WorldWideScience

Sample records for high quality rf

  1. Formation of a high quality electron beam using photo cathode RF electron gun

    International Nuclear Information System (INIS)

    Washio, Masakazu

    2000-01-01

    Formation of a high quality electron beam using photo cathode RF electron gun is expected for formation of a next generation high brilliant X-ray beam and a source for electron and positron collider. And, on a field of material science, as is possible to carry out an experiment under ultra short pulse and extremely high precision in time, it collects large expectation. Recently, formation of high quality beam possible to develop for multi directions and to use by everyone in future has been able to realize. Here were explained on electron beam source, principle and component on RF electron gun, working features on RF gun, features and simulation of RF gun under operation, and some views in near future. (G.K.)

  2. Growth and characterization of high quality ZnS thin films by RF sputtering

    Science.gov (United States)

    Mukherjee, C.; Rajiv, K.; Gupta, P.; Sinha, A. K.; Abhinandan, L.

    2012-06-01

    High optical quality ZnS films are deposited on glass and Si wafer by RF sputtering from pure ZnS target. Optical transmittance, reflectance, ellipsometry, FTIR and AFM measurements are carried out. Effect of substrate temperature and chamber baking for long duration on film properties have been studied. Roughness of the films as measured by AFM are low (1-2Å).

  3. Growth of high quality AlN films on CVD diamond by RF reactive magnetron sputtering

    Science.gov (United States)

    Chen, Liang-xian; Liu, Hao; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; An, Kang; Hua, Chen-yi; Liu, Jin-long; Wei, Jun-jun; Hei, Li-fu; Lv, Fan-xiu

    2018-02-01

    A highly oriented AlN layer has been successfully grown along the c-axis on a polycrystalline chemical vapor deposited (CVD) diamond by RF reactive magnetron sputtering. Structural, morphological and mechanical properties of the heterostructure were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Nano-indentation and Four-probe meter. A compact AlN film was demonstrated on the diamond layer, showing columnar grains and a low surface roughness of 1.4 nm. TEM results revealed a sharp AlN/diamond interface, which was characterized by the presence of a distinct 10 nm thick buffer layer resulting from the initial AlN growth stage. The FWHM of AlN (002) diffraction peak and its rocking curve are as low as 0.41° and 3.35° respectively, indicating a highly preferred orientation along the c-axis. AlN sputtered films deposited on glass substrates show a higher bulk resistivity (up to 3 × 1012 Ω cm), compared to AlN films deposited on diamond (∼1010 Ω cm). Finally, the film hardness and Young's modulus of AlN films on diamond are 25.8 GPa and 489.5 GPa, respectively.

  4. High-quality electron pulse generation from a laser photocathode RF gun

    International Nuclear Information System (INIS)

    Yang, Jinfeng; Sakai, Fumio; Aoki, Yasushi

    1999-01-01

    A laser photocathode RF gun system was developed for ultra short X-ray pulse generation via the inverse Compton scattering. The gun is a BNL-type S-band RF gun and the performance test of the gun was performed at the Linear Accelerator Facility in the Institute of Scientific and Industries Research, Osaka University. The gun system produced 115 pC electron bunches with the energy of 1.6 MeV under the condition of RF peak power of 1.5 MW and laser pulse energy of 65 μJ. The quantum efficiency and dark current were obtained to be 10 -5 and 0.6 nA at the repetition rate of 10 Hz, respectively. The energy and charge of the electron bunch were measured as a function of laser injection phase. Furthermore, the electron bunches were accelerated up to 117 MeV by three s-band TW linacs and the energy monochromaticity (ΔE/E) of the beam was 1.2%. The transverse emittance was also experimentally investigated at the end of the linacs. (author)

  5. BRS 369RF and BRS 370RF: Glyphosate tolerant, high-yielding upland cotton cultivars for central Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Camilo de Lelis Morello

    2015-12-01

    Full Text Available BRS 369RF and BRS 370RF were developed by the EMBRAPA as a part of efforts to create high-yielding germplasm with combinations of transgenic traits. BRS 369RF and BRS 370RF are midseason cultivars and have yield stability, adaptation to the central Brazilian savanna, good fiber quality and tolerance to glyphosate herbicide.

