    SiO2 was successfully coated on the surface of flaky carbonyl iron particles using a chemical bath deposition method in the presence of 3-aminopropyl triethoxysilane (APTES). The morphologies, composition, valence states of elements, as well as antioxidation and electromagnetic properties of the samples were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and microwave network analyzer. TG curve shows the obvious weight gain of carbonyl iron was deferred to 360 °C after SiO2-coated, which can be ascribed to the exits of SiO2 overlayer. Compared with the raw carbonyl iron, SiO2-coated sample shows good wave absorption performance due to its impedance matching. The electromagnetic properties of raw and SiO2-coated carbonyl iron particles were characterized in X band before and after heat treatment at 250 °C for 10 h. It was established that SiO2-coated carbonyl iron demonstrate good thermal stability, indicating SiO2-coating is useful in the usage of microwave absorbers operating at temperature up to 250 °C.

  9. Diamond Windows for High Powered Microwave Transmission. Final Report

    International Nuclear Information System (INIS)

    Gat, R.

    2011-01-01

    This phase II SBIR developed technology for manufacturing diamond windows for use in high energy density photon transmission e.g. microwave or laser light photons. Microwave sources used in fusion research require microwave extraction windows with high thermal conductivity, low microwave absorption, and low resistance to thermal cracking. Newly developed, man made diamond windows have all three of these properties, but these windows are prohibitively expensive. This limits the natural progress of these important technologies to higher powers and slows the development of additional applications. This project developed a lower cost process for manufacturing diamond windows using microwave plasma. Diamond windows were deposited. A grinding process was used to provide optical smoothness for 2 cm diameter diamond windows that met the parallelism specifications for fusion beam windows. The microwave transmission performance (loss tangent) of one of the windows was measured at 95GHz to be less than 10-4, meeting specifications for utilization in the ITER tokamak.

  10. Hematite from Natural Iron Stones as Microwave Absorbing Material on X-Band Frequency Ranges

    Science.gov (United States)

    Zainuri, Mochamad

    2017-05-01

    This study has been investigated the effect of hematite as microwave absorbing materials (RAM) on X-Band frequency ranges. Hematite was succesfully processed by coprecipitation method and calcined at 500 °C for 5 hour. It was synthesized from natural iron stones from Tanah Laut, South Kalimantan, Indonesia. The products were characterized by X-ray diffraxtion (XRD), conductivity measurement, Vibrating Sample Magnetometer (VSM), and Vector Network Analyzer (VNA). The result was shown that hematite has conductivity value on (2.5-3).10-7 S/cm and be included as dielectric materials. The hysterisis curve was shown that hematite was a super paramagnetic materials. The product was mixed on paint with procentage 10% of total weight and coated on steel grade AH36 with spray methods. Then, the maximum of reflection loss on x - band’s frequency range (8,2-12,4) GHz was -7 dB on frequency of 10.5 GHz. It mean that almost 50% electromagnetic energy was absorbed by hematite.

  11. A New Compact Octagonal Shape Perfect Metamaterial Absorber for Microwave Applications

    Directory of Open Access Journals (Sweden)

    Mohammad Jakir Hossain

    2017-12-01

    Full Text Available A new compact octagonal shape perfect metamaterial absorber (PMA design, numerical simulation, fabrication, and investigational verification of unit cell that is based on a simple structure are presented in this paper. The suggested structure comprised of three layers, in which interact to produce the plasmonic resonances. The finite-integration technique (FIT based Computer Simulation Technology (CST microwave electromagnetic simulator was utilized to examine the design parameters and conduct absorption analysis. The design structure exhibited peak absorption values as 99.64% and 99.95% at frequencies 8.08 GHz and 11.41 GHz, respectively. The absorption characteristics were analysed using the polarization angle of the structure, layer thickness, PMA with resistive load, and number of rings. An N5227A vector network analyser was used for the measurement. The measured results of the fabricated prototype were in good agreement with the simulation results. The suggested perfect absorber structure enables innumerable application aimed at X-band for applications like, defence, security, and stealth technology.

  12. A promising lightweight multicomponent microwave absorber based on doped barium hexaferrite/calcium titanate/multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, Seyyed Salman Seyyed [Imam Hossein University, Department of Materials Science and Engineering (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Islamic Azad University, Young Researchers and Elite Club, Science and Research Branch (Iran, Islamic Republic of); Atassi, Yomen [Higher Institute for Applied Sciences and Technology, Department of Applied Physics (Syrian Arab Republic)

    2016-07-15

    We present the design of a microwave absorber in the X band based on ternary nanocomposite of doped barium hexaferrite (Ba-M)/calcium titanate (CTO)/multiwall carbon nanotubes (MWCNTs) in epoxy matrix. The hydrothermal method has been used to synthesize Ba-M and CTO nanopowder. The phase identification has been investigated using XRD patterns. Scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, and vector network analyzer are used to analyze the morphology of the different components and the magnetic, electromagnetic, and microwave absorption properties of the final composite absorbers, respectively. As far as we know, the design of this type of multicomponent microwave absorber has not been investigated before. The results reveal that the combination of these three components with their different loss mechanisms has a synergistic effect that enhances the attenuation properties of the final composite. The absorber of only 2.5-mm thickness and 35 wt% of loading ratio exhibits a minimum reflection loss of −43 dB at 10.2 GHz with a bandwidth of 3.6 GHz, while the corresponding absorber based on pure (Ba-M) shows a minimum reflection loss of −34 dB at 9.8 GHz with a bandwidth of 0.256 GHz and a thickness of 4 mm.Graphical Abstract.

  13. Microwave power coupling in a surface wave excited plasma

    Directory of Open Access Journals (Sweden)

    Satyananda Kar

    2015-01-01

    Full Text Available In recent decades, different types of plasma sources have been used for various types of plasma processing, such as, etching and thin film deposition. The critical parameter for effective plasma processing is high plasma density. One type of high density plasma source is Microwave sheath-Voltage combination Plasma (MVP. In the present investigation, a better design of MVP source is reported, in which over-dense plasma is generated for low input microwave powers. The results indicate that the length of plasma column increases significantly with increase in input microwave power.

  14. Measurement of high-power microwave pulse under intense ...

    Indian Academy of Sciences (India)

    KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator (VIRCATOR) device. HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) ...

  15. Measurement of high-power microwave pulse under intense ...

    Indian Academy of Sciences (India)

    Abstract. KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator. (VIRCATOR) device. HPM power measurements were carried out using a transmitting– receiving system in the presence of intense high frequency (a few ...

  16. Electromagnetic property of SiO2-coated carbonyl iron/polyimide composites as heat resistant microwave absorbing materials

    Science.gov (United States)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-02-01

    Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated carbonyl iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from -25 dB to -33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.

  17. [Design of broadband power divider in microwave hyperthermia system].

    Science.gov (United States)

    Sun, Bing; Jiang, Guotai; Lu, Xiaofeng; Cao, Yi

    2010-10-01

    In clinical application of microwave hyperthermia, multi-applicators are often simultaneously required to irradiate the tumor because of its large volume or its deep location. Power divider separates the input microwave energy into equal, or unequal, energy to each applicator. In this paper, the design procedure for the three-section transmission-line transformer based one-to-two equal-split Wilkinson power divider is introduced. By impedance analysis on equivalent scheme, the design parameter of power divider is provided, and by simulation and optimization on Ansoft HFSS, a microstrip structure Wilkinson power divider operating frequency 2. 45 GHz is given. Measurement test results from network analyzer show that it has 25% bandwidth and good isolation in output with this structure. Besides, it is characterized by small size and easy processing. This power divider suits microwave hyperthermia.

  18. Preparation and microwave absorbing properties of graphene oxides/ferrite composites

    Science.gov (United States)

    Liang, Kun; Qiao, Xiao-Jing; Sun, Zhi-Gang; Guo, Xiao-Dang; Wei, Long; Qu, Yang

    2017-06-01

    The graphene oxides (GO) and the graphene-based composites have been synthesized successfully by Hummer method and Hydrothermal-calcination process, respectively. The effects of solvent (water, ethylene glycol, glycerol and glycol-glycerol), the consumption of graphite oxides (GO = 0.1, 0.5, 1.0, 2.0 wt%) on the crystallization, morphology and performance of the target samples have been investigated. The obtained samples have been characterized by FTIR, XRD, SEM and HRTEM. The precursors obtained through hydrothermal process are composed of 80 nm ferromagnetic polyhedral particles and the uniformly distributed covering GO layers. After calcination, the 200 nm ferromagnetic nanoparticles can be achieved on the surface of graphene films. The results indicate that the optimized samples can be obtained at GO = 0.1 wt% under water system. Also, the electromagnetic properties and microwave absorbing performance have been measured by VNA. The addition of GO is conducive to improve the absorbing property of ferrites by shifting the reflectivity peak into lower frequency range and sharping the maximum value. At GO = 0.1%, the maximum RL peaks can reach -17.15 dB at 3.3 GHz, with the bandwidth below -10 dB ranging from 2.8 to 3.8 GHz under 3 mm thickness. For GO = 1.0 wt%, twin peaks appear at 4.3 and 15.6 GHz of 3.5 mm thickness, and the bandwidth below -10 dB reaches 2.6 GHz (10.3-12.9 GHz) at 1.5 mm thickness.

  19. Magnetic and microwave absorbing properties of magnetite-thermoplastic natural rubber nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Ing, E-mail: kong_ing_2005@yahoo.co [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia); Hj Ahmad, Sahrim; Hj Abdullah, Mustaffa [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia); Hui, David [Department of Mechanical Engineering, University of New Orleans, New Orleans, LA 70148 (United States); Nazlim Yusoff, Ahmad [Diagnostic Imaging and Radiotherapy Programme, Faculty of Allied Health Sciences, Universiti Kebangsaan Malaysia, 50300 Jalan Raja Muda Abdul Aziz, Kuala Lumpur (Malaysia); Puryanti, Dwi [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia)

    2010-11-15

    Magnetic and microwave absorbing properties of thermoplastic natural rubber (TPNR) filled magnetite (Fe{sub 3}O{sub 4}) nanocomposites were investigated. The TPNR matrix was prepared from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) in the ratio of 70:20:10 with the LNR as the compatibilizer. TPNR-Fe{sub 3}O{sub 4} nanocomposites with 4-12 wt% Fe{sub 3}O{sub 4} as filler were prepared via a Thermo Haake internal mixer using a melt-blending method. XRD reveals the presence of cubic spinel structure of Fe{sub 3}O{sub 4} with the lattice parameter of a=8.395 A. TEM micrograph shows that the Fe{sub 3}O{sub 4} nanoparticles are almost spherical with the size ranging 20-50 nm. The values of saturation magnetization (M{sub S}), remanence (M{sub R}), initial magnetic susceptibility ({chi}{sub i}) and initial permeability ({mu}{sub i}) increase, while the coercivity (H{sub C}) decreases with increasing filler content for all compositions. For nanocomposites, the values of the real ({epsilon}{sub r}') and imaginary permittivity ({epsilon}{sub r}'') and imaginary permeability ({mu}{sub r}'') increase, while the value of real permeability ({mu}{sub r}') decreases as the filler content increases. The absorption or minimum reflection loss (R{sub L}) continuously increases and the dip shifts to a lower frequency region with the increasing of both filler content in nanocomposites and the sample thickness. The R{sub L} is -25.51 dB at 12.65 GHz and the absorbing bandwidth in which the R{sub L} is less than -10 dB is 2.7 GHz when the filler content is 12 wt% at 9 mm sample thickness.

  20. Two-step fast microwave-assisted pyrolysis of biomass for bio-oil production using microwave absorbent and HZSM-5 catalyst.

    Science.gov (United States)

    Zhang, Bo; Zhong, Zhaoping; Xie, Qinglong; Liu, Shiyu; Ruan, Roger

    2016-07-01

    A novel technology of two-step fast microwave-assisted pyrolysis (fMAP) of corn stover for bio-oil production was investigated in the presence of microwave absorbent (SiC) and HZSM-5 catalyst. Effects of fMAP temperature and catalyst-to-biomass ratio on bio-oil yield and chemical components were examined. The results showed that this technology, employing microwave, microwave absorbent and HZSM-5 catalyst, was effective and promising for biomass fast pyrolysis. The fMAP temperature of 500°C was considered the optimum condition for maximum yield and best quality of bio-oil. Besides, the bio-oil yield decreased linearly and the chemical components in bio-oil were improved sequentially with the increase of catalyst-to-biomass ratio from 1:100 to 1:20. The elemental compositions of bio-char were also determined. Additionally, compared to one-step fMAP process, two-step fMAP could promote the bio-oil quality with a smaller catalyst-to-biomass ratio. Copyright © 2016. Published by Elsevier B.V.

  1. Synthesis, Characterization, and Microwave-Absorbing Properties of Polypyrrole/MnFe2O4 Nanocomposite

    Directory of Open Access Journals (Sweden)

    Seyed Hossein Hosseini

    2012-01-01

    Full Text Available Conductive polypyrrole (PPy-manganese ferrite (MnFe2O4 nanocomposites with core-shell structure were synthesized by in situ polymerization in the presence of dodecyl benzene sulfonic acid (DBSA as the surfactant and dopant and iron chloride (FeCl3 as the oxidant. The structure and magnetic properties of manganese ferrite nanoparticles were measured by using powder X-ray diffraction (XRD and vibrating sample magnetometer (VSM, respectively. Its morphology, microstructure, and DC conductivity of the nanocomposite were characterized by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, and four-wire technique, respectively. The microwave-absorbing properties of the nanocomposite powders dispersing in resin acrylic coating with the coating thickness of 1.5 mm were investigated by using vector network analyzers in the frequency range of 8–12 GHz. A minimum reflection loss of −12 dB was observed at 11.3 GHz.

  2. Ni-Zn Ferrite-graphene Nanohybrids: Synthesis and Characterization of Magnetic and Microwave Absorbing Properties

    Directory of Open Access Journals (Sweden)

    Thim Ng Yau

    2017-01-01

    Full Text Available An in-situ deposition technique was used in the synthesis of Ni-Zn ferrite-graphene (NZFG nanohybrids. The XRD patterns revealed the presence of cubic spinel structure of Ni-Zn ferrite (NZF nanoparticles with good crystallinity and small crystallite sizes. The SEM images showed NZF nanoparticles were uniformly deposited on graphene sheets. The effect of different loading amounts of NZF nanoparticles in the nanohybrids was also investigated by tuning the mass ratio of FeCl3 and expanded graphite (EG. The magnetic measurements showed ferromagnetic behaviour with low coercivity. Improvements in saturation magnetization of the nanohybrids can be seen with increasing mass ratio of FeCl3:EG. The microwave absorption properties were determined based on the measured relative complex permittivity and permeability. For the nanohybrids, the minimum reflection loss (RL obtained is -37.57 dB at 7.54 GHz and the absorbing bandwidth in which the RL is less than -10 dB is 7.30 GHz when the NZF content was 79 wt·% at 7 mm thickness. The enhancement in the minimum RL was due to the synergistic effect between NZF nanoparticles and graphene.

  3. Comparative study of experimental and numerical behaviors of microwave absorbers based on ultrathin Al and Cu films

    Energy Technology Data Exchange (ETDEWEB)

    Costa, D.S., E-mail: daniel_eng_aero@hotmail.com [Instituto de Ciência e Tecnologia/UNIFESP, Rua Talim, 330, CEP 12.231-280, São José dos Campos, SP (Brazil); Nohara, E.L. [Universidade de Taubaté, Rua Daniel Danelli, s/n, CEP 12060-440, Taubaté, SP (Brazil); Rezende, M.C. [Instituto de Ciência e Tecnologia/UNIFESP, Rua Talim, 330, CEP 12.231-280, São José dos Campos, SP (Brazil)

    2017-06-15

    The study of radar absorbing materials increasingly thin, lightweight and flexible has gained growing importance in recent years. In military area these characteristics allow the reduction of weight and volume of platforms, and in civilian sector these materials stimulate innovative projects of electronic and microwave devices. The present work was devoted to studying ultrathin films of Al (20–80 nm) and Cu (10–100 nm) deposited on poly(ethylene terephthalate) (PET) substrate by magnetron sputtering technique. The electrical conductivity values of the films were determined by 4 probes method, the S parameters (S{sub 11} and S{sub 12}) were obtained by transmission line using a X-band waveguide and the skin depth calculated. The results show the dependence of the electrical conductivity with the thickness for both films. The experimental values of microwave attenuation were compared with calculated values based on the equivalent electric circuit theory. This comparison shows a good adjustment and confirms the use of electrical conductivity measurements to predict the microwave absorption behavior of ultrathin films. - Highlights: • This article focuses on recent progresses in ultrathin films aiming microwave absorption. • Nanometric films of Al and Cu deposited on poly(ethylene terephthalate) substrate were produced. • Electrical conductivity (4-probes) and S-parameters (S{sub 11} and S{sub 12}) of nanofilms were measured. • Calculated microwave attenuations were obtained based on the equivalent electric circuit theory. • A good fit between experimental and predictions data of microwave absorption was observed.

  4. Synthesis and electromagnetic, microwave absorbing properties of core-shell Fe3O4-poly(3, 4-ethylenedioxythiophene) microspheres.

    Science.gov (United States)

    Zhou, Wencai; Hu, Xiujie; Bai, Xiaoxia; Zhou, Shuyun; Sun, Chenghua; Yan, Jun; Chen, Ping

    2011-10-01

    Highly regulated core-shell Fe(3)O(4)-poly(3, 4-ethylenedioxythiophene) (PEDOT) microspheres were successfully synthesized by a two-step method in the presence of polyvinyl alcohol (PVA) and p-toluenesulfonic acid (p-TSA). And their morphology, microstructure, electromagnetic and microwave absorbing properties were subsequently characterized. By simply adjusting the molar ratio of 3, 4-ethylenedioxythiophene (EDOT) to Fe(3)O(4) (represented by (EDOT)/(Fe(3)O(4))), the thickness of the polymer shell can be tuned from tens to hundreds of nanometers. Moreover, it was found that the composite exhibited excellent microwave absorbing property with a minimum reflection loss (RL) of about -30 dB at 9.5 GHz with a (EDOT)/(Fe(3)O(4)) ratio of 20. © 2011 American Chemical Society

  5. The study on microstructure and microwave-absorbing properties of lithium zinc ferrites doped with magnesium and copper

    Energy Technology Data Exchange (ETDEWEB)

    Cao Xiaofei [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China); Engineering Ceramics Key Laboratory of Shandong Province, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China); Sun Kangning [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China); Engineering Ceramics Key Laboratory of Shandong Province, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China)], E-mail: xiaowenhoulvbu1@yahoo.com.cn; Sun Chang; Leng Liang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China); Engineering Ceramics Key Laboratory of Shandong Province, Shandong University (south part), Jingshi Road 73, Jinan 250061 (China)

    2009-09-15

    Lithium zinc ferrites doped with magnesium and copper were prepared by means of a combination of sol-gel method and subsequent calcination. The crystalline phase and microstructure of different doped lithium zinc ferrites were measured by X-ray powder diffraction and scanning electronic microscopy analysis. The results indicate that there are no remarkable differences in phase composition between pure lithium zinc ferrite and the as-doped lithium zinc ferrites. The effects of magnesium and copper dopants on microwave absorption in low-frequency region were investigated by the transmission/reflection coaxial line method. It was found from the present work that doping with copper improved microwave-absorbing properties, while doping with magnesium had little effect on microwave absorption of pure lithium zinc ferrite.

  6. Microwave Heating of Metal Power Clusters

    Science.gov (United States)

    Rybakov, K. I.; Semenov, V. E.; Volkovskaya, I. I.

    2018-01-01

    The results of simulating the rapid microwave heating of spherical clusters of metal particles to the melting point are reported. In the simulation, the cluster is subjected to a plane electromagnetic wave. The cluster size is comparable to the wavelength; the perturbations of the field inside the cluster are accounted for within an effective medium approximation. It is shown that the time of heating in vacuum to the melting point does not exceed 1 s when the electric field strength in the incident wave is about 2 kV/cm at a frequency of 24 GHz or 5 kV/cm at a frequency of 2.45 GHz. The obtained results demonstrate feasibility of using rapid microwave heating for the spheroidization of metal particles with an objective to produce high-quality powders for additive manufacturing technologies.

  7. Ultra high vacuum broad band high power microwave window

    Science.gov (United States)

    Nguyen-Tuong, Viet; Dylla, III, Henry Frederick

    1997-01-01

    An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost.

  8. Electromagnetic, morphological and structural characterization of microwave absorbers based on POMA/magnetic filament composites

    Science.gov (United States)

    de Souza Pinto, Simone; Machado, João Paulo Barros; Gomes, Newton A. S.; Rezende, Mirabel Cerqueira

    2018-03-01

    This study aims to combine dielectric and magnetic properties of different materials in an unique composite. For this, poly(o-methoxyaniline), POMA, was chemically synthesized in situ on magnetic metallic filaments (MF). The obtained composite was inserted into an epoxy resin matrix in the proportions of 40, 50 and 70%, in weight (wt%). The samples were characterized by scanning electron microscopy (SEM), X ray diffraction (XRD) and electromagnetic measurements. On the last case, the measurements considered the reflectivity and the complex parameters of electrical permittivity and magnetic permeability in the frequency range of 8.2-12.4 GHz (X-band). Specimens with different thicknesses were evaluated by reflectivity. XRD results show that the filaments are based on Fe-α steel and SEM analyses show the good incorporation of POMA/MF in the epoxy resin composite. The complex parameters show that the real component of permittivity shows the largest variation with the POMA/MF concentration increasing in epoxy resin and the loss tangent indicates that the magnetic losses are preponderant on dielectric ones. The reflectivity measurements show that the 5 mm-specimen with 50 wt% of POMA/MF presents the best result of attenuation (-21.5 dB, i.e. above 99% of attenuation). Already, the sample containing 70 wt% shows the worst performance (up to -9.0 dB). The increase of POMA/MF concentration in epoxy resin confers maximum attenuation values for less thick specimens. The results show that the combination of dielectric and magnetic materials in a composite contributes for the improvement of microwave absorbing performance, and extends the possibilities of RAM processing with different characteristics.

  9. Y-type hexagonal ferrites for microwave absorber and antenna applications

    Energy Technology Data Exchange (ETDEWEB)

    Stergiou, Charalampos A., E-mail: stergiou@cperi.certh.gr [Laboratory of Inorganic Materials, Centre for Research and Technology Hellas, 57001 Thermi (Greece); Litsardakis, George [Laboratory of Materials for Electrotechnics, Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2016-05-01

    This article examines the potential of the Y-type hexagonal ferrites, BaSrCo{sub 2−x}Ni{sub x}Fe{sub 12}O{sub 22}, as passive microwave absorbing materials and magneto-dielectric antenna substrates. To this effect, we investigated the electromagnetic properties of the fabricated samples up to 18 GHz, in conjunction with the composition, microstructure and static magnetic characteristics. It was found that the Ni substitution yields the increase of permeability μ* and permittivity ε* as a consequence of the weaker magnetocrystalline anisotropy and enhanced dielectric orientation polarization. By virtue of their different ε* and μ* spectra, the Co-rich hexagonal ferrites appear as appropriate for narrowband-yet tunable-reflection reduction in the 2.6–18 GHz range (>20 dB), whereas with Ni addition wideband attenuation of the transmitted waves (>20 dB) is attained in the 7–18 GHz band. In addition, the persistence of high refractive index up to 1 GHz enables the utilization of these hexagonal ferrites in UHF antenna designs with smaller dimensions. Among them, designs with Co{sub 2}-Y compound are liable to higher radiation efficiency, while Ni{sub 2}-Y favours the achievement of wider bandwidth. On this basis, the performance of the produced materials in high frequency applications is evaluated and certain improvement directions are indicated. - Highlights: • Permeability μ and permittivity ε in Co{sub 2}-Y hexaferrites increase with Ni addition. • High Co content favours narrowband tunable reflection damping (RL>20 dB at 3–18 GHz). • High Ni content induces broadband transmission loss peaks at 7–18 GHz (TL>20 dB). • Antenna downsizing is enabled, but high ε substrate compromises performance.

  10. GaN-based Power amplifiers for microwave applications

    Directory of Open Access Journals (Sweden)

    Jorge Julián Moreno-Rubio

    2016-01-01

    Full Text Available This paper presents a discussion about the design strategies of different kind of power amplifiers for RF/Microwave appli- cations, such as the tuned load power amplifier, class F, class F-1 and Doherty. Furthermore, it is shown the continuous wave characterization of the amplifiers above mentioned. A comparison between the obtained results, in terms of gain, efficiency and output power is presented.

  11. Microwave Power Beaming Infrastructure for Manned Lightcraft Operations: Part 2

    International Nuclear Information System (INIS)

    Myrabo, Leik N.

    2008-01-01

    In the past ∼7 years, microwave gyrotron technology has rapidly evolved to a critical threshold wherein ultra-energetic space launch missions based on beamed energy propulsion (BEP) now appear eminently feasible. Over the next 20 years, hundred megawatt-class microwave power-beaming stations could be prototyped on high deserts and 3- to 4 km mountain peaks before migrating into low Earth orbit, along with their passive microwave relay satellites. Described herein is a 20 GW rechargeable nuclear power satellite and microwave power-beaming infrastructure designed for manned space launch operations in the year 2025. The technological readiness of 2500 GJ superconducting magnetic energy storage 'batteries', 433-m ultralight space structures, 100 MW liquid droplet radiators, 1-6+ MW gyrotron sources, and mega-scale arrays (e.g., 3000 phase-locked units) is addressed. Microwave BEP is 'breakthrough' technology with the very real potential to radically reduce space access costs by factors of 100 to 1000 in the forseeable future

  12. Modern Microwave and Millimeter-Wave Power Electronics

    Science.gov (United States)

    Barker, Robert J.; Luhmann, Neville C.; Booske, John H.; Nusinovich, Gregory S.

    2005-04-01

    A comprehensive study of microwave vacuum electronic devices and their current and future applications While both vacuum and solid-state electronics continue to evolve and provide unique solutions, emerging commercial and military applications that call for higher power and higher frequencies to accommodate massive volumes of transmitted data are the natural domain of vacuum electronics technology. Modern Microwave and Millimeter-Wave Power Electronics provides systems designers, engineers, and researchers-especially those with primarily solid-state training-with a thoroughly up-to-date survey of the rich field of microwave vacuum electronic device (MVED) technology. This book familiarizes the R&D and academic communities with the capabilities and limitations of MVED and highlights the exciting scientific breakthroughs of the past decade that are dramatically increasing the compactness, efficiency, cost-effectiveness, and reliability of this entire class of devices. This comprehensive text explores a wide range of topics: * Traveling-wave tubes, which form the backbone of satellite and airborne communications, as well as of military electronic countermeasures systems * Microfabricated MVEDs and advanced electron beam sources * Klystrons, gyro-amplifiers, and crossed-field devices * "Virtual prototyping" of MVEDs via advanced 3-D computational models * High-Power Microwave (HPM) sources * Next-generation microwave structures and circuits * How to achieve linear amplification * Advanced materials technologies for MVEDs * A Web site appendix providing a step-by-step walk-through of a typical MVED design process Concluding with an in-depth examination of emerging applications and future possibilities for MVEDs, Modern Microwave and Millimeter-Wave Power Electronics ensures that systems designers and engineers understand and utilize the significant potential of this mature, yet continually developing technology. SPECIAL NOTE: All of the editors' royalties realized from

  13. FeCo-Anchored Reduced Graphene Oxide Framework-Based Soft Composites Containing Carbon Nanotubes as Highly Efficient Microwave Absorbers with Excellent Heat Dissipation Ability.

    Science.gov (United States)

    Arief, Injamamul; Biswas, Sourav; Bose, Suryasarathi

    2017-06-07

    Conducting polymer composites containing ferromagnetic grafted-graphene derivatives are already appreciated for their lightweight, flexibility, and cost effectiveness in terms of microwave absorption. To further leverage the said properties of this wonder material, we propose a highly efficient replacement by blending conducting multiwall carbon nanotube (MWCNT) and FeCo anchored covalent cross-linked reduced graphene oxide (rGO) with poly(vinylidene fluoride) (PVDF). Interconnected conducting network of MWCNTs introduces higher electrical conductivity in the blend which is essential for microwave absorption. FeCo-anchored porous interconnected rGO framework was designed via solvent-mediated in situ coreduction in the presence of Fe(II) and Co(II) precursors. Resulting cross-linked-rGO/FeCo displays fascinating coexistence of ferromagnetism and conducting-dielectric behavior, while largely preserving the robust 3D porous interconnected structure. Coupled with conducting MWCNTs, diamine cross-linked rGO/FeCo in a soft polymer matrix yields remarkably high total shielding effectiveness (SE T ) of -41.2 dB at 12 GHz, for a meager 10 wt % filler content. In addition, the composite materials display efficient heat dissipation abilities in conjunction with the trend in their thermal conductivities. This new-age microwave-absorbing material, powered by multifunctionality and tunable magnetodielectric properties, henceforth offers an amendable, cost-effective replacement to the existing solutions.

  14. Simulation of D and E region high-power microwave heating with HF ionospheric modification experiments

    International Nuclear Information System (INIS)

    Meltz, G.; Rush, C.M.; Violette, E.J.

    1981-01-01

    The microwave power beam from a Solar Power Satellite (SPS) is sufficiently intense to cause large changes in the properties of the lower ionosphere by ohmic heating of the plasma. Power is absorbed from the beam at a rate that is proportional to the ratio of the flux s and the square of an effective frequency f/sub e/. Throughout most of the lower ionosphere f/sub e/ = f -+ f/sub L/, where f is the wave frequency and f/sub L is a reduced electron gyrofrequency. It follows that SPS equivalent heating can be simulated at much lower power fluxes with HF radio waves. A detailed examination of the frequency scaling, based on fluid and kinetic theory estimates of the change in electron temperature and density, shows that the high-power HF facility at Platteville, CO, can simulate or exceed the ohmic effects of the SPS beam up to 90 km. This paper describes the results of a series of 5.2 and 9.9 MHz underdense heating experiments undertaken to study the effect of high-power microwaves on the lower ionosphere. A pulsed ionosonde probe, located nearly below the most intense portion of the high-power beam, was used to observe the changes in the D and lower E region. Both phase and amplitude measurements were recorded during CW and intermittent heating

  15. Pyrolysis of tyre powder using microwave thermogravimetric analysis: Effect of microwave power.

    Science.gov (United States)

    Song, Zhanlong; Yang, Yaqing; Zhou, Long; Zhao, Xiqiang; Wang, Wenlong; Mao, Yanpeng; Ma, Chunyuan

    2017-02-01

    The pyrolytic characteristics of tyre powder treated under different microwave powers (300, 500, and 700 W) were studied via microwave thermogravimetric analysis. The product yields at different power levels were studied, along with comparative analysis of microwave pyrolysis and conventional pyrolysis. The feedstock underwent preheating, intense pyrolysis, and final pyrolysis in sequence. The main and secondary weight loss peaks observed during the intense pyrolysis stage were attributed to the decomposition of natural rubbers and synthetic rubbers, respectively. The total mass loss rates, bulk temperatures, and maximum temperatures were distinctively higher at higher powers. However, the maximum mass loss rate (0.005 s -1 ), the highest yields of liquid product (53%), and the minimum yields of residual solid samples (43.83%) were obtained at 500 W. Compared with conventional pyrolysis, microwave pyrolysis exhibited significantly different behaviour with faster reaction rates, which can decrease the decomposition temperatures of both natural and synthetic rubber by approximately 110 °C-140 °C.

  16. Measurement of high-power microwave pulse under intense ...

    Indian Academy of Sciences (India)

    Tesla transformer acts as a source of intense electromagnetic noise during the operation of the KALI-1000 pulse power system. After the copper mesh anode flange, there is an axial virtual cathode oscillator chamber (length 25 cm, diameter 25 cm) for microwave generation. The IREB is injected to the VIRCATOR chamber ...

  17. Microwave absorption properties of a wave-absorbing coating employing carbonyl-iron powder and carbon black

    International Nuclear Information System (INIS)

    Liu Lidong; Duan Yuping; Ma Lixin; Liu Shunhua; Yu Zhen

    2010-01-01

    To prevent serious electromagnetic interference, a single-layer wave-absorbing coating employing complex absorbents composed of carbonyl-iron powder (CIP) and carbon black (CB) with epoxy resin as matrix was prepared. The morphologies of CIP and CB were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The electromagnetic parameters of CIP and CB were measured in the frequency range of 2-18 GHz by transmission/reflection technology, and the electromagnetic loss mechanisms of the two particles were discussed, respectively. The microwave absorption properties of the coatings were investigated by measuring reflection loss (RL) using arch method. The effects of CIP ratio, CB content and thickness on the microwave absorption properties were discussed, respectively. The results showed that the higher thickness, CIP or CB content could make the absorption band shift towards the lower frequency range. Significantly, the wave-absorbing coating could be applied in different frequency ranges according to actual demand by controlling the content of CIP or CB in composites.

  18. Microwave power transmission system wherein level of transmitted power is controlled by reflections from receiver

    Science.gov (United States)

    Robinson, W. J., Jr. (Inventor)

    1974-01-01

    A microwave, wireless, power transmission system is described in which the transmitted power level is adjusted to correspond with power required at a remote receiving station. Deviations in power load produce an antenna impedance mismatch causing variations in energy reflected by the power receiving antenna employed by the receiving station. The variations in reflected energy are sensed by a receiving antenna at the transmitting station and used to control the output power of a power transmitter.

  19. Analysis of superconducting microstrip resonator at various microwave power levels

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, G.P.; Jacob, M.V.; Jayakumar, M.; Bhatnagar, P.K. [Department of Electronic Science, University of Delhi, South Campus, Benito Juarez Road, New Delhi 110021 (India); Kataria, N.D. [National Physical Laboratory, K. S. Krishnan Road, New Delhi 110 012 (India)

    1997-05-01

    The real and imaginary parts of the surface impedance of YBCO superconductors have been studied at different microwave power levels. Using the relations for the critical current density and the grain boundary resistance, a relation for calculating the power dependence of the surface resistance has been obtained. Also, a relation to find the resonant frequency of a superconducting microstrip resonator at various input power levels has been derived. Measurements have been carried out on various microstrip resonators to study the variation of surface resistance and resonant frequency at different rf power levels. The experimental results are in good agreement with theoretical results. {copyright} {ital 1997 American Institute of Physics.}

  20. Characterization of a microwave absorbent prepared by coprecipitation reaction of iron oxide on the surface of graphite nanosheet

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yongqing, E-mail: ylqqyyq@yahoo.cn [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Qi, Shuhua [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Jianning [Personnel Department, Ningxia University, Yinchuan 710021 (China)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer NanoG was prepared by ultrasonication of EG. Black-Right-Pointing-Pointer Fe{sub 3}O{sub 4} was precipitated on the NanoG's surface. Black-Right-Pointing-Pointer The structure was characterized by SEM, XRD, EDS and FTIR. Black-Right-Pointing-Pointer Properties such as thermal stability, conductivity and microwave absorbing were measured. - Abstract: Fe{sub 3}O{sub 4} was precipitated on the surface of graphite nanosheet (NanoG) to produce a microwave absorbing material Fe{sub 3}O{sub 4}/NanoG. The structure was characterized by scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Results show that under basic conditions, FeCl{sub 3}{center_dot}6H{sub 2}O and FeSO{sub 4}{center_dot}7H{sub 2}O can be used in a coprecipitation reaction to obtain Fe{sub 3}O{sub 4} nanoparticles, which are bound to and well distributed on the NanoG surface. Thermogravimetric analysis shows that the thermal stability of Fe{sub 3}O{sub 4}/NanoG is good. According to the four-point-probe test, with the increasing mass ratios of Fe{sub 3}O{sub 4} to NanoG, the conductivities of Fe{sub 3}O{sub 4}/NanoG decrease. Measurement of electromagnetic parameters shows that Fe{sub 3}O{sub 4}/NanoG has better microwave absorbing properties than Fe{sub 3}O{sub 4} and NanoG.

  1. Microwave power - An energy transmission alternative for the year 2000

    Science.gov (United States)

    Nalos, E.; Sperber, R.

    1980-01-01

    Recent technological advances related to the feasibility of efficient RF-dc rectification make it likely that by the year 2000 the transmission of power through space will have become a practical reality. Proposals have been made to power helicopters, aircraft, balloons, and rockets remotely. Other proposals consider the transfer of power from point to point on earth via relay through space or a transmission of power from large power sources in space. Attention has also been given to possibilities regarding the transmission of power between various points in the solar system. An outline is provided of the microwave power transmission system envisaged for the solar power satellite, taking into account the transmitting antenna, the receiver on earth, aspects of beam formation and control, transmitter options, the receiving antenna design, and cost and efficiency considerations.

  2. Design of an effective energy receiving adapter for microwave wireless power transmission application

    Directory of Open Access Journals (Sweden)

    Peng Xu

    2016-10-01

    Full Text Available In this paper, we demonstrate the viability of an energy receiving adapter in a 8×8 array form with high power reception efficiency with the resonator of artificial electromagnetic absorber being used as the element. Unlike the conventional reported rectifying antenna resonators, both the size of the element and the separations between the elements are electrically small in our design. The energy collecting process is explained with an equivalent circuit model, and a RF combining network is designed to combine the captured AC power from each element to one main terminal for AC-to-DC conversion. The energy receiving adapter yields a total reception efficiency of 67% (including the wave capture efficiency of 86% and the AC-to-DC conversion efficiency of 78%, which is quite promising for microwave wireless power transmission.

  3. Prediction of microwave absorption properties of tetrapod-needle zinc oxide whisker radar absorbing material without prior knowledge

    Science.gov (United States)

    Zhao, Yu-Chen; Wang, Jie; Liu, Jiang-Fan; Song, Zhong-Guo; Xi, Xiao-Li

    2017-07-01

    The radar absorbing material (RAM) containing a tetrapod-needle zinc oxide whisker (T-ZnOw) has been proved to have good efficiency of microwave absorption. However, the available theoretical models, which are intended to predict the microwave absorbing properties of such an interesting composite, still cannot work well without some prior knowledge, like the measured effective electromagnetic parameters of the prepared T-ZnOw composite. Hence, we propose a novel predictive method here to calculate the reflectivity of T-ZnOw RAM without prior knowledge. In this method, the absorbing ability of this kind of material is divided into three main aspects: the unstructured background, the conductive network, and the nanostructured particle. Then, the attenuation properties of these three parts are represented, respectively, by three different approaches: the equivalent spherical particle and the static strong fluctuation theory, the equivalent circuit model obtained from the complex impedance spectra technology, and the combination of four different microscopic electromagnetic responses. The operational calculation scheme can be obtained by integrating these three absorption effects into the existing theoretical attenuation model. The reasonable agreement between the theoretical and experimental data of a T-ZnON/SiO2 composite in the range of 8-14 GHz shows that the proposed scheme can predict the microwave absorption properties of the T-ZnOw RAM. Furthermore, a detailed analysis of these three mechanisms indicates that, on the one hand, the background plays a dominant role in determining the real part of the effective permittivity of the T-ZnOw composite while the network and the particle are the decisive factors of its material loss; on the other hand, an zero-phase impedance, i.e., a pure resistance, with appropriate resonance characteristic might be a rational physical description of the attenuation property of the conductive network, but it is difficult to realize

  4. Microwave power divider with arbitrary distribution ratio

    International Nuclear Information System (INIS)

    Gu Pengda; Geng Zheqiao; Cui Yanyan; Syratchev, I.

    2004-01-01

    As is well known, the EM field of TE11 mode at the wall of the circular waveguide changes as sine (or cosine) function azimuthally. So when we attach two perpendicular waveguides to the wall of the circular waveguide and rotate them around the axis of the waveguide, authors can distribute the input power between the two waveguides with arbitrary distribution proportion. The authors have designed a new power divider following this idea. The 3D electromagnetic simulation software HFSS is used in the design. And a new type circular TE11 mode launcher is developed. (author)

  5. On Distortion in Digital Microwave Power Amplifiers

    Science.gov (United States)

    Al-Mozani, Dhamia; Wentzel, Andreas; Heinrich, Wolfgang

    2017-01-01

    In this paper, a first study of distortion in digital power amplifiers (PA) is presented. The work is based on a voltage mode class-S PA with a GaN MMIC for the 900 MHz frequency band. The investigation focuses on the quasi-static amplitude-to-amplitude (AM-AM) and amplitude-to-phase (AM-PM) distortions. Different digital modulation schemes are applied and studied versus output power back-off. This includes two pulse-width modulation (PWM) versions as well as band-pass delta-sigma (BPDS) modulation. The results are verified by measurement data.

  6. Thin and Broadband Two-Layer Microwave Absorber in 4-12 GHz with Developed Flaky Cobalt Material

    Science.gov (United States)

    Gill, Neeraj; Singh, Jaydeep; Puthucheri, Smitha; Singh, Dharmendra

    2018-03-01

    Microwave absorbing materials (MAMs) in the frequency range of 2.0-18.0 GHz are essential for the stealth and communication applications. Researchers came up with effective MAMs for the higher frequency regions, i.e., 8.0-18.0 GHz, while absorbers with comparable properties in the lower frequency band are still not in the limelight. Designing a MAM for the lower frequency range is a critical task. It is known that the factors governing the absorption in this frequency predominantly depend on the permeability and conductivity of the material, whereas the shape anisotropy of the particles can initiate different absorption mechanisms like multiple internal reflections, phase cancellations, surface charge polarization and enhanced conductivity that can promote the microwave absorption towards lower frequencies. But the material alone may not serve the purpose of getting broad absorption bandwidth. With the effective use of advanced electromagnetic technique like multi-layering this problem may be solved. Therefore, in this paper, a material with shape anisotropy (cobalt flakes with high shape anisotropy) has been prepared and a two-layer structure is developed which gives the absorption bandwidth in 4.17-12.05 GHz at a coating thickness of 2.66 mm.

  7. Preparation and microwave absorbing properties in the X-band of natural ferrites from iron sands by high energy milling

    Science.gov (United States)

    Mashuri, X.; Lestari, W.; Triwikantoro, X.; Darminto, X.

    2018-01-01

    Bulk natural ferrites based in iron sands were synthesized at room temperature by high energy ball milling. The reduced particle sizes of the ferrites were milled at 100 rpm at selected time intervals of 0, 2, 4, and 6 h. The as-milled products were then characterized by x-ray diffraction (XRD), a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA). The results showed that the magnetite phase contents, their mean size and the saturated magnetization of the natural ferrites were about 95 nm and 36–.50 emu g‑1 without a new phase. The microwave absorbing characteristics were investigated by measuring the absorption of electromagnetic waves in the frequency range 7–12 GHz. The maximum reflection loss (RL m) and matching frequency (f m) for the best process of milling (100 rpm, 6 h) of natural ferrites were RL m1  =  ‑7.28 dB in f m1  =  7.50 GHz (▵f  =  1.50 GHz) and RL m2  =  ‑4.31 dB in f m2  =10.28 GHz (▵f  =  2.57 GHz). These results suggest that synthesized natural ferrites can be employed as effective microwave absorbers in various devices.

  8. Solvothermal synthesis and good microwave absorbing properties for magnetic porous-Fe3O4/graphene nanocomposites

    Directory of Open Access Journals (Sweden)

    Xiaojun Zeng

    2017-05-01

    Full Text Available The magnetic porous-Fe3O4/graphene nanocomposites have been fabricated by a facile solvothermal method. The porous Fe3O4 nanospheres are embedded uniformly in the graphene oxide (GO sheets to form a 3D Fe3O4/GO nanocomposite network. The dielectric properties for the Fe3O4/GO composites can be greatly improved by the 7 wt% GO additions. Good impedance matching can be also obtained in these Fe3O4/GO composites, which is proved to dominate their excellent microwave absorbing properties including the minimum reflection loss (RL value of -43.7 dB at 6.8 GHz with a sample thickness of 5 mm and a broad absorption bandwidth of 5.92 GHz (below -10 dB. These porous-Fe3O4/GO composites also exhibit the good structural stability and low density, which shows their great potential application in high-performance electromagnetic microwave-absorbing materials.

  9. Manganese and Zinc Spinel Ferrites Blended with Multi-Walled Carbon Nanotubes as Microwave Absorbing Materials

    Directory of Open Access Journals (Sweden)

    Ahmet Teber

    2017-01-01

    Full Text Available Magnetic and dielectric materials can be blended to enhance absorption properties at microwave frequencies, although the materials may have relatively weak attenuation capabilities by themselves. The specific goal of this work is to enhance microwave absorption properties of materials with interesting dielectric behavior by blending them with magnetic materials based on transition metals. The synthesized Mn1−xZnxFe2O4 (x = 0.0 and 1.0 spinel ferrite nanoparticles (MZF NPs were blended with commercial multi-walled carbon nanotubes (MWCNTs in various proportions with a binder matrix of paraffin. This simple and efficient process did not cause a significant variation in the energy states of MWCNTs. MZF NPs were synthesized with a citric acid assisted sol–gel method. Their electromagnetic characteristics and microwave absorption properties were investigated. These properties were derived from the microwave scattering parameters measured via the transmission line technique by using a vector network analyzer (VNA in conjunction with an X band waveguide system. The return loss (RL values of the samples were obtained from the electromagnetic constitutive parameters (permittivity and permeability. The results indicate that the minimum RL value and the bandwidth change significantly with the amount of ferrite material in the blend. These results encourage further development of MWCNTs blended with ferrite nanoparticles for broadband microwave applications.

  10. Study on microwave absorbing properties of carbonyl-iron composite coating based on PVC and Al sheet

    Energy Technology Data Exchange (ETDEWEB)

    Duan Yuping, E-mail: duanyp@dlut.edu.cn [School of Material and Engineering, Dalian University of Technology, Dalian 116085 (China); Wu Guangli; Gu Shuchao [School of Material and Engineering, Dalian University of Technology, Dalian 116085 (China); Li Shuqing [School of Material and Engineering, Dalian University of Technology, Dalian 116085 (China); Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China); Ma Guojia [Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China)

    2012-05-15

    To suppress the increasingly terrible electromagnetic pollution, microwave absorption coatings based on polyvinyl chloride (PVC) sheet have been fabricated, employing polyurethane varnish (PU) as matrix and carbonyl-iron particle (CIP) as absorbent. The morphology, static magnetic and microwave absorption properties of CIP were characterized by scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA), respectively. Bruggeman's equation was introduced to calculate the electromagnetic parameters of materials in the frequency range of 2-18 GHz and the loss mechanisms were discussed. Furthermore, the microwave absorption properties of composite coatings with different component content and thickness were investigated. The results show that the electromagnetic properties of the composite heavily depended on the particle loadings. The minimum reflection peaks of the coatings shift towards the lower frequency region with the increase of CIP content or coating thickness. PVC-based coatings with a component content of 1:7 (PU:CIP mass ratio) in CIP/PU layer, exhibit a minimum reflection loss value of -29 dB at 4 GHz and a permissible reflection loss (RL {<=} -10 dB) frequency band of 2-6 GHz, which is much better than the performance of the common metal-based coatings in the lower frequency.

  11. Effect of resonant microwave power on a PIG ion source

    International Nuclear Information System (INIS)

    Brown, I.G.; Galvin, J.E.; Gavin, B.F.; MacGill, R.A.

    1984-08-01

    We have investigated the effect of applying microwave power at the electron cyclotron frequency on the characteristics of the ion beam extracted from a hot-cathode PIG ion source. No change was seen in the ion charge state distribution. A small but significant reduction in the beam noise level was seen, and it is possible that the technique may find application in situations where beam quiescence is important. 29 references, 2 figures

  12. Hydrothermal synthesis of magnetic Fe{sub 3}O{sub 4}/graphene composites with good electromagnetic microwave absorbing performances

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Lingyu; Zeng, Xiaojun; Li, Xiaopan; Yang, B., E-mail: byang@buaa.edu.cn; Yu, Ronghai, E-mail: rhyu@buaa.edu.cn

    2017-03-15

    The Fe{sub 3}O{sub 4} sub-microspheres have been embedded uniformly into the reduced graphene oxide (rGO) to form a new-type Fe{sub 3}O{sub 4}/rGO composites through a one-pot solvothermal method. The dielectric properties for these magnetic Fe{sub 3}O{sub 4}/rGO composites can be greatly tuned by their different rGO additions. A good impedance matching from the balanced dielectric and magnetic loss is achieved in the Fe{sub 3}O{sub 4}/rGO composites with 4 wt% rGO addition, which dominates their excellent microwave absorbing performances including the minimum reflection loss (RL) value of −45 dB at a frequency of 8.96 GHz with a sample thickness of 3.5 mm and an effective absorption bandwidth of 3.2 GHz (below −10 dB) superior to those of the most magnetic materials and carbon-based composites. The controlled Fe{sub 3}O{sub 4}/rGO composite structure also exhibits high chemical stability and low density, which shows great potential application in high-performance electromagnetic microwave-absorbing materials. - Highlights: • Magnetic Fe{sub 3}O{sub 4}/rGO composites are fabricated by a facile solvothermal method. • The dielectric properties for the Fe{sub 3}O{sub 4}/rGO composites can be tuned. • The Fe{sub 3}O{sub 4}/rGO composites exhibits high chemical stability and low density. • Excellent microwave absorption performances for the composites are obtained.

  13. Microwave Power Measurements on the Recirculating Planar Magnetron

    Science.gov (United States)

    Jordan, N. M.; Franzi, M.; Greening, G. B.; Gilgenbach, R. M.; Simon, D. H.; Lau, Y. Y.; Hoff, B. W.; Luginsland, J. W.