  6. Characterization of high quality Cu(In,Ga)Se{sub 2} thin films prepared by rf-magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bouchama, Idris [Departement d' Electronique, Faculte de Technologie, Universite de Msila (Algeria); Djessas, Kamal [Laboratoire Procedes Materiaux et Energie Solaire, PROMES-CNRS, Rambla de la Thermodynamique, Technosud, 66100 Perpignan (France); Bouloufa, Abdeslam [Laboratoire d' Electrochimie et Materiaux, Universite Ferhat Abbas de Setif (Algeria); Gauffier, Jean-Luc [Departement de Physique, INSA de Toulouse, 135, Avenue de Rangueil, 31077 Toulouse Cedex 4 (France)

    2013-01-15

    This paper reports the production of high quality polycrystalline thin layers of CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} (CIGS), using rf-magnetron sputtering, from a powder target. These films are designed to be used as absorbers in solar cells. The depositions were carried out at substrate temperatures below 250 C and glass substrates was used. The influence of the substrate temperatures on the crystalline quality as well as structural, optical and electrical properties of thin layers obtained has been studied. X-ray diffraction showed that the films were highly orientated in the (112) and/or (204)/(220) direction. In{sub 2}Se{sub 3} secondary phase was observed on the samples grown at lower substrate temperatures. The surface morphology of CIGS layers studied by Atomic Force Microscopy (AFM) and Scanning Electronic Microscopy (SEM) has been also discussed. The most surprising and exciting outcome of this study was that the as grown films were of near stoichiometric composition. Resistivity measurements were carried out using the four point probe method. The optical absorption showed that energy gap values are between 1.13 and 1.18 eV and rather sharp absorption fronts. Thin film resistivities are between 10.7 and 60.9 {Omega}.cm depending on the experimental growth conditions (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. High-quality beam generation using an RF gun and a 150 MeV microtron

    Science.gov (United States)

    Kuroda, R.; Washio, M.; Kashiwagi, S.; Kobuki, T.; Ben-Zvi, I.; Wang, X. J.; Hori, T.; Sakai, F.; Tsunemi, A.; Urakawa, J.; Hirose, T.

    2000-11-01

    Low-emittance sub-picosecond electron pulses are expected to be used in a wide field, such as free electron laser, laser acceleration, femtosecond X-ray generation by Inverse Compton scattering, pulse radiolysis, etc. In order to produce the low-emittance sub-picosecond electron pulse, we are developing a compact Racetrack Microtron (RTM) with a new 5 MeV injection system adopting a laser photo cathode RF gun (Washio et al., Seventh China-Japan Bilateral Symposium on Radiation Chemistry, October 28, Cengdu, China, 1996). The operation of RTM has been kept under a steady state of beam loading for long pulse mode so far (Washio et al., J. Surf. Sci. Soc. Jpn. 19 (2) (1998) 23). In earlier work (Washio et al., PAC99, March 31, New York, USA, 1999), we have succeeded in the numerical simulation for the case of single short pulse acceleration. Finally, the modified RTM was demonstrated as a useful accelerator for a picosecond electron pulse generation under a transient state of beam loading. In the simulation, a picosecond electron pulse was accelerated to 149.6 MeV in RTM for the injection of 5 MeV electron bunch with a pulse length of 10 ps (FWHM), a charge of 1 nC per pulse, and an emittance of 3 πmm mrad.

  8. Design of an L-band normally conducting RF gun cavity for high peak and average RF power

    Energy Technology Data Exchange (ETDEWEB)

    Paramonov, V., E-mail: paramono@inr.ru [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Philipp, S. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Rybakov, I.; Skassyrskaya, A. [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Stephan, F. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany)

    2017-05-11

    To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design.

  9. Discussion of high brightness rf linear accelerators

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1987-01-01

    The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

  10. High-brightness rf linear accelerators

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines

  11. High-quality laser-produced proton beam realized by the application of a synchronous RF electric field

    International Nuclear Information System (INIS)

    Nakamura, Shu; Ikegami, Masahiro; Iwashita, Yoshihisa; Shirai, Toshiyuki; Tongu, Hiromu; Souda, Hikaru; Noda, Akira; Daido, Hiroyuki; Mori, Michiaki; Kado, Masataka; Sagisaka, Akito; Ogura, Koichi; Nishiuchi, Mamiko; Orimo, Satoshi; Hayashi, Yukio; Yogo, Akifumi; Pirozhkov, Alexander S.; Bulanov, Sergei V.; Esirkepov, Timur; Nagashima, Akira; Kimura, Toyoaki; Tajima, Toshiki; Takeuchi, Takeshi; Fukumi, Atsushi; Li, Zhong

    2007-01-01

    A short-pulse (∼210fs) high-power (∼1 TW) laser was focused on a tape target 3 and 5 μm in thickness to a size of 11 x 15 μm 2 with an intensity of 3 x 10 17 W/cm 2 . Protons produced by this laser with an energy spread of 100% were found to be improved to create peaks in the energy distribution with a spread of ∼7% by the application of the RF electric field with an amplitude of ±40kV synchronous to the pulsed laser. This scheme combines the conventional RF acceleration technique with laser-produced protons for the first time. It is possible to be operated up to 10 Hz, and is found to have good reproducibility for every laser shot with the capability of adjusting the peak positions by control of the relative phase between the pulsed laser and the RF electric field. (author)

  12. High gradient RF breakdown study

    International Nuclear Information System (INIS)

    Laurent, L.; Luhmann, N.C. Jr.; Scheitrum, G.; Hanna, S.; Pearson, C.; Phillips, R.

    1998-01-01

    Stanford Linear Accelerator Center and UC Davis have been investigating high gradient RF breakdown and its effects on pulse shortening in high energy microwave devices. RF breakdown is a critical issue in the development of high power microwave sources and next generation linear accelerators since it limits the output power of microwave sources and the accelerating gradient of linacs. The motivation of this research is to find methods to increase the breakdown threshold level in X-band structures by reducing dark current. Emphasis is focused on improved materials, surface finish, and cleanliness. The test platform for this research is a traveling wave resonant ring. A 30 MW klystron is employed to provide up to 300 MW of traveling wave power in the ring to trigger breakdown in the cavity. Five TM 01 cavities have previously been tested, each with a different combination of surface polish and/or coating. The onset of breakdown was extended up to 250 MV/m with a TiN surface finish, as compared to 210 MV/m for uncoated OFE copper. Although the TiN coating was helpful in depressing the field emission, the lowest dark current was obtained with a 1 microinch surface finish, single-point diamond-turned cavity

  13. High power RF transmission line component development

    International Nuclear Information System (INIS)

    Hong, B. G.; Hwang, C. K.; Bae, Y. D.; Yoon, J. S.; Wang, S. J.; Gu, S. H.; Yang, J. R.; Hahm, Y. S.; Oh, G. S.; Lee, J. R.; Lee, W. I.; Park, S. H.; Kang, M. S.; Oh, S. H.; Lee, W.I.

    1999-12-01

    We developed the liquid stub and phase shifter which are the key high RF power transmission line components. They show reliable operation characteristics and increased insulation capability, and reduced the size by using liquid (silicon oil, dielectric constant ε=2.72) instead of gas for insulating dielectric material. They do not have finger stock for the electric contact so the local temperature rise due to irregular contact and RF breakdown due to scratch in conductor are prevented. They can be utilized in broadcasting, radar facility which require high RF power transmission. Moreover, they are key components in RF heating system for fusion reactor. (author)

  14. High power RF transmission line component development

    Energy Technology Data Exchange (ETDEWEB)