    2014-10-01

    The recirculating planar magnetron (RPM) is a high power microwave generator that recirculates the beam in two-coupled, planar magnetrons. Experiments on the first L-band prototype have successfully produced 50--200 μs, 30-130 MW microwave pulses with instantaneous electronic efficiencies of up to 30% at approximately 1 GHz. The device is driven using MELBA-C, with parameters of: -300 kV for 0.3-1.0 μs, and 0.15-0.3 T axial magnetic fields. Recent RPM experiments have explored the effect of cathode surface treatment on the extracted microwave power, efficiency, and pulse width. This work utilized a proof of principle extraction system with antennas on the center vane of each oscillator to couple RF power into two, coaxial transmission lines. An advanced design, the Coaxial All Cavity Extractor, is in fabrication and will be discussed. Research supported by AFOSR Grant #FA9550-10-1-0104 and by AFRL.

  14. Microwave absorbing property of silicone rubber composites with added carbonyl iron particles and graphite platelet

    International Nuclear Information System (INIS)

    Xu, Yonggang; Zhang, Deyuan; Cai, Jun; Yuan, Liming; Zhang, Wenqiang

    2013-01-01

    Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1–18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum −11.85 dB at 1.5 mm and −15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band. - Highlights: ► The added GP increased the permittivity and permeability of composites filled with CIPs. ► The enhancement was owing to interactions of the two absorbents and the fabrication process. ► The coating process decreased the effective eccentricity of the particles, and increased the conductivity of the composites. ► The composites to which CIPs/GP were added in coating process had excellent absorbing properties in the L-band.

  15. Magnetic and microwave-absorbing properties of SrAl4Fe8O19 ...

    Indian Academy of Sciences (India)

    Key Laboratory of Auxiliary Chemistry & Technology for Chemical Industry, Ministry of Education,. Shaanxi University of ... technique also significantly affected the magnetic properties and microwave-absorptivity. Conversely, calcining tem- ... The grain size was found to be a key factor affecting the property of the powder.

  16. A theoretical and practical clarification on the calculation of reflection loss for microwave absorbing materials

    Science.gov (United States)

    Liu, Ying; Zhao, Kun; Drew, Michael G. B.; Liu, Yue

    2018-01-01

    Reflection loss is usually calculated and reported as a function of the thickness of microwave absorption material. However, misleading results are often obtained since the principles imbedded in the popular methods contradict the fundamental facts that electromagnetic waves cannot be reflected in a uniform material except when there is an interface and that there are important differences between the concepts of characteristic impedance and input impedance. In this paper, these inconsistencies have been analyzed theoretically and corrections provided. The problems with the calculations indicate a gap between the background knowledge of material scientists and microwave engineers and for that reason a concise review of transmission line theory is provided along with the mathematical background needed for a deeper understanding of the theory of reflection loss. The expressions of gradient, divergence, Laplacian, and curl operators in a general orthogonal coordinate system have been presented including the concept of reciprocal vectors. Gauss's and Stokes's theorems have been related to Green's theorem in a novel way.

  17. T-junction waveguide-based combining high power microwave beams

    International Nuclear Information System (INIS)

    Zhang Qiang; Yuan Chengwei; Liu Lie

    2011-01-01

    Waveguide-based combining microwave beams is an attractive technique for enhancing the output capacities of narrow-band high power microwave devices. A specific T-junction combiner is designed for combining the X/X band microwave beams, and the detailed combining method and experimental results are presented. In the experiments, two microwave sources which can generate gigawatt level microwaves are driven by a single accelerator simultaneously, and their operation frequencies are 9.41 and 9.60 GHz, respectively. The two microwave beams with durations of about 35 ns have been successfully combined, and no breakdown phenomenon occurs.

  18. Formation of duct in plasma by high power microwave and self-focusing

    International Nuclear Information System (INIS)

    Ito, H.; Nishida, Y.; Yugami, N.

    1995-01-01

    The first experimental demonstration of ducting of high power microwave in a preformed density channel is studied. The microwave remains trapped and guided in a preformed density channel. These results are in good agreement with a numerical model describing the microwave propagation. (author)

  19. Improvement of the performance of microwave X band absorbers based on pure and doped Ba-hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Afghahi, Seyyed Salman [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Salehi, Mohsen [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic)

    2017-01-01

    Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite prepared via mechanical activation. X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer are used to analyze phases, structures, electromagnetic and microwave absorption properties. The mole ratio of Fe/Ba=10 is detected to be optimum for doping and synthesizing the Ba-hexaferrite. In order to achieve high absorption in X band the ions of Zr{sup 4+}–Sn{sup 4+}–Ti{sup 4+}–M{sup 2+} (M=Mg{sup 2+}, Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}) are used as dopants. The results indicate the formation of single phase Ba-hexaferrite in either pure or doped compounds without any non-magnetic intermediate phases and with spherical and hexagonal morphologies respectively for the pure and doped ferrite. It is found out that BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} compound has the maximum saturation magnetization (49.80 emu/g). Also the composite of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} 50 wt% in epoxy resin exhibits a minimum reflection loss of −29 dB at 12.2 GHz with 2.6 GHz bandwidth. - Highlights: • Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite. • Formation of a single phase M-hexaferrite, pure or doped when Fe/Ba=10. • Preparation of microwave absorber of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19}/epoxy resin, 50 wt%. • The absorber exhibits a minimum RL of −29 dB at 12.2 GHz with 2.6 GHz bandwidth.

  20. Dependence of microwave absorption properties on ferrite volume fraction in MnZn ferrite/rubber radar absorbing materials

    Energy Technology Data Exchange (ETDEWEB)

    Gama, Adriana M., E-mail: adrianaamg@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Rezende, Mirabel C., E-mail: mirabelmcr@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Dantas, Christine C., E-mail: christineccd@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil)

    2011-11-15

    We report the analysis of measurements of the complex magnetic permeability ({mu}{sub r}) and dielectric permittivity ({epsilon}{sub r}) spectra of a rubber radar absorbing material (RAM) with various MnZn ferrite volume fractions. The transmission/reflection measurements were carried out in a vector network analyzer. Optimum conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the impedance matching equation. Both the MnZn ferrite content and the RAM thickness effects on the microwave absorption properties, in the frequency range of 2-18 GHz, were evaluated. The results show that the complex permeability and permittivity spectra of the RAM increase directly with the ferrite volume fraction. Reflection loss calculations by the impedance matching degree (reflection coefficient) show the dependence of this parameter on both thickness and composition of RAM. - Highlights: > Permeability and permittivity spectra of a MnZn ferrite RAM (2-18 GHz) are given. > Higher MnZn volume fraction favors increase of RAM/'s permeability and permittivity. > Minimum RL as a function of frequency, thickness and MnZn volume fraction given. > Higher thicknesses imply better absorption; optimum band shifts to lower frequencies. > For higher volume fractions, smaller thickness might offer better absorption (>10 GHz).

  1. Progress in Low-Power Digital Microwave Radiometer Technologies

    Science.gov (United States)

    Piepmeier, Jeffrey R.; Kim, Edward J.

    2004-01-01

    Three component technologies were combined into a digital correlation microwave radiometer. The radiometer comprises a dual-channel X-band superheterodyne receiver, low-power high-speed cross-correlator (HSCC), three-level ADCs, and a correlated noise source (CNS). The HSCC dissipates 10 mW and operates at 500 MHz clock speed. The ADCs are implemented using ECL components and dissipate more power than desired. Thus, a low-power ADC development is underway. The new ADCs arc predicted to dissipated less than 200 mW and operate at 1 GSps with 1.5 GHz of input bandwidth. The CNS provides different input correlation values for calibration of the radiometer. The correlation channel had a null offset of 0.0008. Test results indicate that the correlation channel can be calibrated with 0.09% error in gain.

  2. Initial assessment: electromagnetic compatibility aspects of proposed SPS Microwave Power Transmission System (MPTS) operations

    Energy Technology Data Exchange (ETDEWEB)

    1978-02-01

    An analysis of major concerns with regard to the effects on radio and electronic systems by the proposed Microwave Power Transmission System for transmitting power from a satellite solar power station to earth is presented. (LCL)

  3. Complex permittivity, permeability and microwave absorbing properties of Co–Ti substituted strontium hexaferrite

    Directory of Open Access Journals (Sweden)

    Bindra Narang Sukhleen

    2016-03-01

    Full Text Available M-type strontium ferrite with compositions SrFe(12-2xCoxTixO19 (x = 0.0, 0.3, 0.5, 0.7, 1.0, were prepared by two route ceramic method. The effects of Co–Ti substitution on their microstructure, electromagnetic properties, and microwave absorptive behavior were analyzed. The complex permittivity (∊′-j∊″ and complex permeability (μ′-jμ″ have been measured from 8.2 to 12.4 GHz using a network analyzer. Scanning electron microscope was used to analyze the grain size distribution and porosity of the ferrite. X-ray diffraction confirmed the M-type structure of the doped strontium ferrite. Vibrating sample magnetometer was used to study hysteresis loop of the ferrite. This study suggests that the control of grain size, decrease in coercivity and enhanced values of dielectric constant and loss are effective means to improve microwave absorption. The dielectric constant and loss were enhanced in comparison to the permeability constant and loss over the entire frequency range.

  4. Nano-crystalline Magnesium Substituted Cadmium Ferrites as X-band Microwave Absorbers

    Science.gov (United States)

    Bhongale, S. R.; Ingawale, H. R.; Shinde, T. J.; Pubby, Kunal; Bindra Narang, Sukhleen; Vasambekar, P. N.

    2017-11-01

    The magnetic and electromagnetic properties of nanocrystalline spinel ferrites with chemical formula MgxCd1-xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) prepared by oxalate co-precipitation method under microwave sintering technique were studied. The magnetic and dielectric parameters of ferrites were determined by using vibrating sample magnetometer (VSM) and vector network analyzer (VNA) respectively. Magnetic parameters such as saturation magnetizations (Ms), coercive force (Hc), remnant magnetization (Mr), Yafet-Kittel (Y-K) angle of ferrites were determined from hysteresis loops. The variation of real permittivity (ε‧), dielectric loss tangent (tanδe), real permeability (μ‧) and magnetic loss tangent (tanδm) with frequency and Mg2+content were studied in X-band frequency range. The values of ε‧, tanδe, μ‧ and tanδm of ferrites were observed to be in range of 4.2 - 6.12, 2.9 × 10-1 - 6 × 10-2, 0.6 - 1.12 and 4.5 × 10-1 - 2 × 10-3 respectively for the prepared compositions. The study of variation of reflection loss with frequency of all ferrites shows that ferrite with magnesium content x = 0.4 can be potential candidate for microwave applications in X-band.

  5. A theoretical and practical clarification on the calculation of reflection loss for microwave absorbing materials

    Directory of Open Access Journals (Sweden)

    Ying Liu

    2018-01-01

    Full Text Available Reflection loss is usually calculated and reported as a function of the thickness of microwave absorption material. However, misleading results are often obtained since the principles imbedded in the popular methods contradict the fundamental facts that electromagnetic waves cannot be reflected in a uniform material except when there is an interface and that there are important differences between the concepts of characteristic impedance and input impedance. In this paper, these inconsistencies have been analyzed theoretically and corrections provided. The problems with the calculations indicate a gap between the background knowledge of material scientists and microwave engineers and for that reason a concise review of transmission line theory is provided along with the mathematical background needed for a deeper understanding of the theory of reflection loss. The expressions of gradient, divergence, Laplacian, and curl operators in a general orthogonal coordinate system have been presented including the concept of reciprocal vectors. Gauss’s and Stokes’s theorems have been related to Green’s theorem in a novel way.

  6. Synthesis and absorbing mechanism of two-layer microwave absorbers containing flocs-like nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27} and carbonyl iron

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Miaojie, E-mail: qmj1933@sina.com [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China); Zhang, Cunrui, E-mail: zcr19831616@sina.com [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China); Jia, Haiye [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China)

    2012-08-15

    Flocs-like nano-barium ferrite (BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}) was synthesized by sol-gel method using the absorbent cotton as template for the first time. A possible mechanism for the formation of flocs-like nano-barium ferrite had been proposed. Two-layer microwave nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite has been prepared by as-prepared material. The structure, morphology and properties of the composites are characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), Net-work Analyzer. The complex permittivity and reflection loss (dB) of the composites have been measured at different microwave frequencies from 30 MHz to 6000 MHz employing vector network analyzer model PNA 3629D vector. The effect of the layer thickness of carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite has been proposed. The nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite can find applications in suppression of electromagnetic interference (EMI), and reduction of radar signature. -- Highlights: Black-Right-Pointing-Pointer Flocs-like BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27} was synthesized for the first time. Black-Right-Pointing-Pointer A possible formation mechanism for flocs-like ferrite had been proposed. Black-Right-Pointing-Pointer Two-layer microwave composite has been prepared. Black-Right-Pointing-Pointer A possible microwave absorbing mechanism of the composite has been proposed.

  7. Carbon nanotubes filled with ferromagnetic alloy nanowires: Lightweight and wide-band microwave absorber

    Science.gov (United States)

    Lv, Ruitao; Kang, Feiyu; Gu, Jialin; Gui, Xuchun; Wei, Jinquan; Wang, Kunlin; Wu, Dehai

    2008-12-01

    Thin-walled carbon nanotubes (CNTs) filled with different ferromagnetic alloy (FeCo, FeNi, and FeCoNi) nanowires were prepared by using trichlorobenzene as carbon precursor. They were dispersed into epoxy resin and then coated onto 180×180 mm2 aluminum substrates to form microwave-absorption coatings with 2.0 mm thickness. Reflection loss exceeding -5 dB was obtained between 5 and 18 GHz for coating containing 1.3 wt % FeCo-filled CNTs. A minimum reflection loss value of -28.2 dB was achieved at 15.2 GHz in FeCoNi-filled CNTs/epoxy coating. The areal densities of coatings are only 2.35 kg/m2, which is favorable for the applications requiring low density.

  8. GaN Monolithic Power Amplifiers for Microwave Backhaul Applications

    Directory of Open Access Journals (Sweden)

    Roberto Quaglia

    2016-06-01

    Full Text Available Gallium nitride integrated technology is very promising not only for wireless applications at mobile frequencies (below 6 GHz but also for network backhaul radiolink deployment, now under deep revision for the incoming 5G generation of mobile communications. This contribution presents three linear power amplifiers realized on 0.25 μ m Gallium Nitride on Silicon Carbide monolithic integrated circuits for microwave backhaul applications: two combined power amplifiers working in the backhaul band around 7 GHz, and a more challenging third one working in the higher 15 GHz band. Architectures and main design steps are described, highlighting the pros and cons of Gallium Nitride with respect to the reference technology which, for these applications, is represented by gallium arsenide.

  9. Microwave design and analysis of a micromachined self-heating power sensor based on matching thermocouples

    Science.gov (United States)

    Zhang, Zhiqiang; Liao, Xiaoping

    2017-08-01

    Microwave performance is a basic index of the sensors used at microwave frequencies, but also affects the sensing output. For the purpose of low-loss microwave applications, it is important for different microwave sensors to develop microwave design. This paper presents the microwave design and analysis of a micromachined self-heating microwave power sensor in the GaAs MMIC process, where the microwave power is dissipated and converted into output thermovoltages by two matching thermocouples. A dc-blocking capacitor is connected to the thermocouples in series and used to avoid the output short-circuit. In order to characterize the microwave performance, an S-parameter model of this self-heating power sensor is established. Using the model, the effects of the capacitor and the thermocouples on the reflection loss are investigated under different microwave frequencies. To demonstrate the validity of the microwave model, the microwave performance of the self-heating sensor is simulated using an electromagnetic software. In the simulation, the relationship between the substrate membrane underneath the thermocouples and the reflection loss is analyzed. Measured reflection losses of the self-heating sensor are between  -15.5 to  -15.9 dB at 8-12 GHz. The measured results show good agreement with the microwave model and simulation, and the source of small deviations is discussed. The proposed microwave design and analysis contributes to achieving low reflection loss for the sensor, with the fact that more power is used to convert into the thermovoltages.

  10. Microwave and Millimeter-Wave Signal Power Generation

    DEFF Research Database (Denmark)

    Hadziabdic, Dzenan

    concentrate on single-tone performance, this study also encompasses two-tone intermodulation distortion measurements. An 8GHz two-stage power amplifier (PA) MMIC was developed. Harmonic tuning was performed to enhance the power-added efficiency (PAE). The transistors were biased in deep class-AB where low......Among the major limitations in high-speed communications and highresolution radars is the lack of efficient and powerful signal sources with low distortion. Microwave and millimeter-wave (mm-wave) signal power is needed for signal transmission. Progress in signal generation stems largely from...... distortion and high PAE were observed. The estimated output power of 42.5 dBm and PAE of 31.3% are comparable to the state-of-the-art results reported for GaN HEMT amplifiers. Wireless communication systems planned in the near future will operate at E-band, around 71-86 GHz, and require mm-wave-PAs to boost...

  11. A Broadband Waveguide Transfer Standard for Dissemination of UK National Microwave Power Standards,

    Science.gov (United States)

    1982-01-01

    electrically isolated from the waveguide, to make it independent of the laboratory environment. The coupler feeds a fixed fraction of the microwave power...Weidman, "An international intercomparison of power standards in WR-28 waveguide". Metrologia, 17, June 1981. 4 G F Engen . "A refined X-band microwave

  12. Effect of microwave power on kinetics and characteristics of microwave vacuum-dried longan (Dimocarpus longan Lour.) pulp.

    Science.gov (United States)

    Su, Dongxiao; Zhang, Mingwei; Wei, Zhencheng; Tang, Xiaojun; Zhang, Ruifen; Liu, Lei; Deng, Yuanyuan

    2015-03-01

    The drying kinetics of longan (Dimocarpus longan Lour.) pulp processed by microwave vacuum under different microwave levels (2.67, 5.33, 8.00, and 10.67 W/g) was investigated (pressure controlled at -85 ± 2 kPa) in the present study. It was found that the drying rate of longan pulp was dependent on the microwave power, and the rehydration rate increased from 1.96 to 2.17 with the increase of microwave power from 2.67 to 10.67 W/g. Among nine selected thin layer models, the microwave vacuum drying of longan pulp was well represented by five models, which were Page, Modified Henderson and Pabis, Wang and Singh, Logarithmic, and Midilli models. Furthermore, the results of statistical analysis indicated that the Midilli model could describe the best experimental data. In addition, scanning electron microscope observation showed that the microwave vacuum-dried longan pulp had a porous structure. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. Microwave Powered Gravitationally Independent Medical Grade Water Generation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative microwave system is proposed for the continuous production of medical grade water. This system will utilize direct absorption of microwave radiation to...

  14. Space-Based Solar Power Conversion and Delivery Systems Study. Volume 3: Microwave Power Transmission Studies

    Science.gov (United States)

    1977-01-01

    The Microwave Fower Beam Ionosphere effects and critical interfaces between th Microwave Power Transmission System (MPTS) and the Satellite were studied as part of the NASA/MSFC continuing research on the feasibility of power transmission from geosynchronous orbit. Theoretical predications of ionospheric modifications produced by the direct interaction of the MPTS on the earth's upper atmosphere are used to determine their impact on the performance of the Microwave Power Beam and Pilot Beam System as well as on other RF systems effected by the ionosphere. A technology program to quantitatively define these interactions is developed. Critical interface areas between the MPTS and the satellite which could have a major impact on cost and performance of the power system are idenfified and analyzed. The areas selected include: use of either a 20 kV versus 40 kV Amplitron, thermal blockage effects of Amplitron heat radiation by the satellite structure, effect of dielectric carry-through structure on power beam, and effect of material sublimation on performance of the Amplitron in Geosynchronous Orbit.

  15. Metallic plates lens focalizing a high power microwave beam

    International Nuclear Information System (INIS)

    Rebuffi, L.

    1987-08-01

    A metallic grating composed of thin parallel plates opportunely spaced, permits to correct the phase of an incident high power microwave beam. In this work we show how it is possible to obtain a beam focalisation (lens), a beam deflection (prisma), or a variation in the polarization (polarizer) using parallel metallic plates. The main design parameters are here presented, in order to obtain the wanted phase modification keeping low the diffraction, the reflected power, the ohmic losses and avoiding breakdowns. Following the given criteria, a metallic plate lens has been realized to focalize the 200 KW, 100 msec 60 GHz beam used in the ECRH experiment on the TFR tokamak. The experimental beam concentration followed satisfactory the design requirements. In fact, the maximum intensity increased about twice the value without lens. In correspondence of this distance a reduction of the beam size of about 50% have been measured for the -3 dB radius. The lens supported high power tests without breakdowns or increase of the reflected power

  16. Power Absorption by Closely Spaced Point Absorbers in Constrained Conditions

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.

    2010-01-01

    , representing the wave climate at Westhinder on the Belgian Continental Shelf The impact of slamming, stroke and force restrictions on the power absorption is evaluated and optimal PTO parameters are determined For multiple bodies optimal control parameters (CP) are not only dependent on the incoming waves...... are applied to two array layouts consisting of 12 buoys in a staggered grid and 21 buoys in an aligned grid Compared to DO, it was found that individually optimising the CP increased the energy absorption at Westhinder with about 16-18% for the two layouts, respectively...

  17. Investigation of a metallic photonic crystal high power microwave mode converter

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2015-02-01

    Full Text Available It is demonstrated that an L band metallic photonic crystal TEM-TE11 mode converter is suitable for narrow band high power microwave application. The proposed mode converter is realized by partially filling metallic photonic crystals along azimuthal direction in a coaxial transmission line for phase-shifting. A three rows structure is designed and simulated by commercial software CST Microwave Studio. Simulation results show that its conversion efficiency is 99% at the center frequency 1.58 GHz. Over the frequency range of 1.56-1.625 GHz, the conversion efficiency exceeds 90 %, with a corresponding bandwidth of 4.1 %. This mode converter has a gigawatt level power handling capability which is suitable for narrow band high power microwave application. Using magnetically insulated transmission line oscillator(MILO as a high power microwave source, particle-in-cell simulation is carried out to test the performance of the mode converter. The expected TE11 mode microwave output is obtained and the MILO works well. Mode conversion performance of the converter is tested by far-field measurement method. And the experimental result confirms the validity of our design. Then, high power microwave experiment is carried out on a Marx-driven Blumlein water line pulsed power accelerator. Microwave frequency, radiated pattern and power are measured in the far-field region and the results agree well with simulation results. The experiment also reveals that no microwave breakdown or pulse shortening took place in the experimental setup.

  18. Influence of the aspect ratio of magnetic metallic additives on the microwave absorbing performance

    Science.gov (United States)

    de Souza Pinto, Simone; Barros Machado, João Paulo; Gomes, Newton A. S.; Cerqueira Rezende, Mirabel

    2017-09-01

    This work aims to show the behavior of radar absorbing materials (RAM) based on magnetic metallic additives with different aspect ratios. For this, two materials, carbonyl iron, constituted of spherical iron particles, and carbon-steel filaments were used. These additives were characterized considering their morphological and structural features. X-ray diffraction analysis shows that the two additives have the same crystallographic structure, but their morphologies are quite different in micrometer scale. Epoxy resin/metallic additive composites using the neat additives and their mixtures were prepared. The electromagnetic characterization of the composites evaluated the permittivity, permeability and reflectivity behaviors in the frequency range of 8.2-12.4 GHz. The results show that the samples obtained with the mixture of the two additives resulted in composites with high complex parameters of permittivity and permeability. Better RAM performance is observed for samples based on metallic filaments and for more concentrated mixtures containing the two additives (values up to  -14 dB or ~96% of attenuation). The influence of specimen-thickness on the RAM performance is also observed.

  19. Progress of compact Marx generators high power microwave source

    International Nuclear Information System (INIS)

    Liu Jinliang; Fan Xuliang; Bai Guoqiang; Cheng Xinbing

    2012-01-01

    The compact Marx generators, which can operate at a certain repetition frequency with small size, light weight, and high energy efficiency, are widely used in narrowband, wideband and ultra-wideband high power microwave (HPM) sources. This type of HPM source based on compact Marx generators is a worldwide research focus in recent years, and is important trend of development. The developments of this type of HPM source are described systemically in this paper. The output parameters and structural characteristics are reviewed, and the trends of development are discussed. This work provides reference and evidence for us to master the status of the HPM source based on compact Marx generators correctly and to explore its technical routes scientifically. (authors)

  20. Air breakdown induced by a high-power short-pulse microwave

    International Nuclear Information System (INIS)

    Wakisaka, T.; Yatsuzuka, M.; Nobuhara, S.

    1996-01-01

    At Himeji Institute of Technology, the high power microwaves with the peak power of 20 MW, frequency of 12 GHz and pulse duration of 14 ns have been produced with a virtual cathode oscillator (vircator). These high power microwaves offer new applications in various fields. One problem in laser-triggered lightning experiment is the strong attenuation of laser energy by rain, cloud and laser-produced plasma. Microwaves propagate in thundercloud with small loss, and also are able to irradiate much extensive region of targets. In this paper, the fundamental experiment on the air breakdown induced by high power, short pulse microwaves is reported. The experimental setup of the vircator diode for microwave generation is shown. The typical evolution of diode voltage, electron beam current and microwave emission from the top in the course of time is shown. The experimental setup for microwave-induced air breakdown and the experimental procedure are explained. The results of negative polarity and positive polarity are reported. In the pressure range lower than 150 Torr, microwave-induced breakdown occurred without corona discharge in both polarities. Microwave-induced breakdown occurred more easily in negative polarity than in positive polarity. (K.I.)

  1. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

    Directory of Open Access Journals (Sweden)

    Sukanta Das

    2014-01-01

    Full Text Available In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth.

  2. Thermal infrared and microwave absorbing properties of SrTiO{sub 3}/SrFe{sub 12}O{sub 19}/polyaniline nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Seyed Hossein, E-mail: shhosseini@iiau.ac.ir [Department of Chemistry, Faculty of Science, Islamshahr Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Zamani, Parisa [Department of Applied Chemistry, Faculty of Pharmaceutical Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Mousavi, S.Y. [Faculty of Passive Defense, Imam Hossein University, Tehran (Iran, Islamic Republic of)

    2015-09-25

    Graphical abstract: We have developed a new perspective of applications and properties of conducting polymers. The combination of absorption ability prepared nanocomposites in the present of PANI display a great potential in organization of shielding structures into thermal IR and microwave. Further investigations using other conducting polymers to demonstrate their capability for advance thermal IR and microwave shielding devices is under way. The application of these samples may improve the IR thermographic detection, catalysis, sensors, magnetic data storage, electromagnetic resonance wave absorption, photonic crystals, and microelectronic devices and military aspects. - Highlights: • The SrTiO{sub 3}/SrFe{sub 12}O{sub 19}/PANI exhibited electric and electromagnetic properties. • The SrTiO{sub 3}/SrFe{sub 12}O{sub 19}/PANI has shielding structures into thermal IR and microwave. • Increasing weight ratios and thicknesses will increase thermal IR ability. • Increasing weight ratios and thicknesses will increase microwave absorption ability. - Abstract: Polyaniline (PANI) as a unique polymer that also has electromagnetic absorption used as the substrate. In this research, SrTiO{sub 3} was synthesized as IR absorbent and core and then SrFe{sub 12}O{sub 19} as microwave absorbent was prepared on SrTiO{sub 3} via co-precipitation method as the first shell. As the next step, PANI was coated on SrTiO{sub 3}/SrFe{sub 12}O{sub 19} nanoparticles via in situ polymerization by multi core–shell structures (SrTiO{sub 3}/SrFe{sub 12}O{sub 19}/PANI). Nanometer size and structures of samples were measured by TEM, XRD and FTIR. Morphology of nanocomposite was showed by SEM images. The magnetic and electric properties were also performed by VSM and four probe techniques. Thermal infrared (IR) absorption and microwave reflection loss of nanocomposites were investigated at 10–40 μm and 8–12 GHz, IR and microwave frequencies, respectively. The results showed that the Sr

  3. Microwave Powered Gravitationally Independent Medical Grade Water Generation, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of an innovative microwave-based continuous flow sterilization system for the energy efficient gravitationally independent production of Medical Grade...

  4. High-power microwave generation from a frequency-stabilized virtual cathode source

    International Nuclear Information System (INIS)

    Fazio, M.V.; Hoeberling, R.F.; Kinross-Wright, J.

    1988-01-01

    The evolution of virtual cathode based high-power microwave-source technology has been directed primarily toward achieving higher peak-power levels. As peak powers in excess of 10 GW have been reported, attention has begun to focus on techniques for producing a more frequency- and phase-stable virtual cathode source. Free-running virtual cathode microwave sources characteristically exhibit bandwidths in a single pulse of tens of percent, which makes them unsuitable for many applications such as power sources for phased array antennas and microwave linear accelerators. Presented here are results of an experimental approach utilizing a high-Q, resonant cavity surrounding the oscillating virtual cathode to achieve frequency stabilization and repeatable narrow-band operation. A cylindrical cavity resonator is used with the microwave power being extracted radially through circumferential slot apertures into L-band waveguide

  5. Fe/amorphous ceramics core/shell structured nanoflakes-assembled rod-like architecture for efficient microwave absorber

    Science.gov (United States)

    Li, Xiaolong; Li, Zhenxing; Liu, Xianguo; Zhang, Shihong; Ran, Songlin

    2017-12-01

    A rod-like architecture self-assembled from Fe/amorphous ceramics core/shell structured nanoflakes has been prepared by arc discharging steelmaking slag in an Ar/H2 atmosphere, in which the amorphous ceramic shell is composed of MgO, Al2O3, MgSiO3 and CaSiO3. The electromagnetic absorbing performance of the rod-like architecture is evaluated over the range of 2–18 GHz. Multiple dielectric relaxation of the permittivity is attributed to the size distribution and novel morphology of the rod-like architecture. The experimental permeability is in good agreement with the calculated curves based on the Landau–Lifshitz–Gilbert equation. The magnetic loss ability is superior to the dielectric loss ability, due to the planar anisotropy of flake-shaped particles. At a thickness of 2.4 mm, the minimal reflection loss (RL) can reach  ‑35.04 dB at 10.96 GHz. In particular, the effective bandwidth with RL exceeding  ‑10 dB remains at least 2.56 GHz at a thickness of 1.6–4.1 mm, and exhibits a red shift phenomenon as layer thickness increases. Such efficient EM absorption performances originate from magnetic/dielectric loss ability accompanied by 1/4-wave elimination. The represented work not only provides a good reference for efficient microwave absorption, but also broadens the application of steelmaking slag.

  6. Generation of microwave-induced plasmas in automotive exhaust gas mixtures using pulsed microwave energy.

    Science.gov (United States)

    Destefani, Carlos A; Siores, Elias; Murphy, Anthony B

    2003-01-01

    Microwave energy at 2.45 GHz was applied to a mixture of exhaust gases from a petrol engine at atmospheric pressure. It was found that by pulsing the microwave energy with a 50% duty cycle, the average power required to sustain a microwave-induced plasma discharge was decreased by about 40%. The ratio of absorbed to incident power was unaffected. These findings were confirmed for pulse frequencies from 10 to 300 Hz.

  7. The influence of the combined microwave power and hot air ...

    African Journals Online (AJOL)

    User

    Microwave drying maintained the superior colour of tomato slices after drying period, compared to the other treatments. Key words: Microwave, tomato slice, drying equation, colour, drying rate, moisture content. INTRODUCTION. There is sufficient market demand for dehydrated fruits and vegetables worldwide (Zhang et al., ...

  8. Behavioral modeling of microwave power amplifiers using a look up table method

    NARCIS (Netherlands)

    Shen, Y.; Gajadharsing, J.; Tauritz, J.L.

    2007-01-01

    The possibility of building a microwave power amplifier (PA) behavioral model based on the look-up table principle is investigated. The model so constructed avoids the difficulties in model structure selection and/or its parameter estimation.

  9. Stable high-power saturable absorber based on polymer-black-phosphorus films

    Science.gov (United States)

    Mao, Dong; Li, Mingkun; Cui, Xiaoqi; Zhang, Wending; Lu, Hua; Song, Kun; Zhao, Jianlin

    2018-01-01

    Black phosphorus (BP), a rising two-dimensional material with a layer-number-dependent direct bandgap of 0.3-1.5 eV, is very interesting for optoelectronics applications from near- to mid-infrared wavebands. In the atmosphere, few-layer BP tends to be oxidized or degenerated during interacting with lasers. Here, we fabricate few-layer BP nanosheets based on a liquid exfoliation method using N-methylpyrrolidone as the dispersion liquid. By incorporating BP nanosheets with polymers (polyvinyl alcohol or high-melting-point polyimide), two flexible filmy BP saturable absorbers are fabricated to realize passive mode locking in erbium-doped fiber lasers. The polymer-BP saturable absorber, especially the polyimide-BP saturable absorber, can prevent the oxidation or water-induced etching under high-power laser illuminations, providing a promising candidate for Q-switchers, mode lockers, and light modulators.

  10. Design study for remotely piloted, high-altitude airplanes powered by microwave energy

    Science.gov (United States)

    Morris, C. E. K., Jr.

    1983-01-01

    A design study has been conducted for unmanned, microwave-powered airplanes that must fly with long endurance at high altitude. They are proposed to conduct communications-relay, observation, or various scientific missions above approximately 55,000 feet altitude. The special characteristics of the microwave-power system and high-altitude, low-speed vehicle are reviewed. Examples of both sizing and performance analysis are used to suggest design procedure guidelines.

  11. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    Science.gov (United States)

    2008-07-21

    against HEMP effects resulting from a nuclear exchange.40 The Limited Test Ban Treaty of 1963 prohibits nuclear explosions in the atmosphere, in space, and...Order Code RL32544 High Altitude Electromagnetic Pulse ( HEMP ) and High Power Microwave (HPM) Devices: Threat Assessments Updated July 21, 2008 Clay...2008 to 00-00-2008 4. TITLE AND SUBTITLE High Altitude Electromagnetic Pulse ( HEMP ) and High Power Microwave (HPM) Devices: Threat Assessments 5a

  12. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    Science.gov (United States)

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1). © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Air breakdown induced by a high-power short-pulse microwave

    International Nuclear Information System (INIS)

    Wakisaka, T.; Yatsuzuka, M.; Nobuhara, S.

    1996-01-01

    Air breakdown induced by a high-power short-pulse microwave in the pressure range from 100 to 760 Torr was studied experimentally. The high-power microwaves with the peak power of 20 MW, frequency of 12 GHz and pulse duration of 14 ns was irradiated to a pair of needle and plane electrodes biased at the potential less than the breakdown voltage. The gap separation between the needle and plane electrodes was 1.5 cm. Microwave-induced breakdowns occurred at the pressure range from 150 to 760 Torr for negative potential and from 150 to 350 Torr for positive polarity at the presence of corona discharges. At the pressure range less than 150 Torr, the microwave-induced breakdown occurred without corona discharge at both polarities. (author). 5 figs., 4 refs

  14. Measurement of total ultrasonic power using thermal expansion and change in buoyancy of an absorbing target.

    Science.gov (United States)

    Dubey, P K; Kumar, Yudhisther; Gupta, Reeta; Jain, Anshul; Gohiya, Chandrashekhar

    2014-05-01

    The Radiation Force Balance (RFB) technique is well established and most widely used for the measurement of total ultrasonic power radiated by ultrasonic transducer. The technique is used as a primary standard for calibration of ultrasonic transducers with relatively fair uncertainty in the low power (below 1 W) regime. In this technique, uncertainty comparatively increases in the range of few watts wherein the effects such as thermal heating of the target, cavitations, and acoustic streaming dominate. In addition, error in the measurement of ultrasonic power is also caused due to movement of absorber at relatively high radiated force which occurs at high power level. In this article a new technique is proposed which does not measure the balance output during transducer energized state as done in RFB. It utilizes the change in buoyancy of the absorbing target due to local thermal heating. The linear thermal expansion of the target changes the apparent mass in water due to buoyancy change. This forms the basis for the measurement of ultrasonic power particularly in watts range. The proposed method comparatively reduces uncertainty caused by various ultrasonic effects that occur at high power such as overshoot due to momentum of target at higher radiated force. The functionality of the technique has been tested and compared with the existing internationally recommended RFB technique.

  15. Absorber for wakefield interference management at the entrance of the wiggler of a free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Marchlik, Matthew; Biallas, George Herman

    2017-03-07

    A method for managing the broad band microwave and TeraHertz (THz) radiation in a free electron laser (FEL) having a wiggler producing power in the electromagnetic spectrum. The method includes placement of broadband microwave and TeraHertz (THz) radiation absorbers on the upstream end of the wiggler. The absorbers dampen the bounced back, broad band microwave and THz radiation returning from the surfaces outside the nose of the cookie-cutter and thus preventing broadening of the electron beam pulse's narrow longitudinal energy distribution. Broadening diminishes the ultimate laser power from the wiggler. The broadband microwave and THz radiation absorbers are placed on either side of the slot in the cookie-cutter that shapes the wake field wave of the electron pulse to the slot shape of the wiggler chamber aperture. The broad band microwave and THz radiation absorber is preferably a non-porous pyrolytic grade of graphite with small grain size.

  16. Preparation of thermal infrared and microwave absorber using SrTiO{sub 3}/BaFe{sub 12}O{sub 19}/polyaniline nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Seyed Hossein, E-mail: shhosseini@iiau.ac.ir [Department of Chemistry, Faculty of Science, Islamshahr Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Zamani, Parisa [Department of Applied Chemistry, Faculty of Pharmaceutical Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-01-01

    In this research, first, SrTiO{sub 3} was synthesized as thermal infrared (TIR) absorbent and core and then BaFe{sub 12}O{sub 19} as microwave absorbent was prepared on SrTiO{sub 3} via co-precipitation method as first shell. Second, polyaniline (PANI) was coated on SrTiO{sub 3}/BaFe{sub 12}O{sub 19} NPs (NPs) via in situ polymerization by multi core–shell structures (SrTiO{sub 3}/BaFe{sub 12}O{sub 19}/PANI). Nanometer size and structures of samples were measured by TEM, XRD and FTIR. Morphology of nanocomposite was showed by SEM images. The magnetic and electric properties were also performed by VSM and four probe methods. The TIR absorption and microwave reflection loss of nanocomposites were investigated at 10–40 µm and 8–12 GHz, TIR and microwave frequencies, respectively. The results showed that the SrTiO{sub 3}/BaFe{sub 12}O{sub 19}/PANI nanocomposites have good compatible electric and magnetic properties and hence the microwave absorbency show wide bandwidth properties. The infrared thermal image testing showed that the ability of infrared thermal imaging was increased by increasing SrTiO{sub 3}/BaFe{sub 12}O{sub 19} as core and independent to increasing PANI as final shell. - Graphical abstract: The light reflectivity times of samples on human body are higher than metallic disks. So, they are suitable for TIR as absorbers. The light reflectivity times of samples were increased by increasing weight ratio and thickness. Human temperature could not transmit to samples by increasing weight ratio of core. Therefore weight ratio (SrTiO{sub 3}/BaFe{sub 12}O{sub 19} as core) above 40% and 1 mm diameter are the best result as TIR absorber. The SrTiO{sub 3}/BaFe{sub 12}O{sub 19}/PANI enhanced broad band IR light absorption was observed in the wavelength range of 10–40 µm. A minimum RL of −19 dB was observed at 9.2 GHz for a 1.5-mm thickness nanocomposite. The application of these samples may improve the IR thermographic detection, catalysis, sensors

  17. Critical power for self-focusing of optical beam in absorbing media

    Science.gov (United States)

    Qi, Pengfei; Zhang, Lin; Lin, Lie; Zhang, Nan; Wang, Yan; Liu, Weiwei

    2018-04-01

    Self-focusing effects are of central importance for most nonlinear optical effects. The critical power for self-focusing is commonly investigated theoretically without considering a material’s absorption. Although this is practicable for various materials, investigating the critical power for self-focusing in media with non-negligible absorption is also necessary, because this is the situation usually met in practice. In this paper, the simple analytical expressions describing the relationships among incident power, absorption coefficient and focal position are provided by a simple physical model based on the Fermat principle. Expressions for the absorption dependent critical power are also derived; these can play important roles in experimental and applied research on self-focusing-related nonlinear optical phenomena in absorbing media. Numerical results, based on the nonlinear wave equation—and which can predict experimental results perfectly—are also presented, and agree quantitatively with the analytical results proposed in this paper.

  18. Improved high temperature solar absorbers for use in Concentrating Solar Power central receiver applications.

    Energy Technology Data Exchange (ETDEWEB)

    Stechel, Ellen Beth; Ambrosini, Andrea; Hall, Aaron Christopher; Lambert, Timothy L.; Staiger, Chad Lynn; Bencomo, Marlene

    2010-09-01

    Concentrating solar power (CSP) systems use solar absorbers to convert the heat from sunlight to electric power. Increased operating temperatures are necessary to lower the cost of solar-generated electricity by improving efficiencies and reducing thermal energy storage costs. Durable new materials are needed to cope with operating temperatures >600 C. The current coating technology (Pyromark High Temperature paint) has a solar absorptance in excess of 0.95 but a thermal emittance greater than 0.8, which results in large thermal losses at high temperatures. In addition, because solar receivers operate in air, these coatings have long term stability issues that add to the operating costs of CSP facilities. Ideal absorbers must have high solar absorptance (>0.95) and low thermal emittance (<0.05) in the IR region, be stable in air, and be low-cost and readily manufacturable. We propose to utilize solution-based synthesis techniques to prepare intrinsic absorbers for use in central receiver applications.

  19. Dehydration of sodium carbonate monohydrate with indirect microwave heating

    International Nuclear Information System (INIS)

    Seyrankaya, Abdullah; Ozalp, Baris

    2006-01-01

    In this study, dehydration of sodium carbonate monohydrate (Na 2 CO 3 .H 2 O) (SCM) in microwave (MW) field with silicon carbide (SiC) as an indirect heating medium was investigated. SCM samples containing up to 3% free moisture were placed in the microwave oven. The heating experiments showed that SCM is a poor microwave energy absorber for up to 6 min of irradiation at an 800 W of microwave power. The heat for SCM calcination is provided by SiC which absorbs microwave. The monohydrate is then converted to anhydrous sodium carbonate on the SiC plate by calcining, i.e. by removing the crystal water through heating of the monohydrate temperatures of over 120 deg. C. The calcination results in a solid phase recrystallization of the monohydrate into anhydrate. In the microwave irradiation process, dehydration of SCM in terms of indirect heating can be accelerated by increasing the microwave field power

  20. Environmental assessment for the Satellite Power System (SPS) Concept Development and Evaluation Program (CDEP). [Microwave and non-microwave health and ecological assessment

    Energy Technology Data Exchange (ETDEWEB)

    Valentino, A.R.

    1980-08-01

    In the satellite power system (SPS), satellites in geosynchronous earth orbit would collect solar energy in space, convert it to microwaves, and transmit the microwaves to receiving antennas (rectennas) on earth. At the rectennas, the microwave energy would be converted to electricity. This SPS environmental assessment considers the microwave and nonmicrowave effects on the terrestrial environment and human health, atmospheric effects, and effects on electromagnetic systems. No environmental problem has been identified that would preclude the continued study of SPS technology. To increase the certainty of the assessment, some research has been initiated and long-term research is being planned.

  1. Effect of high power microwaves on rats locomotion and cognition

    International Nuclear Information System (INIS)

    Seze, Rene de; Ammari, Mohamed; Sakly, Mohsen; Abdelmelek, Hafedh

    2008-01-01

    Full text: Introduction: High power microwaves (HPM) are suspected to produce some behavioural deficits in rats, however very few studies have been published on this topics. The aim of our experiment was to determine if exposure to HPM could affect behaviour in locomotor (open field) and memory (objects recognition) tasks. Materials and methods: Exposure Six-weeks male rats were exposed to a 13 cm-diameter electromagnetic beam at 10 GHz ; radiation was emitted through 10 seconds trains of 1 ns-pulses at 100 Hz. Power of the source was 350 MW and peak-intensity of the field was 50 GW/m 2 (6100 kV/m) at 5 cm from the conical emitting horn. A single exposure was applied every 5 minutes for 1 h and the behavioural test was performed in the following hour. Time-averaged SAR over that period was estimated at 0.34 W/kg. Peak-power in one pulse was 95 MW/kg and in any second, 9.5 W/kg. Groups: A group of 12 individually exposed animals was compared to a group of 12 sham-exposed animals, set at the same place and in the same ambient conditions as the exposed animals, but omitting HPM emission. Behaviour: An open-field video-track was performed during the different phases. Each phase includes 3 successive trials of 5 min, with 3 minutes in between. Phase 1 studied spontaneous locomotor activity and animal anxiety by recording its position in the arena (periphery meaning anxiety). Phase 2 looked at exploratory behaviour, adding three objects in the field. Time spent close to the objects reflects curiosity. Phase 3 looked at habituation and spatial memory, changing an object from one quadrant (Nr.3) to another one (Nr.4). Phase 4 looked at memory and attention, changing one object by a new one in quadrant Nr.3. Measured parameters were, for any central or peripheral area, containing or not a previously present or a new object: time spent in a quadrant, number of crossed quadrants and run distance. Results and discussion: No significant difference was found for the different

  2. A Novel Microwave Tunable Band-Pass Filter Integrated Power Divider Based on Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Yupeng Liu

    2015-01-01

    Full Text Available This paper proposes a novel microwave continuous adjustable band-pass filter integrated power divider based on nematic liquid crystals (LCs. The proposed power divider uses liquid crystal (LC as the dielectric material. It can realize phase shift by changing the dielectric anisotropy, when biasing the high anisotropy nematic liquid crystal. It is mainly used in microwave frequencies. It has a large number of advantages compared to conventional filter integrated power divider, such as low loss, multifunction integration, continuous adjustable, miniaturization, low processing costs, low operating voltage, high phase shift, and convenient manufacture. Therefore, it has shown great potential for application.

  3. Parametric study on a collocated PZT beam vibration absorber and power harvester

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shyh Chin [Mechanical Engineering, Ming Chi University of Technology, New Taipei (China); Tsai, Chao Yang [Mechanical Engineering Army Academy, R.O.C., Taoyuan (China); Liao, Hsiao Hui [LNG Construction and Project Division, CPC Corp., Taipei (China)

    2016-11-15

    The parametric effects of a PZT beam that is simultaneously used as a vibration absorber and a power harvester were investigated in this study. A cantilever beam paved with PZT layers and with added tip mass has been widely used as a harvester or sometimes as a Dynamic vibration absorber (DVA). However, the beam is rarely considered a collocated device. In this study, the first step was theoretical derivation of a distributed beam covered with bimorph PZT layers. Then, the beam was attached to a 1DOF vibratory main system. Two indicators for vibration absorption and power harvesting were defined. Numerical results demonstrated that the lumped mass ratio favored both of the abilities, but that the DVA mass ratio influenced these two abilities in exactly the opposite way. The conjunction of a harvester circuit into a DVA shifted its resonance frequency up to 5 % (an extreme case of open circuit R→∞). Simultaneous power harvesting diminished the absorption capability up to 35 % for each set of mass ratios. To achieve the maximum degree of power harvesting, a corresponding load resistance that somewhat increases with the lumped mass ratio is applied. Experimental results verified the existence of the best load resistance, but the measured harvested curve was lower than the theoretical calculation because of structure damping and deviations of PZT material properties.

  4. High Power Microwave Diagnostic for the Fusion Energy Experiment ITER

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Leipold, Frank; Gonçalves, B.

    2016-01-01

    Microwave diagnostics will play an increasingly important role in burning plasma fusion energy experiments like ITER and beyond. The Collective Thomson Scattering (CTS) diagnostic to be installed at ITER is an example of such a diagnostic with great potential in present and future experiments. Th...

  5. Development of low-power loss Mn–Zn ferrites using microwave ...

    Indian Academy of Sciences (India)

    Unknown

    Mn–Zn ferrite has been selected as a material of choice due to its high saturation magnetization and low power loss for high frequency applications. The microwave sintering technique has been used in the preparation of Mn–. Zn ferrites. The magnetic properties and power losses are measured and the results obtained are ...

  6. Structural and magnetic properties of La{sup 3+} substituted barium−natural nanoferrites as microwave absorber in X-band

    Energy Technology Data Exchange (ETDEWEB)

    Widanarto, W., E-mail: wahyu.widanarto@unsoed.ac.id [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia); Amirudin, F. [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia); Ghoshal, S.K. [Department of Physics, AMORG, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Effendi, M.; Cahyanto, W.T. [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia)

    2017-03-15

    Selection of proper microwave absorbers in the X-band is vital to prevent the interference issues that often damage devices and cause signal degradation. In this spirit, we prepared three La{sup 3+} substituted barium-natural nanoferrites (BNFs) samples with chemical composition of BaO:(x)La{sub 2}O{sub 3}:(6-x)Fe{sub 2}O{sub 3} (x=0, 0.1, 0.2 in mol) via solid-state reaction route. Synthesized samples were characterized via SEM, XRD, VSM, and VNA measurements to determine the La{sup 3+} ions concentration dependent variation in the structural, magnetic and microwave absorption properties. Transmission/reflection line (TRL) method was used to evaluate the samples reflection loss. La{sup 3+} free samples sintered at 1100 °C revealed hexagonal BaFe{sub 12}O{sub 19} and rhombohedral Fe{sub 2}O{sub 3} phases. SEM images displayed the growth of new particle with the average size of 0.2 – 0.8 µm as filler in BNFs. Furthermore, an incorporation of La{sup 3+} into the BNF system manifested the emergence of new BaLa{sub 2}Fe{sub 2}O{sub 7} tetragonal crystal phase. The average crystallite size of BNF was found to decrease with increasing La{sup 3+} ion concentrations. Conversely, substitution of La{sup 3+} in the BNF caused insignificant changes in the magnetic properties, the real part of the relative permittivity and the natural resonance frequency. Meanwhile, a reasonable shift in the microwave frequency absorption and enhancement in the reflection loss was evidenced due to the inclusion of La{sup 3+}. BNF sample containing 0.2 mol La{sub 2}O{sub 3} exhibited a saturation magnetization and magnetic field anisotropy of 19.02 and 0.36 T, respectively, where the maximum reflection loss is discerned to be −26.61 dB at 10.87 GHz with 1.25 GHz bandwidth. This new class of ferrites may be prospective for microwave absorber in the X-band. - Highlights: • La{sup 3+} ions substitution into barium–natural nanoferrite via the solid-state reaction. • Influence of La{sup 3

  7. A facile one-pot strategy for fabrication of carbon-based microwave absorbers: effects on annealing and paraffin content.

    Science.gov (United States)

    Zhang, Yanan; Quan, Bin; Liu, Wei; Liang, Xiaohui; Ji, Guangbin; Du, Youwei

    2017-07-18

    In this work, a one-pot strategy was proposed to synthesize carbon-coated Fe 3 O 4 and carbon-coated Fe 3 C via the pyrolysis of colloidal Fe 3 O 4 nanocrystals capped with oleic acid (OA) at different calcination temperatures. After exploring the microwave absorption performance of these composites, we found that carbon-coated Fe 3 C obtained at 700 °C possesses higher reflection loss (RL) and broader effective bandwidth (RL ≤ -10 dB) at low thickness. So the further investigation of the microwave absorption performance for carbon-capped Fe 3 C composites mixed with different mass percentages of paraffin was also carried out. The results demonstrated that the multi-dielectric relaxation process and better impedance matching, especially at low thickness and high frequency, contributed to the preferable microwave absorption greatly.

  8. Stability analysis of the Gyroscopic Power Take-Off wave energy point absorber

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Zhang, Zili; Kramer, Morten Mejlhede

    2015-01-01

    The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber consists of a float rigidly connected to a lever. The operational principle is somewhat similar to that of the so-called gyroscopic hand wrist exercisers, where the rotation of the float is brought forward by the rotational particle...... motion of the waves. At first, the equations of motion of the system are derived based on analytical rigid body dynamics. Next, assuming monochromatic waves simplified equations are derived, valid under synchronisation of the ring of the gyro to the angular frequency of the excitation. Especially...

  9. Particle size effect on microwave absorbing of La0.67Ba0.33Mn0.94Ti0.06O3 powders prepared by mechanical alloying with the assistance of ultrasonic irradiation

    International Nuclear Information System (INIS)

    Saptari, Sitti Ahmiatri; Manaf, Azwar; Kurniawan, Budhy

    2016-01-01

    Doped manganites have attracted substantial interest due to their unique chemical and physics properties, which makes it possible to be used for microwave absorbing materials. In this paper we report synthesizes and characterization of La 0.67 Ba 0.33 Mn 0.94 Ti 0.06 O 3 powders prepared by mechanical alloying with the assistance of a high power ultrasonic treatment. After solid state reaction, the presence of single phase was confirmed by X-ray Diffraction (XRD). Refinement results showed that samples are single phase with monoclinic structure. It was found that powder materials derived from mechanical alloying results in large variation in the particle size. A significant improvement was obtained upon subjecting the mechanically milled powder materials to an ultrasonication treatment for a relatively short period of time. As determined by particle size analyzer (PSA), the mean particle size gradually decreased from the original size of 5.02 µm to 0.36 µm. Magnetic properties were characterized by VSM, and hysteresis loops results showed that samples are soft magnetic. It was found that when the mean particle size decreases, saturation was increases and coersitivity was decreases. Microwave absorption properties were investigated in the frequency range of 8-12 GHz using vector network analyzer. An optimal reflection loss of 24.44 dB is reached at 11.4 GHz.

  10. Komparacija sekundarnih etalona mikrotalasne snage / Comparison of microwave power secondary standards

    Directory of Open Access Journals (Sweden)

    Sanja Suruliz

    2003-07-01

    Full Text Available U ovom radu opisana je komparacija grupe sekundarnih etalona mikrotalasne snage kao način za održavanje metrološke sledljivosti u nedostatku primarnog etalona mikrotalasne snage. Obavljene su dve komparacije i to sa termopretvaračkim glavama, 2000. godine, a 2002. godine prošireno i na termistorske glave u opsegu frekvencija 18 do 26,5 GHz. / In absence of primary standards for microwave power, a group of microwave power secondary standards was compared as a method of sustaining metrological traceability. The comparison included thermoelectric and thermistor mounts in the frequency range from 18 to 26,5 GHz.

  11. S-band 300 W pulsed solid state microwave amplifier development for driving high power klystrons for electron accelerators

    International Nuclear Information System (INIS)

    Mohania, Praveen; Shrivastava, Purushottam; Hannurkar, P.R.

    2005-01-01

    S-Band Microwave electron accelerators like microtrons and linear accelerators need pulsed microwaves from few megawatts to tens of megawatts to accelerator the electrons to desired energy and intensity. Klystron tube based driver amplifiers were used to drive the high power klystrons, which need microwave power from few tens of watts to 1 kW depending on tube output power and gain. A endeavour was initiated at Centre for Advanced Technology to develop state of art solid state S-band microwave amplifiers indigenously to drive the klystron tubes. A modular design approach was used and individual modules up to 160 W power levels were developed and tested. Finally combining 160 W modules will give up to 300 W output power. Several more modules can be combined to achieve even high power levels. Present paper describes the developmental efforts of 300 W S-band solid-state amplifiers and related microwave technologies. (author)

  12. Effect of microwave power on the morphology and optical property of zinc oxide nano-structures prepared via a microwave-assisted aqueous solution method

    International Nuclear Information System (INIS)

    Al-Gaashani, R.; Radiman, S.; Tabet, N.; Daud, A. Razak

    2011-01-01

    The effect of the microwave power on the morphology and optical properties of zinc oxide nanostructures prepared using a microwave-assisted aqueous solution method has been investigated. The ZnO nanostructures were synthesized from zinc chloride and sodium hydroxide mixed aqueous solutions exposed for 5 min to microwave radiation at four different powers, namely 150, 450, 700 and 1000 W. The morphologies of the samples have been characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the power of microwave radiation influenced the shape and size of the synthesized nanostructures. It is also found that the average particle size of nanostructures decreased with decreasing microwave power. The results of X-ray diffraction (XRD) showed that all the as-prepared ZnO nanostructures are in crystalline form with high purity. The infrared (IR) spectra indicated that the as-prepared nano ZnO product can be used as infrared gas sensors such as an infrared carbon dioxide (CO 2 ) and/or CO sensor. Optical properties of the as-prepared ZnO nanostructures were investigated by UV-vis spectroscopy and showed that the optical properties of as-synthesized ZnO samples are sensitive to the variation of the power of microwave radiation.

  13. Rare earth ions doped polyaniline/cobalt ferrite nanocomposites via a novel coordination-oxidative polymerization-hydrothermal route: Preparation and microwave-absorbing properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunming; Jiang, Junjun; Liu, Xiaohua; Yin, Chengjie; Deng, Cuifen

    2016-04-15

    Polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites were successfully synthesized by a novel coordination-oxidative polymerization-hydrothermal method, and doped by sulfosalicylic acid. The resultant nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and electromagnetic measurements. The composites mainly showed nanofibers with a diameter of ca. 70 nm and a length longer than 2 μm. The surface of composites was uniformly covered with numerous nanoparticles with an average size of ca. 10–20 nm. Microwave absorption properties of polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites doped with La ion were found to be better than those doped with Ce and Y ions. For the polyaniline/CoLa{sub x}Fe{sub 2−x}O{sub 4} nanocomposite, the optimal microwave absorption performance is at x=0.15, that is, the mass ratio of La in CoLa{sub x}Fe{sub 2−x}O{sub 4} is 7.5%, with the conductivity of the composite about 0.833 S/cm. Furthermore, when the layer thickness is 2 mm, the maximum reflection loss achieves the maximum number of −42.65 dB at 15.91 GHz with a bandwidth of 6.14 GHz above −10 dB loss, suggesting that these nanocomposites are excellent in microwave absorbing capacity. - Graphical abstract: Scheme PAn/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites prepared via a novel coordination-oxidative polymerization-hydrothermal route. - Highlights: • An organic–inorganic hybrid―polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} (RE=La, Ce, Y, x=0.05–0.25) nanocomposites was prepared via a novel coordination-oxidative polymerization-hydrothermal route. • The as-prepared polyaniline/CoRE{sub x}Fe{sub 2−x}O{sub 4} nanocomposites exhibit excellent microwave absorbing performance compared with the composites prepared by using conventional method. • The novel method reported in this work could

  14. Value of forestation in absorbing carbon dioxide surrounding a coal fired power plant

    Energy Technology Data Exchange (ETDEWEB)

    Dang, V.D.; Steinberg, M.

    1980-08-01

    The dispersion of carbon dioxide emitted from 1000 MW(e) coal fired power plant is investigated. Calculated ground level carbon dioxide concentrations as a function of distance from the power plant stack is validated by the results derived from sulfur dioxide dispersion measurements. Forestation is examined as a means for removal and control of atmospheric carbon dioxide at a distance of 5 to 10 km away from the power plant stack. An equilibrium and a dynamic approach are considered. For an average temperate zone forest growth rate (7.42 mg/dm/sup 2/ h), the overall reduction in forested land area required to remove the equivalent of all of the CO/sub 2/ from a 1000 MW(e) power plant would be less than 3.3% compared to removing the equivalent amount of CO/sub 2/ by planting forests remotely from the plant. If faster growing tropical plants or trees having up to 4 times the temperate plant growth rate were used, there would be a maximum savings of 15% in forested land area compared to a remote planting. This magnitude of reduction in cultivated forest area is insufficient to recommend planting forested areas adjacent to central power stations as a means of controlling CO/sub 2/ emission. Rather it is suggested to provide sufficient increased regional forested areas on a global scale for the purposes of absorbing the equivalent increase in CO/sub 2/ emission due to increased fossil fuel use.

  15. The effect of microwave power on the production of biodiesel from nyamplung

    Science.gov (United States)

    Qadariyah, L.; Mujaddid, F.; Raka; Dhonny, S. B.; Mahfud, M.

    2017-12-01

    Today, energy needs in Indonesia still rely on fossil energy sources that its availability in the world is increasingly depleted. Therefore, the research for alternative energy of petroleum must be developed, one of them is biodiesel. The use of microwave as energy source of biodiesel production can speed up the reaction time. So the microwave is considered more efficient. Seeds of nyamplung has an oil content of 71.4% (w/w) by weight. With the oil content of the nyamplung seeds has great potential when used as a raw material for biodiesel production. The aim of this research to study the effect of microwave power on the production of biodisel from nyamplung oil. Microwave power affects density, viscosity and yield of the product. The used of alkali catalyst, with higher the power, the lower the density and viscosity of the resulting product, but the resulting yield is 300 W. The power of more than 300 W is the opposite, resulting in the production of biodiesel using the optimum base catalyst at 300 W power.

  16. High power microwave diagnostic for the fusion energy experiment ITER

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Leipold, Frank; Goncalves, B.

    2016-01-01

    Microwave diagnostics will play an increasingly important role in burning plasma fusion energy experiments like ITER and beyond. The Collective Thomson Scattering (CTS) diagnostic to be installed at ITER is an example of such a diagnostic with great potential in present and future experiments....... The ITER CTS diagnostic will inject a 1 MW 60 GHz gyrotron beam into the ITER plasma and observe the scattering off fluctuations in the plasma — to monitor the dynamics of the fast ions generated in the fusion reactions....

  17. On the impact of low power density microwaves in some living tissues

    International Nuclear Information System (INIS)

    Creanga, M.; Tufescu, D.E.

    2006-01-01

    The biomedical and ecological interest for the microwave impact on the Earth biosphere is continuously increased since the industrial, military and communication activities strongly contribute to the electromagnetic stress of living bodies. In the next the authors present some of the main results obtained regarding the microwave exposure of various types of biological material: bacteria, fungi, young plant seedlings, dry seeds, animal tissues. The electromagnetic exposure was carried out in open space in well controlled environmental conditions by using 10.75 GHz/1 m W cm -2 microwaves. Biochemical assays and cytogenetic tests have been carried out to reveal the changes induced post irradiation. The response of some pathogen bacteria, have been emphasized by means of turbidimetric measurements - the stimulatory effect being noticed at the level of the microbial population density (the stimulation of the human body microbial flora seems to be one of the side effects of microwave exposures). The behavior of some fungus species was investigated by spectrophotometric assay of various enzyme systems: either inhibitor y or stimulatory effects have been revealed, depending on the species and enzyme peculiarities (certain biotechnological tools could be developed based on fungi exposure to microwaves). The genetic effects of seed exposure have been studied by applying cytogenetic tests to meristem tissues provided by freshly germinated cereal plantlets. Significant rate of chromosomal aberrations has been observed following the microwave exposure as well as stimulatory influence on the proliferation rate (the possibility of plant growth stimulation is suggested). The vegetal tissue cultures (in vitro micro propagated pharmaceutical plants) exposed to low power density microwaves presented increased levels of assimilatory pigments (the controlled development of technical plants for medical uses is proposed). The chlorophyll ratio in young tree seedlings after

  18. Development of low-power loss Mn–Zn ferrites using microwave ...

    Indian Academy of Sciences (India)

    Unknown

    1996; Yasuhara and Takagawa 2000). This requires deve- lopment of new ferrite materials with constantly improv- ing loss characteristics. To reduce power loss, both hysteresis loss and eddy current loss should be suppressed by available processing techniques. In this connection, it was found that the microwave sintering ...

  19. Monotron and azimuthally corrugated: application to the high power microwaves generation

    International Nuclear Information System (INIS)

    Castro, Pedro Jose de

    2003-01-01

    The present document reports the activity of construction and initial operation of 6.7 GHz operation for high power microwave generation, the study on cylindrical resonators with azimuthally corrugated cross section, the determination of electrical conductivity of metallic materials and development of dielectric resonators for telecommunication applications

  20. Stratified spherical model for microwave imaging of the brain: Analysis and experimental validation of transmitted power

    DEFF Research Database (Denmark)

    Bjelogrlic, Mina; Volery, Maxime; Fuchs, Benjamin

    2018-01-01

    This work presents the analysis of power transmission of a radiating field inside the human head for microwave imaging applications. For this purpose, a spherical layered model composed of dispersive biological tissues is investigated in the range of (0.5–4) GHz and is confronted to experimental...

  1. Control Strategies for a simple Point-Absorber Connected to a Hydraulic Power Take-off

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, P.; Lopez, J.; Santos, M.; Villate, J.L.; Ruiz Minguela, P.; Salcedo, F. [Tecnalia-Energia Sede de Robotiker-Tecnalia, Parque Tecnologico, Edificio 202, E-48170, Zamudio (Spain); Falcao, A.F.de O. [IDMEC, Instituto Superior Tecnico, Av. Rovisco Pais, 1, 1049-001, Lisbon (Portugal)

    2009-07-01

    Among the various types of wave energy converters currently being developed, heaving point absorbers are one of the simplest and most promising concepts, possibly due to their ease of deployment and integration in larger arrays structures. A typical efficient energy conversion system for point absorbers is based on hydraulic power take-off (PTO) systems, consisting in a double-acting cylinder and two or more accumulators, reserving fluid at different pressures and linked between them by a hydraulic motor connected to an electric generator. For the purpose of control and modulation of the power output the hydraulic circuit might include a certain number of valves that can set the pressure levels within the accumulators. This paper presents a simple model of a heaving oscillating buoy, represented by a surface-piercing cylinder, extracting power by means of a hydraulic system. The hydrodynamic behaviour of the absorber is modelled through application of the linear water wave theory. Apart from the basic elements listed above, the model of the hydraulic system includes leakages and pressure losses and takes into account the compressibility of the fluid. Also possible extra accumulators are considered in order to improve the performance of the hydraulic system by means of properly controlled valves. The function of these extra accumulators consists in storing and releasing energy to the system when this is desirable for the improvement of the power output. Simulations were carried out through a time-domain approach making use of the Cummins equation and considering regular monochromatic waves and irregular wave-trains. The control of the system is managed by means of control valves whose opening will be depending on the sign of the velocity of the buoy and the pressure levels. Three possible aims were assumed for the control strategies investigated: maximisation of the average power output, stabilisation of the output (in terms of rotational velocity and/or electrical

  2. Microwave absorption properties of lightweight absorber based on Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bin [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Jun, E-mail: wgdfrp@whut.edu.cn [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Junpeng; Huo, Siqi [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Bin [School of Science, Wuhan University of Technology, Wuhan 430070 (China); Tang, Yushan [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-09-01

    In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the −10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than −10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25–0.34 g/cm{sup 3}. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber. - Highlights: • PANS@SMF – RGO epoxy composite was fabricated by a facile method. • The absorption bandwidth less than −10 dB can reach up to 4.5 GHz with layer thickness of 2.5 mm. • The density of the composites is in the range of 0.25–0.34 g/cm{sup 3} and can be considered as a lightweight microwave absorber.

  3. Ultralow-Power Digital Correlator for Microwave Polarimetry

    Science.gov (United States)

    Piepmeier, Jeffrey R.; Hass, K. Joseph

    2004-01-01

    A recently developed high-speed digital correlator is especially well suited for processing readings of a passive microwave polarimeter. This circuit computes the autocorrelations of, and the cross-correlations among, data in four digital input streams representing samples of in-phase (I) and quadrature (Q) components of two intermediate-frequency (IF) signals, denoted A and B, that are generated in heterodyne reception of two microwave signals. The IF signals arriving at the correlator input terminals have been digitized to three levels (-1,0,1) at a sampling rate up to 500 MHz. Two bits (representing sign and magnitude) are needed to represent the instantaneous datum in each input channel; hence, eight bits are needed to represent the four input signals during any given cycle of the sampling clock. The accumulation (integration) time for the correlation is programmable in increments of 2(exp 8) cycles of the sampling clock, up to a maximum of 2(exp 24) cycles. The basic functionality of the correlator is embodied in 16 correlation slices, each of which contains identical logic circuits and counters (see figure). The first stage of each correlation slice is a logic gate that computes one of the desired correlations (for example, the autocorrelation of the I component of A or the negative of the cross-correlation of the I component of A and the Q component of B). The sampling of the output of the logic gate output is controlled by the sampling-clock signal, and an 8-bit counter increments in every clock cycle when the logic gate generates output. The most significant bit of the 8-bit counter is sampled by a 16-bit counter with a clock signal at 2(exp 8) the frequency of the sampling clock. The 16-bit counter is incremented every time the 8-bit counter rolls over.

  4. Design and Fabrication of a Novel Wideband DNG Metamaterial with the Absorber Application in Microwave X-Band

    Directory of Open Access Journals (Sweden)

    Ahmed Mahmood

    2017-01-01

    Full Text Available A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, designed, and investigated in this paper. The metamaterial is composed of modified S-shaped split-ring resonators (S-SRR. The periodic structure is designed and simulated using CST MWs. Next, the experiments are carried out, and it is shown that the simulation and the experimental results agree well and the designed structure has a wide bandwidth in X-band. An absorber application of this metamaterial is also provided, and the structure can be used as an absorber with absorption rate of over 80% for the polarization angles between 0° and 40°.

  5. Preparation of hollow microspheres of Ce{sup 3+} doped NiCo ferrite with high microwave absorbing performance

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hong-zhen, E-mail: duanhz2000@163.com; Zhou, Fang-ling; Cheng, Xia; Chen, Guo-hong; Li, Qiao-ling

    2017-02-15

    Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method with carbon sphere as the template. The phase structure, morphology, magnetic properties and wave absorbing properties of the sample were characterized by X-ray powder diffraction(XRD), Scanning electronic microscopy(SEM), Vibration sample magnetometer (VSM) and a network vector analyzer (NVA), respectively. The results indicated that the particle size of the carbon sphere sample prepared by hydrothermal method was about 0.5 µm and the particle size of the Ni{sub 0.5}Co{sub 0.5}Fe{sub 2}O{sub 4} sample prepared by template-based method was about 300 nm. The influence of the amount of rare earth element on the magnetic and absorbing properties of sample was studied. The saturation magnetization and coercivity decreased gradually with the increase of the content of Ce. When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively. The associated ferrite hollow spheres have good absorbing performance, and the return loss value was −18.8 dB at 5500 MHz. - Highlights: • Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method. • The influence of rare earth Ce{sup 3+} on the magnetic and absorbing properties of sample was studied. • When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively.

  6. High-power microwave LDMOS transistors for wireless data transmission technologies (Review)

    International Nuclear Information System (INIS)

    Kuznetsov, E. V.; Shemyakin, A. V.

    2010-01-01

    The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10-15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceivers for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).

  7. Study of a microwave power source for a two-beam accelerator

    International Nuclear Information System (INIS)

    Houck, T.L.

    1994-01-01

    A theoretical and experimental study of a microwave power source suitable for driving a linear e + e - collider is reported. The power source is based on the Relativistic Klystron Two-Beam Accelerator (RK-TBA) concept, is driven by a 5-MeV, 1-kA induction accelerator electron beam, and operates at X-band frequencies. The development of a computer code to simulate the transverse beam dynamics of an intense relativistic electron beam transiting a system of microwave resonant structures is presented. This code is time dependent with self-consistent beam-cavity interactions and uses realistic beam parameters. Simulations performed with this code are compared with analytical theory and experiments. The concept of spacing resonant structures at distances equal to the betatron wavelength of the focusing system to suppress the growth of transverse instabilities is discussed. Simulations include energy spread over the beam to demonstrate the effect of Landau damping and establish the sensitivity of the betatron wavelength spacing scheme to errors in the focusing system. The design of the Reacceleration Experiment is described in detail and includes essentially all the issues related to a full scale RK-TBA microwave source. A total combined power from three output structures in excess of 170 MW with an amplitude stability of ±4% over a 25 ns pulse was achieved. The results of the experiment are compared to simulations used during the design phase to validate the various codes and methods used. The primary issue for the RK-TBA concept is identified as transverse beam instability associated with the excitation of higher order modes in the resonant structures used for extracting microwave power from the modulated beam. This work represents the first successful experimental demonstration of repeated cycles of microwave energy extraction from and reacceleration of a modulated beam

  8. Environmental remediation by an integrated microwave/UV illumination technique. 3. A microwave-powered plasma light source and photoreactor to degrade pollutants in aqueous dispersions of TiO2 illuminated by the emitted UV/visible radiation.

    Science.gov (United States)

    Horikoshi, Satoshi; Hidaka, Hisao; Serpone, Nick

    2002-12-01

    The characteristic features of a novel double-quartz cylindrical plasma photoreactor (DQCPP) were assessed by examining the photodegradation of rhodamine-B dye (RhB+) in aqueous TiO2 dispersions irradiated simultaneously by both microwave radiation and UV/visible radiation emitted from a microwave-powered (MW, 2.45 GHz) electrodeless mercury lamp. The features of the DQCPP lamp are given and discussed in terms of the experimental output UV energy in the wavelength ranges 210-300 and 310-400 nm for applied MW powers from 74 to 621 W. The DQCPP and a water-cooled DQCPP reactor absorbed more than 50% MW radiation (50-88 and 50-75%, respectively). The emitted light irradiance scaled sublinearly with applied MW power. Relative to the DQCPP lamp, loss of irradiance by the water-cooled DQCPP lamp was approximately 28-46% at 250 nm and approximately 41-58% at 360 nm in the range of MW power used. The smallest loss occurred at 178.9 W at which the degradation of RhB+ was subsequently examined by UV/visible spectroscopy and by total organic carbon analyses. Highly intense mercury lines were seen at 365, 404, 435, 546, and 579 nm (those below 365 nm were more than 10 times weaker). About 80% of the RhB+ solution was photomineralized after 60 min of irradiation of the aqueous RhB+/TiO2 dispersion with the DQCPP lamp; no UV/ visible spectral features of RhB+ were evident at wavelengths below 250 nm after 30 min. Possible effects of microwave radiation and temperature on the degradative process are described.

  9. Experimental progress on virtual-cathode very high power microwave source development

    International Nuclear Information System (INIS)

    Fazio, M.V.; Hoeberling, R.F.

    1987-01-01

    The evolution of rf accelerator technology toward high-power, high-current, low-emittance beams produces an ever-increasing demand for efficient, very high power microwave sources. The present klystron technology has performed very well but is not expected to produce reliable gigawatt peak-power units in the 1- to 10-GHz regime. Further major advancements must involve other types of sources. The reflexing electron sources can produce microwave powers at the gigawatt level and have demonstrated operation from 800 MHz to 40 GHz. Pulse length appears to be limited by electron-beam diode closure, and reflexing electron devices have been operated in a repetitively pulsed mode. An experiment is under way to investigate concepts to stabilize the frequency of the virtual cathode source. If one can successfully frequency and phase lock this source to an external signal, then this source can operate as a very high power microwave amplifier making it practical for accelerator applications. The progress on an experiment to test these concepts will be discussed

  10. Fabrication, magnetic and microwave absorbing properties of Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} hexagonal ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Bayrakdar, Harun, E-mail: h.bayrakdar@comu.edu.tr

    2016-07-25

    We have investigated the magnetic and microwave absorbing behavior of Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} Nano Particles (NPs)/polyaniline (PANI) and polyacrylonitrile (PAN) nanocomposite materials. Particles showed phase purity and crystallinity in powder X ray diffraction (XRD) analysis. Temperature dependence of magnetic parameters was observed. Microwave absorbing showed very broad and high reflection loss. - Highlights: • Ba{sub 2}Co{sub 2}Cr{sub 2}Fe{sub 12}O{sub 22} NPs were investigated magnetic and absorbing behavior. • VSM measurements of NPs were showed the existence of superparamagnetism with very small coercivity and soft ferrite materials. • Nanocomposites showed higher EM absorption frequency and wider absorption bandwidth.

  11. Preparation and microwave-absorbing property of EP/BaFe{sub 12}O{sub 19}/PANI composites

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huixia, E-mail: fenghx@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Bai, Dezhong [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Tan, Lin; Chen, Nali [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Wang, Yueyi [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China)

    2017-07-01

    In this paper, we introduced expanded perlite (EP) into the system of ferrite composites for the first time. By sol-gel self-propagating combustion method, expanded perlite/barium ferrite (EP/BaFe{sub 12}O{sub 19}) was prepared, and then ternary composites of expanded perlite/barium ferrite/polyaniline (EP/BaFe{sub 12}O{sub 19}/PANI) were obtained by in-situ oxidative polymerization of aniline on EP/BaFe{sub 12}O{sub 19} mixture. Although, as is well known, the values of saturation magnetization (Ms), remnant magnetization (Mr) and coercivity (Hc) of composites are all lower than the pure BaFe{sub 12}O{sub 19} particles owing to the existence of the nonmagnetic EP and PANI, the EP/BaFe{sub 12}O{sub 19}/PANI composites exhibit absorption characteristics at the range of 2–18 GHz, the effective absorption bandwidth (less than −4 dB) reached 12.12 GHz and the minimum reflection loss of −5.66 dB at 8.48 GHz with only 2 mm thickness of absorbing layer. So the composites could resist urban electromagnetic pollution, such as wireless network, communication and so on, effectively. - Highlights: • The expanded perlite (EP) was introduced into the system of ferrite composites at the first time. • Novel ternary nanocomposite of EP/BaFe{sub 12}O{sub 19}/PANI is prepared by in-situ oxidative polymerization. • Composite absorber exhibit a minimum reflection loss of -5.66 dB at 8.48 GHz with a matching thickness of 2 mm. • Composite absorber possess the features like low-cost, lightweight and wide bandwidth absorption of civil EM radiation.

  12. Plasma Stabilization in Low-Power C Band Microwave Arcjets

    National Research Council Canada - National Science Library

    Micci, Michael

    1999-01-01

    .... Emission spectroscopy of the plasma was made in order to measure the plasma electron temperature at different specific power levels, and the assumption of Local Thermodynamic Equilibrium (LTE) was examined...

  13. Magnet power system for the Microwave Tokamak Experiment (MTX)

    International Nuclear Information System (INIS)

    Jackson, M.C.; Musslewhite, R.C.

    1987-01-01

    The system configuration, layout, and general philosophy for the MTX magnet power system is described. The vast majority of the magnet power equipment was quite successfully used on the ALCATOR-C experiment at the Massachusetts Institute of Technology. The AC power for the magnet system at MIT was obtained from a 225MVA alternator. The power for the system at LLNL is obtained directly from the local utility's 230 kV line. This installation, therefore, necessitates the addition of a great deal of equipment in ranges from new switchgear in the substation to using existing switchgear obtained from MIT as contractors for intershop electrical isolation as well as safety isolation for personnel entry into the experimental area. Additionally, some discussion is made of the unique layout of this facility and the tradeoffs made to accommodate them. 2 refs., 6 figs

  14. Sr hexaferrite/Ni ferrite nanocomposites: Magnetic behavior and microwave absorbing properties in the X-band

    Energy Technology Data Exchange (ETDEWEB)

    Jacobo, Silvia E. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Bercoff, Paula G., E-mail: bercoff@famaf.unc.edu.ar [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, IFEG, CONICET, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Herme, Carlos A. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Vives, Leandro A. [División Antenas, Instituto de Investigaciones Científicas para la Defensa CITEDEF, Ministerio de Defensa, San Juan Bautista de La Salle 4397, Villa Martelli, B1603ALO Buenos Aires (Argentina)

    2015-05-01

    Nickel ferrite nanoparticles were synthesized by a self-combustion method over nanocrystalline powders of Nd–Co substituted strontium hexaferrite with nominal composition Sr{sub 0.5}Nd{sub 0.5}Co{sub 0.5}Fe{sub 10.5}O{sub 19}, at different mass relations. The samples were structurally characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). The M vs. H loops of the composites were determined with a vibrating sample magnetometer (VSM) and the interaction with the X-band microwave radiation of the nanocomposites dispersed in epoxy resin was measured with a vector network analyzer (VNA). The hysteresis loops showed strong exchange-coupling between the two magnetic phases for the 30:70 and 50:50 Sr{sub 0.5}Co{sub 0.5}Nd{sub 0.5}Fe{sub 10.5}O{sub 19}/NiFe{sub 2}O{sub 4} nanocomposites, while a weak interaction was observed for the 70:30 mass ratio. The nanocomposite with an equal amount of hard and soft phase shows the highest performance both in reflectivity and in bandwidth, reaching a maximum in reflectivity of −34.4 dB at 11.1 GHz while the bandwidth below −10 dB is 3.5 GHz. - Highlights: • Sr{sub 0.5}Co{sub 0.5}Nd{sub 0.5}Fe{sub 10.5}O{sub 19}/NiFe{sub 2}O{sub 4} nanocomposites were synthesized at different mass ratios. • The systems were structurally and magnetically characterized. • The X-band microwave radiation of the composites was evaluated. • Enhancement in reflectivity is related to exchange interaction between hard and soft phases.

  15. Effects of microwave power and irradiation time on pectin extraction from watermelon rinds (Citrullus lanatus) with acetic acid using microwave assisted extraction method

    Science.gov (United States)

    Sari, A. M.; Ishartani, D.; Dewanty, P. S.

    2018-01-01

    The aims of this research are to study the effect of microwave power (119.7 W, 199.5 W and 279.3 W) and irradiation time (6, 9 and 12 min) on pectin extraction by using Microwave Assisted Extraction (MAE) with acetic acid and to do a preliminary characterization of pectin from watermelon rinds. A randomized factorial design with two factors was used to determine the effect of microwave power and processing time on the yield, equivalent weight, degree of methoxylation (DM), galacturonic acid content (GA) and the degree of esterification (DE) of extracted pectin. The results showed that extracted pectin from watermelon rinds using MAE method have yield ranged from 3.925% to 5.766%, with equivalent weight ranged from 1249.702 to 2007.756. Extracted pectin have a DM value ranged from 3.89% to 10.81%. Galacturonic acid content that meets with IPPA standard resulted from extraction condition of 279.3-watt microwave power for 9 min and 12 min. The degree of esterification (DE) value ranged from 56.86% to 85.76%, and this value exhibited a relatively high methoxyl pectin (>50%). The best pectin properties was obtained at a microwave power of 279.3 watts for 12 min.

  16. On-off temperature and power controller for improvement of the processes conditions assisted with microwaves

    Directory of Open Access Journals (Sweden)

    Viviana Marcela Hernández Velásquez

    2017-07-01

    Full Text Available Introduction: The use of microwaves in the process of fruits and vegetables dehydration is presented as an alternative process to the conventional ones because of the benefits in a reduction of transport costs, less processing time and final product volume, as well as a greater time of conservation and storage. Objective: Therefore, the aim of this study is to modify the microwave radiation supply, implementing an ON-OFF control of power and temperature in order to evaluate these parameters in the process and energy yield in the papaya. Methodology: For the development of the project, a factorial design of experiments was done taking into account the time on and off of the radiation and the sample geometry (slice and cube; runs were performed in duplicate and randomly in the modified microwave oven of 2.45GHz and 1kW of power. Results: The amount of moisture removed, the energy yield of the process and the initial organoleptic properties were analyzed. In the tests carried out, a maximum energy yield was 0.014kg/kJ with a reduction of 86% of the papaya sample weight processed in the radiation rate of 6x12 for a slice of 0,01m of thickness. Conclusions: It was achieved modification of the control in the microwave oven and the runs were carried out concluding that the parameters evaluated and are influential in the process and can be achieved moisture removal of 86%.

  17. High power microwave source with a three dimensional printed metamaterial slow-wave structure

    International Nuclear Information System (INIS)

    French, David M.; Shiffler, Don

    2016-01-01

    For over the last decade, the concept of metamaterials has led to new approaches for considering the interaction of radiation with complex structures. However, practical manifestations of such a device operating at high power densities have proven difficult to achieve due to the resonant nature of metamaterials and the resultant high electric fields, which place severe constraints on manufacturing the slow wave structures. In this paper, we describe the first experimental manifestation of a high power microwave device utilizing a metallic slow wave structure (metamaterial-like) fabricated using additive manufacturing. The feasibility of utilizing additive manufacturing as a technique for building these relatively complicated structures has thus been demonstrated. The MW class microwave source operates in the C-band and shows frequency tunablility with electron beam voltage. The basic electromagnetic characteristics of this device, the construction using additive manufacturing, and the basic performance as a microwave oscillator are considered. Due to the tunable nature of the device, it shows promise not only as an oscillator but also as a microwave amplifier. Therefore, the dispersive characteristics and a discussion of the anticipated gain is included as it relates to an amplifier configuration.

  18. Influence of a falling edge on high power microwave pulse combination

    Science.gov (United States)

    Li, Jiawei; Huang, Wenhua; Zhu, Qi; Xiao, Renzhen; Shao, Hao

    2016-07-01

    This paper presents an explanation of the influence of a microwave falling edge on high-power microwave pulse combination. Through particle-in-cell simulations, we discover that the falling edge is the driving factor that limits the output power of the combined pulses. We demonstrate that the space charge field, which accumulates to become comparable to the E-field at the falling edge of the former pulse, will trap the electrons in the gas layer and decrease its energy to attain a high ionization rate. Hence, avalanche discharge, caused by trapped electrons, makes the plasma density to approach the critical density and cuts off the latter microwave pulse. An X-band combination experiment is conducted with different pulse intervals. This experiment confirms that the high density plasma induced by the falling edge can cut off the latter pulse, and that the time required for plasma recombination in the transmission channel is several microseconds. To ensure a high output power for combined pulses, the latter pulse should be moved ahead of the falling edge of the former one, and consequently, a beat wave with high peak power becomes the output by adding two pulses with normal amplitudes.

  19. Effects of increased microwave heating power in the stellarator TJ-K

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, Alejandro; Koehn, Alf; Ali, Ahmed; Ramisch, Mirko [Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart, Stuttgart (Germany)

    2015-05-01

    One of the microwave heating systems at the stellarator TJ-K has been recently upgraded: a third klystron has been installed, increasing the heating power from 4 kW to 6 kW operating at 14 GHz. A phased-array antenna is used which allows to vary the injection angle by sweeping the microwave frequency in order control the coupling mechanism of the microwave to the plasma. With the two klystrons already installed, ionization degrees of α ≅ 1 have been reached. We expect that an increased heating power, by means of the third klystron put into operation, leads to an increase in the electron temperature T{sub e} only, rather than in electron density n{sub e}, and thus a decrease in the collision frequency ν{sub ei} ∝ n{sub e}T{sub e}{sup -3/2} which has an impact on heating flow damping and neoclassical properties. Parameter scans have been performed in order to characterize the new heating scenario. A radial movable Langmuir probe has been used to obtain radial profiles of the electron density and temperature. An arrangement of bolometers and an optical diode have been used to obtain the power losses by radiation. A particle and power balance model is used to obtain estimated densities and temperatures in order to compare with the experimental results.

  20. Wireless Power Transfer to a Microaerial Vehicle with a Microwave Active Phased Array

    Directory of Open Access Journals (Sweden)

    Shotaro Nako

    2014-01-01

    Full Text Available A wireless power transfer system using a microwave active phased array was developed. In the system, power is transferred to a circling microaerial vehicle (MAV by a microwave beam of 5.8 GHz, which is formed and directed to the MAV using an active phased array antenna. The MAV is expected to support observation of areas that humans cannot reach. The power beam is formed by the phased array with eight antenna elements. Input power is about 5.6 W. The peak power density at 1,500 mm altitude was 2.63 mW/cm2. The power is sent to a circling MAV. Therefore, the transfer beam should be polarized circularly to achieve a constant power supply independent of its yaw angle. To minimize the polarization loss, a sequentially routed antenna (SRA was applied to the transmitter antenna. Results show that the axial ratio of 0.440 dB was accomplished and that power fluctuation was kept below 1%.

  1. Plasma Electronics. Theoretical and Experimental Investigations of Plasma Nonlinearity in the Powerful Microwave Oscillators

    International Nuclear Information System (INIS)

    Bliokh, Yu.P.

    2001-01-01

    either new steady-state, or automodulation regime can appear. Developed theory predicts appearance of a deep low-frequency automodulation of microwave power when the beam current exceeds some threshold. This effect was observed experimentally and parameters of automodulation are close to calculated ones. The ion-sound waves, which are the reason of auto modulation appearance, were also observed experimentally. It was shown theoretically and experimentally that non-stationary self-consistent plasma density and microwave power redistribution along the system can be the reason of microwave pulse shortening and power limiting mechanism in plasma-filled microwave radiation sources. It was shown also that the same mechanism leads to the stochastization of the microwave signal. Stochastic radiation, which is obtained by plasma-filled structure use, differs strongly by it spectral density homogeneity from stochastic radiation of analogous vacuum devices

  2. A reappraisal of optimum output matching conditions in microwave power transistors

    OpenAIRE

    Quaglia, Roberto; Shepphard, Daniel; Cripps, Stephen

    2017-01-01

    This paper presents a novel approach to the identification\\ud of output power and efficiency contours in microwave\\ud power transistors in compressed regime. The formulation is based\\ud on a polynomial representation of the drain-source voltage profile\\ud accounting for the knee region. Closed-form equations for the\\ud output power and efficiency as function of the fundamental load\\ud are demonstrated, enabling the plot of contours on a Smith\\ud Chart. From these, a further simplified drawing...

  3. Research on the honeycomb restrain layer application to the high power microwave dielectric window

    Science.gov (United States)

    Zhang, Qingyuan; Shao, Hao; Huang, Wenhua; Guo, Letian

    2018-01-01

    Dielectric window breakdown is an important problem of high power microwave radiation. A honeycomb layer can suppress the multipactor in two directions to restrain dielectric window breakdown. This paper studies the effect of the honeycomb restrain layer on improving the dielectric window power capability. It also studies the multipactor suppression mechanism by using the electromagnetic particle-in-cell software, gives the design method, and accomplishes the test experiment. The experimental results indicated that the honeycomb restrain layer can effectively improve the power capability twice.

  4. A method for eliminating the impact of microwave sweeper power fluctuation in BOTDA system

    Science.gov (United States)

    Jiang, Shuo; Chang, Jun; Zhang, Sasa; Wang, Zongliang; Luo, Sha; Sun, Boning; Liu, Xiaohui; Liu, Yongning; Tian, Junqiang; Jia, Chuanwu

    2014-03-01

    The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algorithm to realize probe wave power normalization for eliminating this impact was proposed. The principle of the proposed method was described theoretically. And the contrast test between our new method and conventional one was carried out. The experiment results indicated that the temperature accuracy was effectively improved from ±5 °C to ±2 °C.

  5. Applications of power beaming from space-based nuclear power stations. [Laser beaming to airplanes; microwave beaming to ground

    Energy Technology Data Exchange (ETDEWEB)

    Powell, J.R.; Botts, T.E.; Hertzberg, A.

    1981-01-01

    Power beaming from space-based reactor systems is examined using an advanced compact, lightweight Rotating Bed Reactor (RBR). Closed Brayton power conversion efficiencies in the range of 30 to 40% can be achieved with turbines, with reactor exit temperatures on the order of 2000/sup 0/K and a liquid drop radiator to reject heat at temperatures of approx. 500/sup 0/K. Higher RBR coolant temperatures (up to approx. 3000/sup 0/K) are possible, but gains in power conversion efficiency are minimal, due to lower expander efficiency (e.g., a MHD generator). Two power beaming applications are examined - laser beaming to airplanes and microwave beaming to fixed ground receivers. Use of the RBR greatly reduces system weight and cost, as compared to solar power sources. Payback times are a few years at present prices for power and airplane fuel.

  6. Measurement of high-power microwave pulse under intense ...

    Indian Academy of Sciences (India)

    HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) electromagnetic noise. Initially, the diode detector output signal could not be recorded due to the high noise level persisting in the ambiance. It was found that the HPM pulse can be ...

  7. Complex permeability and permittivity variation of radar absorbing materials based on MnZn ferrite in microwave frequencies

    Directory of Open Access Journals (Sweden)

    Adriana Medeiros Gama

    2013-01-01

    Full Text Available The complex dielectric permittivity (ε and magnetic permeability (µ of Radar Absorbing Materials (RAM based on magnetic particles (MnZn ferrite particles embedded in a dielectric matrix (silicon rubber have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of MnZn ferrite-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the evaluated frequency range is analyzed. In a general way, the results show ε' parameter presenting more significant variation among the evaluated parameters (ε", µ", µ'. The comparison of dielectric and magnetic loss tangents (ε"/ε' and µ"/µ', respectively shows more clearly the variation of both parameters (ε and µ according to the frequency. It is also observed that higher MnZn ferrite content fractions favor both dielectric and magnetic loss tangents.

  8. Effect of Microwave Power on the Physical Properties of Carboxylic Acid-Coated Manganese-Ion-Doped Zinc Sulfide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Baibaswata Bhattacharjee

    2011-01-01

    Full Text Available Bright ZnS : Mn2+ nanoparticles have been synthesized employing microwave irradiation technique and using zinc 2-ethylhexanoate as a novel zinc precursor. A series of samples is obtained by changing the microwave power (from 150 W to 500 W to study its effect on the physical properties of the ZnS : Mn2+ nanoparticles. The particle size increases with increasing microwave power for the samples synthesized in the microwave range of 150 W to 300 W. The decrease in particle size for higher microwave power (400 W and 500 W can be described as an onset of the secondary nucleation due to the excess energy associated with the higher microwave power. The sample synthesized with microwave power of 300 W shows highest luminescence intensity suggesting increase in Mn2+ luminescence center for the sample synthesized at 300 W, as supported by the quantity analysis results.

  9. Status of an induction accelerator driven, high-power microwave generator at Livermore

    International Nuclear Information System (INIS)

    Houck, T.L.; Westenskow, G.A.

    1993-01-01

    The authors are testing an enhanced version of the Choppertron, a high-power rf generator which shows great promise of achieving greater than 400 MW of output power at 11.4 GHz with stable phase and amplitude. This version of the Choppertron is driven by a 5-MeV, 1-kA induction accelerator beam. Modifications to the original Choppertron included aggressive suppression of high order modes in the two output structures, lengthening of the modulation section to match for higher beam energy, and improved efficiency. Final results of the original Choppertron experiment, status of the ongoing experiment and planned experiments for the next year are presented. The motivation of the research program at the LLNL Microwave Source Facility is to develop microwave sources which could be suitable drivers for a future TeV linear e + e - collider

  10. Effect of resonant microwave power on a PIG ion source. Revision

    International Nuclear Information System (INIS)

    Brown, I.G.; Galvin, J.E.; Gavin, B.F.; MacGill, R.A.

    1984-08-01

    We have investigated the effect of applying microwave power at the electron cyclotron frequency on the characteristics of the ion beam extracted from a hot-cathode PIG ion source. No change was seen in the ion charge state distribution. A small but significant reduction in the beam noise level was seen, and it is possible that the technique may find application in situations where beam quiescence is important. 32 refs., 2 figs

  11. Low power microwave tests on RF gun prototype of the Iranian Light Source Facility

    Directory of Open Access Journals (Sweden)

    A Sadeghipanah

    2017-08-01

    Full Text Available In this paper, we introduce RF electron gun of Iranian Light Source Facility (ILSF pre-injection system. Design, fabrication and low-power microwave tests results of the prototype RF electron gun have been described in detail. This paper also explains the tuning procedure of the prototype RF electron gun to the desired resonant frequency. The outcomes of this project brighten the path to the fabrication of the RF electron gun by the local industries  

  12. Controlled ion-beam transformation of silicon bipolar microwave power transistor's characteristics

    International Nuclear Information System (INIS)

    Solodukha, V.A.; Snitovskij, Yu.P.

    2015-01-01

    In this article, a method for changing the silicon bipolar microwave power transistor's characteristics in a direct and deliberate manner by modifying the chemical composition at the molybdenum - silicon boundary, the electro-physical properties of molybdenum - silicon contacts, and the electrophysical characteristics of transistor structure areas by the phosphorus ions irradiation of generated ohmic molybdenum - silicon contacts to the transistor emitters is proposed for the first time. The possibilities of this method are investigated and confirmed experimentally. (authors)

  13. Stability analysis of the Gyroscopic Power Take-Off wave energy point absorber

    Science.gov (United States)

    Nielsen, Søren R. K.; Zhang, Zili; Kramer, Morten M.; Olsen, Jan

    2015-10-01

    The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber consists of a float rigidly connected to a lever. The operational principle is somewhat similar to that of the so-called gyroscopic hand wrist exercisers, where the rotation of the float is brought forward by the rotational particle motion of the waves. At first, the equations of motion of the system are derived based on analytical rigid body dynamics. Next, assuming monochromatic waves simplified equations are derived, valid under synchronisation of the ring of the gyro to the angular frequency of the excitation. Especially, it is demonstrated that the dynamics of the ring can be described as an autonomous nonlinear single-degree-of-freedom system, affected by three different types of point attractors. One where the ring vibrations are attracted to a static equilibrium point indicating unstable synchronisation and two types of attractors where the ring is synchronised to the wave angular frequency, either rotating in one or the opposite direction. Finally, the stability conditions and the basins of attraction to the point attractors defining the synchronised motion are determined.

  14. Environmental assessment for the satellite power system-concept development and evaluation program-microwave health and ecological effects

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    This report is concerned with the potential health and ecological effects of the microwave beam from the microwave power transmission system (MPTS) of the satellite power system (SPS). The report is written in the form of a detailed critical review of selected scientific articles from the published literature on the biological effects of nonionizing electromagnetic radiation, followed by an assessment of the possible effects of the SPS, based on exposure values for the reference system (US DOE and NASA, 1978).

  15. High-temperature stable absorber coatings for linear concentrating solar thermal power plants; Hochtemperaturstabile Absorberschichten fuer linear konzentrierende solarthermische Kraftwerke

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Christina

    2009-03-23

    This work describes the development of new absorber coatings for different applications - para-bolic trough and linear Fresnel collectors - and operating conditions - absorber in vacuum or in air. The demand for higher efficiencies of solar thermal power plants using parabolic trough technology results in higher temperatures in the collectors and on the absorber tubes. As heat losses increase strongly with increasing temperatures, the need for a lower emissivity of the absorber coating at constant absorptivity arises. The linear Fresnel application envisions ab-sorber tubes stable in air at high temperatures of about 450 C, which are to date commercially not available. This work comprises the theoretical background, the modeling and the fabrication of absorber tubes including the technology transfer to a production-size inline sputter coater. In annealing tests and accompanying optical measurements, degradation processes have been observed and specified more precisely by material characterization techniques. The simulations provided the capability of different materials used as potential IR-reflector. The highest selectivity can be achieved by applying silver which consequently has been chosen for the application in absorber coatings of the parabolic trough technology. Thin silver films how-ever need to be stabilized when used at high temperatures. Appropriate barrier layers as well as process and layer parameters were identified. A high selectivity was achieved and stability of the absorber coating for 1200 h at 500 C in vacuum has been demonstrated. For the application in air, silver was also analyzed as a potential IR-reflector. Even though the stability could be increased considerably, it nevertheless proved to be insufficient. The main factors influencing stability in a positive way are the use of higher quality polishing, additional barrier layers and adequate process parameters. This knowledge was applied for developing coatings which are stable in air at

  16. Multiple magnetic resonance and microwave absorption of metamaterial absorbers composed of double split ring resonators on grounded carbonyl iron composites

    Science.gov (United States)

    Lim, Jun-Hee; Kim, Sung-Soo

    2017-12-01

    This study investigates the triple-band absorption properties of metamaterial absorbers composed of a double split ring resonator (DSRR) on a grounded magnetic substrate of carbonyl iron powders. Computational tools are used to model the interaction between electromagnetic waves and the metamaterial structure. For perpendicular polarization with the electric field perpendicular to the SRR gap, triple-band absorption peaks are predicted in the simulation result of reflection loss. Magnetic resonance resulting from antiparallel currents between the upper DSRR and the lower ground plane is identified at the frequencies of the absorption peaks. The orientation of the two resonators influences the absorption characteristics, especially in the second and third peaks where the coupling between the inner SRR and outer SRR is strong. The current density distribution indicates that the two resonators oriented in the same direction achieve reduced coupling between them, which results in two absorption frequencies close to each other. For parallel polarization with the electric field parallel to the SRR gap, this study predicts dual-band absorption peaks corresponding to the magnetic resonance at the SRR wire.

  17. Gyroscopic power take-off wave energy point absorber in irregular sea states

    DEFF Research Database (Denmark)

    Zhang, Zili; Chen, Bei; Nielsen, Søren R.K.

    2017-01-01

    Highlights •A GyroPTO wave energy point absorber with magnetic coupling mechanism is proposed. •A 4DOF nonlinear model of the GyroPTO absorber has been derived. •Rational approximations are performed on the radiation damping moments. •Synchronization of the device is more easily maintained...

  18. Compilation and assessment of microwave bioeffects. Final report. A selective review of the literature on biological effects of microwaves in relation to the Satellite Power System (SPS)

    Energy Technology Data Exchange (ETDEWEB)

    Justesen, D.R.; Ragan, H.A.; Rogers, L.E.; Guy, A.W.; Hjeresen, D.L.; Hinds, W.T.; Phillips, R.D.

    1978-05-01

    One of many alternate sources of electrical energy that are being considered by the Department of Energy is a microwave-mediated Satellite Power System (SPS). Once inserted into geosynchronous orbit at an altitude of more than 40,000 kilometers, a satellite would collect then convert the sun's energy to 2450-MHz microwaves, which would be beamed to the Earth's surface, where a rectifying antenna (rectenna) would convert the microwaves to electrical current suitable for industrial and domestic use. The expanse of each rectenna (about 10 by 13 kilometers), the power density of the continuous-wave microwave beam (approx. 23 mW/cm/sup 2/ at center, with fall off to 1 mW/cm/sup 2/ or less at the periphery of the rectenna), and the possibility that 20 or more satellite systems will eventually be operating, creates two sets of interrelated problems for biological/ecological assessment. These are 1) the effects of microwave fields of higher intensity on airborne biota (including human beings in aircraft) that may traffic the area above the rectenna and 2) the effects of virtually perpetual fields of much lower intensity on all forms of life at and beyond the rectennae's zone of exclusion. In this review, the scientific literature is examined, not only for biological effects that are pertinent to assessment of SPS, but for hiatuses of knowledge that will have to be filled before SPS can be vouched for operational safety.

  19. Compilation and assessment of microwave bioeffects. Final report. A selective review of the literature on biological effects of microwaves in relation to the satellite power system

    Energy Technology Data Exchange (ETDEWEB)

    Justesen, D. R.; Ragan, H. A.; Rogers, L. E.; Guy, A. W.; Hjeresen, D. L.; Hinds, W. T.

    1978-05-01

    Potential biological and ecological problems are the focus of a review of the world's scientific literature on biological effects of microwave radiation. The emphasis is on recently reported data and on the 2450-MHz continuous-wave (CW) radiation that is envisioned for a Satellite Power System (SPS).

  20. High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2010-03-04

    Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5–9 MW level of incident power. The compressed pulses observed had powers of 50–70 MW and durations of 40–70 ns. Peak power gains were measured to be in the range of 7:1–11:1 with efficiency in the range of 50–63%.

  1. High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

    International Nuclear Information System (INIS)

    Hirshfield, Jay L.

    2010-01-01

    Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5-9 MW level of incident power. The compressed pulses observed had powers of 50-70 MW and durations of 40-70 ns. Peak power gains were measured to be in the range of 7:1-11:1 with efficiency in the range of 50-63%.

  2. Simulating the effect of high column density absorbers on the one-dimensional Lyman α forest flux power spectrum

    Science.gov (United States)

    Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

    2018-03-01

    We measure the effect of high column density absorbing systems of neutral hydrogen (H I) on the one-dimensional (1D) Lyman α forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column density absorbers (which we define to be those with H I column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}) cause broadened absorption lines with characteristic damping wings. These damping wings bias the 1D Lyman α forest flux power spectrum by causing absorption in quasar spectra away from the location of the absorber itself. We investigate the effect of high column density absorbers on the Lyman α forest using hydrodynamical simulations for the first time. We provide templates as a function of column density and redshift, allowing the flexibility to accurately model residual contamination, i.e. if an analysis selectively clips out the largest damping wings. This flexibility will improve cosmological parameter estimation, for example, allowing more accurate measurement of the shape of the power spectrum, with implications for cosmological models containing massive neutrinos or a running of the spectral index. We provide fitting functions to reproduce these results so that they can be incorporated straightforwardly into a data analysis pipeline.

  3. Pyrolysis of Municipal Solid Waste for Syngas Production by Microwave Irradiation

    International Nuclear Information System (INIS)

    Gedam, Vidyadhar V.; Regupathi, Iyyaswami

    2012-01-01

    In the present study, we discuss the application of microwave-irradiated pyrolysis of municipal solid waste (MSW) for total recovery of useful gases and energy. The MSW pyrolysis under microwave irradiation highly depends on the process parameters, like microwave power, microwave absorbers, and time of irradiation. The thoroughness of pyrolysis and product recovery were studied by changing the abovesaid variables. Pyrolysis of MSW occurs in the power rating range of 450–850 W—outside this power rating range, pyrolysis is not possible. Experiments were carried out using various microwave absorbers (i.e., graphite, charcoal, and iron) to enhance the pyrolysis even at lower power rating. The results show that the pyrolysis of MSW was possible even at low power ratings. The major composition of the pyrolysis gaseous product were analyzed with GC–MS which includes CO 2 , CO, CH 4 , etc.

  4. Wireless microwave acoustic sensor system for condition monitoring in power plant environments

    Energy Technology Data Exchange (ETDEWEB)

    Pereira da Cunha, Mauricio [Univ. of Maine, Orno, ME (United States)

    2017-03-30

    This project successfully demonstrated novel wireless microwave acoustic temperature and pressure sensors that can be embedded into equipment and structures located in fossil fuel power plant environments to monitor the condition of components such as steam headers, re-heat lines, water walls, burner tubes, and power turbines. The wireless microwave acoustic sensor technology researched and developed through a collaborative partnership between the University of Maine and Environetix Technologies Corporation can provide a revolutionary impact in the power industry since it is anticipated that the wireless sensors will deliver reliable real-time sensing information in harsh power plant conditions that involve temperatures up to 1100oC and pressures up to 750 psi. The work involved the research and development of novel high temperature harsh environment thin film electrodes, piezoelectric smart microwave acoustic sensing elements, sensor encapsulation materials that were engineered to function over long times up to 1100oC, and a radio-frequency (RF) wireless interrogation electronics unit that are located both inside and outside the high temperature harsh environment. The UMaine / Environetix team have interacted with diverse power plant facilities, and identified as a testbed a local power generation facility, which burns municipal solid waste (MSW), the Penobscot Energy Recovery Company (PERC), Orrington, Maine. In this facility Environetix / UMaine successfully implemented and tested multiple wireless temperature sensor systems within the harsh-environment of the economizer chamber and at the boiler tubes, transferring the developed technology to the power plant environment to perform real-time sensor monitoring experiments under typical operating conditions, as initially targeted in the project. The wireless microwave acoustic sensor technology developed under this project for power plant applications offers several significant advantages including wireless

  5. Progress in GaAs Metamorphic HEMT Technology for Microwave Applications. High Efficiency Ka-Band MHEMT Power MMICs

    Science.gov (United States)

    Smith, P. M.; Dugas, D.; Chu, K.; Nichols, K.; Duh, K. H.; Fisher, J.; MtPleasant, L.; Xu, D.; Gunter, L.; Vera, A.

    2003-01-01

    This paper reviews recent progress in the development of GaAs metamorphic HEMT (MHEMT) technology for microwave applications. Commercialization has begun, while efforts to further improve performance, manufacturability and reliability continue. We also report the first multi-watt MHEMT MMIC power amplifiers, demonstrating up to 3.2W output power and record power-added efficiency (PAE) at Ka-band.

  6. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    International Nuclear Information System (INIS)

    Robert C. Brown; Robert J. Weber; Andrew A. Suby

    2002-01-01

    Three test instruments are to be used to determine the abilities of photo-acoustic technology for the ultimate purpose of measuring unburned carbon in fly ash in an on-line configuration. The first test instrument is in a single microwave frequency system previously constructed to measure photo-acoustic signals in an off-line configuration. This system was assembled and used to begin testing parameters thought to be influential in the resulting photo-acoustic signal output. A standard modulation frequency was chosen based upon signal to noise data gained from experimentation and sample heterogeneity was tested and found not to be influential. Simultaneously, a second instrument is to be constructed based in part on lessons learned with the first instrument, and to expand the capabilities of the first instrument. Improvements include a control loop to allow more constant microwave power output and an ability to operate over a range of microwave frequencies. To date, the design of the second instrument has been completed and components ordered. The third instrument will be designed based on the experiences of the first two instruments and will operate in an on-line carbon-in-ash monitoring system for coal-fired power plants

  7. The effect of power intensity properties of microwave modified oil palm trunk lumber

    Science.gov (United States)

    Izzati Ibrahim, Anis; Salim, Nurjannah; Roslan, Rasidi; Ashry Jusoh, Mohammad; Hashim, Rokiah

    2018-04-01

    In the decade, oil palm (Elaeis guineensis) in Malaysia is one of the conventional sources that will be rising, and the rate of biomass will considerably increase in yet to come. Presently, oil palm biomass is going through research and development and appears to be the most sustainable alternative. Investigations on oil palm biomass have been conducted to support in draw out waste of oil palm and in the meantime can help economic yield to the country. This study was expected to estimate the effect of power intensity properties of microwave modified oil palm trunk lumber. Microwave treatment of oil palm trunk samples was set of connections by using a microwave operating at 2.45 GHz with the liberated process input power intensity (600-1000W) were studied under the given condition. Impact and compression of the samples were tested. The analysis of properties of the fresh material and dry samples was employed by scanning electron microscopy. Oven drying technique also was involved as a comparison of the conventional drying process in this research. Based on the outcomes of this study, both drying methods improved the characteristics of the specimens.

  8. Emission spectra from direct current and microwave powered Hg lamps at very high pressure

    International Nuclear Information System (INIS)

    Hamady, M; Stafford, L; Lister, G G

    2013-01-01

    Discharge lamps containing mercury at pressures above 100 bar are commercially used in data projectors and television projector systems. Due to their small size, these lamps are difficult to investigate experimentally, but spectral measurements, combined with radiation transport calculations, have provided useful information on the visible spectrum. However, classical spectral line broadening theory is inadequate to describe the UV portion of the spectrum, so self-consistent modelling of these discharges is not possible at present. This paper discusses the differences between discharges containing electrodes and discharges sustained by a microwave (mw) electromagnetic field, on the basis of the experimentally measured temperature profile in an electroded discharge, and a temperature profile computed from a 1D power balance model for a microwave discharge. A model based on the ray-tracing method is employed to simulate the radiation transport in these lamps. The model has been validated by comparing the emission spectrum from dc discharge lamps with those obtained experimentally. The output flux, luminous flux, luminous efficacy, the correlated colour temperature, the chromaticity coordinates and photometric curves of the lamp were then obtained. These results were also compared with those of a theoretically calculated temperature profile for the same lamp, excited by microwave power in the TM 010 mode. (paper)

  9. A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity

    Directory of Open Access Journals (Sweden)

    Juan D. Reverte-Ors

    2017-06-01

    Full Text Available In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs for different food samples (laboratory medium, soup, or fish-based animal by-products. The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

  10. Contamination cannot explain the lack of large-scale power in the cosmic microwave background radiation

    International Nuclear Information System (INIS)

    Bunn, Emory F.; Bourdon, Austin

    2008-01-01

    Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of the Wilkinson Microwave Anisotropy Probe. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural to consider perturbations of the standard model as possible explanations. We show that, as long as the source of the perturbation is statistically independent of the source of the primary CMB anisotropy, no such model can explain this large-scale power deficit. On the contrary, any such perturbation always reduces the probability of obtaining any given low value of large-scale power. We rigorously prove this result when the lack of large-scale power is quantified with a quadratic statistic, such as the quadrupole moment. When a statistic based on the integrated square of the correlation function is used instead, we present strong numerical evidence in support of the result. The result applies to models in which the geometry of spacetime is perturbed (e.g., an ellipsoidal universe) as well as explanations involving local contaminants, undiagnosed foregrounds, or systematic errors. Because the large-scale power deficit is arguably the most significant of the observed anomalies, explanations that worsen this discrepancy should be regarded with great skepticism, even if they help in explaining other anomalies such as multipole alignments.

  11. Experimental Demonstration of Coexistence of Microwave Wireless Communication and Power Transfer Technologies for Battery-Free Sensor Network Systems

    Directory of Open Access Journals (Sweden)

    Satoshi Yoshida

    2013-01-01

    Full Text Available This paper describes experimental demonstrations of a wireless power transfer system equipped with a microwave band communication function. Battery charging using the system is described to evaluate the possibility of the coexistence of both wireless power transfer and communication functions in the C-band. A battery-free wireless sensor network system is demonstrated, and a high-power rectifier for the system is also designed and evaluated in the S-band. We have confirmed that microwave wireless power transfer can coexist with communication function.

  12. Effect of thermal management on the properties of saturable absorber mirrors in high-power mode-locked semiconductor disk lasers

    International Nuclear Information System (INIS)

    Rantamäki, Antti; Lyytikäinen, Jari; Jari Nikkinen; Okhotnikov, Oleg G

    2011-01-01

    The thermal management of saturable absorbers is shown to have a critical impact on a high-power mode-locked disk laser. The absorber with efficient heat removal makes it possible to generate ultrashort pulses with high repetition rates and high power density.

  13. Investigation of the delay time distribution of high power microwave surface flashover

    Science.gov (United States)

    Foster, J.; Krompholz, H.; Neuber, A.

    2011-01-01

    Characterizing and modeling the statistics associated with the initiation of gas breakdown has proven to be difficult due to a variety of rather unexplored phenomena involved. Experimental conditions for high power microwave window breakdown for pressures on the order of 100 to several 100 torr are complex: there are little to no naturally occurring free electrons in the breakdown region. The initial electron generation rate, from an external source, for example, is time dependent and so is the charge carrier amplification in the increasing radio frequency (RF) field amplitude with a rise time of 50 ns, which can be on the same order as the breakdown delay time. The probability of reaching a critical electron density within a given time period is composed of the statistical waiting time for the appearance of initiating electrons in the high-field region and the build-up of an avalanche with an inherent statistical distribution of the electron number. High power microwave breakdown and its delay time is of critical importance, since it limits the transmission through necessary windows, especially for high power, high altitude, low pressure applications. The delay time distribution of pulsed high power microwave surface flashover has been examined for nitrogen and argon as test gases for pressures ranging from 60 to 400 torr, with and without external UV illumination. A model has been developed for predicting the discharge delay time for these conditions. The results provide indications that field induced electron generation, other than standard field emission, plays a dominant role, which might be valid for other gas discharge types as well.

  14. Standard test method for determination of "microwave safe for reheating" for ceramicware

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This test method determines the suitability of ceramicware for use in microwave re-heating applications. Microwave ovens are mainly used for reheating and defrosting frozen foods. Severe thermal conditions can occur while reheating foods. Typical reheating of foods requires one to five min. in the microwave at the highest power settings. Longer periods than five minutes are considered cooking. Cooking test methods and standards are not addressed in this test method. Most ceramicware is minimally absorbing of the microwave energy and will not heat up significantly. Unfortunately there are some products that absorb microwave energy to a greater extent and can become very hot in the microwave and pose a serious hazard. Additionally, the nature of microwave heating introduces radiation in a non-uniform manner producing temperature differentials in the food being cooked as well as the ceramic container holding it. The differential may become great enough to thermal shock the ware and create dangerous condition...

  15. Cosmic microwave background power spectrum estimation and map reconstruction with the expectation-maximization algorithm

    Science.gov (United States)

    Martínez-González, E.; Diego, J. M.; Vielva, P.; Silk, J.

    2003-11-01

    We apply the iterative expectation-maximization algorithm (EM) to estimate the power spectrum of the cosmic microwave background (CMB) from multifrequency microwave maps. In addition, we are also able to provide a reconstruction of the CMB map. By assuming that the combined emission of the foregrounds plus the instrumental noise is Gaussian distributed in Fourier space, we have simplified the EM procedure, finding an analytical expression for the maximization step. By using the simplified expression, the CPU time can be greatly reduced. We test the stability of our power spectrum estimator with realistic simulations of Planck data, including point sources and allowing for spatial variation of the frequency dependence of the Galactic emissions. Without prior information about any of the components, our new estimator can recover the CMB power spectrum up to scales l~ 1500 with less than 10 per cent error. This result is significantly improved if the brightest point sources are removed before applying our estimator. In this way, the CMB power spectrum can be recovered up to l~ 1700 with 10 per cent error and up to l~ 2100 with 50 per cent error. This result is very close to the one that would be obtained in the ideal case of only CMB plus white noise, for which all our assumptions are satisfied. Moreover, the EM algorithm also provides a straightforward mechanism for reconstructing the CMB map. The recovered cosmological signal shows a high degree of correlation (r= 0.98) with the input map and low residuals.

  16. Disintegration of water molecules in a steam-plasma torch powered by microwaves

    Science.gov (United States)

    Uhm, Han S.; Kim, Jong H.; Hong, Yong C.

    2007-07-01

    A pure steam torch is generated by making use of 2.45GHz microwave. Steam from a steam generator enters the discharge tube as a swirl gas at a temperature higher than 150°C. This steam becomes a working gas and produces a stable steam torch. The torch volume is almost linearly proportional to the microwave power. The temperature of the torch flame is measured by making use of optical spectroscopy and a thermocouple device. Two distinctive regions are exhibited, a bright, whitish region of a high-temperature zone and a reddish, dimmer region of a relatively low-temperature zone. The bright, whitish region is a typical torch based on plasma species and the reddish, dimmer region is hydrogen burning in oxygen. Study of water molecule disintegration and gas temperature effects on the molecular fraction characteristics in steam-plasma of a microwave plasma torch at the atmospheric pressure is carried out. An analytical investigation of water disintegration indicates that a substantial fraction of water molecules disintegrate and form other compounds at high temperatures in the steam-plasma torch. Emission profiles of the hydroxide radical and water molecules confirm the theoretical predictions of water disintegration in the torch.

  17. Effects of ordered mesoporous structure and La-doping on the microwave absorbing properties of CoFe2O4

    Science.gov (United States)

    Shang, Tao; Lu, Qingshan; Chao, Luomeng; Qin, Yanli; Yun, Yuehou; Yun, Guohong

    2018-03-01

    Low-density ordered mesoporous CoFe2O4 (Osbnd CFO) and CoLa0.12Fe1.88O4 (Osbnd CLFO) are prepared by nanocasting method using mesoporous silica SBA-15 as a hard-template. The crystal structure, surface chemical state, magnetic properties and electromagnetic parameters are characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement, X-ray photoelectron spectroscopy, physical property measurement system and vector network analyzer. The results show that all the samples formed a single phase with cubic spinel structure. Meanwhile Osbnd CFO and Osbnd CLFO possess a highly ordered mesostructure. Comparing with particle CoFe2O4 (P-CFO), Osbnd CFO with high specific surface area exhibits lower magnetic saturation (Ms), higher imaginary part of complex permittivity (ε‧‧) and imaginary part of the complex permeability (μ‧‧). The minimum reflection loss (RL) of Osbnd CFO reaches -27.36 dB with a matching thickness of 3.0 mm. The enhancement of the microwave absorbing performances of Osbnd CFO can be mainly attributed to the good impedance matching, high electromagnetic wave attenuation and multiple reflections of electromagnetic wave originated from the ordered mesoporous structure. The Ms of Osbnd CLFO decreases after La3+ doping, while the specific surface area, coercivity value, ε‧‧ and μ‧‧ of Osbnd CLFO increase. The minimum RL of Osbnd CLFO reaches -46.47 dB with a thickness of 3.0 mm, and the effective absorption frequency bandwidth reaches 4.9 GHz.

  18. High power water load for microwave and millimeter-wave radio frequency sources

    Science.gov (United States)

    Ives, R. Lawrence; Mizuhara, Yosuke M.; Schumacher, Richard V.; Pendleton, Rand P.

    1999-01-01

    A high power water load for microwave and millimeter wave radio frequency sources has a front wall including an input port for the application of RF power, a cylindrical dissipation cavity lined with a dissipating material having a thickness which varies with depth, and a rear wall including a rotating reflector for the reflection of wave energy inside the cylindrical cavity. The dissipation cavity includes a water jacket for removal of heat generated by the absorptive material coating the dissipation cavity, and this absorptive material has a thickness which is greater near the front wall than near the rear wall. Waves entering the cavity reflect from the rotating reflector, impinging and reflecting multiple times on the absorptive coating of the dissipation cavity, dissipating equal amounts of power on each internal reflection.

  19. Gas mixing enhanced by power modulations in atmospheric pressure microwave plasma jet

    Science.gov (United States)

    Voráč, J.; Potočňáková, L.; Synek, P.; Hnilica, J.; Kudrle, V.

    2016-04-01

    Microwave plasma jet operating in atmospheric pressure argon was power modulated by audio frequency sine envelope in the 102 W power range. Its effluent was imaged using interference filters and ICCD camera for several different phases of the modulating signal. The combination of this fast imaging with spatially resolved optical emission spectroscopy provides useful insights into the plasmachemical processes involved. Phase-resolved schlieren photography was performed to visualize the gas dynamics. The results show that for higher modulation frequencies the plasma chemistry is strongly influenced by formation of transient flow perturbation resembling a vortex during each period. The perturbation formation and speed are strongly influenced by the frequency and power variations while they depend only weakly on the working gas flow rate. From application point of view, the perturbation presence significantly broadened lateral distribution of active species, effectively increasing cross-sectional area suitable for applications.

  20. The Nanophysics of Electron Emission and Breakdown for High Power Microwave Source

    Science.gov (United States)

    2009-12-21

    structures. 22 4. Personnel Supported   4.1. UC­Berkeley  Prof. John Verboncoeur (faculty) Prof. Charles K. Birdsall (faculty) Dr. Hyun-Chul... Dickens , Co-PI Dr. Hermann Krompholz Dr. John Krile, post-doctoral research associate John Krile, Ph. D. Student EE Greg Edmiston, Ph. D. Student EE...Science 36, 946 - 947 (2008). 4. Edmiston, G., Krile, J., Neuber, A., Dickens , J., and Krompholz, H., “High Power Microwave Surface Flashover of a Gas

  1. Modeling of low-pressure microwave discharges in Ar, He, and O sub 2; Similarity laws for the maintenance field and mean power transfer

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, C.M.; Alves, L.L.; Pinheiro, M.; Sa, A.B. (Centro de Electrodinamica de Universidade, Tecnica de Lisboa, Instituto Superior Tecnico, 1096 Lisboa Codex (PT))

    1991-04-01

    A kinetic study of low-pressure microwave discharges in Ar, He, and O{sub 2} is carried out using electron-transport parameters and rate coefficients derived from solutions to the Boltzmann equation, together with the continuity and transport equations for the charged particles, taking into account stepwise-ionization processes. The Boltzmann equation is solved over a wide range of the applied frequency, {omega}/2{pi}, but assuming that {omega} {gt} {tau}{sup {minus}1}{sub e}, {tau}{sub e}, denoting the characteristic time for electron-energy relaxation by collisions. The formulation provides discharge characteristics for the maintenance field and for mean absorbed power per electron in the three gases, which are shown to agree satisfactorily with experimental data obtained from surface-wave discharges. In this paper it is shown that such an agreement would not always be obtained without consideration of the role played by stepwise-ionization processes in sustaining the discharge.

  2. Protecting Against Damage from Refraction of High Power Microwaves in the DIII-D Tokamak

    Science.gov (United States)

    Lohr, John; Brambila, Rigo; Cengher, Mirela; Chen, Xi; Gorelov, Yuri; Grosnickle, William; Moeller, Charles; Ponce, Dan; Prater, Ron; Torrezan, Antonio; Austin, Max; Doyle, Edward; Hu, Xing; Dormier, Calvin

    2017-07-01

    Several new protective systems are being installed on the DIII D tokamak to increase the safety margins for plasma operations with injected ECH power at densities approaching cutoff. Inadvertent overdense operation has previously resulted in reflection of an rf beam back into a launcher causing extensive arcing and melt damage on one waveguide line. Damage to microwave diagnostics, which are located on the same side of the tokamak as the ECH launchers, also has occurred. Developing a reliable microwave based interlock to protect the many vulnerable systems in DIII-D has proved to be difficult. Therefore, multiple protective steps have been taken to reduce the risk of damage in the future. Among these is a density interlock generated by the plasma control system, with setpoint determined by the ECH operators based on rf beam trajectories and plasma parameters. Also installed are enhanced video monitoring of the launchers, and an ambient light monitor on each of the waveguide systems, along with a Langmuir probe at the mouth of each launcher. Versatile rf monitors, measuring forward and reflected power in addition to the mode content of the rf beams, have been installed as the last miter bends in each waveguide line. As these systems are characterized, they are being incorporated in the interlock chains, which enable the ECH injection permits. The diagnostics most susceptible to damage from the ECH waves have also been fitted with a variety of protective devices including stripline filters, thin resonant notch filters tuned to the 110 GHz injected microwave frequency, blazed grating filters and shutters. Calculations of rf beam trajectories in the plasmas are performed using the TORAY ray tracing code with input from kinetic profile diagnostics. Using these calculations, strike points for refracted beams on the vacuum vessel are calculated, which allows evaluation of the risk of damage to sensitive diagnostics and hardware.

  3. Protecting Against Damage from Refraction of High Power Microwaves in the DIII-D Tokamak

    Directory of Open Access Journals (Sweden)

    Lohr John

    2017-01-01

    Full Text Available Several new protective systems are being installed on the DIII D tokamak to increase the safety margins for plasma operations with injected ECH power at densities approaching cutoff. Inadvertent overdense operation has previously resulted in reflection of an rf beam back into a launcher causing extensive arcing and melt damage on one waveguide line. Damage to microwave diagnostics, which are located on the same side of the tokamak as the ECH launchers, also has occurred. Developing a reliable microwave based interlock to protect the many vulnerable systems in DIII-D has proved to be difficult. Therefore, multiple protective steps have been taken to reduce the risk of damage in the future. Among these is a density interlock generated by the plasma control system, with setpoint determined by the ECH operators based on rf beam trajectories and plasma parameters. Also installed are enhanced video monitoring of the launchers, and an ambient light monitor on each of the waveguide systems, along with a Langmuir probe at the mouth of each launcher. Versatile rf monitors, measuring forward and reflected power in addition to the mode content of the rf beams, have been installed as the last miter bends in each waveguide line. As these systems are characterized, they are being incorporated in the interlock chains, which enable the ECH injection permits. The diagnostics most susceptible to damage from the ECH waves have also been fitted with a variety of protective devices including stripline filters, thin resonant notch filters tuned to the 110 GHz injected microwave frequency, blazed grating filters and shutters. Calculations of rf beam trajectories in the plasmas are performed using the TORAY ray tracing code with input from kinetic profile diagnostics. Using these calculations, strike points for refracted beams on the vacuum vessel are calculated, which allows evaluation of the risk of damage to sensitive diagnostics and hardware.

  4. Microwave undulator

    International Nuclear Information System (INIS)

    Batchelor, K.

    1986-03-01

    The theory of a microwave undulator utilizing a plane rectangular waveguide operating in the TE/sub 10n/ mode and other higher order modes is presented. Based on this, a possible undulator configuration is analyzed, leading to the conclusion that the microwave undulator represents a viable option for undulator wavelength down to about 1 cm where peak voltage and available microwave power considerations limit effectiveness. 4 refs., 4 figs

  5. The compound Chinese medicine "Kang Fu Ling" protects against high power microwave-induced myocardial injury.

    Directory of Open Access Journals (Sweden)

    Xueyan Zhang

    Full Text Available BACKGROUND: The prevention and treatment of Microwave-caused cardiovascular injury remains elusive. This study investigated the cardiovascular protective effects of compound Chinese medicine "Kang Fu Ling" (KFL against high power microwave (HPM-induced myocardial injury and the role of the mitochondrial permeability transition pore (mPTP opening in KFL protection. METHODS: Male Wistar rats (100 were divided into 5 equal groups: no treatment, radiation only, or radiation followed by treatment with KFL at 0.75, 1.5, or 3 g/kg/day. Electrocardiography was used to Electrophysiological examination. Histological and ultrastructural changes in heart tissue and isolated mitochondria were observed by light microscope and electron microscopy. mPTP opening and mitochondrial membrane potential were detected by confocal laser scanning microscopy and fluorescence analysis. Connexin-43 (Cx-43 and endothelial nitric oxide synthase (eNOS were detected by immunohistochemistry. The expression of voltage-dependent anion channel (VDAC was detected by western blotting. RESULTS: At 7 days after radiation, rats without KFL treatment showed a significantly lower heart rate (P<0.01 than untreated controls and a J point shift. Myocyte swelling and rearrangement were evident. Mitochondria exhibited rupture, and decreased fluorescence intensity, suggesting opening of mPTP and a consequent reduction in mitochondrial membrane potential. After treatment with 1.5 g/kg/day KFL for 7 d, the heart rate increased significantly (P<0.01, and the J point shift was reduced flavorfully (P<0.05 compared to untreated, irradiated rats; myocytes and mitochondria were of normal morphology. The fluorescence intensities of dye-treated mitochondria were also increased, suggesting inhibition of mPTP opening and preservation of the mitochondrial membrane potential. The microwave-induced decrease of Cx-43 and VDAC protein expression was significantly reversed. CONCLUSION: Microwave radiation can

  6. Metamaterial Absorbers for Microwave Detection

    Science.gov (United States)

    2015-06-01

    adhesives, resulting in inaccurate dimensions. The conformal infusion of epoxy resin in woven glass of FR4 material creating a non -uniform surface and the...and a non -periodic, gradient medium, from [19]. ..........................................................................................16 Figure 5...29 Figure 17. Measured reflection data and filtered data comparison. ..................................30 Figure 18. Direct measurement and Fourier

  7. Detection of the power spectrum of cosmic microwave background lensing by the Atacama Cosmology Telescope.

    Science.gov (United States)

    Das, Sudeep; Sherwin, Blake D; Aguirre, Paula; Appel, John W; Bond, J Richard; Carvalho, C Sofia; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, John P; Irwin, Kent D; Klein, Jeff; Kosowsky, Arthur; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; Wollack, Ed

    2011-07-08

    We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2° angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda cold dark matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4σ detection of the lensing signal measures the amplitude of density fluctuations to 12%.

  8. Effect of Passivation on Microwave Power Performances of AlGaN/GaN/Si HEMTs

    Directory of Open Access Journals (Sweden)

    H. MOSBAHI

    2014-05-01

    Full Text Available This paper reports on the use of plasma assisted molecular beam epitaxy of AlGaN/GaN high electron mobility transistors (HEMTs grown on silicon substrate. Surface passivation effects on AlGaN/GaN HEMTs were studied using SiO2/SiN dielectric layers grown by plasma enhanced chemical vapor deposition. The direct current measurement, pulsed characteristics and microwave small-signal characteristics were studied before and after passivation. An improvement of drain-source current density and the extrinsic transconductance was observed on the passivated HEMTs when compared with the unpassivated HEMTs. An enhancement of cut-off frequency (ft and maximum power gain (fmax was also observed for the devices with full SiO2/SiN passivation. A good correlation is found between pulsed and power measurements.

  9. Characteristics of a four element gyromagnetic nonlinear transmission line array high power microwave source

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J. M., E-mail: jared.johnson@ttu.edu; Reale, D. V.; Garcia, R. S.; Cravey, W. H.; Neuber, A. A.; Dickens, J. C.; Mankowski, J. J. [Center for Pulsed Power and Power Electronics Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Krile, J. T. [Department of Electromagnetics and Sensor Systems, Naval Surface Warfare Center - Dahlgren Division, Dahlgren, Virginia 22448 (United States)

    2016-05-15

    In this paper, a solid-state four element array gyromagnetic nonlinear transmission line high power microwave system is presented as well as a detailed description of its subsystems and general output capabilities. This frequency agile S-band source is easily adjusted from 2-4 GHz by way of a DC driven biasing magnetic field and is capable of generating electric fields of 7.8 kV/m at 10 m correlating to 4.2 MW of RF power with pulse repetition frequencies up to 1 kHz. Beam steering of the array at angles of ±16.7° is also demonstrated, and the associated general radiation pattern is detailed.

  10. SPS microwave subsystem potential impacts and benefits. [environmental and societal effects of Solar Power System construction and operation

    Science.gov (United States)

    Dickinson, R. M.

    1978-01-01

    The paper examines the possible environmental and societal effects of the construction, installation, and operation of the space end and earth end of the microwave power transmission subsystem that delivers satellite power system (SPS) energy (at about 5 GW per beam) to the power grid on earth. The intervening propagation medium near the earth is also considered. Separate consideration is given to the spacecraft transmitting array, propagation in the ionosphere, and the ground-based rectenna. Radio frequency interference aspects are also discussed.

  11. Effects of low power microwave radiation on biological activity of Collagenase enzyme and growth rate of S. Cerevisiae yeast

    Science.gov (United States)

    Alsuhaim, Hamad S.; Vojisavljevic, Vuk; Pirogova, E.

    2013-12-01

    Recently, microwave radiation, a type/subset of non-ionizing electromagnetic radiation (EMR) has been widely used in industry, medicine, as well as food technology and mobile communication. Use of mobile phones is rapidly growing. Four years from now, 5.1 billion people will be mobile phone users around the globe - almost 1 billion more mobile users than the 4.3 billion people worldwide using them now. Consequently, exposure to weak radiofrequency/microwave radiation generated by these devices is markedly increasing. Accordingly, public concern about potential hazards on human health is mounting [1]. Thermal effects of radiofrequency/microwave radiation are very well-known and extensively studied. Of particular interest are non-thermal effects of microwave exposures on biological systems. Nonthermal effects are described as changes in cellular metabolism caused by both resonance absorption and induced EMR and are often accompanied by a specific biological response. Non-thermal biological effects are measurable changes in biological systems that may or may not be associated with adverse health effects. In this study we studied non-thermal effects of low power microwave exposures on kinetics of L-lactate dehydrogenase enzyme and growth rate of yeast Saccharomyces Cerevisiae strains type II. The selected model systems were continuously exposed to microwave radiation at the frequency of 968MHz and power of 10dBm using the designed and constructed (custom made) Transverse Electro-Magnetic (TEM) cell [2]. The findings reveal that microwave radiation at 968MHz and power of 10dBm inhibits L-lactate dehydrogenase enzyme activity by 26% and increases significantly (15%) the proliferation rate of yeast cells.

  12. Microwave Absorbing and Magnetic Properties of the Polyaniline-Co0.7Cr0.1Zn0.2Fe2O4 Composites

    Directory of Open Access Journals (Sweden)

    Fanling MENG

    2016-09-01

    Full Text Available The spinel cobalt chromium zinc ferrites (Co0.7Cr0.1Zn0.2Fe2O4 and the polyaniline (PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites were prepared by polyacrylamide gel and an in situ polymerization method, respectively. The structure of the synthesized material was characterized by X-ray diffraction (XRD and Fourier transform infrared spectrometer (FT-IR, which shows that the spinel Co0.7Cr0.1Zn0.2Fe2O4 ferrites and the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are obtained. Because a small amount Co2+ ion of the octahedron ferrite is replaced by Cr3+ ions, the lattice constant of the Co0.8Zn0.2Fe2O4 ferrites reduces from 0.8409nm to 0.8377nm. The magnetic properties of the two materials were investigated using vibrating sample magnetometer (VSM. The VSM results confirm that the saturation magnetization (Ms, remnant magnetization (Mr and coercive force (Hc of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are 8.80emu/g, 3.14emu/g and 37.22kA/m, respectively, which are smaller than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites. The microwave absorbing capability of the two materials were studied by wave-guide method. In the measuring frequency range of 5.0~20.0GHz, two reflection loss maximum value of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites appear at 14.1GHz and 17.9GHz with -13.17dB and -15.36dB, respectively, which is obviously higher than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7177

  13. A facile synthesis of superparamagnetic hybrid hollow nanospheres based on monodisperse nickel–zinc ferrite/polyethylene glycol and their electromagnetic, microwave absorbing properties

    International Nuclear Information System (INIS)

    Li, Quanfang; Li, Yanfeng; Li, Xin; Chen, Suli; Zhang, Sidi; Wang, Jianzhi; Hou, Chen

    2014-01-01

    Highlights: • A superparamagnetic hybrid nanocomposite based on Ni–Zn ferrite and polyethylene glycol (PEG) was prepared. • The minimum reflection loss (RL) reaches −50.15 dB with the volume fraction of 35% just at the thickness of 2.9 mm. • The optimal RL is –46.43 dB with the volume fraction of 45%, while the specimen thickness is only 2.2 mm. • A formation mechanism is proposed according to FTIR, XRD, TGA, TEM, SAED and a series of experiments. - Abstract: Ni 0.3 Zn 0.5 Fe 2 O 4 /polyethylene glycol (PEG) hybrid hollow nanospheres have been successfully prepared using a facile synthesis method. Their shape, size and structure have been characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The determination from inductively coupled plasma (ICP) indicates that the atomic ratio of Ni/Zn/Fe is 3:5:20, the results from fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA) show that the PEG is also contained by the nanospheres, and thus an expression of Ni 0.3 Zn 0.5 Fe 2 O 4 /PEG is presented. A formation mechanism is suggested according to FTIR, XRD, TGA, TEM and selected area electron diffraction (SAED) with different reaction time: 4, 6, 8, 10, and 12 h. The magnetic measurement of the Ni 0.3 Zn 0.5 Fe 2 O 4 /PEG nanospheres reveals that the saturation magnetization is 86.26 emu g −1 . The sample of 35% volume fraction (Ni 0.3 Zn 0.5 Fe 2 O 4 /PEG/paraffin containing Ni 0.3 Zn 0.5 Fe 2 O 4 /PEG nanospheres) exhibits a minimum reflection loss (RL) of −50.15 dB at about 8.8 GHz in the range of 2–18 GHz. The Ni 0.3 Zn 0.5 Fe 2 O 4 /PEG nanospheres show unique morphology, favorable magnetism, as well as excellent microwave absorbing properties

  14. Influence of multi-walled carbon nanotubes (MWCNTs) volume percentage on the magnetic and microwave absorbing properties of BaMg0.5Co0.5TiFe10O19/MWCNTs nanocomposites

    International Nuclear Information System (INIS)

    Alam, Reza Shams; Moradi, Mahmood; Nikmanesh, Hossein

    2016-01-01

    Graphical abstract: Reflection losses of (a) doped barium hexaferrite, BaMg 0.5 Co 0.5 TiFe 10 O 19 , sample and their nanocomposites with (b) 4 vol. (c) 8 vol. and (d) 12 vol.% of MWCNTs are presented. - Highlights: • BaMg 0.5 Co 0.5 TiFe 10 O 19 /MWCNTs nanocomposites were synthesized. • The structural, magnetic and microwave absorption properties were investigated. • The microwave absorption is strongly influenced by volume percentage of MWCNTs. • The nanocomposite with 8 vol.% of MWCNTs can be proposed as a wideband absorber. - Abstract: In this study BaMg 0.5 Co 0.5 TiFe 10 O 19 /MWCNTs nanocomposites with different amount of MWCNTs (0, 4, 8 and 12 vol.%) were synthesized. Here, the X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to demonstrate the structural and morphological characteristics of the prepared samples. XRD along with FTIR examinations exhibited that the nanocomposites were successfully synthesized. Vibrating sample magnetometer (VSM) showed the relatively strong dependence of saturation magnetization and coercivity on the volume percentage of MWCNTs. The microwave evaluation also confirmed that the complex permittivity of nanocomposites could be enhanced by adding MWCNTs. Finally, the nanocomposite with 8% vol. of MWCNTs exhibited the best microwave absorption performance among the samples.

  15. Solid waste treatment by microwave irradiation technology

    International Nuclear Information System (INIS)

    Farid Nasir Ani; Arshad Adam Salema

    2010-01-01

    Strict legislative laws both nationally and internationally have enforced the waste management expertise to develop new technologies with regard to waste treatment facilities. This is because the waste is directly linked to human development, technologically, socially and environmentally. In present research work, solid (oil palm biomass and scrap tire) wastes were subjected to microwave irradiation system. Since these wastes are found abundantly locally as well as in surrounding areas of Malaysia. The aim of the present work was to investigate the pyrolysis behavior of oil palm biomass and scrap tires under microwave radiation. Microwave induced fast pyrolysis process was used to produce pyrolysis-oil by mixing waste materials with suitable microwave absorber at different ratio. A modified domestic microwave system with maximum power of 1000 W and 2450 MHz frequency was used. The results showed that the ratio of biomass to microwave absorber plays a significant role on the yield of bio-oil. Temperature profiles revealed the heating characteristics of the waste materials. Generation of heat within the material under microwave is so instantaneous that it takes few seconds to reach high temperature which otherwise is difficult to achieve in conventional systems. Hence, the time and energy consumption of process is significantly reduced by using microwaves irradiation technique. This leads to a lower process cost. Pyrolysis oil from scrap tires showed high heating values. Bio-oil from oil palm biomass showed lower viscosity due to presence of water content and compounds such as phenol, aldehyde and others were detected through FT-IR analysis. Biomass char image analysis showed porous nature when treated with microwave technique however it showed large cracks when treated with conventional electrical furnace. Overall, the results revealed that the waste can be treated efficiently, effectively and environmentally by using new microwave irradiation technique. (author)

  16. Plasma Physics Challenges of MM-to-THz and High Power Microwave Generation

    Science.gov (United States)

    Booske, John

    2007-11-01

    Homeland security and military defense technology considerations have stimulated intense interest in mobile, high power sources of millimeter-wave to terahertz regime electromagnetic radiation, from 0.1 to 10 THz. While sources at the low frequency end, i.e., the gyrotron, have been deployed or are being tested for diverse applications such as WARLOC radar and active denial systems, the challenges for higher frequency sources have yet to be completely met for applications including noninvasive sensing of concealed weapons and dangerous agents, high-data-rate communications, and high resolution spectroscopy and atmospheric sensing. The compact size requirements for many of these high frequency sources requires miniscule, micro-fabricated slow wave circuits with high rf ohmic losses. This necessitates electron beams with not only very small transverse dimensions but also very high current density for adequate gain. Thus, the emerging family of mm-to-THz e-beam-driven vacuum electronics devices share many of the same plasma physics challenges that currently confront ``classic'' high power microwave (HPM) generators [1] including bright electron sources, intense beam transport, energetic electron interaction with surfaces and rf air breakdown at output windows. Multidimensional theoretical and computational models are especially important for understanding and addressing these challenges. The contemporary plasma physics issues, recent achievements, as well as the opportunities and outlook on THz and HPM will be addressed. [1] R.J. Barker, J.H. Booske, N.C. Luhmann, and G.S. Nusinovich, Modern Microwave and Millimeter-Wave Power Electronics (IEEE/Wiley, 2005).

  17. Role of advanced RF/microwave technology and high power switch technology for developing/upgrading compact/existing accelerators

    International Nuclear Information System (INIS)

    Shrivastava, Purushottam

    2001-01-01

    With the advances in high power microwave devices as well as in microwave technologies it has become possible to go on higher frequencies at higher powers as well as to go for newer devices which are more efficient and compact and hence reducing the power needs as well as space and weight requirement for accelerators. New devices are now available in higher frequency spectrum for example at C-Band, X-band and even higher. Also new devices like klystrodes/Higher Order Mode Inductive Output Tubes (HOM IOTs) are now becoming competitors for existing tubes which are in use at present accelerator complexes. The design/planning of the accelerators used for particle physics research, medical accelerators, industrial irradiation, or even upcoming Driver Accelerators for Sub Critical Reactors for nuclear power generation are being done taking into account the newer technologies. The accelerators which use magnetrons, klystrons and similar devices at S-Band can be modified/redesigned with devices at higher frequencies like X-Band. Pulsed accelerators need high power high voltage pulsed modulators whereas CW accelerators need high voltage power supplies for functioning of RF / Microwave tubes. There had been a remarkable growth in the development and availability of solid state switches both for switching the pulsed modulators for microwave tubes as well as for making high frequency switch mode power supplies. Present paper discusses some of the advanced devices/technologies in this field as well as their capability to make advanced/compact/reliable accelerators. Microwave systems developed/under development at Centre for Advanced Technology are also discussed briefly along with some of the efforts done to make them compact. An overview of state of art vacuum tube devices and solid state switch technologies is given. (author)

  18. Plasma physics and related challenges of millimeter-wave-to-terahertz and high power microwave generationa)

    Science.gov (United States)

    Booske, John H.

    2008-05-01

    Homeland security and military defense technology considerations have stimulated intense interest in mobile, high power sources of millimeter-wave (mmw) to terahertz (THz) regime electromagnetic radiation, from 0.1 to 10THz. While vacuum electronic sources are a natural choice for high power, the challenges have yet to be completely met for applications including noninvasive sensing of concealed weapons and dangerous agents, high-data-rate communications, high resolution radar, next generation acceleration drivers, and analysis of fluids and condensed matter. The compact size requirements for many of these high frequency sources require miniscule, microfabricated slow wave circuits. This necessitates electron beams with tiny transverse dimensions and potentially very high current densities for adequate gain. Thus, an emerging family of microfabricated, vacuum electronic devices share many of the same plasma physics challenges that are currently confronting "classic" high power microwave (HPM) generators including long-life bright electron beam sources, intense beam transport, parasitic mode excitation, energetic electron interaction with surfaces, and rf air breakdown at output windows. The contemporary plasma physics and other related issues of compact, high power mmw-to-THz sources are compared and contrasted to those of HPM generation, and future research challenges and opportunities are discussed.

  19. A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source

    Science.gov (United States)

    Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de

    2017-06-01

    A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

  20. Design and fabrication of high power microwave window for 4 MeV LINAC

    International Nuclear Information System (INIS)

    Syunry, T.S.; Bhide, S.S.; Madan, R.S.; Das, S.; D'Sa, J.M.

    1988-01-01

    One of the critical components in the design and fabrication of 4 MeV LINAC is the R.F. window, through which 2 MW pulse R.F. power at 3 GHZ passes from the high pressure side to the chain of cavities under very high vacuum. Readymade windows, which can be incorporated in the LINAC are not easily available. These windows were fabricated inhouse, based upon some standard designs available in literature. However, the fabrication technique proved to be very difficult. The windows have been made successfully and tested for microwave performance. They were also rigorously thermally cycled and pressure tested. Fabrication details, test procedures and data are reported in this paper. (author). 5 figs., 2 tables

  1. GaN MODFET microwave power technology for future generation radar and communications systems

    Science.gov (United States)

    Grider, D. E.; Nguyen, N. X.; Nguyen, C.

    1999-08-01

    In order to gain a better understanding of the role that GaN MODFET technology will play in future generation radar and communications systems, a comparison of the state-of-the-art performance of alternative microwave power technologies will be reviewed. The relative advantages and limitations of each technology will be discussed in relation to system needs. Device results from recent MBE-grown GaN MODFETs will also be presented. In particular, 0.25 μm gate GaN MODFETs grown by MBE have been shown to exhibit less than 5% variation in maximum drain current density ( Idmax) from the center to the edge of a 2 inch wafer. This level of uniformity is a substantially higher than that normally found in MOCVD-grown GaN devices (˜28% variation). In addition, evidence is also presented to demonstrate the excellent reproducibility of MBE-grown GaN MODFETs.

  2. Applications of Microwave Antenna Array for Wireless Power Transmission and Radar Imaging in Complex Environment

    Science.gov (United States)

    Zhang, Ce

    The focus of my research interests lies in the application of microwave antenna array system and array signal processing techniques to problems in wireless power transmission and radar imaging. The two research areas share the same underlying mathematical principle of time reversality of electromagnetic wave propagation. Based on this principle, the array antenna system and the associated signal processing algorithm are further improved to adapt to different scenarios. In my dissertation, the rest part presents an optimal algorithm for wireless power transmission with beamforming array. The optimal weight distribution on antenna array elements is found based on time reversal eigenmode technique. Our method is adaptive to the medium of the channel and can be applied to arbitrarily positioned antenna without degradation of efficiency. This novel method is analytically studied and verified with numerical electromagnetic simulations. The second part presents a new problem called "Hard-Wall Radar Imaging" (HWRI) has been proposed when the electromagnetic waves cannot penetrate the shielding walls (such as metallic walls). The research methodology involves algorithm development combined with experimental results to gain more insights into the real microwave imaging system. First, we implemented the imaging system with the conventional time reversal DORT (Decomposition of Time-Reversal Operator) imaging algorithm and adapted it into a new signal processing technique (multiplicative array technique) to obtain the image in the proposed scenario. Second, after having identified the drawbacks of the rest imaging system, the imaging system is improved to distributed MIMO radar configuration. The new imaging algorithm is also developed based on the techniques of Direction-of-Arrival(DoA) estimation and adaptive nulling. From this algorithm, the experimental results show that the new imaging system can localize two targets correctly. To resolve the problem of spurious clutter

  3. Observations of electron heating during 28 GHz microwave power application in proto-MPEX

    Science.gov (United States)

    Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Diem, S. J.; Green, D. L.; Kafle, N.; Rapp, J.; Proto-MPEX Team

    2018-02-01

    The Prototype Material Plasma Exposure Experiment at the Oak Ridge National Laboratory utilizes a variety of power systems to generate and deliver a high heat flux plasma onto the surface of material targets. In the experiments described here, a deuterium plasma is produced via a ˜100 kW, 13.56 MHz RF helicon source, to which ˜20 kW of 28 GHz microwave power is applied. The electron density and temperature profiles are measured using a Thomson scattering (TS) diagnostic, and indicate that the electron density is centrally peaked. In the core of the plasma column, the electron density is higher than the cut-off density (˜0.9 × 1019 m-3) for the launched mixture of X- and O-mode electron cyclotron heating waves to propagate. TS measurements indicate electron temperature increases from ˜5 eV to ˜20 eV during 28 GHz power application when the neutral deuterium pressure is reduced below 0.13 Pa (˜1 mTorr.).

  4. High power microwave transmission systems for electron cyclotron resonance plasma heating

    International Nuclear Information System (INIS)

    Vernon, R.J.

    1989-08-01

    This progress report is for the fourth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRF transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The development and testing of new and improved components for such systems and underlying theory, where necessary, is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. During the last year, we developed a preliminary design for a Te 15,2 --TE 15, 1 mode converter for the MIT 150 GHz gyrotron and considered its performance as the frequency and mode was step tuned. A preliminary design for a combined uptaper and TE 15,2 --TE 15,1 converter for possible use with the Varian 140 GHz gyrotron was also developed. Work was begun on a combined TE 15,n uptaper -- mode converter to produce a mode combination which would reduce microwave radiation into an azimuthal waveguide gap. Simple models for the radiation from TE 0n and TM 0n Vlasov launcher baffles were developed and compared with measurements which were taken in our radiation pattern measurement facility. Work began on testing possible methods for generating high azimuthal index rotating modes. Work on the further refinement of the method of mode content determination from open-end radiation pattern measurement was carried out. An investigation of the Wiener-Hopf method for obtaining open- end radiation patterns produced improved radiation patterns for the TE 0n modes in a circular waveguide. 15 refs., 15 figs

  5. Microwave interaction with nonuniform hydrogen gas in carbon nanotubes

    International Nuclear Information System (INIS)

    Babaei, S.; Babaei, Sh.

    2009-01-01

    In this paper we study the reflection, absorption, and transmission of microwave from nonuniform hydrogen gas in carbon nanotubes, grown by iron-catalyzed high-pressure carbon monoxide disproportionate (HiPco) process. A discussion on the effect of various hydrogen gas parameters on the reflected power, absorbed power, and transmitted power is presented. The nonuniform hydrogen gas slab is modeled by a series of subslabs. The overall number density profile across the whole slab follows a parabolic function. The total reflected, absorbed, and transmitted powers are then deduced and their functional dependence on the number density, collision frequency, and angle of propagation is studied

  6. Monodisperse Ni{sub x}Fe{sub 3-x}O{sub 4} nanospheres: Metal-ion-steered size/composition control mechanism, static magnetic and enhanced microwave absorbing properties

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Kedan, E-mail: 17858961652@163.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Liu, Yun, E-mail: liuyun650403@163.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Pan, Yefei, E-mail: 3083780256@qq.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Wang, Ru, E-mail: 631081137@qq.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Hu, Panbing, E-mail: 1036855954@qq.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); He, Rujia, E-mail: 634185782@qq.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Zhang, Lingli, E-mail: 786510121@qq.com [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Tong, Guoxiu, E-mail: tonggx@zjnu.cn [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China)

    2017-05-15

    Highlights: • A metal-ion-steered solvothermal method for synthesizing Ni{sub x}Fe{sub 3-x}O{sub 4} nanospheres. • Proposing an in situ-reduction, coordination-precipitation transformation mechanism. • Investigating size- and composition-dependent static magnetic properties. • Investigating size- and composition-dependent microwave absorbing properties. - Abstract: An easy metal-ion-steered solvothermal method was developed for the one-step synthesis of monodisperse, uniform Ni{sub x}Fe{sub 3-x}O{sub 4} polycrystalline nanospheres with tunable sphere diameter (40–400 nm) and composition (0 ≤ x ≤ 0.245) via changing just Ni{sup 2+}/Fe{sup 3+} molar ratio (γ). With g increased from 0:1 to 2:1, sphere diameter gradually decreased and crystal size exhibited an inversed U-shaped change tendency, followed by increased Ni/Fe atom ratio from 0% to 0.0888%. An in situ-reduction, coordination-precipitation transformation mechanism was proposed to interpret the metal-ion-steered growth. Size- and composition-dependent static magnetic and microwave absorbing properties were systematically investigated. Saturation magnetization declines with g in a Boltzmann model due to the changes of crystal size, sphere diameter, and Ni content. The coercivity reaches a maximum at γ = 0.75:1 because of the critical size of Fe{sub 3}O{sub 4} single domain (25 nm). Studies on microwave absorption reveal that 150–400 nm Fe{sub 3}O{sub 4} nanospheres mainly obey the quarter-wavelength cancellation model with the single-band absorption; 40–135 nm Ni{sub x}Fe{sub 3-x}O{sub 4} nanospheres (0 ≤ x ≤ 0.245) obey the one and three quarter-wavelength cancellation model with the multi-band absorption. 150 nm Fe{sub 3}O{sub 4} nanospheres exhibit the optimal EM wave-absorbing property with an absorbing band of 8.94 GHz and the maximum R{sub L} of −50.11 dB.

  7. Experimental Testing of a Metamaterial Slow Wave Structure for High-Power Microwave Generation

    Science.gov (United States)

    Shipman, K.; Prasad, S.; Andreev, D.; Fisher, D. M.; Reass, D. B.; Schamiloglu, E.; Gilmore, M.

    2017-10-01

    A high-power L band source has been developed using a metamaterial (MTM) to produce a double negative slow wave structure (SWS) for interaction with an electron beam. The beam is generated by a 700 kV, 6 kA short pulse (10 ns) accelerator. The design of the SWS consists of a cylindrical waveguide, loaded with alternating split-rings that are arrayed axially down the waveguide. The beam is guided down the center of the rings, where electrons interact with the MTM-SWS producing radiation. Power is extracted axially via a circular waveguide, and radiated by a horn antenna. Microwaves are characterized by an external detector placed in a waveguide. Mode characterization is performed using a neon bulb array. The bulbs are lit by the electric field, resulting in an excitation pattern that resembles the field pattern. This is imaged using an SLR camera. The MTM structure has electrically small features so breakdown is a concern. In addition to high speed cameras, a fiber-optic-fed, sub-ns photomultiplier tube array diagnostic has been developed and used to characterize breakdown light. Work supported by the Air Force Office of Scientific Research, MURI Grant FA9550-12-1-0489.

  8. Plasma-assisted CO2 conversion: optimizing performance via microwave power modulation

    Science.gov (United States)

    Britun, Nikolay; Silva, Tiago; Chen, Guoxing; Godfroid, Thomas; van der Mullen, Joost; Snyders, Rony

    2018-04-01

    Significant improvement in the energy efficiency of plasma-assisted CO2 conversion is achieved with applied power modulation in a surfaguide microwave discharge. The obtained values of CO2 conversion and energy efficiency are, respectively, 0.23 and 0.33 for a 0.95 CO2  +  0.05 N2 gas mixture. Analysis of the energy relaxation mechanisms shows that power modulation can potentially affect the vibrational-translational energy exchange in plasma. In our case, however, this mechanism does not play a major role, likely due to the low degree of plasma non-equilibrium in the considered pressure range. Instead, the gas residence time in the discharge active zone together with plasma pulse duration are found to be the main factors affecting the CO2 conversion efficiency at low plasma pulse repetition rates. This effect is confirmed experimentally by the in situ time-resolved two-photon absorption laser-induced fluorescence measurements of CO molecular density produced in the discharge as a result of CO2 decomposition.

  9. High voltage systems (tube-type microwave)/low voltage system (solid-state microwave) power distribution

    Science.gov (United States)

    Nussberger, A. A.; Woodcock, G. R.

    1980-01-01

    SPS satellite power distribution systems are described. The reference Satellite Power System (SPS) concept utilizes high-voltage klystrons to convert the onboard satellite power from dc to RF for transmission to the ground receiving station. The solar array generates this required high voltage and the power is delivered to the klystrons through a power distribution subsystem. An array switching of solar cell submodules is used to maintain bus voltage regulation. Individual klystron dc voltage conversion is performed by centralized converters. The on-board data processing system performs the necessary switching of submodules to maintain voltage regulation. Electrical power output from the solar panels is fed via switch gears into feeder buses and then into main distribution buses to the antenna. Power also is distributed to batteries so that critical functions can be provided through solar eclipses.

  10. Contribution to the theoretical study of a high power microwave radiation produced by a relativistic electron beam

    International Nuclear Information System (INIS)

    Sellem, F.

    1997-01-01

    This thesis is dedicated to the study of microwave radiation produced by relativistic electron beams. The vircator (virtual cathode oscillator) is a powerful microwave source based on this principle. This device is described but the complexity of the physical processes involved makes computer simulation necessary before proposing a simplified model. The existent M2V code has been useful to simulate the behaviour of a vircator but the representation of some phenomena such as hot points, the interaction of waves with particles lacks reliability. A new code CODEX has been written, it can solve Maxwell equations on a double mesh system by a finite difference method. The electric and magnetic fields are directly computed from the scalar and vectorial potentials. This new code has been satisfactorily tested on 3 configurations: the bursting of an electron beam in vacuum, the evolution of electromagnetic fields in diode and the propagation of waves in a wave tube. CODEX has been able to simulate the behaviour of a vircator, the frequency and power are well predicted and some contributions to the problem of origin of microwave production have been made. It seems that the virtual cathode is not directly involved in the microwave production. (A.C.)

  11. Design and Control of the PowerTake-Off System for a Wave Energy Converter with Multiple Absorbers

    DEFF Research Database (Denmark)

    Hansen, Rico Hjerm

    on converting bi-directional motions into electricity. All PTO technologies are kept open and based on a thorough analysis and evaluation of state-of-the-art, the PTO technologies with greatest potential are identified. The state-of-the-art covers both PTOs for wave energy, but also general advances in high...... powertransmissions, which have applicability to wave energy. One of the difficulties in PTO design is performing the trade-off between contradicting PTO characteristics, e.g. controllability, efficiency and peak power capacity. A PTO system for wave energy is a classic example of a mechatronic design problem, where...... feasibility for real PTO systems still causes dispute. In this dissertation an analytical result is provided, proving that reactive control is highly beneficial at even “low” PTO efficiencies. The formulated reactive control is tested in a wave tank with 1:20 scale absorbers, validating the expected...

  12. Analysis of mobile phone design features affecting radiofrequency power absorbed in a human head phantom.

    Science.gov (United States)

    Kuehn, Sven; Kelsh, Michael A; Kuster, Niels; Sheppard, Asher R; Shum, Mona

    2013-09-01

    The US FCC mandates the testing of all mobile phones to demonstrate compliance with the rule requiring that the peak spatial SAR does not exceed the limit of 1.6 W/kg averaged over any 1 g of tissue. These test data, measured in phantoms with mobile phones operating at maximum antenna input power, permitted us to evaluate the variation in SARs across mobile phone design factors such as shape and antenna design, communication technology, and test date (over a 7-year period). Descriptive statistical summaries calculated for 850 MHz and 1900 MHz phones and ANOVA were used to evaluate the influence of the foregoing factors on SARs. Service technology accounted for the greatest variability in compliance test SARs that ranged from AMPS (highest) to CDMA, iDEN, TDMA, and GSM (lowest). However, the dominant factor for SARs during use is the time-averaged antenna input power, which may be much less than the maximum power used in testing. This factor is largely defined by the communication system; e.g., the GSM phone average output can be higher than CDMA by a factor of 100. Phone shape, antenna type, and orientation of a phone were found to be significant but only on the order of up to a factor of 2 (3 dB). The SAR in the tilt position was significantly smaller than for touch. The side of the head did not affect SAR levels significantly. Among the remaining factors, external antennae produced greater SARs than internal ones, and brick and clamshell phones produced greater SARs than slide phones. Assuming phone design and usage patterns do not change significantly over time, we have developed a normalization procedure and formula that permits reliable prediction of the relative SAR between various communication systems. This approach can be applied to improve exposure assessment in epidemiological research. Copyright © 2013 Wiley Periodicals, Inc.

  13. Measurement of energy distribution in flowing hydrogen microwave plasmas

    Science.gov (United States)

    Chapman, R.; Morin, T.; Finzel, M.; Hawley, M. C.

    1985-01-01

    An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into kinetic energy of a flowing gas is investigated. A calorimetry system enclosing a microwave plasma system has been developed to accurately measure the energy inputs and outputs of the microwave plasma system. The rate of energy transferred to the gas can be determined to within + or - 1.8 W from an energy balance around the microwave plasma system. The percentage of the power absorbed by the microwave plasma system transferred to the hydrogen gas as it flows through the system is found to increase with the increasing flow rate, to decrease with the increasing pressure, and to be independent of the absorbed power. An upper bound for the hydrogen gas temperature is estimated from the energy content, heat capacity, and flow rate of the gas stream. A lower bound for an overall heat-transfer coefficient is then calculated, characterizing the energy loss from the hydrogen gas stream to the air cooling of the plasma discharge tube wall. The heat-transfer coefficient is found to increase with the increasing flow rate and pressure and to be independent of the absorbed power. This result indicates that a convective-type mechanism is responsible for the energy transfer.

  14. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED THERMAL-ACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Robert J. Weber; Jeffrey J. Swetelitsch

    2005-01-01

    The objective of this project is to explore microwave-excited thermal-acoustic (META) phenomena for quantitative analysis of granular and powdered materials, with the culmination of the research to be an on-line carbon-in-ash monitor for coal-fired power plants. This technique of analyzing unburned carbon in fly ash could be a less tedious and time consuming method as compared to the traditional LOI manual procedure. Phase 1 of the research focused on off-line single-frequency thermal-acoustic measurements where an off-line fly ash monitor was constructed that could operate as analytical tool to explore instrument and methodology parameters for quantifying the microwave-excited thermal-acoustic effect of carbon in fly ash, and it was determined that the off-line thermal-acoustic technique could predict the carbon content of a random collection of fly ashes with a linear correlation constant of R{sup 2} = 0.778. Much higher correlations are expected for fly ashes generated from a single boiler. Phase 2 of the research developing a methodology to generate microwave spectra of various powders, including fly ash, coal, and inorganic minerals, and to determine if these microwave spectra could be used for chemical analyses. Although different minerals produced different responses, higher resolution microwave spectra would be required to be able to distinguish among minerals. Phase 3 of the research focused on the development of an on-line fly ash monitor that could be adapted to measure either a thermal-acoustic or thermal-elastic response to due microwave excitation of fly ash. The thermal-acoustic response was successfully employed for this purpose but the thermal-elastic response was too weak to yield a useful on-line device.

  15. Acute exposure to high-peak-power pulsed microwaves affecting the histamine H3 receptor expression in rat hippocampus

    International Nuclear Information System (INIS)

    Yu Xiaodong; Li Bo; Li Dehua; He Qiyi; Yu Zhengping

    2006-01-01

    In the Morris Water test, high-peak-power pulsed microwave (MW)-exposed rats displayed some learning and memory behavior dysfunctions, and their escape time and swimming distance to the submerged platform were longer than those of the sham-exposed rats. to understand the molecular mechanism involved, the reverse transcription-polymerase chain reation (RT-PCR) and the Western-blotting technique were used for investigating the mRNA and protein expression patterns of the histamine H 3 receptor (H 3 R) in rat hippocampus. High-peak-power pulsed microwave-exposure did not remarkably lead to the change in expression of H 3 R mRNA in rat hippocampi; however, it promoted the up-regulatory expression of the H 3 R protein, which was possibly triggered through the mitogen-activated protein kinase (MAPK) pathways. Therefore, further investigation of the molecular mechanism of the MW effects on the learning and memory behaviors is required. (authors)

  16. SECOND SEASON QUIET OBSERVATIONS: MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND POLARIZATION POWER SPECTRUM AT 95 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, D.; Dumoulin, R. N.; Newburgh, L. B.; Zwart, J. T. L. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bischoff, C.; Brizius, A.; Buder, I.; Kusaka, A. [Kavli Institute for Cosmological Physics, Department of Physics, Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States); Chinone, Y. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Cleary, K.; Reeves, R. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd M/C 249-17, Pasadena, CA 91125 (United States); Monsalve, R.; Bustos, R. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Naess, S. K.; Eriksen, H. K. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Wehus, I. K. [Department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Bronfman, L. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Church, S. E. [Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University, Varian Physics Building, 382 Via Pueblo Mall, Stanford, CA 94305 (United States); Dickinson, C. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Gaier, T., E-mail: ibuder@uchicago.edu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Collaboration: QUIET Collaboration; and others

    2012-12-01

    The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95 GHz. The 43 GHz results have been published in a previous paper, and here we report the measurement of CMB polarization power spectra using the 95 GHz data. This data set comprises 5337 hr of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 {mu}K{radical}s. Four low-foreground fields were observed, covering a total of {approx}1000 deg{sup 2} with an effective angular resolution of 12.'8, allowing for constraints on primordial gravitational waves and high signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-C {sub l} (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB, and BB power spectra between l = 25 and 975 and find that the EE spectrum is consistent with {Lambda}CDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r = 1.1{sup +0.9} {sub -0.8} (r < 2.8 at 95% C.L.) as derived by the ML pipeline, and r = 1.2{sup +0.9} {sub -0.8} (r < 2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r = 0.01, the lowest level yet reported in the literature.

  17. Spatially adjustable microplasma generation in proto-metamaterials using microwave radiative power transfer

    Science.gov (United States)

    Kim, Hyunjun; Parsons, Stephen; Hopwood, Jeffrey

    2018-01-01

    A proto-metamaterial structure creates periodic microplasma in three-dimensions within a sub-wavelength volume. A typical implementation consists of a 3 × 3 × 3 rectangular array of 2.4 GHz split ring resonators with each resonator’s split forming a 150 μm discharge gap. All 27 plasmas can be simultaneously ignited in argon up to 260 Torr and sustained by 50 W of radiation power at 650 Torr. Periodic microplasma formation alters the original properties of the material as demonstrated by the electromagnetic transmission spectra between 2.1 and 2.6 GHz with and without plasma. The average electron density of microplasmas at 650 Torr is estimated to be 2–5 × 1019 m‑3 by comparing simulated and measured microwave transmission spectra. In addition, both simulation and experimental results demonstrate that the spatial variation of plasma is configurable according to coupled mode theory. Therefore, this structure allows spatially adjustable plasma creation through frequency-selective electromagnetic coupling.

  18. The cosmic microwave background radiation power spectrum as a random bit generator for symmetric- and asymmetric-key cryptography.

    Science.gov (United States)

    Lee, Jeffrey S; Cleaver, Gerald B

    2017-10-01

    In this note, the Cosmic Microwave Background (CMB) Radiation is shown to be capable of functioning as a Random Bit Generator, and constitutes an effectively infinite supply of truly random one-time pad values of arbitrary length. It is further argued that the CMB power spectrum potentially conforms to the FIPS 140-2 standard. Additionally, its applicability to the generation of a (n × n) random key matrix for a Vernam cipher is established.

  19. Multi criteria analysis with regards to selecting optimal absorbent supply option to Ugljevik thermal power plant

    Directory of Open Access Journals (Sweden)

    Stojanović Cvjetko P.

    2015-01-01

    Full Text Available Concept of sustainable development implies an effective long-term development, both in developed and developing countries, and must be based on three pillars: environmental protection, economic development and social cohesion, both on the state and on a global level. This clear definition of sustainable development suggests a necessity of a combined action on environmental protection, economic development and the achievement of social cohesion. As a rule, by investing in environmental protection projects, power generation companies implement previously defined growth targets, development policies, and business strategies. Investment projects for the given coal type are considered as the capital ones, for they use great financial resources, significant resources and are long-lasting. The companies untertake investing in such projects to be affirmed in the new business environment, adapt to anticipated changes or to overcome the handicaps of their current position and thus adjust their production capabilities with the opportunities offered by the market. All the above implies that environmentally based capital project investments are the prerequisite of existence, sustainable growth and the acquisition of competitive advantages. However, investing in such projects is a very complex process comprised of multidimensional testing activities of all relevant determinants of future conditions and changes that the project entails. Bearing in mind that such projects are associated with the company's strategic development objectives, in the realization of such projects all the internal and external factors of development shall be taken into account, as well as a number of constraints arising from the socio-economic environment.

  20. Using the Full Power of the Cosmic Microwave Background to Probe Axion Dark Matter

    Science.gov (United States)

    Hložek, Renée; Marsh, David J. E.; Grin, Daniel

    2018-02-01

    The cosmic microwave background (CMB) places stringent constraints on models of dark matter (DM), and on the initial conditions of the Universe. The full Planck data set is used to test the possibility that some fraction of the DM is composed of ultralight axions (ULAs). This represents the first use of CMB lensing to test the ULA model. We find no evidence for a ULA component in the mass range 10-33 ≤ ma ≤ 10-24eV. We put percent-level constraints on the ULA contribution to the DM, improving by up to a factor of two compared using temperature anisotropies alone. Axion DM also provides a low-energy window onto the physics of inflation through isocurvature perturbations. We perform the first systematic investigation into the parameter space of ULA isocurvature, using an accurate isocurvature transfer function at all ma values. We precisely identify a "window of co-existence" for 10-25eV ≤ ma ≤ 10-24eV where the data allow, simultaneously, a ˜10% contribution of ULAs to the DM, and ˜1% contributions of isocurvature and tensor modes to the CMB power. ULAs in this window (and all lighter ULAs) are shown to be consistent with a large inflationary Hubble parameter, HI ˜ 1014GeV. The window of co-existence will be fully probed by proposed CMB Stage-IV observations with increased accuracy in the high-ℓ lensing power and low-ℓ E and B-mode polarisation. If ULAs in the window exist, this could allow for two independent measurements of HI in the CMB using isocurvature, and the tensor contribution to B-modes.

  1. High-power microwave transmission systems for electron-cyclotron-resonance plasma heating

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, R.J.

    1991-08-01

    This progress report is for the sixth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRH transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The design and low-power testing of new and improved components for such systems and development of underlying theory is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. The development of possible designs for sections of gyrotrons themselves, such as tapers or Vlasov-type launchers, in support of the Varian gyrotron development program is also considered when appropriate. We also provide support to other groups working on ECR heating of magnetically confined plasmas such as the groups at General Atomics, the University of Texas at Austin, and Lawrence Livermore National Laboratory. During the last year, we designed and had fabricated a two-dimensional Vlasov antenna system for a 110 GHz TE{sub 15,2} mode gyrotron for possible use at General Atomics. The system included the launcher section, a visor, main reflector, and focusing reflector. Programs to generate the tool-path profiles to cut the General Atomics'' Vlasov components on a milling machine were developed. We have also developed state-of-the art theory and programs for three-dimensional whispering-gallery-mode Vlasov antenna systems. A design for a 110 GHz TE{sub 01}-TE{sub 15,2} mode converter system for cold testing WGM Vlasov antenna systems was developed and is currently being fabricated also.

  2. Using the full power of the cosmic microwave background to probe axion dark matter

    Science.gov (United States)

    Hložek, Renée; Marsh, David J. E.; Grin, Daniel

    2018-05-01

    The cosmic microwave background (CMB) places stringent constraints on models of dark matter (DM), and on the initial conditions of the Universe. The full Planck data set is used to test the possibility that some fraction of the DM is composed of ultralight axions (ULAs). This represents the first use of CMB lensing to test the ULA model. We find no evidence for a ULA component in the mass range 10-33 ≤ ma ≤ 10-24 eV. We put percent-level constraints on the ULA contribution to the DM, improving by up to a factor of two compared using temperature anisotropies alone. Axion DM also provides a low-energy window on to the physics of inflation through isocurvature perturbations. We perform the first systematic investigation into the parameter space of ULA isocurvature, using an accurate isocurvature transfer function at all ma values. We precisely identify a `window of co-existence' for 10-25 eV ≤ ma ≤ 10-24 eV where the data allow, simultaneously, a {˜ }10 {per cent} contribution of ULAs to the DM, and {˜ } 1 {per cent} contributions of isocurvature and tensor modes to the CMB power. ULAs in this window (and all lighter ULAs) are shown to be consistent with a large inflationary Hubble parameter, HI ˜ 1014 GeV. The window of co-existence will be fully probed by proposed CMB Stage-IV observations with increased accuracy in the high-ℓ lensing power and low-ℓ E- and B-mode polarizations. If ULAs in the window exist, this could allow for two independent measurements of HI in the CMB using isocurvature, and the tensor contribution to B modes.

  3. The Compound Chinese Medicine “Kang Fu Ling” Protects against High Power Microwave-Induced Myocardial Injury

    Science.gov (United States)

    Zhang, Xueyan; Gao, Yabing; Dong, Ji; Wang, Shuiming; Yao, Binwei; Zhang, Jing; Hu, Shaohua; Xu, Xinping; Zuo, Hongyan; Wang, Lifeng; Zhou, Hongmei; Zhao, Li; Peng, Ruiyun

    2014-01-01

    Background The prevention and treatment of Microwave-caused cardiovascular injury remains elusive. This study investigated the cardiovascular protective effects of compound Chinese medicine “Kang Fu Ling” (KFL) against high power microwave (HPM)-induced myocardial injury and the role of the mitochondrial permeability transition pore (mPTP) opening in KFL protection. Methods Male Wistar rats (100) were divided into 5 equal groups: no treatment, radiation only, or radiation followed by treatment with KFL at 0.75, 1.5, or 3 g/kg/day. Electrocardiography was used to Electrophysiological examination. Histological and ultrastructural changes in heart tissue and isolated mitochondria were observed by light microscope and electron microscopy. mPTP opening and mitochondrial membrane potential were detected by confocal laser scanning microscopy and fluorescence analysis. Connexin-43 (Cx-43) and endothelial nitric oxide synthase (eNOS) were detected by immunohistochemistry. The expression of voltage-dependent anion channel (VDAC) was detected by western blotting. Results At 7 days after radiation, rats without KFL treatment showed a significantly lower heart rate (Pmicrowave-induced decrease of Cx-43 and VDAC protein expression was significantly reversed. Conclusion Microwave radiation can cause electrophysiological, histological and ultrastructural changes in the heart. KFL at 1.5 g/kg/day had the greatest protective effect on these cardiovascular events. mPTP plays an important role in the protective effects of KFL against microwave-radiation-induced myocardial injury. PMID:24992449

  4. Simple method for highlighting the temperature distribution into a liquid sample heated by microwave power field

    International Nuclear Information System (INIS)

    Surducan, V.; Surducan, E.; Dadarlat, D.

    2013-01-01

    Microwave induced heating is widely used in medical treatments, scientific and industrial applications. The temperature field inside a microwave heated sample is often inhomogenous, therefore multiple temperature sensors are required for an accurate result. Nowadays, non-contact (Infra Red thermography or microwave radiometry) or direct contact temperature measurement methods (expensive and sophisticated fiber optic temperature sensors transparent to microwave radiation) are mainly used. IR thermography gives only the surface temperature and can not be used for measuring temperature distributions in cross sections of a sample. In this paper we present a very simple experimental method for temperature distribution highlighting inside a cross section of a liquid sample, heated by a microwave radiation through a coaxial applicator. The method proposed is able to offer qualitative information about the heating distribution, using a temperature sensitive liquid crystal sheet. Inhomogeneities as smaller as 1°-2°C produced by the symmetry irregularities of the microwave applicator can be easily detected by visual inspection or by computer assisted color to temperature conversion. Therefore, the microwave applicator is tuned and verified with described method until the temperature inhomogeneities are solved

  5. Electron-beam and microwave treatment of some microbial strains

    International Nuclear Information System (INIS)

    Martin, D.; Ferdes, O.S.; Minea, R.; Tirlea, A.; Badea, M.; Plamadeala, S.; Ferdes, M.

    1998-01-01

    The experimental results concerning the combined effects of microwaves and accelerated electron beams on various microbial strains such as E. coli, Salmonella sp. and Monascus purpureus are presented. A special designed microwave applicator with a 2.45 GHz frequency CW magnetron of 850 maximum output power and with associate electronics that allow to control the microwave power, the current intensity, and the exposure time was used. The electron-beam irradiation was performed at different irradiation doses and at a dose rate of 1.5 - 2.0 kGy/min by using a linac at a mean electron energy about 6 MeV, mean bean current of 10 μA, pulse period of 3.5 μs and repetition frequency 100 Hz. The experiments were carried out in 5 variants: microwave treatment; electron-beam irradiation; microwaves followed by electron beam; electrons followed by microwaves; and simultaneous application of microwaves and electron beam. The microbiocidal effect was found to be enhanced by additional use of microwave energy to electron beam irradiation. Enhancement of inactivation rate is only remarkable for the microwave treatment or simultaneous electron beam and microwave irradiation at a temperature above the critical value at which microorganisms begin to perish by heat. Simultaneous irradiation with electron beam and microwaves results in a reduction of temperature and time as well as in the decrease of the upper limit of required electron beam absorbed dose for an assumed microbiological quality parameter. The results obtained indicate the occurrence of a synergistic effect of the two physical fields on a non-thermal basis. Hence, combined microwave-electron beam treatment may be applied as an effective method to reduce microbial load

  6. Automated system for efficient microwave power coupling in an S-band ECR ion source driven under different operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Muguira, L., E-mail: lmuguira@essbilbao.org [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain); Portilla, J. [University of Basque Country (UPV/EHU), Department of Electricity and Electronics, Science and Technology Faculty, 48940 Leioa (Bizkaia) (Spain); Gonzalez, P.J.; Garmendia, N.; Feuchtwanger, J. [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain); Etxebarria, V. [University of Basque Country (UPV/EHU), Department of Electricity and Electronics, Science and Technology Faculty, 48940 Leioa (Bizkaia) (Spain); Eguiraun, M.; Arredondo, I.; Miracoli, R.; Belver, D. [ESS-Bilbao, Edificio Rectorado, Vivero de Empresas, 48940 Leioa (Bizkaia) (Spain)

    2014-03-21

    This article presents an automated system for optimizing the microwave power coupling to the plasma generated in a proton/deuteron Electron Cyclotron Resonance (ECR) source, based on a specific model of a rectangular waveguide triple-stub tuner and the integrated measurement and control electronics, helping to get stable plasma states. The control and improvement of the RF power absorption into the plasma is a complex process, essential for the ion source development and optimization under different operating conditions. A model and a matching algorithm for the triple-stub tuner have been developed and, besides, different methods to accurately measure the power transfer in a waveguide RF system have been studied and deployed in the ESS-Bilbao ion source system. The different parts have been integrated through a controller, which allows to run an automatic plasma matching system in closed loop. The behavior of the system implemented for low and high power regimes has been tested under different conditions: with several load impedances, with plasma inside the chamber, in continuous wave and pulsed wave operation modes, demonstrating power absorption typically over 90% in all the ion source configurations. The developed system allows to achieve significant improvement in the ECR ion source power absorption efficiency, both in continuous and pulsed mode. The automatic tuning unit enhances the system operation finding an optimum solution much faster than manually, also behaving as an adaptive system able to respond in few pulses to ion source configuration changes to maintain the power coupling as high as possible. - Highlights: • An automated system optimizing plasma and microwave power interaction is presented. • A model and a matching algorithm for the triple-stub tuner have been developed. • Different methods to measure the power transfer have been studied and deployed. • The system works for low or high power regimes under different ion source conditions.

  7. Dielectric properties of Zea mays kernels - studies for microwave power processing applications

    Energy Technology Data Exchange (ETDEWEB)

    Surducan, Emanoil; Neamtu, Camelia; Surducan, Vasile, E-mail: emanoil.surducan@itim-cj.r [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

    2009-08-01

    Microwaves absorption in biological samples can be predicted by their specific dielectrical properties. In this paper, the dielectric properties ({epsilon}' and {epsilon}'') of corn (Zea mays) kernels in the 500 MHz - 20 GHz frequencies range are presented. A short analysis of the microwaves absorption process is also presented, in correlation with the specific thermal properties of the samples, measured by simultaneous TGA-DSC method.

  8. Widely power-tunable polarization-independent ultrafast mode-locked fiber laser using bulk InN as saturable absorber.

    Science.gov (United States)

    Jimenez-Rodriguez, M; Monteagudo-Lerma, L; Monroy, E; González-Herráez, M; Naranjo, F B

    2017-03-06

    The growing demand of ultrafast mode-locked fiber lasers in the near infrared has boosted the research activity in this area. One of the most convenient ways to achieve passive mode locking consists of inserting a semiconductor saturable absorber in the laser cavity to modulate the losses. However, in such a configuration, the limited power range of operation is still an unsolved issue. Here we report the fabrication of an ultrafast, high-power, widely power-tunable and non-polarization-dependent mode-locked fiber laser operating at 1.55 µm, using an InN layer as saturable absorber. With post-amplification, this laser delivers 55-fs pulses with a repetition rate of 4.84 MHz and peak power in the range of 1 MW in an all-fiber arrangement.

  9. A program of high power microwave source research and development from 8 GHz to 600 GHz

    International Nuclear Information System (INIS)

    Granatstein, V.L.; Antonsen, T.M. Jr.; Bidwell, S.; Booske, J.; Carmel, Y.; Destler, W.W.; Kehs, R.A.; Latham, P.E.; Levush, B.; Lou, W.R.; Mayergoyz, I.D.; Minami, K.; Radack, D.J.

    1990-01-01

    We review research results both on a plasma filled, backward wave oscillator (BWO), and on a free electron laser (FEL) driven by a sheet electron beam. Recently, it was demonstrated that a plasma filled BWO driven by an intense relativistic electron beam can generate hundreds of megawatts of microwave radiation at an unusually high efficiency of 40% compared with a typical efficiency of ∼10% in a BWO without a background plasma. Furthermore, the enhanced efficiency can be maintained even for large electron beam currents approaching the vacuum space charge limiting current, and we anticipate this might hold even for larger current values. Theoretical studies and numerical simulations indicate that the enhanced efficiency as well as a lower value for the start oscillation current in the linear regime may be due to the finite length of the BWO circuit coupled with modification of the dispersion relation due to the background plasma. In the case of our FEL studies, we present designs for a 1 MW, CW, tapered FEL amplifier operating at frequencies of 280 GHz and 560 GHz. A short wiggler period (ell w ∼ 1 cm) is combined with a sheet beam of electrons having energy ∼1 MeV. Depressed collector techniques would allow the main power supply rating to be reduced to ∼200 kV. Efficient sheet beam transport (>99%) has been demonstrated through 10 wiggler periods, and transport through 60 wiggler periods is currently under study. Finally, plans for a proof-of-principle tapered FEL amplifier experiment at 94 GHz are presented. 8 refs., 7 figs

  10. Shock absorber

    International Nuclear Information System (INIS)

    Housman, J.J.

    1978-01-01

    A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

  11. Nuclear reactor core having nuclear fuel and composite burnable absorber arranged for power peaking and moderator temperature coefficient control

    International Nuclear Information System (INIS)

    Kapil, S.K.

    1991-01-01

    This patent describes a nuclear reactor core. It comprises a first group of fuel rods containing fissionable material and being free of burnable absorber material; and a second group of fuel rods containing fissionable material and first and second burnable absorber material; the first burnable absorber material being a boron-bearing material which does not contain erbium and the second burnable absorber material being an erbium material; the first and second burnable absorber materials being in the form of an outer coating on the fissionable material, the outer coating being composed of an inner layer of one of the boron-bearing material which does not contain erbium and the erbium material and an outer layer of the other of the boron-bearing material which does not contain erbium and the erbium material

  12. Poly(4-vinylphenol gate insulator with cross-linking using a rapid low-power microwave induction heating scheme for organic thin-film-transistors

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2016-03-01

    Full Text Available A Microwave-Induction Heating (MIH scheme is proposed for the poly(4-vinylphenol (PVP gate insulator cross-linking process to replace the traditional oven heating cross-linking process. The cross-linking time is significantly decreased from 1 h to 5 min by heating the metal below the PVP layer using microwave irradiation. The necessary microwave power was substantially reduced to about 50 W by decreasing the chamber pressure. The MIH scheme is a good candidate to replace traditional thermal heating for cross-linking of PVP as the gate insulator for organic thin-film-transistors.

  13. Evaluation of electromagnetic absorbing capacity of materials in foundry industry

    Directory of Open Access Journals (Sweden)

    D. Nowak

    2010-01-01

    Full Text Available In the paper, a research on determining the standing wave ratio as a measure of electromagnetic absorbing capacity of moulding materials is presented. Preliminary tests performed using a microwave strip line showed that high-silica, chromite and magnesite moulding sands are characterised by low absorbing capacity of microwaves. It was demonstrated that microwave absorbing capacity is significantly affected by chemical compounds included in the examined substrates. It was found that use of a microwave strip line permits precise determining characteristic microwave absorbing capacities of various moulding materials and thus their suitability for microwave drying/hardening of moulds and cores or for other foundry processes. Such a microwave drier can be applied for identifying mass components and for determining e.g. base granularity by means of precisely determined reflection ratios |Γ| and positions of minimum signal values.

  14. High-Power Microwave Metamaterials for Phased-Array, anti-HPM, and Pulse-Shaping Applications

    Science.gov (United States)

    2014-07-23

    DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...new types of microwave lenses and investigated their applications in high-gain, high-power antenna systems as described in Section 5 of this...each dev breaks do trend ob FSSs dev The deta in IEEE T , the true po value. How vel, we cond esults of thi aper in the J n and Expe ces oject, we

  15. Influence of Microwave Power on the Properties of Hydrogenated Diamond-Like Carbon Films Prepared by ECR Plasma Enhanced DC Magnetron Sputtering

    International Nuclear Information System (INIS)

    Ru Lili; Huang Jianjun; Gao Liang; Qi Bing

    2010-01-01

    Electron cyclotron resonance (ECR) plasma was applied to enhance the direct current magnetron sputtering to prepare hydrogenated diamond-like carbon (H-DLC) films. For different microwave powers, both argon and hydrogen gas are introduced separately as the ECR working gas to investigate the influence of microwave power on the microstructure and electrical property of the H-DLC films deposited on P-type silicon substrates. A series of characterization methods including the Raman spectrum and atomic force microscopy are used. Results show that, within a certain range, the increase in microwave power affects the properties of the thin films, namely the sp 3 ratio, the hardness, the nanoparticle size and the resistivity all increase while the roughness decreases with the increase in microwave power. The maximum of resistivity amounts to 1.1 x 10 9 Ω · cm. At the same time it is found that the influence of microwave power on the properties of H-DLC films is more pronounced when argon gas is applied as the ECR working gas, compared to hydrogen gas.

  16. Automated system for efficient microwave power coupling in an S-band ECR ion source driven under different operating conditions

    Science.gov (United States)

    Muguira, L.; Portilla, J.; Gonzalez, P. J.; Garmendia, N.; Feuchtwanger, J.; Etxebarria, V.; Eguiraun, M.; Arredondo, I.; Miracoli, R.; Belver, D.

    2014-03-01

    This article presents an automated system for optimizing the microwave power coupling to the plasma generated in a proton/deuteron Electron Cyclotron Resonance (ECR) source, based on a specific model of a rectangular waveguide triple-stub tuner and the integrated measurement and control electronics, helping to get stable plasma states. The control and improvement of the RF power absorption into the plasma is a complex process, essential for the ion source development and optimization under different operating conditions. A model and a matching algorithm for the triple-stub tuner have been developed and, besides, different methods to accurately measure the power transfer in a waveguide RF system have been studied and deployed in the ESS-Bilbao ion source system. The different parts have been integrated through a controller, which allows to run an automatic plasma matching system in closed loop. The behavior of the system implemented for low and high power regimes has been tested under different conditions: with several load impedances, with plasma inside the chamber, in continuous wave and pulsed wave operation modes, demonstrating power absorption typically over 90% in all the ion source configurations. The developed system allows to achieve significant improvement in the ECR ion source power absorption efficiency, both in continuous and pulsed mode. The automatic tuning unit enhances the system operation finding an optimum solution much faster than manually, also behaving as an adaptive system able to respond in few pulses to ion source configuration changes to maintain the power coupling as high as possible.

  17. Microbial decontamination of onion powder using microwave-powered cold plasma treatments.

    Science.gov (United States)

    Kim, Jung Eun; Oh, Yeong Ji; Won, Mee Yeon; Lee, Kwang-Sik; Min, Sea C

    2017-04-01

    The effects of microwave-integrated cold plasma (CP) treatments against spores of Bacillus cereus and Aspergillus brasiliensis and Escherichia coli O157:H7 on onion powder were investigated. The growth of B. cereus, A. brasiliensis, and E. coli O157:H7 in the treated onion powder was assessed during storage at 4 and 25 °C, along with the physicochemical and sensory properties of the powder. Onion powder inoculated with B. cereus was treated with CP using helium as a plasma-forming gas, with simultaneous exposure to low microwave density at 170 mW m -2 or high microwave density at 250 mW m -2 . High microwave density-CP treatment (HMCPT) was more effective than low microwave density-CP treatment (LMCPT) in inhibiting B. cereus spores, but induced the changes in the volatile profile of powder. Increase in treatment time in HMCPT yielded greater inhibition of B. cereus spores. Vacuum drying led to greater inhibition of spores of B. cereus and A. brasiliensis than hot-air drying. HMCPT at 400 W for 40 min, determined as the optimum conditions for B. cereus spore inhibition, initially reduced the numbers of B. cereus, A. brasiliensis, and E. coli O157:H7 by 2.1 log spores/cm 2 , 1.6 log spores/cm 2 , and 1.9 CFU/cm 2 , respectively. The reduced number of B. cereus spores remained constant, while the number of A. brasiliensis spores in the treated powder increased gradually during storage at 4 and 25 °C and was not different from the number of spores in untreated samples by the end of storage at 4 °C. The E. coli counts in the treated powder fell below the level of detection after day 21 at both temperatures. HMCPT did not affect the color, antioxidant activity, or quercetin concentration of the powder during storage at both temperatures. The microwave-integrated CPTs showed potential for nonthermal decontamination of onion powder. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. High power pulsed/microwave technologies for electron accelerators vis a vis 10MeV, 10kW electron LINAC for food irradiation at CAT

    International Nuclear Information System (INIS)

    Shrivastava, Purushottam; Mulchandani, J.; Mohania, P.; Baxy, D.; Wanmode, Y.; Hannurkar, P.R.

    2005-01-01

    Use of electron accelerators for irradiation of food items is gathering momentum in India. The various technologies for powering the electron LINAC were needed to be developed in the country due to embargo situations as well as reservations of the developers worldwide to share the information related to this development. Centre for Advanced Technology, CAT, Indore, is engaged in the development of particle accelerators for medical industrial and scientific applications. Amongst other electron accelerators developed in CAT, a 10MeV, 10kW LINAC for irradiation of food items has been commissioned and tested for full rated 10kW beam power. The high power pulsed microwave driver for the LINAC was designed, developed and commissioned with full indigenous efforts, and is right now operational at CAT. It consists of a 6MW, 25kW S-band pulsed klystron, 15MW peak power pulse modulator system for the klystron, microwave driver amplifier chain, stabilized generator, protection and control electronics, waveguide system to handle the high peak and average power, gun modulator electronics, grid electronics etc. The present paper highlights various technologies like the pulsed power systems and components, microwave circuits and systems etc. Also the performance results of the high power microwave driver for the 10MeV LINAC at CAT are discussed. Future strategies for developing the state of art technologies are highlighted. (author)

  19. Absorber for terahertz radiation management

    Science.gov (United States)

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  20. Damage effect and mechanism of the GaAs high electron mobility transistor induced by high power microwave

    Science.gov (United States)

    Yang, Liu; Chang-Chun, Chai; Yin-Tang, Yang; Jing, Sun; Zhi-Peng, Li

    2016-04-01

    In this paper, we present the damage effect and mechanism of high power microwave (HPM) on AlGaAs/GaAs pseudomorphic high-electron-mobility transistor (pHEMT) of low-noise amplifier (LNA). A detailed investigation is carried out by simulation and experiment study. A two-dimensional electro-thermal model of the typical GaAs pHEMT induced by HPM is established in this paper. The simulation result reveals that avalanche breakdown, intrinsic excitation, and thermal breakdown all contribute to damage process. Heat accumulation occurs during the positive half cycle and the cylinder under the gate near the source side is most susceptible to burn-out. Experiment is carried out by injecting high power microwave into GaAs pHEMT LNA samples. It is found that the damage to LNA is because of the burn-out at first stage pHEMT. The interiors of the damaged samples are observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Experimental results accord well with the simulation of our model. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (Grant No. 2015-0214.XY.K).

  1. Energy issues in microwave food processing: A review of developments and the enabling potentials of solid-state power delivery.

    Science.gov (United States)

    Atuonwu, J C; Tassou, S A

    2018-01-23

    The enormous magnitude and variety of microwave applications in household, commercial and industrial food processing creates a strong motivation for improving the energy efficiency and hence, sustainability of the process. This review critically assesses key energy issues associated with microwave food processing, focusing on previous energy performance studies, energy performance metrics, standards and regulations. Factors affecting energy-efficiency are categorised into source, load and source-load matching factors. This highlights the need for highly-flexible and controllable power sources capable of receiving real-time feedback on load properties, and effecting rapid control actions to minimise reflections, heating non-uniformities and other imperfections that lead to energy losses. A case is made for the use of solid-state amplifiers as alternatives to conventional power sources, magnetrons. By a full-scale techno-economic analysis, including energy aspects, it is shown that the use of solid-state amplifiers as replacements to magnetrons is promising, not only from an energy and overall technical perspective, but also in terms of economics.

  2. Performance simulation of the JPL solar-powered distiller. Part 1: Quasi-steady-state conditions. [for cooling microwave equipment

    Science.gov (United States)

    Yung, C. S.; Lansing, F. L.

    1983-01-01

    A 37.85 cu m (10,000 gallons) per year (nominal) passive solar powered water distillation system was installed and is operational in the Venus Deep Space Station. The system replaced an old, electrically powered water distiller. The distilled water produced with its high electrical resistivity is used to cool the sensitive microwave equipment. A detailed thermal model was developed to simulate the performance of the distiller and study its sensitivity under varying environment and load conditions. The quasi-steady state portion of the model is presented together with the formulas for heat and mass transfer coefficients used. Initial results indicated that a daily water evaporation efficiency of 30% can be achieved. A comparison made between a full day performance simulation and the actual field measurements gave good agreement between theory and experiment, which verified the model.

  3. The Behavioral Toxicology of High-Peak, Low Average Power, Pulsed Microwave Irradiation

    Science.gov (United States)

    1993-01-25

    is to communicate our findings, many of which can be found in the scientific literature, to those non- psychologists who may find them relevant to...Local SARs were determined using implantable , RF transpaent Luxtron temperature probes. Euthanasia of the animals was accomplished by carbon dioxide...Hearing Research, 26, 105-116. Seaman, R. L., and Lebovitz, R. M. (1989). Thresholds of cat cochlear nucleus neurons to microwave pulses

  4. Specific Electromagnetic Effects of Microwave Radiation on Escherichia coli▿

    OpenAIRE

    Shamis, Yury; Taube, Alex; Mitik-Dineva, Natasa; Croft, Rodney; Crawford, Russell J.; Ivanova, Elena P.

    2011-01-01

    The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m3, and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Softwa...

  5. Fire detection behind a wall by using microwave techniques

    Science.gov (United States)

    Alkurt, Fatih Özkan; Baǧmancı, Mehmet; Karaaslan, Muharrem; Bakır, Mehmet; Altıntaş, Olcay; Karadaǧ, Faruk; Akgöl, Oǧuzhan; Ünal, Emin

    2018-02-01

    In this work, detection of the fire location behind a wall by using microwave techniques is illustrated. According to Planck's Law, Blackbody emits electromagnetic radiation in the microwave region of the electromagnetic spectrum. This emitted waves penetrates all materials except that metals. These radiated waves can be detected by using directional and high gain antennas. The proposed antenna consists of a simple microstrip patch antenna and a 2×2 microstrip patch antenna array. FIT based simulation results show that 2×2 array antenna can absorb emitted power from a fire source which is located behind a wall. This contribution can be inspirational for further works.

  6. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS

    International Nuclear Information System (INIS)

    Larson, D.; Bennett, C. L.; Gold, B.; Dunkley, J.; Hinshaw, G.; Kogut, A.; Wollack, E.; Komatsu, E.; Nolta, M. R.; Halpern, M.; Hill, R. S.; Odegard, N.; Weiland, J. L.; Jarosik, N.; Page, L.; Limon, M.; Meyer, S. S.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.

    2011-01-01

    The WMAP mission has produced sky maps from seven years of observations at L2. We present the angular power spectra derived from the seven-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. With the seven-year data, the temperature (TT) spectrum measurement has a signal-to-noise ratio per multipole that exceeds unity for l m h 2 = 0.1334 +0.0056 -0.0055 , and on the epoch of matter-radiation equality, z eq = 3196 +134 -133 . The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20σ, compared to 13σ with the five-year data. We now detect the second dip in the TE spectrum near l ∼ 450 with high confidence. The TB and EB spectra remain consistent with zero, thus demonstrating low systematic errors and foreground residuals in the data. The low-l EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5σ significance when averaged over l = 2-7: l(l + 1)C EE l /(2π) = 0.074 +0.034 -0.025 μK 2 (68% CL). We now detect the high-l, 24 ≤ l ≤ 800, EE spectrum at over 8σ. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero; when averaged over l = 2-7, l(l + 1)C BB l /(2π) 2 (95% CL). The upper limit on tensor modes from polarization data alone is a factor of two lower with the seven-year data than it was using the five-year data. The data remain consistent with the simple ΛCDM model: the best-fit TT spectrum has an effective χ 2 of 1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of ΛCDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the ΛCDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n s , is biased

  7. Scanning Microwave Induced Acoustic Tomography

    National Research Council Canada - National Science Library

    Wang, Lihong V

    2001-01-01

    .... Cancerous breast tissues are found to be 2-5 times more strongly absorbing than surrounding normal breast tissues in the microwave, which has been attributed to an increase in bound water and sodium...

  8. Single and double-layer composite microwave absorbers with hexaferrite BaZn{sub 0.6}Zr{sub 0.3}X{sub 0.3}Fe{sub 10.8}O{sub 19} (X = Ti, Ce, Sn) powders

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, Seyyed Salman Seyyed [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic); Stergiou, Charalampos A. [Lab. of Inorganic Materials, Centre for Research and Technology Hellas, 57001, Thermi (Greece)

    2017-01-15

    In the present study, substituted barium hexaferrites with the composition BaZn{sub 0.6}Zr{sub 0.3} × {sub 0.3}Fe{sub 10.8}O{sub 19} (where X = Ti, Ce, Sn) are prepared with the solid-state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and network analysis techniques are used to analyze the crystal phases, morphology, static magnetic and microwave absorption properties, respectively. Based on the recorded results, barium hexaferrite is the major phase obtained after milling of the powders for 20 h, followed by calcination at 1000 °C for 5 h. The morphology of the particles of the substituted ferrite samples is plate-like with hexagonal shape. The microwave absorption in the X-band of epoxy composites loaded with the ferrite fillers, either separately, in pairs or all together, has been extensively investigated. Multicomponent composites filled with the new hexaferrites under study are promising candidates for electromagnetic absorbers in the 8–12 GHz range. It is found that single-layer absorbers of 5 mm thickness with 45 wt% of a binary (Sn and Ti-doped hexaferrite) or ternary filler mixture exhibit the maximum bandwidth of 2.7 GHz at the level of −10 dB or maximum losses of 26.4 dB at 10.8 GHz, respectively. - Highlights: • Preparation of substituted hexaferrites via mechanical activation. • We designed a broad band microwave absorber with mixing powders. • We designed single layer absorber with RL{sub min} = −26.4 dB and 1.6 GHz bandwidth. • We designed double layer absorbers, as monoband absorbers at a matching frequency.

  9. An omnidirectional electromagnetic absorber made of metamaterials

    International Nuclear Information System (INIS)

    Cheng Qiang; Cui Tiejun; Jiang Weixiang; Cai Bengeng

    2010-01-01

    In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.

  10. The influence of microwave irradiation on thermal properties of main rock-forming minerals

    International Nuclear Information System (INIS)

    Lu, Gao-ming; Li, Yuan-hui; Hassani, Ferri; Zhang, Xiwei

    2017-01-01

    Highlights: • Different rock-forming minerals present very different microwave absorption capacity to microwave energy. • The test results can be used to estimate the heating behaviors of rocks to microwave irradiation. • SEM-EDX technique was used to determine the elemental distribution and mineralogical composition. • Ferrum may influence the interacting mechanisms between rock-forming minerals and microwaves. - Abstract: The sample will burst into fragment when the thermal stress induced by thermal expansion greater than the ultimate strength of the rock after microwave irradiation. Microwave-assisted rock fragmentation has been illustrated to be potentially beneficial for mineral processing, mining and geotechnical engineering. In order to have a comprehensive understanding on the influence of microwave on thermo-mechanical properties of rocks, it is necessary to investigate the interaction effect between microwaves and the main rock-forming minerals. In this work, eleven rock-forming minerals were tested in a multimode cavity at 2.45G Hz with a power of 2 kW, subsequently, the Scanning Electron Microscopy–Energy Dispersive X-ray (SEM-EDX) was used to determine the elemental distribution and mineralogical composition of the tested samples. It was observed that different rock-forming minerals present very different susceptibility induced by microwave treatment. Enstatite presents the strongest microwave absorption capacity by a large margin and most of the rock-forming minerals are weak microwave absorbers. It is significant that the results can be used to predict the heating behaviors of rocks subjected to microwave energy. Furthermore, the SEM-EDX elemental analysis demonstrates that the microwave absorption capacity of rock-forming minerals could link to the contribution of the ferrum, which may influence the interacting mechanisms between microwaves and the rock-forming minerals.

  11. Development of novel high power-short time (HPST) microwave assisted commercial decontamination process for dried turmeric powder (Curcuma Longa L.).

    Science.gov (United States)

    Behera, G; Sutar, P P; Aditya, S

    2017-11-01

    The commercially available dry turmeric powder at 10.34% d.b. moisture content was decontaminated using microwaves at high power density for short time. To avoid the loss of moisture from turmeric due to high microwave power, the drying kinetics were modelled and considered during optimization of microwave decontamination process. The effect of microwave power density (10, 33.5 and 57 W g -1 ), exposure time (10, 20 and 30 s) and thickness of turmeric layer (1, 2 and 3 mm) on total plate, total yeast and mold (YMC) counts, color change (∆E), average final temperature of the product (T af ), water activity (a w ), Page model rate constant (k) and total moisture loss (ML) was studied. The perturbation analysis was carried out for all variables. It was found that to achieve more than one log reduction in yeast and mold count, a substantial reduction in moisture content takes place leading to the reduced output. The microwave power density significantly affected the YMC, T af and a w of turmeric powder. But the thickness of sample and microwave exposure time showed effect only on T af , a w and ML. The colour of turmeric and Page model rate constant were not significantly changed during the process as anticipated. The numerical optimization was done at 57.00 W g -1 power density, 1.64 mm thickness of sample layer and 30 s exposure time. It resulted into 1.6 × 10 7 CFU g -1 YMC, 82.71 °C T af , 0.383 a w and 8.41% (d.b.) final moisture content.

  12. Microwave-assisted synthesis of sensitive silver substrate for surface-enhanced Raman scattering spectroscopy

    International Nuclear Information System (INIS)

    Xia Lixin; Wang Haibo; Wang Jian; Gong Ke; Jia Yi; Zhang Huili; Sun Mengtao

    2008-01-01

    A sensitive silver substrate for surface-enhanced Raman scattering (SERS) spectroscopy is synthesized under multimode microwave irradiation. The microwave-assisted synthesis of the SERS-active substrate was carried out in a modified domestic microwave oven of 2450 MHz, and the reductive reaction was conducted in a polypropylene container under microwave irradiation with a power of 100 W for 5 min. Formaldehyde was employed as both the reductant and microwave absorber in the reductive process. The effects of different heating methods (microwave dielectric and conventional) on the properties of the SERS-active substrates were investigated. Samples obtained with 5 min of microwave irradiation at a power of 100 W have more well-defined edges, corners, and sharper surface features, while the samples synthesized with 1 h of conventional heating at 40 deg. C consist primarily of spheroidal nanoparticles. The SERS peak intensity of the ∼1593 cm -1 band of 4-mercaptobenzoic acid adsorbed on silver nanoparticles synthesized with 5 min of microwave irradiation at a power of 100 W is about 30 times greater than when it is adsorbed on samples synthesized with 1 h of conventional heating at 40 deg. C. The results of quantum chemical calculations are in good agreement with our experimental data. This method is expected to be utilized for the synthesis of other metal nanostructural materials.

  13. Measurements of complex impedance in microwave high power systems with a new bluetooth integrated circuit.

    Science.gov (United States)

    Roussy, Georges; Dichtel, Bernard; Chaabane, Haykel

    2003-01-01

    By using a new integrated circuit, which is marketed for bluetooth applications, it is possible to simplify the method of measuring the complex impedance, complex reflection coefficient and complex transmission coefficient in an industrial microwave setup. The Analog Devices circuit AD 8302, which measures gain and phase up to 2.7 GHz, operates with variable level input signals and is less sensitive to both amplitude and frequency fluctuations of the industrial magnetrons than are mixers and AM crystal detectors. Therefore, accurate gain and phase measurements can be performed with low stability generators. A mechanical setup with an AD 8302 is described; the calibration procedure and its performance are presented.

  14. Theoretical scaling law of coronal magnetic field and electron power-law index in solar microwave burst sources

    Science.gov (United States)

    Huang, Y.; Song, Q. W.; Tan, B. L.

    2018-04-01

    It is first proposed a theoretical scaling law respectively for the coronal magnetic field strength B and electron power-law index δ versus frequency and coronal height in solar microwave burst sources. Based on the non-thermal gyro-synchrotron radiation model (Ramaty in Astrophys. J. 158:753, 1969), B and δ are uniquely solved by the observable optically-thin spectral index and turnover (peak) frequency, the other parameters (plasma density, temperature, view angle, low and high energy cutoffs, etc.) are relatively insensitive to the calculations, thus taken as some typical values. Both of B and δ increase with increasing of radio frequency but with decreasing of coronal height above photosphere, and well satisfy a square or cubic logarithmic fitting.

  15. Monotron and azimuthally corrugated: application to the high power microwaves generation; Monotron e cavidades azimutalmente corrugadas: aplicacao a geracao de microondas de alta potencia

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Pedro Jose de

    2003-07-01

    The present document reports the activity of construction and initial operation of 6.7 GHz operation for high power microwave generation, the study on cylindrical resonators with azimuthally corrugated cross section, the determination of electrical conductivity of metallic materials and development of dielectric resonators for telecommunication applications.

  16. Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianjian [Illinois Inst. of Technology, Chicago, IL (United States)

    2008-12-01

    Superconducting cavity resonators offer the advantage of high field intensity for a given input power, making them an attractive contender for particle accelerator applications. Power coupling into a superconducting cavity employed in a particle accelerator requires unique provisions to maintain high vacuum and cryogenic temperature on the cavity side, while operating with ambient conditions on the source side. Components introduced to fulfill mechanical requirements must show negligible obstruction of the propagation of the microwave with absence of critical locations that may give rise to electron multipaction, leading to a multiple section design, instead of an aperture, a probe, or a loop structure as found in conventional cavities. A coaxial power coupler for a superconducting multiple-cell cavity at 3.9 GHz has been developed. The cavity is intended to be employed as an accelerator to provide enhanced electron beam quality in a free-electron laser in Hamburg (FLASH) user facility. The design of the coupler called for two windows to sustain high vacuum in the cavity and two bellows to accommodate mechanical dimensional changes resulting from cryogenics. Suppression of multipacting was accomplished by the choice of conductor dimensions and materials with low second yield coefficients. Prior to integration with the cavity, the coupler was tested for intrinsic properties in a back-to-back configuration and conditioned for high-power operation with increasing power input. Maximum incident power was measured to be 61 kW. When integrated with the superconducting cavity, a loaded quality factor of 9 x 10 5 was measured by transient method. Coupler return loss and insertion loss were estimated to be around -21 dB and -0.2 dB, respectively.

  17. PROBING THE INFLATON: SMALL-SCALE POWER SPECTRUM CONSTRAINTS FROM MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND ENERGY SPECTRUM

    International Nuclear Information System (INIS)

    Chluba, Jens; Erickcek, Adrienne L.; Ben-Dayan, Ido

    2012-01-01

    In the early universe, energy stored in small-scale density perturbations is quickly dissipated by Silk damping, a process that inevitably generates μ- and y-type spectral distortions of the cosmic microwave background (CMB). These spectral distortions depend on the shape and amplitude of the primordial power spectrum at wavenumbers k ∼ 4 Mpc –1 . Here, we study constraints on the primordial power spectrum derived from COBE/FIRAS and forecasted for PIXIE. We show that measurements of μ and y impose strong bounds on the integrated small-scale power, and we demonstrate how to compute these constraints using k-space window functions that account for the effects of thermalization and dissipation physics. We show that COBE/FIRAS places a robust upper limit on the amplitude of the small-scale power spectrum. This limit is about three orders of magnitude stronger than the one derived from primordial black holes in the same scale range. Furthermore, this limit could be improved by another three orders of magnitude with PIXIE, potentially opening up a new window to early universe physics. To illustrate the power of these constraints, we consider several generic models for the small-scale power spectrum predicted by different inflation scenarios, including running-mass inflation models and inflation scenarios with episodes of particle production. PIXIE could place very tight constraints on these scenarios, potentially even ruling out running-mass inflation models if no distortion is detected. We also show that inflation models with sub-Planckian field excursion that generate detectable tensor perturbations should simultaneously produce a large CMB spectral distortion, a link that could potentially be established with PIXIE.

  18. Microwave-assisted addition of azomethines to isatoic anhydride

    Indian Academy of Sciences (India)

    TECS

    . Kenstar domestic, multimode, without on and off mode, microwave oven, with rotating platform tray, with a power source of 230 V, 50 Hz, and micro- wave energy output 800 W, microwave input power. 1200 W and microwave frequency 2450 ...

  19. Evolution of Monolithic Technology for Wireless Communications: GaN MMIC Power Amplifiers For Microwave Radios

    Directory of Open Access Journals (Sweden)

    Vittorio Camarchia

    2014-09-01

    Full Text Available This paper presents the progress of monolithic technology for microwaveapplication, focusing on gallium nitride technology advances in the realization of integratedpower amplifiers. Three design examples, developed for microwave backhaul radios, areshown. The first design is a 7 GHz Doherty developed with a research foundry, while thesecond and the third are a 7 GHz Doherty and a 7–15 GHz dual-band combined poweramplifiers, both based on a commercial foundry process. The employed architectures, themain design steps and the pros and cons of using gallium nitride technology are highlighted.The measured performance demonstrates the potentialities of the employed technology, andthe progress in the accuracy, reliability and performance of the process.

  20. Study of microwave components for an electron cyclotron resonance ...

    Indian Academy of Sciences (India)

    The system consists of a microwave source, an isolator, a directional coupler, a threestub tuner, a high voltage break, a microwave vacuum window, and a microwave launcher. These microwave components were simulated using microwave studio software. The low power and full term characterization of the microwave ...

  1. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  2. Microwave Ablation of Porcine Kidneys in vivo: Effect of two Different Ablation Modes (“Temperature Control” and “Power Control”) on Procedural Outcome

    International Nuclear Information System (INIS)

    Sommer, C. M.; Arnegger, F.; Koch, V.; Pap, B.; Holzschuh, M.; Bellemann, N.; Gehrig, T.; Senft, J.; Nickel, F.; Mogler, C.; Zelzer, S.; Meinzer, H. P.; Stampfl, U.; Kauczor, H. U.; Radeleff, B. A.

    2012-01-01

    Purpose: This study was designed to analyze the effect of two different ablation modes (“temperature control” and “power control”) of a microwave system on procedural outcome in porcine kidneys in vivo. Methods: A commercially available microwave system (Avecure Microwave Generator; MedWaves, San Diego, CA) was used. The system offers the possibility to ablate with two different ablation modes: temperature control and power control. Thirty-two microwave ablations were performed in 16 kidneys of 8 pigs. In each animal, one kidney was ablated twice by applying temperature control (ablation duration set point at 60 s, ablation temperature set point at 96°C, automatic power set point; group I). The other kidney was ablated twice by applying power control (ablation duration set point at 60 s, ablation temperature set point at 96°C, ablation power set point at 24 W; group II). Procedural outcome was analyzed: (1) technical success (e.g., system failures, duration of the ablation cycle), and (2) ablation geometry (e.g., long axis diameter, short axis diameter, and circularity). Results: System failures occurred in 0% in group I and 13% in group II. Duration of the ablation cycle was 60 ± 0 s in group I and 102 ± 21 s in group II. Long axis diameter was 20.3 ± 4.6 mm in group I and 19.8 ± 3.5 mm in group II (not significant (NS)). Short axis diameter was 10.3 ± 2 mm in group I and 10.5 ± 2.4 mm in group II (NS). Circularity was 0.5 ± 0.1 in group I and 0.5 ± 0.1 in group II (NS). Conclusions: Microwave ablations performed with temperature control showed fewer system failures and were finished faster. Both ablation modes demonstrated no significant differences with respect to ablation geometry.

  3. High-power Microwave Pulse Compression of Klystrons by Phase-Modulation of High-Q Storage Cavities

    CERN Document Server

    Bossart, Rudolf; Mourier, J; Syratchev, I V; Tanner, L

    2004-01-01

    At the CERN linear electron accelerators LIL and CTF, the peak RF power from the 3GHz-klystrons was doubled by means of LIPS microwave pulse compressors. To produce constant RF power from the cavity-based pulse compressors, the klystrons were driven by a fast RF-phase modulation program. For the CLIC Test Facility CTF3, a new type of a Barrel Open Cavity (BOC) with a high quality factor Q0 has been developed. Contrary to LIPS with two resonant cavities, BOC operates with a single cavity supporting two orthogonal resonant modes TM 10,1,1 in the same cavity. For both LIPS and BOC storage cavities, it is important that the RF power reflected back to the klystron is minimal. This implies that the resonant frequencies, Q-factors and coupling factors of the two resonant modes of a pulse compressor are closely matched, and that the resonant frequencies are accurate to within a few KHz. The effects of small differences between the two orthogonal modes of the BOC cavity have been investigated. The dynamic pulse respon...

  4. Numerical investigation of the electric field distribution and the power deposition in the resonant cavity of a microwave electrothermal thruster

    Directory of Open Access Journals (Sweden)

    Mehmet Serhan Yildiz

    2017-04-01

    Full Text Available Microwave electrothermal thruster (MET, an in-space propulsion concept, uses an electromagnetic resonant cavity as a heating chamber. In a MET system, electromagnetic energy is converted to thermal energy via a free floating plasma inside a resonant cavity. To optimize the power deposition inside the cavity, the factors that affect the electric field distribution and the resonance conditions must be accounted for. For MET thrusters, the length of the cavity, the dielectric plate that separates the plasma zone from the antenna, the antenna length and the formation of a free floating plasma have direct effects on the electromagnetic wave transmission and thus the power deposition. MET systems can be tuned by adjusting the lengths of the cavity or the antenna. This study presents the results of a 2-D axis symmetric model for the investigation of the effects of cavity length, antenna length, separation plate thickness, as well as the presence of free floating plasma on the power absorption. Specifically, electric field distribution inside the resonant cavity is calculated for a prototype MET system developed at the Bogazici University Space Technologies Laboratory. Simulations are conducted for a cavity fed with a constant power input of 1 kW at 2.45 GHz using COMSOL Multiphysics commercial software. Calculations are performed for maximum plasma electron densities ranging from 1019 to 1021 #/m3. It is determined that the optimum antenna length changes with changing plasma density. The calculations show that over 95% of the delivered power can be deposited to the plasma when the system is tuned by adjusting the cavity length.

  5. Fabrication of an Absorber-Coupled MKID Detector

    Science.gov (United States)

    Brown, Ari; Hsieh, Wen-Ting; Moseley, Samuel; Stevenson, Thomas; U-Yen, Kongpop; Wollack, Edward

    2012-01-01

    Absorber-coupled microwave kinetic inductance detector (MKID) arrays were developed for submillimeter and far-infrared astronomy. These sensors comprise arrays of lambda/2 stepped microwave impedance resonators patterned on a 1.5-mm-thick silicon membrane, which is optimized for optical coupling. The detector elements are supported on a 380-mm-thick micro-machined silicon wafer. The resonators consist of parallel plate aluminum transmission lines coupled to low-impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The transmission lines simultaneously act to absorb optical power and employ an appropriate surface impedance and effective filling fraction. The fabrication techniques demonstrate high-fabrication yield of MKID arrays on large, single-crystal membranes and sub-micron front-to-back alignment of the micro strip circuit. An MKID is a detector that operates upon the principle that a superconducting material s kinetic inductance and surface resistance will change in response to being exposed to radiation with a power density sufficient to break its Cooper pairs. When integrated as part of a resonant circuit, the change in surface impedance will result in a shift in its resonance frequency and a decrease of its quality factor. In this approach, incident power creates quasiparticles inside a superconducting resonator, which is configured to match the impedance of free space in order to absorb the radiation being detected. For this reason MKIDs are attractive for use in large-format focal plane arrays, because they are easily multiplexed in the frequency domain and their fabrication is straightforward. The fabrication process can be summarized in seven steps: (1) Alignment marks are lithographically patterned and etched all the way through a silicon on insulator (SOI) wafer, which consists of a

  6. Broadband Microwave Wireless Power Transfer for Weak-Signal and Multipath Environments

    Science.gov (United States)

    Barton, Richard J.

    2014-01-01

    In this paper, we study the potential benefits of using relatively broadband wireless power transmission WPT strategies in both weak-signal and multipath environments where traditional narrowband strategies can be very inefficient. The paper is primarily a theoretical and analytical treatment of the problem that attempts to derive results that are widely applicable to many different WPT applications, including space solar power SSP.

  7. DEVELOPMENT OF MATHEMATICAL MODEL OF PROCESS OF BLACK CURRANT BERRIES DRYING IN VACUUMDEVICE WITH THE MICROWAVE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2014-01-01

    Full Text Available Summary. The mathematical model allowed to reproduce and study at qualitative level the change of berries form and the structure of the berries layer in the course of drying. The separate berry in the course of drying loses gradually its elasticity, decreases in volume, the peel gathers in folds, there appear internal emptiness. In the course of drying the berries layer decreases in thickness, contacting berries stick strongly with each other due to the coordinated folds of peel appearing, the layer is condensed due to penetration of the berries which have lost elasticity into emptiness between them. The model with high specification describes black currant drying process and therefore has a large number of the parameters available to change. Among them three most important technological parameters, influencing productivity and the drying quality are chosen: the power of microwave radiation P, thickness of the berries layer h, environmental pressure p. From output indicators of the model the most important are three functions from time: dependence of average humidity of the layer on time Wcp (t, dependence of the speed of change of average humidity on time dWcp (t/dt, dependence of the layer average temperature on time Tср (t. On the standard models classification the offered model is algorithmic, but not analytical. It means that output characteristics of model are calculated with the entrance ones, not by analytical transformations (it is impossible principally for the modeled process, but by means of spatial and temporary sampling and the corresponding calculation algorithm. Detailed research of the microwave drying process by means of the model allows to allocate the following stages: fast heating, the fast dehydration, the slowed-down dehydration, consolidation of a layer of a product, final drying, heating after dehydration.

  8. Standing surface waves in dusty microwave slot-excited plasma

    International Nuclear Information System (INIS)

    Ostrikov, K.N.; Yu, M.Y.; Sugai, H.

    2000-01-01

    resonance. In reality, this can result in an increase of microwave power reflection, and hence a large reduction of the power absorbed by the plasma. The latter can eventually become less than that necessary to maintain the ionization-recombination balance and the discharge can be therefore disrupted. An increase in the input power will not necessarily be efficient, since most of the deposited microwave power will be reflected by the chamber due to poor generator frequency - SW frequency matching. For certain proportions of dusts, mode conversion appears to be possible. We have also found that the dust specific dissipations, such as the variation of the plasma particles momenta due electron/ion capture/release by the grains, noticeably increase the microwave power loss in the discharge, which diminishes the operating mode quality factor

  9. Microwave Kinetic Inductance Detector with Selective Polarization Coupling

    Science.gov (United States)

    Wollack, Edward; U-yen, Kongpop; Stevenson, Thomas; Brown, Ari; Moseley, Samuel; Hsieh, Wen-Ting

    2013-01-01

    A conventional low-noise detector requires a technique to both absorb incident power and convert it to an electrical signal at cryogenic temperatures. This innovation combines low-noise detector and readout functionality into one device while maintaining high absorption, controlled polarization sensitivity, and broadband detection capability. The resulting far-infrared detectors can be read out with a simple approach, which is compact and minimizes thermal loading. The proposed microwave kinetic inductance detector (MKID) consists of three basic elements. The first is the absorptive section in which the incident power is coupled to a superconducting resonator at far-infrared frequency above its superconducting critical frequency (where superconductor becomes normal conductor). This absorber's shape effectively absorbs signals in the desired polarization state and is resonant at the radio frequency (RF) used for readout of the device. Control over the metal film used in the absorber allows realization of structures with either a 50% broadband or 100% resonance absorptance over a 30% fractional bandwidth. The second element is a microwave resonator - which is realized from the thin metal films used to make the absorber as transmission lines - whose resonance frequency changes due to a variation in its kinetic inductance. The resonator's kinetic inductance is a function of the power absorbed by the device. A low-loss dielectric (mono-crystalline silicon) is used in a parallel-plate transmission line structure to realize the desired superconducting resonators. There is negligible coupling among the adjacent elements used to define the polarization sensitivity of each detector. The final component of the device is a microwave transmission line, which is coupled to the resonator, and allows detection of changes in resonance frequency for each detector in the focal plane array. The spiral shape of the detector's absorber allows incident power with two polarizations to

  10. Detailed spectra of high-power broadband microwave radiation from interactions of relativistic electron beams with weakly magnetized plasmas

    International Nuclear Information System (INIS)

    Kato, K.G.; Benford, G.; Tzach, D.

    1983-01-01

    Prodigious quantities of microwave energy distributed uniformly across a wide frequency band are observed when a relativistic electron beam (REB) penetrates a plasma. Typical measured values are 20 MW total for Δνapprox. =40 GHz with preliminary observations of bandwidths as large as 100 GHz. An intense annular pulsed REB (Iapprox. =128 kA; rapprox. =3 cm; Δrapprox. =1 cm; 50 nsec FWHM; γapprox. =3) is sent through an unmagnetized or weakly magnetized plasma column (n/sub plasma/approx.10 13 cm -3 ). Beam-to-plasma densities of 0.01 >ω/sub p/ and weak harmonic structure is wholly unanticipated from Langmuir scattering or soliton collapse models. A model of Compton-like boosting of ambient plasma waves by the beam electrons, with collateral emission of high-frequency photons, qualitatively explains these spectra. Power emerges largely in an angle approx.1/γ, as required by Compton mechanisms. As n/sub b//n/sub p/ falls, ω/sub p/-2ω/sub p/ structure and harmonic power ratios consistent with soliton collapse theories appear. With further reduction of n/sub b//n/sub p/ only the ω/sub p/ line persists

  11. W-band PELDOR with 1 kW microwave power: Molecular geometry, flexibility and exchange coupling

    Science.gov (United States)

    Reginsson, Gunnar W.; Hunter, Robert I.; Cruickshank, Paul A. S.; Bolton, David R.; Sigurdsson, Snorri Th.; Smith, Graham M.; Schiemann, Olav

    2012-03-01

    A technique that is increasingly being used to determine the structure and conformational flexibility of biomacromolecules is Pulsed Electron-Electron Double Resonance (PELDOR or DEER), an Electron Paramagnetic Resonance (EPR) based technique. At X-band frequencies (9.5 GHz), PELDOR is capable of precisely measuring distances in the range of 1.5-8 nm between paramagnetic centres but the orientation selectivity is weak. In contrast, working at higher frequencies increases the orientation selection but usually at the expense of decreased microwave power and PELDOR modulation depth. Here it is shown that a home-built high-power pulsed W-band EPR spectrometer (HiPER) with a large instantaneous bandwidth enables one to achieve PELDOR data with a high degree of orientation selectivity and large modulation depths. We demonstrate a measurement methodology that gives a set of PELDOR time traces that yield highly constrained data sets. Simulating the resulting time traces provides a deeper insight into the conformational flexibility and exchange coupling of three bisnitroxide model systems. These measurements provide strong evidence that W-band PELDOR may prove to be an accurate and quantitative tool in assessing the relative orientations of nitroxide spin labels and to correlate those orientations to the underlying biological structure and dynamics.

  12. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons; Desenvolvimento de uma metodologia para estimativa da dose absorvida e do poder de freamento para eletrons de conversao de baixa energia

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Ivan Pedro Salati de

    1995-08-01

    The evaluation of absorbed dose in the case of external and internalcontamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy {sup 109} Cd conversion electrons, working with a 4 {pi} proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin {sup 109} Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  13. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    National Research Council Canada - National Science Library

    Wilson, Clay

    2006-01-01

    Electromagnetic Pulse (EMP) is an instantaneous, intense energy field that can disrupt at a distance numerous electrical systems and high technology microcircuits that are especially sensitive to power surges...

  14. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments

    National Research Council Canada - National Science Library

    Wilson, Clay

    2008-01-01

    Electromagnetic Pulse (EMP) is an instantaneous, intense energy field that can overload or disrupt at a distance numerous electrical systems and high technology microcircuits, which are especially sensitive to power surges...

  15. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    Abstract. A mass of hollow carbon nanospheres (HCNSs) was fabricated by chemical vapour deposition of methane over Ni/Al2O3 catalyst at 600 ◦C. The products were characterized with high-resolution transmission elec- tron microscope images, and the results showed that the external diameter of the HCNSs was ...

  16. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Airworthiness Certification Technology Research and Management Centre, Civil Aviation University of China, Tianjin 300 300, China; School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300 130, China; School of Materials Science and Engineering, Tianjin University, ...

  17. Considerations for Choosing Microwave Transistors in High Power Shipboard Search Radars.

    Science.gov (United States)

    1983-09-30

    EMVNr PROjECT. TASK AREA & WORK W NIT’ NUMBERS Naval Research Laboratory 22NSF2116; Washington, DC 20375 53-0615-0-0 MI CONTROLLING OFFICE N AME AND...addressed. Internal Impedance Matching The ED manufacturer who supplies devices for radar trasmitters must determine the length of emitter periphery...Frequency Range o Instaneous Bandwidth o Peak Power o Average Power o Max Pulse Width o Pulse Modes o Efficiency o AM to PM Conversion o Reliability

  18. Microwave power transmission system studies. Volume 2: Introduction, organization, environmental and spaceborne systems analyses

    Science.gov (United States)

    Maynard, O. E.; Brown, W. C.; Edwards, A.; Haley, J. T.; Meltz, G.; Howell, J. M.; Nathan, A.

    1975-01-01

    Introduction, organization, analyses, conclusions, and recommendations for each of the spaceborne subsystems are presented. Environmental effects - propagation analyses are presented with appendices covering radio wave diffraction by random ionospheric irregularities, self-focusing plasma instabilities and ohmic heating of the D-region. Analyses of dc to rf conversion subsystems and system considerations for both the amplitron and the klystron are included with appendices for the klystron covering cavity circuit calculations, output power of the solenoid-focused klystron, thermal control system, and confined flow focusing of a relativistic beam. The photovoltaic power source characteristics are discussed as they apply to interfacing with the power distribution flow paths, magnetic field interaction, dc to rf converter protection, power distribution including estimates for the power budget, weights, and costs. Analyses for the transmitting antenna consider the aperture illumination and size, with associated efficiencies and ground power distributions. Analyses of subarray types and dimensions, attitude error, flatness, phase error, subarray layout, frequency tolerance, attenuation, waveguide dimensional tolerances, mechanical including thermal considerations are included. Implications associated with transportation, assembly and packaging, attitude control and alignment are discussed. The phase front control subsystem, including both ground based pilot signal driven adaptive and ground command approaches with their associated phase errors, are analyzed.

  19. Microwave Ovens

    Science.gov (United States)

    ... Products and Procedures Home, Business, and Entertainment Products Microwave Ovens Share Tweet Linkedin Pin it More sharing ... 1030.10 - Microwave Ovens Required Reports for the Microwave Oven Manufacturers or Industry Exemption from Certain Reporting ...

  20. Gold Nanoparticle Microwave Synthesis

    International Nuclear Information System (INIS)

    Krantz, Kelsie E.; Christian, Jonathan H.; Coopersmith, Kaitlin; Washington II, Aaron L.; Murph, Simona H.

    2016-01-01

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  1. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  2. Microwave engineering

    CERN Document Server

    Pozar, David M

    2012-01-01

    The 4th edition of this classic text provides a thorough coverage of RF and microwave engineering concepts, starting from fundamental principles of electrical engineering, with applications to microwave circuits and devices of practical importance.  Coverage includes microwave network analysis, impedance matching, directional couplers and hybrids, microwave filters, ferrite devices, noise, nonlinear effects, and the design of microwave oscillators, amplifiers, and mixers. Material on microwave and RF systems includes wireless communications, radar, radiometry, and radiation hazards. A large

  3. Metamaterial electromagnetic wave absorbers.

    Science.gov (United States)

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Comparison Between Numerical Modeling and Experimental Testing of a Point Absorber WEC Using Linear Power Take-Off System

    DEFF Research Database (Denmark)

    Zurkinden, Andrew Stephen; Kramer, Morten; Sichani, Mahdi Teimouri

    2012-01-01

    and the response of the device for regular and irregular waves were measured. Good correspondence is found between the numerical and the physical model for relatively mild wave conditions. For higher waves the numerical model seems to underestimate the response of the device due to its linear fluidstructure......Currently, a number of wave energy converters are being analyzed by means of numerical models in order to predict the electrical power generation under given wave conditions. A common characteristic of this procedure is to integrate the loadings from the hydrodynamics, power take-off and mooring...... systems into a central wave to wire model. The power production then depends on the control strategy which is applied to the device. The objective of this paper is to develop numerical methods for motion analysis of marine structures with a special emphasis on wave energy converters. Two different time...

  5. Influence of multi-walled carbon nanotubes (MWCNTs) volume percentage on the magnetic and microwave absorbing properties of BaMg{sub 0.5}Co{sub 0.5}TiFe{sub 10}O{sub 19}/MWCNTs nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Reza Shams [Physics Department, College of Sciences, Shiraz University, Shiraz 71946-84795 (Iran, Islamic Republic of); Moradi, Mahmood, E-mail: moradi@susc.ac.ir [Physics Department, College of Sciences, Shiraz University, Shiraz 71946-84795 (Iran, Islamic Republic of); Institute of Nanotechnology, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Nikmanesh, Hossein [Physics Department, College of Sciences, Shiraz University, Shiraz 71946-84795 (Iran, Islamic Republic of)

    2016-01-15

    Graphical abstract: Reflection losses of (a) doped barium hexaferrite, BaMg{sub 0.5}Co{sub 0.5}TiFe{sub 10}O{sub 19}, sample and their nanocomposites with (b) 4 vol. (c) 8 vol. and (d) 12 vol.% of MWCNTs are presented. - Highlights: • BaMg{sub 0.5}Co{sub 0.5}TiFe{sub 10}O{sub 19}/MWCNTs nanocomposites were synthesized. • The structural, magnetic and microwave absorption properties were investigated. • The microwave absorption is strongly influenced by volume percentage of MWCNTs. • The nanocomposite with 8 vol.% of MWCNTs can be proposed as a wideband absorber. - Abstract: In this study BaMg{sub 0.5}Co{sub 0.5}TiFe{sub 10}O{sub 19}/MWCNTs nanocomposites with different amount of MWCNTs (0, 4, 8 and 12 vol.%) were synthesized. Here, the X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to demonstrate the structural and morphological characteristics of the prepared samples. XRD along with FTIR examinations exhibited that the nanocomposites were successfully synthesized. Vibrating sample magnetometer (VSM) showed the relatively strong dependence of saturation magnetization and coercivity on the volume percentage of MWCNTs. The microwave evaluation also confirmed that the complex permittivity of nanocomposites could be enhanced by adding MWCNTs. Finally, the nanocomposite with 8% vol. of MWCNTs exhibited the best microwave absorption performance among the samples.

  6. A NEW CROWBAR SYSTEM FOR THE PROTECTION OF HIGH POWER GRIDDED TUBES AND MICROWAVE DEVICES

    Energy Technology Data Exchange (ETDEWEB)

    S.G.E. PRONKO; T.E.HARRIS

    2001-04-01

    As part of the electron cyclotron heating (ECH) facility upgrade at the DIII-D National Fusion Facility, two 8.4 MW modulator/regulator power systems were designed and constructed (Ref. 1). Each power system uses a high power tetrode to modulate and regulate the cathode voltage for two 1 MW-class 110 GHz gyrotrons (Ref. 2). A critical element in the power system is the fault energy divertor, or crowbar switch, that protects the tetrode and the gyrotrons in the event of an arc fault. Traditionally, mercury filled ignitron switches are used for this application, but it was desired to eliminate hazardous materials and improve overall switching performance. The new crowbar switch system was required to meet the following requirements: Operating voltage: -105 kVdc; Peak current (750 ms e-fold): 1.6 kA; Follow-on current: <1 kA (25 ms); Charge transfer per shot: <15 Cb; and Turn-on time: <1 {micro}s. The switch that was chosen for the new design is a low pressure deuterium filled device, called a metal-arc thyratron, manufactured by Marconi Applied Technologies (Ref. 3). In addition to the new crowbar switch assembly, improved fault signal processing circuitry was developed. This new circuitry uses fiber-optics for signal and trigger transmission and a complex programmable logic device for high speed signal and logic processing. Two generations of metal-arc thyratrons have been commissioned in the two ECH power systems constructed at DIII-D. In the first, the crowbar system performed extremely well, meeting all of the operating requirements and demonstrating its ability to protect a 36 gauge copper wire from fusing (energy let-through <10 J). However, after accumulating over 500 shots, the metal-arc thyratrons lost their ability to reliably hold-off voltage. This problem was solved by Marconi with a design modification of the thyratron electrodes. The second generation tubes were installed in the second ECH power system. The crowbar system was fully commissioned and all

  7. Generation and heating of toroidally confined overdense plasmas with 2.45 GHz microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Koehn, A; Birkenmeier, G; Holzhauer, E; Ramisch, M; Stroth, U, E-mail: koehn@ipf.uni-stuttgart.d [Institut fuer Plasmaforschung, Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2010-03-15

    In the stellarator TJ-K, overdense low-temperature plasmas are created by means of microwaves at 2.45 GHz. Extensive studies have been carried out to understand the heating process. The plasma breakdown at the cyclotron resonance layer has been directly observed with a multiple Langmuir probe array. Profile measurements indicate power deposition at the plasma boundary, where the upper hybrid resonance (UHR) is located. This result is confirmed by full-wave simulations which emphasize the importance of the vacuum vessel to increase the absorbed microwave power due to multiple reflections. Further indications for heating at the UHR layer are found by measurements of the wave electric field of the incident microwave and by power-modulation experiments. In contrast to similar experiments, no indication for heating by electron Bernstein waves was found.

  8. Efficiency and Linearity Enhancement of Microwave GaN Power Amplifiers using Harmonic Injection

    Science.gov (United States)

    Dani, Asmita Rajiv

    This thesis addresses an architecture for enhancing efficiency and linearity of GaN power amplifiers using external second harmonic injection at the output. This transmitter architecture has potential uses in communication and radar systems which have stringent requirements of low DC power dissipation and minimum out of band interference. An idealized theoretical analysis based on expansions of the nonlinear transfer function of a PA predicts the measured improvements in linearity and efficiency. The experimental demostration is performed with both hybrid and integrated harmonically-injected PA using discrete GaN 6W transistors in class-AB mode with 55% PAE at a fundamental frequency of 2.45 GHz. Harmonic injection at the output is shown to enhance the efficiency of the PA to 89%. For a slightly reduced efficiency of 78%, the linearity can be improved and > 15 dB reduction of third and fifth order intermodulation distortion tones is measured in compression. Integration of a dynamic supply of the harmonically-injected PA is also investigated in order to achieve high efficiency and linearity for signals with Peak-to-Average ratios (PARs) of 6 dB and higher. Experimental results demonstrate a 70-80% efficient HI-PA for an output power variation of 6 dB. Reduction in third order nonlinear products and AM-PM distortion shows improved linearity of the PA over the entire range of power levels. Finally, the concept is extended to an X-band GaN MMIC to demonstrate integration and efficiency enhancement at 10 GHz with a 4 W, 47% efficient class-AB PA, with an expected final efficiency of over 60% with harmonic injection.

  9. A direct current rectification scheme for microwave space power conversion using traveling wave electron acceleration

    Science.gov (United States)

    Manning, Robert M.

    1993-01-01

    The formation of the Vision-21 conference held three years ago allowed the present author to reflect and speculate on the problem of converting electromagnetic energy to a direct current by essentially reversing the process used in traveling wave tubes that converts energy in the form of a direct current to electromagnetic energy. The idea was to use the electric field of the electromagnetic wave to produce electrons through the field emission process and accelerate these electrons by the same field to produce an electric current across a large potential difference. The acceleration process was that of cyclotron auto-resonance. Since that time, this rather speculative ideas has been developed into a method that shows great promise and for which a patent is pending and a prototype design will be demonstrated in a potential laser power beaming application. From the point of view of the author, a forum such as Vision-21 is becoming an essential component in the rather conservative climate in which our initiatives for space exploration are presently formed. Exchanges such as Vision-21 not only allows us to deviate from the 'by-the-book' approach and rediscover the ability and power in imagination, but provides for the discussion of ideas hitherto considered 'crazy' so that they may be given the change to transcend from the level of eccentricity to applicability.

  10. The effect of low- and high-power microwave irradiation on in vitro grown Sequoia plants and their recovery after cryostorage.

    Science.gov (United States)

    Halmagyi, A; Surducan, E; Surducan, V

    2017-09-01

    Two distinct microwave power levels and techniques have been studied in two cases: low-power microwave (LPM) irradiation on in vitro Sequoia plants and high-power microwave (HPM) exposure on recovery rates of cryostored (-196°C) Sequoia shoot apices. Experimental variants for LPM exposure included: (a) in vitro plants grown in regular conditions (at 24 ± 1°C during a 16-h light photoperiod with a light intensity of 39.06 μEm -2 s -1 photosynthetically active radiation), (b) in vitro plants grown in the anechoic chamber with controlled environment without microwave irradiation, and (c) in vitro plants grown in the anechoic chamber with LPM irradiation for various times (5, 15, 30, 40 days). In comparison to control plants, significant differences in shoot multiplication and growth parameters (length of shoots and roots) were observed after 40 days of LPM exposure. An opposite effect was achieved regarding the content of total soluble proteins, which decreased with increasing exposure time to LPM. HPM irradiation was tested as a novel rewarming method following storage in liquid nitrogen. To our knowledge, this is the first report using this type of rewarming method. Although, shoot tips subjected to HPM exposure showed 28% recovery following cryostorage compared to 44% for shoot tips rewarmed in liquid medium at 22 ± 1 °C, we consider that the method represent a basis and can be further improved. The results lead to the overall conclusion that LPM had a stimulating effect on growth and multiplication of in vitro Sequoia plants, while the HPM used for rewarming of cryopreserved apices was not effective to achieve high rates of regrowth after liquid nitrogen exposure.

  11. Microwave imaging

    CERN Document Server

    Pastorino, Matteo

    2010-01-01

    An introduction to the most relevant theoretical and algorithmic aspects of modern microwave imaging approaches Microwave imaging-a technique used in sensing a given scene by means of interrogating microwaves-has recently proven its usefulness in providing excellent diagnostic capabilities in several areas, including civil and industrial engineering, nondestructive testing and evaluation, geophysical prospecting, and biomedical engineering. Microwave Imaging offers comprehensive descriptions of the most important techniques so far proposed for short-range microwave imaging-in

  12. Single-layer and double-layer microwave absorbers based on Co{sub 67}Ni{sub 33} microspheres and Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [Engineering Technology Research Center of Magnetic Materials of Anhui Province, School of Physics & Materials Science, Anhui University, Hefei 230601 (China); Wang, Zhongzhu, E-mail: wangzz@ahu.edu.cn [Engineering Technology Research Center of Magnetic Materials of Anhui Province, School of Physics & Materials Science, Anhui University, Hefei 230601 (China); Wang, Peihong; Liao, Yanlin [Engineering Technology Research Center of Magnetic Materials of Anhui Province, School of Physics & Materials Science, Anhui University, Hefei 230601 (China); Bi, Hong [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601 (China)

    2017-03-01

    Co{sub 67}Ni{sub 33} microspheres and Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} nanocrystals were synthesized by hydrothermal method. The complex permeability and complex permittivity of the as-prepared powders dispersing in wax (60 wt% powder) were measured using a vector network analyzer in 2–18 GHz frequency range. The calculated microwave absorption of single-layer and double-layer absorbers based on Co{sub 67}Ni{sub 33} microspheres and Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} nanocrystals were analyzed in 2–18 GHz frequency range. The results show that the Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}nanocrystals with the relatively low permittivity and Co{sub 67}Ni{sub 33} microspheres with the relatively high dielectric loss and magnetic loss can be used as proper matching layer and excellent absorption layer, respectively. The double-layer absorber with a coating thickness of 2.1 mm exhibits a maximum reflection loss of −43.8 dB as well as a bandwidth (reflection loss less than −10 dB) of 5 GHz. Moreover, their absorption peak and the absorption intensity can be adjusted easily through changing the stacking order and each layer thickness. - Highlights: • Ni-Zn ferrite nanocrystals can use as matching layer in double-layer absorbers. • Co{sub 67}Ni{sub 33} microspheres with high dielectric loss can use as absorption layer. • Double-layer absorbers exhibits an excellent microwave absorption in 2–18 GHz.

  13. Generation and acceleration of high-current annular electron beam in linear induction accelerator and generation of the power microwave radiation from Cherenkov TWT

    International Nuclear Information System (INIS)

    Abubakirov, E.V.; Arkhipov, O.V.; Bobyleva, L.V.

    1990-01-01

    The section of linear induction accelerator (LIA) with a strong guiding magnetic field (up to 1.5 T), with output beam power up to 2 GW and beam pulse duration 60 ns is created and investigated by experiment. The beam energy gain is equal to 10 keV/sm with explosive emission is used; the large length of the beam propagation (1.5 m) without spolling of the beam with high beam energy gain has been established. The microwave radiation power about 30-100 MW has achieved from relativistic Cherenkov travelling wave tube with high exponential gain on the basis of LIA and high-current diode

  14. Microwave applications of soft ferrites

    CERN Document Server

    Pardavi-Horvath, M P

    2000-01-01

    Signal processing requires broadband, low-loss, low-cost microwave devices (circulators, isolators, phase shifters, absorbers). Soft ferrites (garnets, spinels, hexaferrites), applied in planar microwave devices, are reviewed from the point of view of device requirements. Magnetic properties, specific to operation in high-frequency electromagnetic fields, are discussed. Recent developments in thick film ferrite technology and device design are reviewed. Magnetic losses related to planar shape and inhomogeneous internal fields are analyzed.

  15. Measurements of energy distribution and wall temperature in flowing hydrogen microwave plasma systems

    Science.gov (United States)

    Chapman, R.; Finzel, M.; Hawley, M. C.

    1985-01-01

    An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into translational energy of the flowing gas is being investigated. A calorimetric experimental system has been designed and built enclosing the microwave plasma system to accurately determine the net energy transferred to the flowing gas. For a flow rate of 8900 micromoles/sec, a pressure of 7.4 torr, and an absorbed power level of 80 W, an energy transfer efficiency of 50 percent has been measured. A heat transfer model that characterizes the energy transfer processes in the plasma is developed. A wall temperature for the plasma system is calculated.

  16. Additive manufacturing of RF absorbers

    Science.gov (United States)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  17. Low Absorbance Measurements

    Science.gov (United States)

    Harris, T. D.; Williams, A. M.

    1983-10-01

    The application of low absorption measurements to dilute solute determination requires specific instrumental characteristics. The use of laser intracavity absorption and thermal lens calorimetry to measure concentration is shown. The specific operating parameters that determine sensitivity are delineated along with the limits different measurement strategies impose. Finally areas of improvement in components that would result in improve sensitivity, accuracy, and reliability are discussed. During the past decade, a large number of methods have been developed for measuring the light absorbed by transparent materials. These include measurements on gases, liquids, and solids. The activity has been prompted by a variety of applications and a similar variety of disciplines. In Table 1 some representative examples of these methods is shown along with their published detection limits.1 It is clear that extraordinarily small absorbances can be measured. Most of the methods can be conveniently divided into two groups. These groups are those that measure the transmission of the sample and those that measure the light absorbed by the sample. The light absorbed methods are calorimetric in character. The advantages and disadvantages of each method varies depending on the principal application for which they were developed. The most prevalent motivation has been to characterize the bulk optical properties of transparent materials. Two examples are the development of extremely transparent glasses for use as fiber optic materials and the development of substrates for high power laser operation.

  18. Electromagnetic properties of carbonyl iron and their microwave ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 33; Issue 5. Electromagnetic properties of carbonyl iron and their microwave absorbing characterization as filler in silicone rubber. Yuping Duan ... These results show that the composites possess good microwave absorbing ability in both low- and highfrequency bands.

  19. Advances in microwaves

    CERN Document Server

    Young, Leo

    1967-01-01

    Advances in Microwaves, Volume 2 focuses on the developments in microwave solid-state devices and circuits. This volume contains six chapters that also describe the design and applications of diplexers and multiplexers. The first chapter deals with the parameters of the tunnel diode, oscillators, amplifiers and frequency converter, followed by a simple physical description and the basic operating principles of the solid state devices currently capable of generating coherent microwave power, including transistors, harmonic generators, and tunnel, avalanche transit time, and diodes. The next ch

  20. The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 AND 218 GHz from the 2008 Southern Survey

    Science.gov (United States)

    Das, Sudeep; Marriage, Tobias A.; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; Barrientos, L. Felipe; Battistelli, Elia A.; Bond, J. Richard; Brown, Ben; hide

    2010-01-01

    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results dearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the ACDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8(sigma) level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.

  1. Microwave Plasma System: PVA Tepla 300

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Name: Microwave AsherA tool using microwave oxygen plasma to remove organics on the surfacesSpecifications / Capabilities:Frequency: 2.45 GHzPower:...

  2. Simultaneous desulfurization and denitrification by microwave reactor with ammonium bicarbonate and zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Wei Zaishan [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)], E-mail: weizaishan98@163.com; Lin Zhehang; Niu Hejingying; He Haiming; Ji Yongfeng [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2009-03-15

    Microwave reactor with ammonium bicarbonate (NH{sub 4}HCO{sub 3}) and zeolite was set up to study the simultaneous removal of sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) from flue gas. The results showed that the microwave reactor filled with NH{sub 4}HCO{sub 3} and zeolite could reduce SO{sub 2} to sulfur with the best desulfurization efficiency of 99.1% and reduce NO{sub x} to nitrogen with the best NO{sub x} purifying efficiency of 86.5%. Microwave desulfurization and denitrification effect of the experiment using ammonium bicarbonate and zeolite together is much higher than that using ammonium bicarbonate or zeolite only. NO{sub x} concentration has little effect on denitrification but has no influence on desulfurization, SO{sub 2} concentration has no effect on denitrification. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and dentrification are 211-280 W and 0.315 s, respectively. The mechanism for microwave reduced desulfurization and denitrification can be described as the microwave-induced catalytic reduction reaction between SO{sub 2}, NO{sub x} and ammonium bicarbonate with zeolite being the catalyst and microwave absorbent.

  3. Magnetic and microwave absorption properties of La-Nd-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Ziqiang [School of Material Science and Engineering & Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Pan, Shunkang, E-mail: skpan88@163.com [School of Material Science and Engineering & Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Xiong, Jilei [Chinalco Guangxi Non Ferrous Jinyuan Rare Earth CO., LTD, Hezhou 542603 (China); Cheng, Lichun; Yao, Qingrong [School of Material Science and Engineering & Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials and Engineering, Central South University, Changsha 410083 (China); Lin, Peihao [School of Material Science and Engineering & Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

    2017-02-01

    Through arc smelting and high energy ball milling method to synthesized the powders of La{sub x}Nd{sub 2-x}Fe{sub 17} (x=0.0, 0.2, 0.4, 0.6). By x-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle analyzer (LPS) to study the structural, morphology, particle size distribution of the powders, respectively. The electromagnetic parameters and saturation magnetization of the powers were measured by a vector network analyzer (VNA) and vibrating sample magnetometer (VSM), respectively. The saturation magnetization decreases with the La increasing. The minimum absorption peak frequency shifts towards a lower frequency region with an increase of La concentration. The microwave absorbing properties of the composite with different ratios of La{sub 0.2}Nd{sub 1.8}Fe{sub 17}/Ni were studied. The microwave absorbing peaks of the composite shift to higher frequencies, and the microwave absorbing properties improved with the Ni content increase to 20%. The minimum reflection loss is −32.5 dB at 9.8 GHz and the bandwidth less than −10 dB (Microwave absorption rate 90%) reaches 3 GHz with a thickness of 1.8 mm.

  4. Emergence of traveling wave endothermic reaction in a catalytic fixed bed under microwave heating

    International Nuclear Information System (INIS)

    Gerasev, Alexander P.

    2017-01-01

    This paper presents a new phenomenon in a packed bed catalytic reactor under microwave heating - traveling wave (moving reaction zones) endothermic chemical reaction. A two-phase model is developed to simulate the nonlinear dynamic behavior of the packed bed catalytic reactor with an irreversible first-order chemical reaction. The absorbed microwave power was obtained from Lambert's law. The structure of traveling wave endothermic chemical reaction was explored. The effects of the gas velocity and microwave power on performance of the packed bed catalytic reactor were presented. Finally, the effects of the change in the location of the microwave source at the packed bed reactor was demonstrated. - Highlights: • A new phenomenon - traveling waves of endothermic reaction - is predicted. • The physical and mathematical model of a packed bed catalytic reactor under microwave heating is presented. • The structure of the traveling waves is explored. • The configuration of heating the packed bed reactor via microwave plays a key role.

  5. Utilization of microwave energy for decontamination of oil polluted soils.

    Science.gov (United States)

    Iordache, Daniela; Niculae, Dumitru; Francisc, Ioan Hathazi

    2010-01-01

    Soil oil (petroleum) product pollution represents a great environmental threat as it may contaminate the neighboring soils and surface and underground water. Liquid fuel contamination may occur anywhere during oil (petroleum) product transportation, storing, handling and utilization. The polluted soil recovery represents a complex process due to the wide range of physical, chemical and biological properties of soils which should be analyzed in connection with the study of the contaminated soil behavior under the microwave field action. The soil, like any other non-metallic material, can be heated through microwave energy absorption due to the dielectric losses, expressed by its dielectric complex constant. Oil polluted soil behaves differently in a microwave field depending on the nature, structure and amount of the polluting fuel. Decontamination is performed through volatilization and retrieval of organic contaminant volatile components. After decontamination only a soil fixed residue remains, which cannot penetrate the underground anymore. In carrying out the soil recovery process by means of this technology we should also consider the soil characteristics such as: the soil type, temperature, moisture.The first part of the paper presents the theoretical aspects relating to the behavior of the polluted soil samples in the microwave field, as well as their relating experimental data. The experimental data resulting from the analysis of soils with a different level of pollution point out that the degree of pollutant recovery is high, contributing to changing the initial classification of soils from the point of view of pollution. The paper graphically presents the levels of microwave generated and absorbed power in soil samples, soil temperature during experimentations, specific processing parameters in a microwave field. It also presents the constructive solution of the microwave equipment designed for the contaminated soil in situ treatment.

  6. Microwave dielectric heating of drops in microfluidic devices.

    Science.gov (United States)

    Issadore, David; Humphry, Katherine J; Brown, Keith A; Sandberg, Lori; Weitz, David A; Westervelt, Robert M

    2009-06-21

    We present a technique to locally and rapidly heat water drops in microfluidic devices with microwave dielectric heating. Water absorbs microwave power more efficiently than polymers, glass, and oils due to its permanent molecular dipole moment that has large dielectric loss at GHz frequencies. The relevant heat capacity of the system is a single thermally isolated picolitre-scale drop of water, enabling very fast thermal cycling. We demonstrate microwave dielectric heating in a microfluidic device that integrates a flow-focusing drop maker, drop splitters, and metal electrodes to locally deliver microwave power from an inexpensive, commercially available 3.0 GHz source and amplifier. The temperature change of the drops is measured by observing the temperature dependent fluorescence intensity of cadmium selenide nanocrystals suspended in the water drops. We demonstrate characteristic heating times as short as 15 ms to steady-state temperature changes as large as 30 degrees C above the base temperature of the microfluidic device. Many common biological and chemical applications require rapid and local control of temperature and can benefit from this new technique.

  7. Microwave Irradiation

    Indian Academy of Sciences (India)

    Microwave Irradiation. Way to Eco-friendly, Green Chemistry. Rashmi Sanghi. This article highlights with examples, the usefulness of microwaves for carrying out a'variety of organic transfor- mations. Introduction and Background. The rapid heating of food in the kitchen using microwave ovens prompted a number of ...

  8. Study and development of different techniques for the generation, conversion, propagation, and radiation of high power microwaves for the electronic cyclotron frequency plasma heating

    International Nuclear Information System (INIS)

    Rebuffi, L.

    1987-10-01

    The development and optimization of a microwave technique, concerning the high frequency (electronic cyclotron frequency) plasma heating is presented. The experiments are effectuated on the Fontenay-aux-Roses TFR tokamak, with 660 kw whole power, during 100 msec, produced at 60 GHz. Low power tests are performed on the different transmission line components (there are 3, formed by metallic circular waveguides). The work also includes: the development of a lens formed by thin metallic plans; the study of slotted surface mirror; the development of a system for the accurate measurement (5.10 -6 ) of the gyrotronic frequency; a theory, based on the equivalent circuits method, generalized to the rotational and polarization mirrors; the development of a numerical simulation code. A practical scheme, for the optimization of the parameters concerning the optical transmission line project, is given. The results of this work can be applied to the experiment involving power levels, frequencies and times of impulsion increasingly higher (respectively about MW, 100 GHz and 10s) than the reported ones. Moreover, they can also be used in any experiment in the microwave field [fr

  9. Microwave-assisted ADMET polymerization

    OpenAIRE

    Rojas Jiménez, Giovanni

    2015-01-01

    Microwave-assisted ADMET polymerization is reported on a series of α,ω-diene monomers, both polar and non-polar. Investigations indicate that of the multiple microwave modes possible, constant power is the most advantageous, providing polymers up to M‾w=31,000g/mol. Molecular weight values are nearly triple in comparison with conventional oil bath heating. Polymers are characterized by NMR, GPC, TGA, and DSC. Microwave irradiation provides a highly controllable and energy efficient ADMET poly...

  10. Synthesis of ammonia with microwave plasma

    International Nuclear Information System (INIS)

    Xu Wenguo; Yu Aimin; Liu Jun; Jin Qinhan

    1991-01-01

    THe synthesis of ammonia absorbed on 13X zeolite with the aid of microwave plasma is described. The ammonia molecule absorbed on 13X zeolite as ammonium ions were detected by IR spectroscopy. The results obtained show that the ammonia synthesis is facilitated by the surface reactions of NH x (x = 1, 2) radicals adsorbed on zeolite with hydrogen atoms

  11. Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

    Science.gov (United States)

    Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

    1982-01-01

    A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

  12. Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate

    International Nuclear Information System (INIS)

    Miotk, R; Hrycak, B; Jasinski, M; Mizeraczyk, J

    2012-01-01

    In this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity-resonant type. The aim of research was determination of electron excitation temperature T exc gas temperature Tg and electron number density n e . All experimental tests were performed with a gas flow rate of 100 and 200 l/min and absorbed microwave power PA from 0.25 to 0.9 kW. The emission spectra at the range of 300 – 600 nm were recorded. Boltzmann plot method for argon 5p – 4s and 5d – 4p transition lines allowed to determine T exc at level of 7000 K. Gas temperature was determined by comparing the measured and simulated spectra using LIFBASE program and by analyzing intensities of two groups of unresolved rotational lines of the OH band. Gas temperature ranged 600 – 800 K. The electron number density was determined using the method based on the Stark broadening of hydrogen H β line. The measured n e rang ed 2 × 10 15 − 3.5×10 15 cm −3 , depending on the absorbed microwave power. The described MPS works very stable with various working gases at high flow rates, that makes it an attractive tool for different gas processing.

  13. On the Mechanism of Microwave Flash Sintering of Ceramics

    Directory of Open Access Journals (Sweden)

    Yury V. Bykov

    2016-08-01

    Full Text Available The results of a study of ultra-rapid (flash sintering of oxide ceramic materials under microwave heating with high absorbed power per unit volume of material (10–500 W/cm3 are presented. Ceramic samples of various compositions—Al2O3; Y2O3; MgAl2O4; and Yb(LaO2O3—were sintered using a 24 GHz gyrotron system to a density above 0.98–0.99 of the theoretical value in 0.5–5 min without isothermal hold. An analysis of the experimental data (microwave power; heating and cooling rates along with microstructure characterization provided an insight into the mechanism of flash sintering. Flash sintering occurs when the processing conditions—including the temperature of the sample; the properties of thermal insulation; and the intensity of microwave radiation—facilitate the development of thermal runaway due to an Arrhenius-type dependency of the material’s effective conductivity on temperature. The proper control over the thermal runaway effect is provided by fast regulation of the microwave power. The elevated concentration of defects and impurities in the boundary regions of the grains leads to localized preferential absorption of microwave radiation and results in grain boundary softening/pre-melting. The rapid densification of the granular medium with a reduced viscosity of the grain boundary phase occurs via rotation and sliding of the grains which accommodate their shape due to fast diffusion mass transport through the (quasi-liquid phase. The same mechanism based on a thermal runaway under volumetric heating can be relevant for the effect of flash sintering of various oxide ceramics under a dc/ac voltage applied to the sample.

  14. The microwave era is just beginning

    International Nuclear Information System (INIS)

    Grad, P.

    1989-01-01

    Microwave energy applicators in curing rubber products and in ceramic manufacture are enunciated by some of the participants at the First Australian Symposium on Microwave Power Applications held in February 1989 at Wollongong. The advantages and disadvantages of microwave heating over conventional methods are stated

  15. Blood-brain barrier permeation in the rat during exposure to low-power 1.7-GHz microwave radiation

    International Nuclear Information System (INIS)

    Ward, T.R.; Ali, J.S.

    1985-01-01

    The permeability of the blood-brain barrier to high-and low-molecular-weight compounds has been measured as a function of continuous-wave (CW) and pulsed-microwave radiation. Adult rats, anesthetized with pentobarbital and injected intravenously with a mixture of [ 14 C] sucrose and [ 3 H] inulin, were exposed for 30 min at a specific absorption rate of 0.1 W/kg to 1.7-GHz CW and pulsed (0.5-microseconds pulse width, 1,000 pps) microwaves. After exposure, the brain was perfused and sectioned into nine regions, and the radioactivity in each region was counted. During identical exposure conditions, temperatures of rats were measured in eight of the brain regions by a thermistor probe that did not perturb the field. No change in uptake of either tracer was found in any of the eight regions as compared with those of sham-exposed animals

  16. Experimental and numerical investigations of microwave return loss of aircraft inlets with low-pressure plasma

    Science.gov (United States)

    Zhang, Yachun; He, Xiang; Chen, Jianping; Chen, Hongqing; Chen, Li; Zhang, Hongchao; Ni, Xiaowu; Lu, Jian; Shen, Zhonghua

    2018-03-01

    The relationships between return losses of the cylindrical inlet and plasma discharge parameters are investigated experimentally and numerically. The return losses are measured using a high dynamic range measurement system and simulated by COMSOL Multiphysics when the frequency band of the microwaves is in the range 1-4 GHz. The profiles of the plasma density are estimated using Epstein and Bessel functions. Results show that the incident microwaves can be absorbed by plasma efficaciously. The maximal return loss can reach -13.84 dB when the microwave frequency is 2.3 GHz. The increase of applied power implies augmentation of the return loss, which behaves conversely for gas pressure. The experimental and numerical results display reasonable agreement on return loss, suggesting that the use of plasma is effective in the radar cross section reduction of aircraft inlets.

  17. Microwave Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Makes ultra-high-resolution field measurements. The Microwave Microscope (MWM) has been used in support of several NRL experimental programs involving sea...

  18. Microwave detector

    Science.gov (United States)

    Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

    1985-02-08

    A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  19. Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol for the Gate Insulator of Pentacene-Based Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2017-07-01

    Full Text Available In this study, a proposed Microwave-Induction Heating (MIH scheme has been systematically studied to acquire suitable MIH parameters including chamber pressure, microwave power and heating time. The proposed MIH means that the thin indium tin oxide (ITO metal below the Poly(4-vinylphenol (PVP film is heated rapidly by microwave irradiation and the heated ITO metal gate can heat the PVP gate insulator, resulting in PVP cross-linking. It is found that the attenuation of the microwave energy decreases with the decreasing chamber pressure. The optimal conditions are a power of 50 W, a heating time of 5 min, and a chamber pressure of 20 mTorr. When suitable MIH parameters were used, the effect of PVP cross-linking and the device performance were similar to those obtained using traditional oven heating, even though the cross-linking time was significantly decreased from 1 h to 5 min. Besides the gate leakage current, the interface trap state density (Nit was also calculated to describe the interface status between the gate insulator and the active layer. The lowest interface trap state density can be found in the device with the PVP gate insulator cross-linked by using the optimal MIH condition. Therefore, it is believed that the MIH scheme is a good candidate to cross-link the PVP gate insulator for organic thin-film transistor applications as a result of its features of rapid heating (5 min and low-power microwave-irradiation (50 W.

  20. Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique.

    Science.gov (United States)

    Toker, Salih; Boone-Kukoyi, Zainab; Thompson, Nishone; Ajifa, Hillary; Clement, Travis; Ozturk, Birol; Aslan, Kadir

    2016-11-30

    Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2-20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20-39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation.

  1. Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

    Science.gov (United States)

    2016-01-01

    Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2–20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20–39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation. PMID:27917407

  2. Removal of NO {sub x} by microwave reactor with ammonium bicarbonate and Ga-A zeolites at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Z.S. [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)]. E-mail: weizaishan98@163.com; Du, Z.Y. [School of Light Industry and Chemical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Lin, Z.H. [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); He, H.M. [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Qiu, R.L. [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2007-08-15

    Microwave reactor with the mixture of ammonium bicarbonate (NH{sub 4}HCO{sub 3}) and Ga-A zeolites was set up to study the removal of nitrogen oxides (NO {sub x} ) from waste gas with excess oxygen concentration (14-19%) at low temperature (80-120 deg. C). The results showed that the microwave reactor filled with NH{sub 4}HCO{sub 3} and Ga-A zeolites could reduce NO {sub x} to nitrogen with the best purifying efficiency of 95.45% and the best denitrification amount of 89.28 mg h{sup -1}. The optimal microwave power and residence time (RT) on denitrification was 259-280 W and 0.259 s, respectively. Microwave denitrification effect of the experiment using ammonium bicarbonate and Ga-A zeolites was much higher than that using ammonium bicarbonate or Ga-A zeolites only. The mechanism for microwave-induced NO {sub x} reduction can be explained as the microwave-induced catalytic reaction between NO {sub x} and ammonium bicarbonate with Ga-A zeolites being the catalyst and microwave absorbent.

  3. Develop Prototype Microwave Interferometry Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, J. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Converse, M. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kane, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-15

    A prototype microwave interferometer was created at NSTec to characterize moving conductive fronts in upcoming experiments. The interferometer is capable of operation in the ~26-40 GHz band, and interrogating fronts with more than 1 W of power.

  4. Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhaoquan, E-mail: zqchen@aust.edu.cn [Faculty of Physics, St. Petersburg State University, St. Petersburg 198504 (Russian Federation); College of Electrical and Information Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Yin, Zhixiang, E-mail: zxyin66@163.com; Chen, Minggong; Hong, Lingli; Hu, Yelin; Huang, Yourui [College of Electrical and Information Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Xia, Guangqing; Liu, Minghai [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Kudryavtsev, A. A. [Faculty of Physics, St. Petersburg State University, St. Petersburg 198504 (Russian Federation)

    2014-10-21

    In present study, a pulsed lower-power microwave-driven atmospheric-pressure argon plasma jet has been introduced with the type of coaxial transmission line resonator. The plasma jet plume is with room air temperature, even can be directly touched by human body without any hot harm. In order to study ionization process of the proposed plasma jet, a self-consistent hybrid fluid model is constructed in which Maxwell's equations are solved numerically by finite-difference time-domain method and a fluid model is used to study the characteristics of argon plasma evolution. With a Guass type input power function, the spatio-temporal distributions of the electron density, the electron temperature, the electric field, and the absorbed power density have been simulated, respectively. The simulation results suggest that the peak values of the electron temperature and the electric field are synchronous with the input pulsed microwave power but the maximum quantities of the electron density and the absorbed power density are lagged to the microwave power excitation. In addition, the pulsed plasma jet excited by the local enhanced electric field of surface plasmon polaritons should be the discharge mechanism of the proposed plasma jet.

  5. A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions.

    Science.gov (United States)

    Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

    2016-04-27

    The use of microwave (MW) irradiation to increase the rate of chemical reactions has attracted much attention recently in nearly all fields of chemistry due to substantial enhancements in reaction rates. However, the intrinsic nature of the effects of MW irradiation on chemical reactions remains unclear. Herein, the highly effective conversion of NO and decomposition of H2S via MW catalysis were investigated. The temperature was decreased by several hundred degrees centigrade. Moreover, the apparent activation energy (Ea') decreased substantially under MW irradiation. Importantly, for the first time, a model of the interactions between microwave electromagnetic waves and molecules is proposed to elucidate the intrinsic reason for the reduction in the Ea' under MW irradiation, and a formula for the quantitative estimation of the decrease in the Ea' was determined. MW irradiation energy was partially transformed to reduce the Ea', and MW irradiation is a new type of power energy for speeding up chemical reactions. The effect of MW irradiation on chemical reactions was determined. Our findings challenge both the classical view of MW irradiation as only a heating method and the controversial MW non-thermal effect and open a promising avenue for the development of novel MW catalytic reaction technology.

  6. A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions

    Science.gov (United States)

    Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

    2016-01-01

    The use of microwave (MW) irradiation to increase the rate of chemical reactions has attracted much attention recently in nearly all fields of chemistry due to substantial enhancements in reaction rates. However, the intrinsic nature of the effects of MW irradiation on chemical reactions remains unclear. Herein, the highly effective conversion of NO and decomposition of H2S via MW catalysis were investigated. The temperature was decreased by several hundred degrees centigrade. Moreover, the apparent activation energy (Ea’) decreased substantially under MW irradiation. Importantly, for the first time, a model of the interactions between microwave electromagnetic waves and molecules is proposed to elucidate the intrinsic reason for the reduction in the Ea’ under MW irradiation, and a formula for the quantitative estimation of the decrease in the Ea’ was determined. MW irradiation energy was partially transformed to reduce the Ea’, and MW irradiation is a new type of power energy for speeding up chemical reactions. The effect of MW irradiation on chemical reactions was determined. Our findings challenge both the classical view of MW irradiation as only a heating method and the controversial MW non-thermal effect and open a promising avenue for the development of novel MW catalytic reaction technology. PMID:27118640

  7. Detailed spectra of high power broadband microwave radiation from interactions of relativistic electron beams with weakly magnetized plasmas

    International Nuclear Information System (INIS)

    Kato, K.G.; Benford, G.; Tzach, D.

    1983-01-01

    Prodigious quantities of microwave energy are observed uniformly across a wide frequency band when a relativistic electron beam (REB) penetrates a plasma. Measurement calculations are illustrated. A model of Compton-like boosting of ambient plasma waves by beam electrons, with collateral emission of high frequency photons, qualitatively explain the spectra. A transition in spectral behavior is observed from the weak to strong turbulence theories advocated for Type III solar burst radiation, and further into the regime the authors characterize as super-strong REB-plasma interactions

  8. Optimizaton of extraction of betalain pigments from beta vulgaris peels by microwave pretreatment

    Science.gov (United States)

    Singh, Aruna; Ganesapillai, Mahesh; Gnanasundaram, Nirmala

    2017-11-01

    The effect of microwave assissted extraction of pigments from beetroot peels was studied. Oven Drying followed by microwave assisted extraction was decided as the experimental procedure to be followed because of better absorbance in the range of 0.2-0.4. A microwave assisted extraction procedure is said to open the vacuolar pores inside beetroot powder.The Box-Behnken method was used as the RSM optimization technique. A quadratic model was suggested for both the solvents used. The optimized conditions for Solvent A were pH 5.20, Microwave Power of 224.61MW and Time 57.06 seconds for a Betanin Concentration of 229.264mg/L. The optimized conditions for Solvent B were found to be pH4.74, Microwave Power 384.25MW, Time 74.91 seconds and Betanin Concentration 472.113mg/L. The order of the extraction process was calculated as 1.42 and the rate constant as 0.00126. FTIR results confirm similar functional groups before and after the treatment. FTIR results confirm the presence of O-H stretch, C-H stretch, H-bonded, C-C stretch, N-H bend.

  9. Carbon Absorber Retrofit Equipment (CARE)

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Eric [Neumann Systems Group, Incorporated, Colorado Springs, CO (United States)

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  10. The microwave Tokamak experiment (MTX)

    International Nuclear Information System (INIS)

    Thomassen, K.I.; Cohen, B.I.; Hooper, E.B.; Lang, D.D.; Nevins, W.M.

    1987-01-01

    A new experimental facility is being assembled at the Lawrence Livermore National Laboratory (LLNL) for studying microwave propagation and absorption in high density plasmas. A unique feature of the facility is the free electron laser (FEL) used to generate high peak power microwaves at 250 GHz, at a repetition rate so as to produce up to 2 MW of average power for up to 30 s. Called the Microwave Tokamak Experiment (MTX), the facility will be used for studies of plasma heating, current drive, and confinement

  11. Combined application of sub-toxic level of silver nanoparticles with low powers of 2450 MHz microwave radiation lead to kill Escherichia coli in a short time

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Shahverdi

    2013-09-01

    Full Text Available   Objective(s: Electromagnetic radiations which have lethal effects on the living cells are currently also considered as a disinfective physical agent.   Materials and Methods: In this investigation, silver nanoparticles were applied to enhance the lethal action of low powers (100 and 180 W of 2450 MHZ electromagnetic radiation especially against Escherichia coli ATCC 8739. Silver nanoparticles were biologically prepared and used for next experiments. Sterile normal saline solution was prepared and supplemented by silver nanoparticles to reach the sub-inhibitory concentration (6.25 μg/mL. Such diluted silver colloid as well as free-silver nanoparticles solution was inoculated along with test microorganisms, particularly E. coli. These suspensions were separately treated by 2450 MHz electromagnetic radiation for different time intervals in a microwave oven operated at low powers (100 W and 180 W. The viable counts of bacteria before and after each radiation time were determined by colony-forming unit (CFU method. Results: Results showed that the addition of silver nanoparticles significantly decreased the required radiation time to kill vegetative forms of microorganisms. However, these nanoparticles had no combined effect with low power electromagnetic radiation when used against Bacillus subtilis spores. Conclusion: The cumulative effect of silver nanoparticles and low powers electromagnetic radiation may be useful in medical centers to reduce contamination in polluted derange and liquid wastes materials and some devices.

  12. Theoretical analysis of the multiple resonances for many-level spin systems. The four-level spin system of s electron ions subjected to strong microwave fields

    International Nuclear Information System (INIS)

    Popescu, F.F.; Marica, F.

    1994-01-01

    The analytic steady state solutions of master equation for the density matrix of a multilevel spin system in dilute paramagnetic crystals at high temperature, subjected to strong microwave fields, are discussed. These solutions enable to obtain the populations of the levels, and the microwave powers absorbed or emitted by the crystal, in the presence of one, two or more microwave fields. A detailed theoretical study of the maser effects for s electron ions with nuclear spin one-half is carried out. In the case of three frequency correlated strong fields, when 'the spectroscopic' bridge conditions are fulfilled, sensitive detections, or high efficient generations of microwaves of frequency higher than those of the pumping fields are predicted. (author) 16 figs., 16 refs

  13. Heterogeneous neutron absorbers development

    International Nuclear Information System (INIS)

    Boccaccini, Aldo; Agueda, Horacio; Russo, Diego; Perez, Edmundo

    1987-01-01

    The use of solid burnable absorber materials in power light water reactors has increased in the last years, specially due to improvements attained in costs of generated electricity. The present work summarizes the basic studies made on an alumina-gadolinia system, where alumina is the inert matrix and gadolinia acts as burnable poison, and describes the fabrication method of pellets with that material. High density compacts were obtained in the range of concentrations used by cold pressing and sintering at 1600 deg C in inert (Ar) atmosphere. Finally, the results of the irradiation experiences made at RA-6 reactor, located at the Bariloche Atomic Center, are given where variations on negative reactivity caused by introduction of burnable poison rods were measured. The results obtained from these experiences are in good agreement with those coming from calculation codes. (Author)

  14. Microwave generation and complex microwave responsivity measurements on small Dayem bridges

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sørensen, O; Mygind, Jesper

    1977-01-01

    Measurements of the active properties of a Dayem micro-bridge at X-band frequencies is described. The bridge was mounted in a microwave cavity designed to match the bridge properly and the microwave output from the cavity was detected using a sensitive X-band spectrometer. Microwave power...

  15. Bend-absorbing clamp

    Science.gov (United States)

    Abbott, J. R.; Valencia, B., Jr.

    1979-01-01

    Compact, inexpensive clamp for flexible cables or rigid tubes absorbs vibrations and other motion. It accomodates wide range of dimensions, and saves space by eliminating pigtails or bellows commonly used to absorb linear movement or vibrations

  16. Microwave Tokamak Experiment

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The Microwave Tokamak Experiment, now under construction at the Laboratory, will use microwave heating from a free-electron laser. The intense microwave pulses will be injected into the tokamak to realize several goals, including a demonstration of the effects of localized heat deposition within magnetically confined plasma, a better understanding of energy confinement in tokamaks, and use of the new free-electron laser technology for plasma heating. The experiment, soon to be operational, provides an opportunity to study dense plasmas heated by powers unprecedented in the electron-cyclotron frequency range required by the especially high magnetic fields used with the MTX and needed for reactors. 1 references, 5 figures, 3 tables

  17. Microwave Measurements

    CERN Document Server

    Skinner, A D

    2007-01-01

    The IET has organised training courses on microwave measurements since 1983, at which experts have lectured on modern developments. Their lecture notes were first published in book form in 1985 and then again in 1989, and they have proved popular for many years with a readership beyond those who attended the courses. The purpose of this third edition of the lecture notes is to bring the latest techniques in microwave measurements to this wider audience. The book begins with a survey of the theory of current microwave circuits and continues with a description of the techniques for the measureme

  18. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  19. Resonant and Ground Experimental Study on the Microwave Plasma Thruster

    Science.gov (United States)

    Yang, Juan; He, Hongqing; Mao, Genwang; Qu, Kun; Tang, Jinlan; Han, Xianwei

    2002-01-01

    resonator, which reduces the energy loss arising from the heat conducting, the wall temperature almost have no limitation. The cavity is partitioned in two halves separated by a dialectic quartz plate. The propellant is swirl-injected tangentially in the nozzle side of the cavity (plasma chamber), which extends lifetime and working reliability of MPT. Compared, coaxial resonator has the characteristic of smaller structure, lighter weight, wider bandwidth of resonating frequency and more stable resonate state. microwave energy can heat propellant gas to produce thrust efficiently. According to the test method on the return loss of passive parts of microwave apparatus, this paper also makes experimental study on the resonating state of MPT cavity with scalar network analyzer operating under low signal. Purpose is to analyze its energy absorbing efficiency and resonant frequency band, research the matching of the cavity dimension, microwave coupling probe position and the isolate plate material within the cavity. The conclusion is helpful for the thruster design and improving the system efficiency. different propellant gases (Ar and He) have been fulfilled. The power, resonant pressure and mass flow rate have been measured and analyzed. Experiments show that MPT can start up reliably and work steadily. Keywords: microwave plasma thrustermicrowaveplasmaresonatorreturn loss

  20. Passive Microwave Components and Antennas

    DEFF Research Database (Denmark)

    State-of-the-art microwave systems always require higher performance and lower cost microwave components. Constantly growing demands and performance requirements of industrial and scientific applications often make employing traditionally designed components impractical. For that reason, the design...... and development process remains a great challenge today. This problem motivated intensive research efforts in microwave design and technology, which is responsible for a great number of recently appeared alternative approaches to analysis and design of microwave components and antennas. This book highlights...... techniques. Modelling and computations in electromagnetics is a quite fast-growing research area. The recent interest in this field is caused by the increased demand for designing complex microwave components, modeling electromagnetic materials, and rapid increase in computational power for calculation...

  1. Continuous microwave regeneration apparatus for absorption media

    Science.gov (United States)

    Smith, Douglas D.

    1999-01-01

    A method and apparatus for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  2. [Application of microwave irradiation technology to the field of pharmaceutics].

    Science.gov (United States)

    Zhang, Xue-Bing; Shi, Nian-Qiu; Yang, Zhi-Qiang; Wang, Xing-Lin

    2014-03-01

    Microwaves can be directly transformed into heat inside materials because of their ability of penetrating into any substance. The degree that materials are heated depends on their dielectric properties. Materials with high dielectric loss are more easily to reach a resonant state by microwaves field, then microwaves can be absorbed efficiently. Microwave irradiation technique with the unique heating mechanisms could induce drug-polymer interaction and change the properties of dissolution. Many benefits such as improving product quality, increasing energy efficiency and reducing times can be obtained by microwaves. This paper summarized characteristics of the microwave irradiation technique, new preparation techniques and formulation process in pharmaceutical industry by microwave irradiation technology. The microwave technology provides a new clue for heating and drying in the field of pharmaceutics.

  3. Low intensity microwave radiation as modulator of the L-lactate dehydrogenase activity.

    Science.gov (United States)

    Vojisavljevic, Vuk; Pirogova, Elena; Cosic, Irena

    2011-07-01

    In this study, we investigated experimentally the possibility of modulating protein activity by low intensity microwaves by measuring alternations of L: -Lactate Dehydrogenase enzyme (LDH) activity. The LDH enzyme solutions were irradiated by microwaves of the selected frequencies and powers using the Transverse Electro-Magnetic (TEM) cell. The kinetics of the irradiated LDH was measured by continuous monitoring of nicotine adenine dinucleotide, reduced (NADH) absorbance at 340 nm. A comparative analysis of changes in the activity of the irradiated LDH enzyme versus the non-radiated enzyme was performed for the selected frequencies and powers. It was found that LDH activity can be selectively increased only by irradiation at the particular frequencies of 500 MHz [electric field: 0.02 V/m (1.2 × 10⁻⁶ W/m²)-2.1 V/m (1.2 × 10⁻² W/m²)] and 900 MHz [electric field: 0.021-0.21 V/m (1.2 × 10⁻⁴ W/m²)]. Based on results obtained it was concluded that LDH enzyme activity can be modulated by specific frequencies of low power microwave radiation. This finding can serve to support the hypothesis that low intensity microwaves can induce non-thermal effects in bio-molecules.

  4. The Atacama Cosmology Telescope: A Measurement of the 600 less than l less than 8000 Cosmic Microwave Background Power Spectrum at 148 GHz

    Science.gov (United States)

    Fowler, J. W.; Acquaviva, V.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.; Barrientos, L. F.; Bassistelli, E. S.; Bond, J. R.; Brown, B.; hide

    2010-01-01

    We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz. The measurement uses maps with 1.4' angular resolution made with data from the Atacama Cosmology Telescope (ACT). The observations cover 228 deg(sup 2) of the southern sky, in a 4 deg. 2-wide strip centered on declination 53 deg. South. The CMB at arc minute angular scales is particularly sensitive to the Silk damping scale, to the Sunyaev-Zel'dovich (SZ) effect from galaxy dusters, and to emission by radio sources and dusty galaxies. After masking the 108 brightest point sources in our maps, we estimate the power spectrum between 600 less than l less than 8000 using the adaptive multi-taper method to minimize spectral leakage and maximize use of the full data set. Our absolute calibration is based on observations of Uranus. To verify the calibration and test the fidelity of our map at large angular scales, we cross-correlate the ACT map to the WMAP map and recover the WMAP power spectrum from 250 less than l less than 1150. The power beyond the Silk damping tail of the CMB (l approximately 5000) is consistent with models of the emission from point sources. We quantify the contribution of SZ clusters to the power spectrum by fitting to a model normalized to sigma 8 = 0.8. We constrain the model's amplitude A(sub sz) less than 1.63 (95% CL). If interpreted as a measurement of as, this implies sigma (sup SZ) (sub 8) less than 0.86 (95% CL) given our SZ model. A fit of ACT and WMAP five-year data jointly to a 6-parameter ACDM model plus point sources and the SZ effect is consistent with these results.

  5. Optically Modulated Multiband Terahertz Perfect Absorber

    DEFF Research Database (Denmark)

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue

    2014-01-01

    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented...

  6. Recoverable neutron absorbers

    International Nuclear Information System (INIS)

    Keay, R.T.; Williams, J.A.

    1982-01-01

    In the reprocessing of irradiated nuclear fuel elements the nuclear fuel material is separated from the material which forms the remainder of the elements by dissolving the nuclear fuel material in nitric acid. Neutron absorbers are added to control criticality. The neutron absorbers comprise pellets each having a core of neutron absorbing material encased in a sheath of a material which is resistant to attack by acid, the core or sheath being magnetic. The sheath protects the core of neutron absorbing material from attack by the acid and the magnetic content of the core or sheath enables the absorbers to be recovered for reuse by magnetic separation techniques. (author)

  7. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2013-01-01

    Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-freq

  8. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Daniel, E-mail: daniel.kersting@usp.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP/USP), Sao Paulo, SP (Brazil); Wiebeck, Helio, E-mail: hwiebeck@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica; Marinucci, Gerson; Silva, Leonardo G.A. e, E-mail: marinuci@ipen.br, E-mail: gasilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  9. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    International Nuclear Information System (INIS)

    Kersting, Daniel; Wiebeck, Helio

    2013-01-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  10. Effect of microwave power on the thermal genesis of Co{sub 3}O{sub 4} nanoparticles from cobalt oxalate micro-rods

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Zied, Bahaa M., E-mail: babuzaid@kau.edu.sa [Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Bawaked, Salem M.; Kosa, Samia A. [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Schwieger, Wilhelm [Institut Für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen 91058 (Germany)

    2015-10-01

    Graphical abstract: - Highlights: • Preparation of CoC{sub 2}O{sub 4}·2H{sub 2}O using a microwave (280 and 700 W) assisted synthesis. • Effect of MWP on the morphology and crystallite size of Co{sub 3}O{sub 4} NPs. • Irrespective of the MWP utilized single phase of the prepared Co{sub 3}O{sub 4} NPs has been confirmed by XRD. • The developed procedure allows for the control of the morphology and size of Co{sub 3}O{sub 4} NPs. - Abstract: This study focuses on investigating the influence of microwave power (MWP) change on the morphology and size of Co{sub 3}O{sub 4} nanoparticles (NPs), which was obtained from the thermal decomposition of cobalt oxalate precursor. The oxalate precursor was prepared via the microwave-assisted route in the presence of cetyltrimethylammonium bromide (CTAB) employing an MWP of 280 and 700 W. Physicochemical properties of the prepared solids were characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetry-differential thermal analyses (TGA-DTA). The results obtained indicated that the applied MWP has a crucial effect in controlling the morphology and the size of CoC{sub 2}O{sub 4}·2H{sub 2}O as well as Co{sub 3}O{sub 4} NPs. Acicular- and rod-like morphologies of both phases were obtained employing an MWP of 280 and 700 W during the preparation, respectively. Further, both the prepared Co{sub 3}O{sub 4} nanoneedles and nanorods are composed of net-like structure of interconnected nanocapsules. Moreover, although all the routes led to the same phase, additional difference existed in terms of surface Co{sup 2+} and hydroxyl-carbonate concentrations. Lower MWP favors high Co{sup 2+} and low cobalt hydroxyl-carbonate surface concentrations.

  11. Síntese e caracterização da hexaferrita de bário tipo m dopada com lantânio e sódio para utilização como absorvedor de microondas Synthesis and characterisation of lanthanum and sodium doped m type barium hexaferrite to be used as microwave absorber

    Directory of Open Access Journals (Sweden)

    R. C. Lima

    2003-03-01

    Full Text Available Hexaferrita de Bário, dopada com lantânio e sódio, foi obtida pelo processo de mistura de óxidos. A composição utilizada foi Ba0,8La0,1Na0,1Fe12O 19. Este trabalho teve como objetivo reduzir o valor da freqüência de ressonância da hexaferrita de bário tipo M de modo que a mesma possa absorver microondas na faixa de freqüência de 8 a 16 GHz. Para se investigar a fase obtida, o material foi submetido a difração de raios X. A morfologia das partículas foi verificada pela técnica de microscopia eletrônica de varredura. Suas propriedades magnéticas e de absorção de microondas foram estudadas utilizando-se o magnetômetro de amostra vibrante e guia de ondas, respectivamente.Lanthanum and sodium doped barium hexaferrite was obtained by the mixed-oxide technique. The composition was Ba0,8La0,1Na0,1Fe12O 19. The aim of this work was to reduce the resonance frequency value of barium hexaferrite in order to be used as microwave absorber material, in the 8-16 GHz frequency range. The analysis of phases was carried out by X-ray diffraction. Particle's morphology was studied by scanning electron microscopy (SEM. Magnetic and microwave absorption properties were evaluated by using a vibrating sample magnetometer and a waveguide measurement set-up.

  12. Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters

    DEFF Research Database (Denmark)

    Aghanim, N.; Akrami, Y.; Ashdown, M.

    2017-01-01

    The six parameters of the standard ΛCDM model have best-fit values derived from the Planck temperature power spectrum that are shifted somewhat from the best-fit values derived from WMAP data. These shifts are driven by features in the Planck temperature power spectrum at angular scales that had ...

  13. Protection of Electronic Systems from the Effects of High-Power Microwave (HPM) and Ultra-Wideband (UWB) Sources

    Science.gov (United States)

    2012-03-24

    capacitor is connected between the power trace and ground through a via positioned closely to the test chip power pin. The input and output signal traces...carriers in the channels in the body region, which governs the diode transients, is responsible for the imbalance between the transient responses of the

  14. Combined effect of microwave and activated carbon on the remediation of polychlorinated biphenyl-contaminated soil.

    Science.gov (United States)

    Liu, Xitao; Yu, Gang

    2006-04-01

    The application of microwave and activated carbon for the treatment of polychlorinated biphenyl (PCB) contaminated soil was explored in this study with a model compound of 2,4,5-trichlorobiphenyl (PCB29). PCB-contaminated soil was treated in a quartz reactor by microwave irradiation at 2450MHz with the addition of granular activated carbon (GAC). In this procedure, GAC acted as microwave absorbent for reaching high temperature and reductant for dechlorination. A sheltered type-K thermocouple was applied to record the temperature rising courses. It was shown that the addition of GAC could effectively promote the temperature rising courses. The determination of PCB residues in soil by gas chromatography (GC) revealed that rates of PCB removal were highly dependent on microwave power, soil moisture content, and the amount of GAC added. GC with mass spectrum (MS) detector and ion chromatography were employed for the analysis of degradation intermediates and chlorine ions, respectively. It was suggested that microwave irradiation with the assistance of activated carbon might be a potential technology for the remediation of PCB-contaminated soil.

  15. Dielectric properties of biomass/biochar mixtures at microwave frequencies

    Science.gov (United States)

    Material dielectric properties are important for understanding their response to microwaves. Carbonaceous materials are considered good microwave absorbers and can be mixed with dry biomasses, which are otherwise low- loss materials, to improve the heating efficiency of biomass feedstocks. In this ...

  16. The research and test of microwave preventer web

    International Nuclear Information System (INIS)

    Tao Songlei; Li Weicai; Ye Jian; Hong Tao; Tao Junbing

    2003-01-01

    To deal with the microwave's harm to the organism, a division-layer composed of several kinds of materials is set between the source of microwave and the protected target. By the use of the division-layer, the power density of field intensity of microwave will come up to a safe amount. The article puts forward a new microwave preventer for mobile telephone. Experiments show that the radiation power density nearby human brain can be reduced to 5 μW/cm 2 and below by using mobile telephone microwave preventer, which is in compliance with the state health standard for microwave radiation from the mobile phone

  17. [Experimental study on spectra of compressed air microwave plasma].

    Science.gov (United States)

    Liu, Yong-Xi; Zhang, Gui-Xin; Wang, Qiang; Hou, Ling-Yun

    2013-03-01

    Using a microwave plasma generator, compressed air microwave plasma was excited under 1 - 5 atm pressures. Under different pressures and different incident microwave power, the emission spectra of compressed air microwave plasma were studied with a spectra measuring system. The results show that continuum is significant at atmospheric pressure and the characteristic will be weakened as the pressure increases. The band spectra intensity will be reduced with the falling of the incident microwave power and the band spectra were still significant. The experimental results are valuable to studying the characteristics of compressed air microwave plasma and the generating conditions of NO active groups.

  18. Active Microwave Technologies Using Ultra-High efficiency P-Band and L -Band Power Amplifiers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AlGaN/GaN devices on SiC substrates will be utilized to achieve Power Added Efficiencies (PAE) in excess of 85%. These wide band-gap solid-state semiconductors...

  19. Continuous microwave flow synthesis of mesoporous hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Akram, Muhammad; Alshemary, Ammar Z.; Goh, Yi-Fan; Wan Ibrahim, Wan Aini [Department of Chemistry, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Lintang, Hendrik O. [Centre for Sustainable Nanomaterials (CSNano), Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Hussain, Rafaqat, E-mail: rafaqat@kimia.fs.utm.my [Centre for Sustainable Nanomaterials (CSNano), Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia)

    2015-11-01

    We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45 GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca{sup 2+} ion released in SBF solution. - Highlights: • Continuous microwave flow synthesis method was used to prepare hydroxyapatite. • Increase in microwave power enhanced the degree of crystallinity. • TEM images confirmed the presence of mesopores on the surface of HA.

  20. Continuous microwave flow synthesis of mesoporous hydroxyapatite

    International Nuclear Information System (INIS)

    Akram, Muhammad; Alshemary, Ammar Z.; Goh, Yi-Fan; Wan Ibrahim, Wan Aini; Lintang, Hendrik O.; Hussain, Rafaqat

    2015-01-01

    We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45 GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca 2+ ion released in SBF solution. - Highlights: • Continuous microwave flow synthesis method was used to prepare hydroxyapatite. • Increase in microwave power enhanced the degree of crystallinity. • TEM images confirmed the presence of mesopores on the surface of HA

  1. Development of high power X-band semiconductor microwave switch for pulse compression systems of future linear colliders

    Directory of Open Access Journals (Sweden)

    Fumihiko Tamura

    2002-06-01

    Full Text Available We describe concepts for high power semiconductor rf switches, designed to handle signals at X-band with power level near 100 MW. We describe an abstract design methodology and derive a general scaling law for these switches. We also present a design and experimental work of a switch operating at the TE_{01} mode in overmoded circular waveguides. The switch is composed of an array of tee junction elements that have a p-i-n diode array window in the third arm.

  2. Microwave phase shifter with controllable power response based on slow-and fast-light effects in semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Xue, Weiqi; Sales, Salvador; Capmany, Jose

    2009-01-01

    We suggest and experimentally demonstrate a method for increasing the tunable rf phase shift of semiconductor waveguides while at the same time enabling control of the rf power. This method is based on the use of slow- and fast-light effects in a cascade of semiconductor optical amplifiers combin...

  3. Calculation of absorbed dose for skin contamination imparted by beta radiation through the VARSKIN modified code for 122 interesting isotopes for nuclear medicine, nuclear power plants and research

    International Nuclear Information System (INIS)

    Alvarez R, J.T.

    1991-01-01

    In this work the implementation of a modification of the VARSKIN code for calculation of absorbed dose for contamination in skin imparted by external radiation fields generated by Beta emitting is presented. The modification consists on the inclusion of 47 isotopes of interest even Nuclear Plants for the dose evaluation in skin generated by 'hot particles'. The approach for to add these isotopes is the correlation parameter F and the average energy of the Beta particle, with relationship to those 75 isotopes of the original code. The methodology of the dose calculation of the VARSKIN code is based on the interpolation, (and integration of the interest geometries: punctual or plane sources), of the distribution functions scaled doses in water for beta and electrons punctual sources, tabulated by Berger. Finally a brief discussion of the results for their interpretation and use with purposes of radiological protection (dose insurance in relation to the considered biological effects) is presented

  4. Microwave synthesis and mechanical characterization of functionally ...

    Indian Academy of Sciences (India)

    skin depth of MW radiation in metal plays decisive role in MW heating of metallic powders. The skin depth for tungsten and copper at 2·45 GHz is in micrometre regime. (Mondal et al 2010). Therefore, tungsten and copper particles cannot efficiently absorb microwave at room tem- perature. To overcome this problem in poor ...

  5. Spectral measurements of the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Kogut, A.J.

    1989-04-01

    Three experiments have measured the intensity of the Cosmic Microwave Background (CMB) at wavelengths 4.0, 3.0, and 0.21 cm. The measurement at 4.0 cm used a direct-gain total-power radiometer to measure the difference in power between the zenith sky and a large cryogenic reference target. Foreground signals are measured with the same instrument and subtracted from the zenith signal, leaving the CMB as the residual. The reference target consists of a large open-mouth cryostat with a microwave absorber submerged in liquid helium; thin windows block the radiative heat load and prevent condensation atmospheric gases within the cryostat. The thermodynamic temperature of the CMB at 4.0 cm is 2.59 +- 0.07 K. The measurement at 3.0 cm used a superheterodyne Dicke-switched radiometer with a similar reference target to measure the zenith sky temperature. A rotating mirror allowed one of the antenna beams to be redirected to a series of zenith angles, permitting automated atmospheric measurements without moving the radiometer. A weighted average of 5 years of data provided the thermodynamic temperature of the CMB at 3.0 cm of 2.62 +- 0.06 K. The measurement at 0.21 cm used Very Large Array observations of interstellar ortho-formaldehyde to determine the CMB intensity in molecular clouds toward the giant HII region W51A (G49.5-0.4). Solutions of the radiative transfer problem in the context of a large velocity gradient model provided estimates of the CMB temperature within the foreground clouds. Collisional excitation from neutral hydrogen molecules within the clouds limited the precision of the result. The thermodynamic temperature of the CMB at 0.21 cm is 3.2 +- 0.9 K. 72 refs., 27 figs., 38 tabs.

  6. Spectral measurements of the cosmic microwave background

    International Nuclear Information System (INIS)

    Kogut, A.J.

    1989-04-01

    Three experiments have measured the intensity of the Cosmic Microwave Background (CMB) at wavelengths 4.0, 3.0, and 0.21 cm. The measurement at 4.0 cm used a direct-gain total-power radiometer to measure the difference in power between the zenith sky and a large cryogenic reference target. Foreground signals are measured with the same instrument and subtracted from the zenith signal, leaving the CMB as the residual. The reference target consists of a large open-mouth cryostat with a microwave absorber submerged in liquid helium; thin windows block the radiative heat load and prevent condensation atmospheric gases within the cryostat. The thermodynamic temperature of the CMB at 4.0 cm is 2.59 +- 0.07 K. The measurement at 3.0 cm used a superheterodyne Dicke-switched radiometer with a similar reference target to measure the zenith sky temperature. A rotating mirror allowed one of the antenna beams to be redirected to a series of zenith angles, permitting automated atmospheric measurements without moving the radiometer. A weighted average of 5 years of data provided the thermodynamic temperature of the CMB at 3.0 cm of 2.62 +- 0.06 K. The measurement at 0.21 cm used Very Large Array observations of interstellar ortho-formaldehyde to determine the CMB intensity in molecular clouds toward the giant HII region W51A (G49.5-0.4). Solutions of the radiative transfer problem in the context of a large velocity gradient model provided estimates of the CMB temperature within the foreground clouds. Collisional excitation from neutral hydrogen molecules within the clouds limited the precision of the result. The thermodynamic temperature of the CMB at 0.21 cm is 3.2 +- 0.9 K. 72 refs., 27 figs., 38 tabs

  7. Microwave Irradiation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 3. Microwave Irradiation - Way to Eco-friendly, Green Chemistry. Rashmi Sanghi. General Article Volume 5 Issue 3 March 2000 pp 77-81. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Microwave mediated synthesis of semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Afrasiabi, Roodabeh; Sugunan, Abhilash; Shahid, Robina; Toprak, Muhammet S.; Muhammed, Mamoun [Division of Functional Materials, Royal Institute of Technology (KTH), Stockholm (Sweden)

    2012-07-15

    Colloidal quantum dots (QD) have tuneable optoelectronic properties and can be easily handled by simple solution processing techniques, making them very attractive for a wide range of applications. Over the past decade synthesis of morphology controlled high quality (crystalline, monodisperse) colloidal QDs by thermal decomposition of organometallic precursors has matured and is well studied. Recently, synthesis of colloidal QDs by microwave irradiation as heating source is being studied due to the inherently different mechanisms of heat transfer, when compared to solvent convection based heating. Under microwave irradiation, polar precursor molecules directly absorb the microwave energy and heat up more efficiently. Here we report synthesis of colloidal II-VI semiconductor QDs (CdS, CdSe, CdTe) by microwave irradiation and compare it with conventional synthesis based on convection heating. Our findings show that QD synthesis by microwave heating is more efficient and the chalcogenide precursor strongly absorbs the microwave radiation shortening the reaction time and giving a high reaction yield (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Influence of microwaves on olive oil stability

    International Nuclear Information System (INIS)

    Farag, R.S.; El-Baroty, G.; Abd El-Aziz, N.; Basuny, A.M.

    1997-01-01

    The fruits of Picual and Shemlalli olive cultivars were exposed to microwaves generated from an oven at low and moderate power settings for 3, 6, 9 and 12 min. The physicochemical constants and fatty acid composition of the olive oil samples extracted from nonmicrowaved and microwaved fruits were determined. The data demonstrated that microwaves did not alter the values of the above mentioned parameters compared with the oil extracted from nonmicrowaved fruits. Quality assurance tests (acid, peroxide and TBA values) elucidated that microwaves generally increased the olive oil stability of Picual and Shemlalli cultivars during storage. In addition, microwaves generated from oven ot moderate power setting for 12 min. exhibited an antioxidant power on olive oil equivalent to that possessed by BHT at 200 ppm [es

  10. Effects of microwave on spin tunneling in single-molecule magnets

    Science.gov (United States)

    Kim, Gwang-Hee; Kim, Tae-Suk

    2005-03-01

    We study theoretically the effects of the irradiated microwave on the magnetization in single-molecule magnets (SMMs) like V15 and Fe8. We find that the shape of magnetization depends on the microwave intensity as well as the microwave polarization. The applied microwave field enhances the tunneling probability. The linearly polarized microwaves induce the suppression of magnetization at both positive and negative magnetic fields. The circularly polarized microwaves are absorbed either at one direction of magnetic field or at both directions of magnetic fields, depending on the polarization directions with respect to the direction of longitudinal magnetic field. The generic features we found will be compared with the recent experimental results.

  11. Conductivity studies on microwave synthesized glasses

    Indian Academy of Sciences (India)

    Keywords. Conductivity; electrical modulus; impedance; microwave; power law; stretched exponent. 1. Introduction. Microwave processing of materials is a relatively new tech- nology undergoing rapid developments due to potential advantages and it offers such as reduced processing time, energy efficiency and products ...

  12. Using a microwave-induced method to regenerate platinum catalyst

    Directory of Open Access Journals (Sweden)

    Chih-Ju G. Jou

    2017-11-01

    Full Text Available When the catalyst is put under the conditions of microwave energy with oxygen, it absorbs microwave energy and turns the energy into heat to support the combustion process. The oxygen is spread into the catalyst through surface pores which allows coke combustion. The laboratory results show that when air flow rate is at 2 L min−1 and microwave energy is at 450 W with an exposure time of 8 h, the coke removal efficiency was 70% as compared to 15% in the control system (without air. This study provides an innovative technique of using microwave energy to regenerate spent platinum catalysts containing coke.

  13. Polarization insensitive metamaterial absorber based on E-shaped all-dielectric structure

    Directory of Open Access Journals (Sweden)

    Liyang Li

    2015-03-01

    Full Text Available In this paper, we designed a metamaterial absorber performed in microwave frequency band. This absorber is composed of E-shaped dielectrics which are arranged along different directions. The E-shaped all-dielectric structure is made of microwave ceramics with high permittivity and low loss. Within about 1 GHz frequency band, more than 86% absorption efficiency was observed for this metamaterial absorber. This absorber is polarization insensitive and is stable for incident angles. It is figured out that the polarization insensitive absorption is caused by the nearly located varied resonant modes which are excited by the E-shaped all-dielectric resonators with the same size but in the different direction. The E-shaped dielectric absorber contains intensive resonant points. Our research work paves a way for designing all-dielectric absorber.

  14. Microwave assisted ignition to achieve combustion synthesis

    Directory of Open Access Journals (Sweden)

    E. Balakrishnan

    2001-01-01

    Full Text Available The use of microwave heating to initiate combustion synthesis has been increasingly investigated in recent years because of its advantages over traditional methods. A simple mathematical model is used to model these experiments. The microwave power absorption term is modelled as the product of an Arrhenius reaction term with a function that decays exponentially with distance. The former represents the temperature-dependent absorption of the microwaves whereas the latter describes the penetration of the material by the microwaves. Combustion kinetics are modelled as a first-order Arrhenius reaction.

  15. Fast Drying of Agriculture Commodities by Using Microwave

    Science.gov (United States)

    Ode Ngkoimani, La; Megawati; Purwana Saputra, Gde; Cahyono, Edi; Aripin, Haji; Gde Suastika, Komang; Nyoman Sudiana, I.

    2017-05-01

    Some progress has been made and reported previously due to investigate microwave effects to materials. The microwave applications for material processing by using wide range microwave frequencies such as in sintering, chemical reaction, and drying have been performed. Microwave drying is based on a unique volumetric heating mode with electromagnetic radiation at 2,450 MHz. However, the quest for a what a true microwave effect is still plagued with difficulties. This paper provides a experimental and theoretical analysis of drying materials using microwave. For drying experiments, in this investigation, we were using a domestic microwave oven which operated at three power levels for drying chamber. The samples are agriculture commodity collected from local farmers. The experimental results show that microwave accelerate drying in most materials. The experimental data were analyzed by using an available model constructed from fundamental physics by other scholars. The model has been applied to more understanding the behavior of the microwave drying material.

  16. A 200 MHz Bandwidth, 4096 Spectral Channels, 3 W Power Consumption, Digital Auto-Correlation Spectrometer Chip for Spaceborne Microwave Radiometers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s program for Exploration of the Solar System requires high-resolution microwave spectrometers for the analysis of chemical composition and physical properties...

  17. Phenomenology of microwave coupling, part 1

    Science.gov (United States)

    King, R. J.; Breakall, J. K.; Hudson, H. G.; Morrison, J. J.; McGevna, V. G.; Kunz, K. S.; Ludwigsen, A. P.; Gnade, D. K.

    1984-11-01

    Advances in the development of high power microwave sources have increased the potential for future deployment of microwave weapons. A key ingredient in being able to predict the vulnerability of military systems to such threats involves understanding the phenomenology of how electromagnetic energy couples into cavity like objects, or the so called back door coupling. A similar but much longer standing problem is that of nuclear electromagnetic pulses (EMP) in which the frequencies extend up to several hundreds of MHz. However, compared to EMP coupling, microwave coupling is distinctively different because the wavelength is comparable to the size of the ports of entry. Coupling paths can be highly resonant at certain microwave frequencies, making the shielding against microwave threats difficult. The initial efforts at Lawrence Livermore National Laboratory to study the phenomenology of back door coupling at the low microwave frequencies (up to 2.5 GHz) are summarized.

  18. Absorber manufacturing made easy

    Energy Technology Data Exchange (ETDEWEB)

    Berner, Joachim

    2010-07-01

    Whether by means of a laser source or an ultrasound head - automation technology is making progress in the solar thermal sector. S and WE presents news developments in welding technology in absorber manufacture. (orig.)

  19. PWR burnable absorber evaluation

    International Nuclear Information System (INIS)

    Cacciapouti, R.J.; Weader, R.J.; Malone, J.P.

    1995-01-01

    The purpose of the study was to evaluate the relative neurotic efficiency and fuel cycle cost benefits of PWR burnable absorbers. Establishment of reference low-leakage equilibrium in-core fuel management plans for 12-, 18- and 24-month cycles. Review of the fuel management impact of the integral fuel burnable absorber (IFBA), erbium and gadolinium. Calculation of the U 3 O 8 , UF 6 , SWU, fuel fabrication, and burnable absorber requirements for the defined fuel management plans. Estimation of fuel cycle costs of each fuel management plan at spot market and long-term market fuel prices. Estimation of the comparative savings of the different burnable absorbers in dollar equivalent per kgU of fabricated fuel. (author)

  20. TOMS Absorbing Aerosol Index

    Data.gov (United States)

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  1. Design and analysis of 30 nm T-gate InAlN/GaN HEMT with AlGaN back-barrier for high power microwave applications

    Science.gov (United States)

    Murugapandiyan, P.; Ravimaran, S.; William, J.; Meenakshi Sundaram, K.

    2017-11-01

    In this article, we present the DC and microwave characteristics of a novel 30 nm T-gate InAlN/AlN/GaN HEMT with AlGaN back-barrier. The device structure is simulated by using Synopsys Sentaurus TCAD Drift-Diffusion transport model at room temperature. The device features are heavily doped (n++ GaN) source/drain regions with Si3N4 passivated device surface for reducing the contact resistances and gate capacitances of the device, which uplift the microwave characteristics of the HEMTs. 30 nm gate length D-mode (E-mode) HEMT exhibited a peak drain current density Idmax of 2.3 (2.42) A/mm, transconductance gm of 1.24(1.65) S/mm, current gain cut-off frequency ft of 262 (246) GHz, power gain cut-off frequency fmax of 246(290) GHz and the three terminal off-state breakdown voltage VBR of 40(38) V. The preeminent microwave characteristics with the higher breakdown voltage of the proposed GaN-based HEMT are the expected to be the most optimistic applicant for future high power millimeter wave applications.

  2. Microwave absorption by a lossy dielectric sphere in a rectangular cavity

    Science.gov (United States)

    Jackson, H. W.; Barmatz, M.

    1991-01-01

    A new theory of absorption of microwave power by a lossy dielectric sphere in a resonant rectangular chamber is developed here. In this treatment, resonant modes of the cavity are resolved into traveling plane-wave fields, and Mie's theory of scattering and absorption of a plane electromagnetic wave by a sphere is utilized. The fields in the cavity containing the sphere are found by superposition of results for the individual scattering problem for each traveling plane wave. Absorbed power is then calculated by evaluating the time-averaged Poynting vector and integrating over the surface of the sphere. Applications of microwave power absorption are discussed, with particular emphasis on processing of materials. Numerical studies based on the newly derived formulas are presented. The results exhibit the manner in which microwave absorption is influenced by a number of different experimentally controllable parameters. The examples considered were chosen with a view toward designing experiments and apparatus for containerless processing of materials in the microgravity environment of space.

  3. A microwave photonic generator of chaotic and noise signals

    Science.gov (United States)

    Ustinov, A. B.; Kondrashov, A. V.; Kalinikos, B. A.

    2016-04-01

    The transition to chaos in a microwave photonic generator has been experimentally studied for the first time, and the generated broadband chaotic microwave signal has been analyzed. The generator represented a ring circuit with the microwave tract containing a low-pass filter and a microwave amplifier. The optical tract comprised a fiber delay line. The possibility of generating chaotic oscillations with uniform spectral power density in a 3-8 GHz range is demonstrated.

  4. Real-time Optimisation of a Microwave Plasma Gasification System

    Science.gov (United States)

    Kabalan, B.; Wylie, S.; Mason, A.; Al-khaddar, R.; Al-Shamma'a, A.; Lupa, C.; Herbert, B.; Maddocks, E.

    2011-08-01

    A microwave plasma gasifier has been designed to produce syngas from waste. Gasification using microwave plasma has various controllable parameters to achieve optimal syngas production. These parameters include the microwave power applied, the reflected power from the microwave plasma jet, the EH tuner arm position, the gas flow and pressure, in addition to the temperature inside the gasifier. A variety of sensors are required to provide feedback and control for each of these parameters. This paper discusses the benefits of gasification, particularly via microwave plasma techniques, the first steps toward the optimisation of such a system and some preliminary results of this optimisation.

  5. Effect of Burnable Absorbers on Inert Matrix Fuel Performance and Transuranic Burnup in a Low Power Density Light-Water Reactor

    Directory of Open Access Journals (Sweden)

    Geoff Recktenwald

    2013-04-01

    Full Text Available Zirconium dioxide has received particular attention as a fuel matrix because of its ability to form a solid solution with transuranic elements, natural radiation stability and desirable mechanical properties. However, zirconium dioxide has a lower coefficient of thermal conductivity than uranium dioxide and this presents an obstacle to the deployment of these fuels in commercial reactors. Here we show that axial doping of a zirconium dioxide based fuel with erbium reduces power peaking and fuel temperature. Full core simulations of a modified AP1000 core were done using MCNPX 2.7.0. The inert matrix fuel contained 15 w/o transuranics at its beginning of life and constituted 28% of the assemblies in the core. Axial doping reduced power peaking at startup by more than ~23% in the axial direction and reduced the peak to average power within the core from 1.80 to 1.44. The core was able to remain critical between refueling while running at a simulated 2000 MWth on an 18 month refueling cycle. The results show that the reactor would maintain negative core average reactivity and void coefficients during operation. This type of fuel cycle would reduce the overall production of transuranics in a pressurized water reactor by 86%.

  6. Magnetic Tunnel Junction-Based On-Chip Microwave Phase and Spectrum Analyzer

    Science.gov (United States)

    Fan, Xin; Chen, Yunpeng; Xie, Yunsong; Kolodzey, James; Wilson, Jeffrey D.; Simons, Rainee N.; Xiao, John Q.

    2014-01-01

    A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance, the frequency of an incident microwave is directly determined. In addition, by integrating a mixer circuit, the MTJ-based microwave detector can also determine the relative phase between two microwave signals. Thus, the MTJbased microwave detector can be used as an on-chip microwave phase and spectrum analyzer.

  7. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    International Nuclear Information System (INIS)

    Shlapakovski, A. S.; Beilin, L.; Krasik, Ya. E.; Hadas, Y.; Schamiloglu, E.

    2015-01-01

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed

  8. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    Science.gov (United States)

    Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

    2015-07-01

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  9. Effect of Electrical Properties of Materials on Effectiveness of Heating Their Systems in Microwave Field

    Directory of Open Access Journals (Sweden)

    Stachowicz M.

    2014-06-01

    Full Text Available In the paper presented are results of a research on influence of electrical and physico-chemical properties of materials being parts of multicomponent and multimaterial systems used in foundry practice on efficiency and effectiveness of microwave heating. Effectiveness of the process was evaluated on the grounds of analysis of interaction between selected parameters of permittivity and loss factor, as well as collective index of energy absorbed, reflected and transmitted by these materials. In the examinations used was a stand of waveguide resonance cavity for determining electrical properties and a stand of microwave slot line for determining balance of microwave power emitted into selected materials. The examinations have brought closer the possibility of forecasting the behaviour of multimaterial systems like e.g. model, moulding sand or moulding box in microwave field on the grounds of various electrical and physico-chemical properties. On the grounds of analysis of the results, possible was selecting a group of materials designed for building foundry instrumentation to be effectively used in electromagnetic field.

  10. Study of federal microwave standards

    Energy Technology Data Exchange (ETDEWEB)

    David, L.

    1980-08-01

    Present and future federal regulatory processes which may impact the permissible levels of microwave radiation emitted by the SPS Microwave Power Transmission (MPTS) were studied. An historical development of US occupational and public microwave standards includes an overview of Western and East European philosophies of environmental protection and neurophysiology which have led to the current widely differing maximum permissible exposure limits to microwaves. The possible convergence of microwave standards is characterized by a lowering of Western exposure levels while Eastern countries consider standard relaxation. A trend toward stricter controls on activities perceived as harmful to public health is under way as is interest in improving the federal regulatory process. Particularly relevant to SPS is the initiation of long-term, low-level microwave exposure programs. Coupled with new developments in instrumentation and dosimetry, the results from chronic exposure program and population exposure studies could be expected within the next five to ten years. Also discussed is the increasing public concern that rf energy is yet another hazardous environmental agent.

  11. Performance of Closely Spaced Point Absorbers with Constrained Floater Motion

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.

    2009-01-01

    The performance of a wave energy converter array of twelve heaving point absorbers has been assessed numerically in a frequency domain model. Each point absorber is assumed to have its own linear power take-off. The impact of slamming, stroke and force restrictions on the power absorption...

  12. Neutron absorbing materials for reactors control; Materiaux absorbants neutroniques pour le pilotage des reacteurs

    Energy Technology Data Exchange (ETDEWEB)

    Gosset, D. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DMN), 91 - Gif sur Yvette (France); Herter, P. [CEA Saclay, Dir. de l' Energie Nucleaire (DEN), 91 - Gif sur Yvette (France)

    2007-01-15

    The different reactivity control systems allow to keep the mastery of the fission reaction inside the reactor core at any time: power control, safe shutdown, compensation of fuel burnup. These systems can be of different type: gaseous (like {sup 3}He in some experimental reactors), liquid (borated water in PWRs), and in most cases solid and combined or not with the previous types. In all cases, the constituents comprise neutron absorbing nuclides. The absorbing materials are contained in elementary absorbing elements, named control rods. This article describes the absorbing materials used in the control rods of the main nuclear power plants and also in the burnable poison rods of water cooled reactors. Content: 1 - general considerations about absorbing materials: neutron absorption cross sections, selection criteria of absorbing materials, main uses of absorbers in reactors, supply sources, wastes; 2 - description of the absorbing materials used: silver-indium-cadmium alloy (ICA), boron carbide (B{sub 4}C), dysprosium titanate, hafnium, burnable poisons and rare earths; 3 - conclusion and perspectives. (J.S.)

  13. Hydrogen production by conversion of ethanol injected into a microwave plasma

    Science.gov (United States)

    Czylkowski, Dariusz; Hrycak, Bartosz; Jasiński, Mariusz; Dors, Mirosław; Mizeraczyk, Jerzy

    2017-12-01

    Reforming of gaseous and liquid hydrocarbon compounds into hydrogen is of high interest. In this paper we present a microwave (2.45 GHz) plasma-based method for hydrogen production by conversion of ethanol (C2H5OH) in the thermal reforming process in nitrogen plasma. In contrast to our earlier investigations, in which C2H5OH vapour was supplied into the microwave plasma region either in the form of a swirl or axial flow, in this experiment we injected C2H5OH vapour directly into the nitrogen microwave plasma flame, behind the microwave plasma generation region. The experimental results were as follows. At an absorbed microwave power of 5 kW, N2 (plasma-generating gas) swirl flow rate of 2700 NL(N2)/h and C2H5OH mass flow rate of 2.7 kg(C2H5OH)/h the hydrogen production rate was 1016 NL(H2)/h, which corresponds to the energy yield of hydrogen production 203 NL(H2)/kWh. After the C2H5OH conversion the outlet gas contained 27.6% (vol.) H2, 10.2% CO, 0.2% CO2, 4.8% CH4, 4.3% C2H2, 3.7% C2H4 and 3.7% C2H6. These results are comparable to those obtained in our earlier investigations, in which different methods of C2H5OH vapour supply to the microwave plasma generation region were employed. Contribution to the Topical Issue: "Advances in Plasma Chemistry", edited by Slobodan Milošević, Nikša Krstulović, and Holger Kersten.

  14. Advances in microwaves 8

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 8 covers the developments in the study of microwaves. The book discusses the circuit forms for microwave integrated circuits; the analysis of microstrip transmission lines; and the use of lumped elements in microwave integrated circuits. The text also describes the microwave properties of ferrimagnetic materials, as well as their interaction with electromagnetic waves propagating in bounded waveguiding structures. The integration techniques useful at high frequencies; material technology for microwave integrated circuits; specific requirements on technology for d

  15. Red palm oil production by microwave irradiation

    Science.gov (United States)

    Sarah, M.; Widyastuti, S.; Ningsih, D.

    2018-02-01

    Preliminary study of red palm oil (RPO) production from palm fruitlets by microwave irradiation carried out in domestic microwave oven equipped with thermocouple. The various mass of fruitlets (800, 900 and 1000 g) were heated for 10-18 minutes with 2 minutes interval and microwave power of 400, 560 and 800 Watt respectively. Heated fruitlets were pressed by hydraulic presser to obtain RPO. This study observed heating time parameter was more crucial to RPO quality rather than temperature. Prolonged heating degraded carotenoids in the fruitlets during heating process yielded less carotenoids content in the palm oil. The best time and microwave power combination to produce RPO in this study was 14 minutes and 800 Watt respectively which yielded 11.67% RPO with 1.27% FFA content and carotenoids concentration of 1219.37 ppm. Overall, RPO production by microwave irradiation proceeded faster as compared to conventional process.

  16. Carbon nanotubes and microwaves: interactions, responses, and applications.

    Science.gov (United States)

    Vázquez, Ester; Prato, Maurizio

    2009-12-22

    The interaction of microwaves with carbon nanotubes (CNTs) is an interesting topic for a variety of potential applications. Microwaves have been used for the purification of CNTs and for their chemical functionalization, providing a technique for simple, green, and large-scale protocols. In addition, the selective destruction of metallic CNTs under microwave irradiation could potentially result in a batch of semiconducting-only nanotubes. As an innovative application, the combination of microwaves with well-aligned CNTs could produce a new illumination technology. Moreover, the microwave absorbing properties of CNTs and their different behavior from typical organic compounds may open the door to the preparation of a wide range of new materials useful in many fields. A few examples of practical applications include electromagnetic interference for protecting the environment from radiation and microwave hyperthermia for cancer treatment as well as other medical therapies requiring precise heating of biological tissues.

  17. Microwave induced fast pyrolysis of scrap rubber tires

    Science.gov (United States)

    Ani, Farid Nasir; Mat Nor, Nor Syarizan

    2012-06-01

    Pyrolysis is the thermal degradation of carbonaceous solid by heat in the absence of oxygen. The feedstocks, such as biomass or solid wastes are heated to a temperature between 400 and 600°C, without introducing oxygen to support the reaction. The reaction produces three products: gas, pyro-fuel oil and char. This paper presents the techniques of producing pyro-oil from waste tires, as well as investigation of the fuel properties suitable for diesel engine applications. In this study, microwave heating technique is employed to pyrolyse the used rubber tires into pyro-oil. Thermal treatment of as received used rubber tires is carried out in a modified domestic microwave heated fixed bed technology. It has been found that, rubber tires, previously used by various researchers, are poor microwave absorbers. Studies have shown that an appropriate microwave-absorbing material, such as biomass char or activated carbon, could be added to enhance the pyrolysis process; thus producing the pyro-oil. The characteristics of pyro-oil, as well as the effect of microwave absorber on its yield, are briefly described in this paper. The temperature profiles during the microwave heating process are also illustratively emphasized. The study provides a means of converting scrap tires into pyro-oil and pyrolytic carbon black production. The proposed microwave thermal conversion process therefore has the potentials of substantially saving time and energy.

  18. Microwave Enhanced Cotunneling in SET Transistors

    DEFF Research Database (Denmark)

    Manscher, Martin; Savolainen, M.; Mygind, Jesper

    2003-01-01

    Cotunneling in single electron tunneling (SET) devices is an error process which may severely limit their electronic and metrologic applications. Here is presented an experimental investigation of the theory for adiabatic enhancement of cotunneling by coherent microwaves. Cotunneling in SET...... transistors has been measured as function of temperature, gate voltage, frequency, and applied microwave power. At low temperatures and applied power levels, including also sequential tunneling, the results can be made consistent with theory using the unknown damping in the microwave line as the only free...

  19. Neutron absorbing article

    International Nuclear Information System (INIS)

    Naum, R.G.; Owens, D.P.; Dooher, G.I.

    1979-01-01

    A neutron absorbing article, in flat plate form and suitable for use in a storage rack for spent fuel, includes boron carbide particles, diluent particles and a solid, irreversibly cured phenolic polymer cured to a continuous matrix binding the boron carbide and diluent particles. The total conent of boron carbide and diluent particles is a major proportion of the article and the content of cured phenolic polymer present is a minor proportion. By regulation of the ratio of boron carbide particles to diluent particles, normally within the range of 1:9 and 9:1 and preferably within the range of 1:5 to 5:1, the neutron absorbing activity of the product may be controlled, which facilitates the manufacture of articles of particular absorbing activities best suitable for specific applications

  20. Microwave absorbing properties of activated carbon fibre polymer ...

    Indian Academy of Sciences (India)

    Author Affiliations. Tianchun Zou1 Naiqin Zhao2 Chunsheng Shi2 Jiajun Li2. Airworthiness Certification Technology Research and Management Centre, Civil Aviation University of China, Tianjin 300300, P.R. China; School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P.R. China ...

  1. Mechanical and microwave absorbing properties of carbon-filled polyurethane

    Czech Academy of Sciences Publication Activity Database

    Kučerová, Z.; Zajíčková, L.; Buršíková, V.; Kudrle, V.; Eliáš, M.; Jašek, O.; Synek, P.; Matějková, Jiřina; Buršík, Jiří

    2009-01-01

    Roč. 40, č. 1 (2009), s. 70-73 ISSN 0968-4328 R&D Projects: GA ČR(CZ) GA202/05/0607 Institutional research plan: CEZ:AV0Z20650511; CEZ:AV0Z20410507 Keywords : carbon nanotubes * composite * polyurethane * mechanical properties Subject RIV: JI - Composite Materials Impact factor: 1.626, year: 2009

  2. Neutron absorbing article

    International Nuclear Information System (INIS)

    Naum, R.G.; Owens, D.P.; Dooker, G.I.

    1981-01-01

    A neutron-absorbing article suitable for use in spent fuel racks is described. It comprises boron carbide particles, diluent particles, and a phenolic polymer cured to a continuous matrix. The diluent may be silicon carbide, graphite, amorphous carbon, alumina, or silica. The combined boron carbide-diluent phase contains no more than 2 percent B 2 O 3 , and the neutron-absorbing article contains from 20 to 40 percent phenol resin. The ratio of boron carbide to diluent particles is in the range 1:9 to 9:1

  3. Absorber for nuclear radiations

    International Nuclear Information System (INIS)

    Planchamp, C.

    1987-01-01

    Neutrons, gamma and x radiations are highly absorbed by an alloy of gadolinium and aluminium. Workability, thermal conductivity, mechanical properties, corrosion resistance of the alloy are good. Possible applications are transport or storage of radioactive wastes or nuclear fuels, fuel racks, shelters, etc [fr

  4. Microwave Sterilization and Depyrogenation System

    Science.gov (United States)

    Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

    2009-01-01

    A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time

  5. Insights into a microwave susceptible agent for minimally invasive microwave tumor thermal therapy.

    Science.gov (United States)

    Shi, Haitang; Liu, Tianlong; Fu, Changhui; Li, Linlin; Tan, Longfei; Wang, Jingzhuo; Ren, Xiangling; Ren, Jun; Wang, Jianxin; Meng, Xianwei

    2015-03-01

    This work develops a kind of sodium alginate (SA) microcapsules as microwave susceptible agents for in vivo tumor microwave thermal therapy for the first time. Due to the excellent microwave susceptible properties and low bio-toxicity, excellent therapy efficiency can be achieved with the tumor inhibiting ratio of 97.85% after one-time microwave thermal therapy with ultralow power (1.8 W, 450 MHz). Meanwhile, the mechanism of high microwave heating efficiency was confirmed via computer-simulated model in theory, demonstrating that the spatial confinement efficiency of microcapsule walls endows the inside ions with high microwave susceptible properties. This strategy offers tremendous potential applications in clinical tumor treatment with the benefits of safety, reliability, effectiveness and minimally invasiveness. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Temperature rising characteristics of ammonium diurante in microwave fields

    International Nuclear Information System (INIS)

    Liu Bingguo; Peng JinHui; Huang Daifu; Zhang Libo; Hu Jinming; Zhuang Zebiao; Kong Dongcheng; Guo Shenghui; Li Chunxiang

    2010-01-01

    The temperature rising characteristics of ammonium diurante, triuranium octaoxide (U 3 O 8 ), and their mixture were investigated under microwave irradiation, aiming at exploring newly theoretical foundation for advanced metallurgical methods. The temperature rising curves showed that ammonium diurante had weak capability to absorb microwave energy, while triuranium octaoxide had the very strong absorption capability. The temperature of mixture containing 20% of U 3 O 8 could rise from room temperature to 1171 K within 280 s. The ability to absorb microwave energy for the mixture with different ratios increased with the increase in the amount of U 3 O 8 . These are in good agreement with the results of Maxwell-Garnett effective medium theory. It is feasible to calcine ammonium diurante by adding of small amounts of U 3 O 8 in microwave fields.

  7. Continuous microwave flow synthesis of mesoporous hydroxyapatite.

    Science.gov (United States)

    Akram, Muhammad; Alshemary, Ammar Z; Goh, Yi-Fan; Wan Ibrahim, Wan Aini; Lintang, Hendrik O; Hussain, Rafaqat

    2015-11-01

    We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca(2+) ion released in SBF solution. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Compact Microwave Fourier Spectrum Analyzer

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  9. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  10. Mechanical property and cutting rate of microwave treated granite rock

    Directory of Open Access Journals (Sweden)

    Lek Sikong

    2009-10-01

    Full Text Available The purpose of this study is to investigate the effect of microwave treatment, especially at low power level on compressive strength and cutting rate of granite rock by using multimodal cavity. The power level and cooling rate of treated samples were found to have an effect on the compressive strength, and the cutting rate. This effect is due to the induction of the plastic zones and micro cracks in the rock matrix, especially at the grain boundaries induced by the thermal stresses of rock forming minerals which have the difference in dielectric properties after microwave heating for a certain exposure time together with the thermal-shock treatment after the heating. It was found that the strength of treated granite is less than 60% of the original after 30 minutes of exposure.The dry heated samples with a water quenching seem to be the most affected samples. They exhibit a significant decrease in compressive strength up to 70% and cutting rate up to 38% after 30-minute treatment at the power of 850W, and after 10-minute treatment at the power of 600W respectively. Prolonged treatment causes the relaxation of induced thermal stresses in the rock mass, leading to a slight increase in compressive strength, and a slight decrease in cutting rate. For dry samples, the cutting rate can be enhanced because of a decrease in hardness of rock mass dropped from 61.5 to 55.4 HRC afterthe 10-minute heating at 600W with thermal shock treatment.The absorbed water in the pores of rock mass also has an effect on a decrease in compressive strength. Because micro cracks developed by the water vapor generated by heat which escapes through open pores. However, it seems to have less effect on the cutting rate because it causes a slight decrease in the hardness.

  11. Effect of Zn doping on the microwave absorption of BFO multiferroic materials

    Science.gov (United States)

    Bi, S.; Li, J.; Mei, B.; Su, X. J.; Ying, C. Z.; Li, P. H.

    2018-01-01

    The microwave absorbing materials were firstly used in the Second World War. And the BiFeO3 (BFO) based microwave absorbers have been widely applied into the microwave absorbing area due to its possession of excellent electromagnetic properties. Various methods have been conducted to improve the microwave absorption performance of the BFO based materials. In the work, the sol-gel method were used to prepare the BFO, and the Zn were doped into the BFO to prepare the Bi1-xZnxFeO3 nanoparticles. The X-ray diffraction, scanning electron microscope, and vector network analysis (VNA) were conducted to characterize the microstructure and electromagnetic properties of the as-prepared samples. The results indicate that the Bi1-xZnxFeO3 nanoparticles were successfully gained and the as-prepared samples possess excellent microwave absorption properties.

  12. Microwave Tissue Ablation: Biophysics, Technology and Applications

    Science.gov (United States)

    2010-01-01

    Microwave ablation is an emerging treatment option for many cancers, cardiac arrhythmias and other medical conditions. During treatment, microwaves are applied directly to tissues to produce rapid temperature elevations sufficient to produce immediate coagulative necrosis. The engineering design criteria for each application differ, with individual consideration for factors such as desired ablation zone size, treatment duration, and procedural invasiveness. Recent technological developments in applicator cooling, power control and system optimization for specific applications promise to increase the utilization of microwave ablation in the future. This article will review the basic biophysics of microwave tissue heating, provide an overview of the design and operation of current equipment, and outline areas for future research for microwave ablation. PMID:21175404

  13. Rapid and Decentralized Human Waste Treatment by Microwave Radiation.

    Science.gov (United States)

    Nguyen, Tu Anh; Babel, Sandhya; Boonyarattanakalin, Siwarutt; Koottatep, Thammarat

    2017-07-01

      This study evaluates the technical feasibility of using microwave radiation for the rapid treatment of human feces. Human feces of 1000 g were radiated with a commercially available household microwave oven (with rotation) at different exposure time lengths (30, 50, 60, 70, and 75 mins) and powers (600, 800, and 1000 W). Volume reduction over 90% occurred after 1000 W microwave radiation for 75 mins. Pathogen eradiation performances of six log units or more at a high range of microwave powers were achieved. Treatments with the same energy input of 1000 Wh, but at lower powers with prolonged exposure times, significantly enhanced moisture removal and volume reduction. Microwave radiation caused carbonization and resulted in a more stable end product. The energy content of the samples after microwave treatment at 1000 W and 75 mins is 3517 ± 8.85 calories/g of dried sample, and the product can also be used as compost.

  14. Kinetic energy absorbing pad

    International Nuclear Information System (INIS)

    Bricmont, R.J.; Hamilton, P.A.; Ming Long Ting, R.

    1981-01-01

    Reactors, fuel processing plants etc incorporate pipes and conduits for fluids under high pressure. Fractures, particularly adjacent to conduit elbows, produce a jet of liquid which whips the broken conduit at an extremely high velocity. An enormous impact load would be applied to any stationary object in the conduit's path. The design of cellular, corrugated metal impact pads to absorb the kinetic energy of the high velocity conduits is given. (U.K.)

  15. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  16. Burnable neutron absorbers

    International Nuclear Information System (INIS)

    Radford, K.C.; Carlson, W.G.

    1985-01-01

    This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al 2 O 3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B 4 C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

  17. Microwave Triggered Laser Ionization of Air

    Science.gov (United States)

    Vadiee, Ehsan; Prasad, Sarita; Jerald Buchenauer, C.; Schamiloglu, Edl

    2012-10-01

    The goal of this work is to study the evolution and dynamics of plasma expansion when a high power microwave (HPM) pulse is overlapped in time and space on a very small, localized region of plasma formed by a high energy laser pulse. The pulsed Nd:YAG laser (8 ns, 600mJ, repetition rate 10 Hz) is focused to generate plasma filaments in air with electron density of 10^17/cm^3. When irradiated with a high power microwave pulse these electrons would gain enough kinetic energy and further escalate avalanche ionization of air due to elastic electron-neutral collisions thereby causing an increased volumetric discharge region. An X-band relativistic backward wave oscillator(RBWO) at the Pulsed Power,Beams and Microwaves laboratory at UNM is constructed as the microwave source. The RBWO produces a microwave pulse of maximum power 400 MW, frequency of 10.1 GHz, and energy of 6.8 Joules. Special care is being given to synchronize the RBWO and the pulsed laser system in order to achieve a high degree of spatial and temporal overlap. A photodiode and a microwave waveguide detector will be used to ensure the overlap. Also, a new shadowgraph technique with a nanosecond time resolution will be used to detect changes in the shock wave fronts when the HPM signal overlaps the laser pulse in time and space.

  18. Measurement of the microwave emitter's inhomogeneity using optical fiber DTS

    Science.gov (United States)

    Jaros, Jakub; Papes, Martin; Liner, Andrej; Vašinek, Vladimir; Smira, Pavel; Nasswettrova, Andrea; Cubik, Jakub; Kepak, Stanislav

    2014-06-01

    Researcher's teams were dealing with the microwave emitter's inhomogeneity problem since the microwaves were used. One possible way, how to measure electromagnetic field is the measurement on inhomogeneous temperature distribution on the irradiated sample, which can cause problems as in other material processing, so in the undesirable change of properties and even security. Inhomogeneity of electromagnetic field is specific by creating spots with higher or lower temperature called "hot spots". This inhomogeneity strongly affects the temperature distribution in the cross section of the material and its resultant heating. Given the impossibility of using classical electronic devices with metal temperature sensors were various indirect methods used in the past. This paper deals with experimental measurement of the microwave emitter's inhomogeneity (2.45 GHz) using the optical fiber DTS. The greatest advantage of this sensor system is just in using of the optical fiber (electromagnetic resistance, small size, safety using in inflammable and explosive area, easy installation). Due to these properties of the optical fiber sensor it's possible to measure the temperature of the sample in real time. These sensor are able to measure the temperature along the fiber, in some cases they use nonlinear effect in optical fiber (Raman nonlinear effect). The verification of non-homogeneity consists in experimental measuring of the temperature distribution within the wooden sample. The method is based on heat exchange in an isolated system where wooden sample serves as an absorber of the irradiated energy. To identify locations with different power density was used DTS system, based on nonlinear phenomena in optical fibers.

  19. [Synergetic effects of silicon carbide and molecular sieve loaded catalyst on microwave assisted catalytic oxidation of toluene].

    Science.gov (United States)

    Wang, Xiao-Hui; Bo, Long-Li; Liu, Hai-Nan; Zhang, Hao; Sun, Jian-Yu; Yang, Li; Cai, Li-Dong

    2013-06-01

    Molecular sieve loaded catalyst was prepared by impregnation method, microwave-absorbing material silicon carbide and the catalyst were investigated for catalytic oxidation of toluene by microwave irradiation. Research work examined effects of silicon carbide and molecular sieve loading Cu-V catalyst's mixture ratio as well as mixed approach changes on degradation of toluene, and characteristics of catalyst were measured through scanning electron microscope, specific surface area test and X-ray diffraction analysis. The result showed that the fixed bed reactor had advantages of both thermal storage property and low-temperature catalytic oxidation when 20% silicon carbide was filled at the bottom of the reactor, and this could effectively improve the utilization of microwave energy as well as catalytic oxidation efficiency of toluene. Under microwave power of 75 W and 47 W, complete-combustion temperatures of molecular sieve loaded Cu-V catalyst and Cu-V-Ce catalyst to toluene were 325 degrees C and 160 degrees C, respectively. Characteristics of the catalysts showed that mixture of rare-earth element Ce increased the dispersion of active components in the surface of catalyst, micropore structure of catalyst effectively guaranteed high adsorption capacity for toluene, while amorphous phase of Cu and V oxides increased the activity of catalyst greatly.

  20. Microwave heating type evaporator

    International Nuclear Information System (INIS)

    Taura, Masazumi; Nishi, Akio; Morimoto, Takashi; Izumi, Jun; Tamura, Kazuo; Morooka, Akihiko.

    1987-01-01

    Purpose: To prevent evaporization stills against corrosion due to radioactive liquid wastes. Constitution: Microwaves are supplied from a microwave generator by way of a wave guide tube and through a microwave permeation window to the inside of an evaporatization still. A matching device is attached to the wave guide tube for transmitting the microwaves in order to match the impedance. When the microwaves are supplied to the inside of the evaporization still, radioactive liquid wastes supplied from a liquid feed port by way of a spray tower to the inside of the evaporization still is heated and evaporated by the induction heating of the microwaves. (Seki, T.)

  1. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  2. Microwave Radiometry and Radiometers for Ocean Applications

    DEFF Research Database (Denmark)

    Skou, Niels

    2008-01-01

    The microwave radiometer system measures, within its bandwidth, the naturally emitted radiation – the brightness temperature – of substances within its antenna’s field of view. Thus a radiometer is really a sensitive and calibrated microwave receiver. The radiometer can be a basic total power rad...... of the sea from space, the intervening atmosphere will disturb the process, and corrections might be required. Also, at some frequencies and for some applications, the Faraday rotation in the Ionosphere must be taken into account....

  3. Atmospheric pressure microwave plasma system with ring waveguide

    International Nuclear Information System (INIS)

    Liu Liang; Zhang Guixin; Zhu Zhijie; Luo Chengmu

    2007-01-01

    Some scientists used waveguide as the cavity to produce a plasma jet, while large volume microwave plasma was relatively hard to get in atmospheric pressure. However, a few research institutes have already developed devices to generate large volume of atmospheric pressure microwave plasma, such as CYRANNUS and SLAN series, which can be widely applied. In this paper, present a microwave plasma system with ring waveguide to excite large volume of atmospheric pressure microwave plasma, plot curves on theoretical disruption electric field of some working gases, emulate the cavity through software, measure the power density to validate and show the appearance of microwave plasma. At present, large volume of argon and helium plasma have already been generated steadily by atmospheric pressure microwave plasma system. This research can build a theoretical basis of microwave plasma excitation under atmospheric pressure and will be useful in study of the device. (authors)

  4. Solar radiation absorbing material

    Science.gov (United States)

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  5. Microwave engineering

    National Research Council Canada - National Science Library

    Pozar, David M

    2012-01-01

    .... Other new material includes a section on transients on transmission lines, the theory of power waves, a discussion of higher order modes and frequency effects for microstrip line, and a discussion...

  6. Power deposition profiles in Maxwellian magneto-active plasmas

    International Nuclear Information System (INIS)

    Ziolkowski, R.W.; Peterson, J.C.

    1983-02-01

    The numerical modeling of the microwave power deposition in a plasma for waves that are launched from an arbitrary array of pyramidal horns will be described. The waves are modeled in three dimensions with geometrical optics assuming the plasma is cold, magneto-active and Maxwellian. The power absorption at the fundamental harmonic is calculated along those rays with warm plasma absorption formulas. A newly developed post-processor synthesizes power deposition profiles from these ray tracing results. Graphical output includes the power density as a function of the distance along the axis of the plasma and the physical or midplane radius, the z-integrated power density as a function of the midplane radius, and the cumulative power absorbed as a function of the midplane radius. Examples for ECRH in the TMX-U and the axisymmetric MFTF-B tandem mirror machines at LLNL will be presented

  7. Detection of carbon nanotubes in plant roots through microwave-induced heating

    Science.gov (United States)

    Irin, Fahmida; Shrestha, Babina; Canas, Jaclyn; Saed, Mohammad; Green, Micah

    2012-02-01

    We demonstrate a novel technique for quantitative detection of CNTs in biological samples by utilizing the thermal response of CNTs under microwave irradiation. In particular, rapid heating of CNTs due to microwave absorption was employed to quantify the amount of CNTs present in alfalfa plant roots. Alfalfa roots were prepared by injecting a known amount of CNTs (single walled and multi walled) and exposed to 30-50 W microwave power to generate calibration curves (temperature rise vs. CNT mass). These calibration curves serve as a characterization tool to determine the unknown amount of CNTs absorbed by alfalfa plant roots grown in CNT-laden soil with superior accuracy and sensitivity. Moreover, the threshold for detectable CNT concentration is much lower than common analytical methods of detecting nanomaterials, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Considering the lack of effective detection methods for CNT uptake in plants, this method is not only unique but also practical, as it addresses a major problem in the field of nanotoxicology risk assessment.

  8. Methods for applying microchannels to separate methane using liquid absorbents, especially ionic liquid absorbents from a mixture comprising methane and nitrogen

    Science.gov (United States)

    Tonkovich, Anna Lee Y [Dublin, OH; Litt, Robert D [Westerville, OH; Dongming, Qiu [Dublin, OH; Silva, Laura J [Plain City, OH; Lamont, Micheal Jay [Plain City, OH; Fanelli, Maddalena [Plain City, OH; Simmons, Wayne W [Plain city, OH; Perry, Steven [Galloway, OH

    2011-10-04

    Methods of using microchannel separation systems including absorbents to improve thermal efficiency and reduce parasitic power loss. Energy is typically added to desorb methane and then energy or heat is removed to absorb methane using a working solution. The working solution or absorbent may comprise an ionic liquid, or other fluids that demonstrate a difference in affinity between methane and nitrogen in a solution.

  9. Advances in microwaves 7

    CERN Document Server

    Young, Leo

    2013-01-01

    Advances in Microwaves, Volume 7 covers the developments in the study of microwaves. The book discusses the effect of surface roughness on the propagation of the TEM mode, as well as the voltage breakdown of microwave antennas. The text also describes the theory and design considerations of single slotted-waveguide linear arrays and the techniques and theories that led to the achievement of wide bandwidths and ultralow noise temperatures for communication applications. The book will prove invaluable to microwave engineers.

  10. Heaving buoys, point absorbers and arrays.

    Science.gov (United States)

    Falnes, Johannes; Hals, Jørgen

    2012-01-28

    Absorption of wave energy may be considered as a phenomenon of interference between incident and radiated waves generated by an oscillating object; a wave-energy converter (WEC) that displaces water. If a WEC is very small in comparison with one wavelength, it is classified as a point absorber (PA); otherwise, as a 'quasi-point absorber'. The latter may be a dipole-mode radiator, for instance an immersed body oscillating in the surge mode or pitch mode, while a PA is so small that it should preferably be a source-mode radiator, for instance a heaving semi-submerged buoy. The power take-off capacity, the WEC's maximum swept volume and preferably also its full physical volume should be reasonably matched to the wave climate. To discuss this matter, two different upper bounds for absorbed power are applied in a 'Budal diagram'. It appears that, for a single WEC unit, a power capacity of only about 0.3 MW matches well to a typical offshore wave climate, and the full physical volume has, unfortunately, to be significantly larger than the swept volume, unless phase control is used. An example of a phase-controlled PA is presented. For a sizeable wave-power plant, an array consisting of hundreds, or even thousands, of mass-produced WEC units is required.

  11. Design of 22-way coaxial power combiner for 20 kW solid state amplifier and 6-1/8″ to N type adapter using CST microwave studio

    International Nuclear Information System (INIS)

    Sharma, Sonal; Mishra, J.K.; Ramarao, B.V.; Pande, Manjiri; Bhagwat, P.V.

    2015-01-01

    A 20 kW, 325 MHz solid state amplifier is being developed in BARC for Fermi Lab collaboration. It is proposed to combine 22 RF amplifiers to get output power of 20 kW. For this purpose a 22 way coaxial power combiner has been designed using CST microwave studio. This combiner is based on Wilkinson combining technology. The inner conductor of the combiner is split into 22 equal plates. Each plate has 1-5/8 flange at input port. These plates are connected to a common disc. The combined output is a 3-1/8 flanged port. The return loss obtained at the combined port is better than 28 dB indicating a very good match. The transmission from the combined port to each split port is about -13.5 dB representing a low insertion loss and equal split. The return loss each of the split port is obtained by simultaneous excitation of each port. The return loss at each port is better than 26 dB. Fabrication of the combiner is under process. The material used for inner conductor will be ETP copper and outer conductor will be made of aluminium. Along with the above design a separate design of 6-1/8″ to N type adapter has been completed in CST microwave studio. A number of these adapters will be used for high power waveguide load characterization which is being developed in BARC. The return loss at each port is better than 30 dB and insertion loss is less than 0.05 dB. Fabrication of these adapters is under process. (author)

  12. Microwave dielectrics: solid solution, ordering and microwave ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 6. Microwave dielectrics: solid solution, ordering and microwave dielectric properties of ( 1 − x ) Ba(Mg 1 / 3 Nb 2 / 3 )O 3 − x Ba(Mg 1 / 8 Nb 3 / 4 )O3 ceramics. YOGITA BISHT RICHA TOMAR PULLANCHIYODAN ABHILASH DEEPA RAJENDRAN LEKSHMI M ...

  13. Microwave processing heats up

    Science.gov (United States)

    Microwaves are a common appliance in many households. In the United States microwave heating is the third most popular domestic heating method food foods. Microwave heating is also a commercial food processing technology that has been applied for cooking, drying, and tempering foods. It's use in ...

  14. PowerSat: A technology demonstration of a solar power satellite

    Science.gov (United States)

    Sigler, Douglas L. (Editor); Riedman, John; Duracinski, Jon; Edwards, Joe; Brown, Garry; Webb, Ron; Platzke, Mike; Yuan, Xiaolin; Rogers, Pete; Khan, Afsar

    1994-01-01

    PowerSat is a preliminary design strategy for microwave wireless power transfer of solar energy. Solar power satellites convert solar power into microwave energy and use wireless power transmission to transfer the power to the Earth's surface. The PowerSat project will show how new developments in inflatable technology can be used to deploy solar panels and phased array antennas.

  15. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    Ebadian, M.A.

    1998-01-01

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber

  16. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contain high levels of bass sound...... energy but still require high definition for good sound quality. The mid- and high-frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. A practical solution to this dilemma...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design....

  17. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contains high levels of bass sound...... energy but still require high definition for good sound quality. The mid- and high-frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. A practical solution to this dilemma...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design....

  18. Proceedings of microwave processing of materials 3

    International Nuclear Information System (INIS)

    Beatty, R.L.

    1992-01-01

    This book contains proceedings of the third MRS Symposium on Microwave Processing of Materials. Topics covered include: Microwave Processing Overviews, Numerical Modeling Techniques, Microwave Processing System Design, Microwave/Plasma Processing, Microwave/Materials Interactions, Microwave Processing of Ceramics, Microwave Processing of Polymers, Microwave Processing of Hazardous Wastes, Microwave NDE Techniques and Dielectric Properties and Measurements

  19. New prospects in pretreatment of cotton fabrics using microwave heating.

    Science.gov (United States)

    Hashem, M; Taleb, M Abou; El-Shall, F N; Haggag, K

    2014-03-15

    As microwaves are known to give fast and rapid volume heating, the present study is undertaken to investigate the use of microwave heating for pretreatment cotton fabrics to reduce the pretreatment time, chemicals and water. The onset of the microwave heating technique on the physicochemical and performance properties of desized, scoured and bleached cotton fabric is elucidated and compared with those obtained on using conventional thermal heating. Combined one-step process for desizing, scouring and bleaching of cotton fabric under microwave heating was also investigated. The dual effect of adding urea, (as microwave absorber and hydrogen peroxide activator) has been exploiting to accelerate the pretreatment reaction of cotton fabric. DSC, FT-IR and SEM have been used to investigate the onset of microwave on the morphological and chemical change of cotton cellulose after pretreatment and bleaching under microwave heating. Results obtained show that, a complete fabric preparation was obtained in just 5 min on using microwave in pretreatments process and the fabric properties were comparable to those obtained in traditional pretreatment process which requires 2.5-3h for completion. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Electromagnetic properties of carbonyl iron and their microwave ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The complex permittivity, permeability and microwave-absorbing properties of rubber composites filled with carbonyl iron are measured at frequencies from 2–18 GHz. The results indicate that the reflection loss peak shifts towards low frequency region with increasing layer thickness or increasing weight concentra-.