    Hong, B. G.; Hwang, C. K.; Bae, Y. D.; Yoon, J. S.; Wang, S. J.; Gu, S. H.; Yang, J. R.; Hahm, Y. S.; Oh, G. S.; Lee, J. R.; Lee, W. I.; Park, S. H.; Kang, M. S.; Oh, S. H.; Lee, W.I

    1999-12-01

    We developed the liquid stub and phase shifter which are the key high RF power transmission line components. They show reliable operation characteristics and increased insulation capability, and reduced the size by using liquid (silicon oil, dielectric constant {epsilon}=2.72) instead of gas for insulating dielectric material. They do not have finger stock for the electric contact so the local temperature rise due to irregular contact and RF breakdown due to scratch in conductor are prevented. They can be utilized in broadcasting, radar facility which require high RF power transmission. Moreover, they are key components in RF heating system for fusion reactor. (author)

  15. High power RF oscillator with Marx generators

    International Nuclear Information System (INIS)

    Murase, Hiroshi; Hayashi, Izumi

    1980-01-01

    A method to maintain RF oscillation by using many Marx generators was proposed and studied experimentally. Many charging circuits were connected to an oscillator circuit, and successive pulsed charging was made. This successive charging amplified and maintained the RF oscillation. The use of vacuum gaps and high power silicon diodes improved the characteristics of RF current cut-off of the circuit. The efficiency of the pulsed charging from Marx generators to a condenser was theoretically investigated. The theoretical result showed the maximum efficiency of 0.98. The practical efficiency obtained by using a proposed circuit with a high power oscillator was in the range 0.50 to 0.56. The obtained effective output power of the RF pulses was 11 MW. The maximum holding time of the RF pulses was about 21 microsecond. (Kato, T.)

  16. High-surface-quality nanocrystalline InN layers deposited on GaN templates by RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Valdueza-Felip, Sirona; Naranjo, Fernando B.; Gonzalez-Herraez, Miguel [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala, Campus Universitario, 28871 Alcala de Henares, Madrid (Spain); Lahourcade, Lise; Monroy, Eva [Equipe mixte CEA-CNRS-UJF, Nanophysique et Semiconducteurs, INAC/SP2M/PSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Fernandez, Susana [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain)

    2011-01-15

    We report a detailed study of the effect of deposition parameters on optical, structural, and morphological properties of InN films grown by reactive radio-frequency (RF) sputtering on GaN-on-sapphire templates in a pure nitrogen atmosphere. Deposition parameters under study are substrate temperature, RF power, and sputtering pressure. Wurtzite crystallographic structure with c-axis preferred growth orientation is confirmed by X-ray diffraction measurements. For the optimized deposition conditions, namely at a substrate temperature of 450 C and RF power of 30 W, InN films present a root-mean-square surface roughness as low as {proportional_to}0.4 nm, comparable to the underlying substrate. The apparent optical bandgap is estimated at 720 nm (1.7 eV) in all cases. However, the InN absorption band tail is strongly influenced by the sputtering pressure due to a change in the species of the plasma. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. High Pressure, High Gradient RF Cavities for Muon Beam Cooling

    CERN Document Server

    Johnson, R P

    2004-01-01

    High intensity, low emittance muon beams are needed for new applications such as muon colliders and neutrino factories based on muon storage rings. Ionization cooling, where muon energy is lost in a low-Z absorber and only the longitudinal component is regenerated using RF cavities, is presently the only known cooling technique that is fast enough to be effective in the short muon lifetime. RF cavities filled with high-pressure hydrogen gas bring two advantages to the ionization technique: the energy absorption and energy regeneration happen simultaneously rather than sequentially, and higher RF gradients and better cavity breakdown behavior are possible than in vacuum due to the Paschen effect. These advantages and some disadvantages and risks will be discussed along with a description of the present and desired RF R&D efforts needed to make accelerators and colliders based on muon beams less futuristic.

  18. Extremely high frequency RF effects on electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Loubriel, Guillermo Manuel; Vigliano, David; Coleman, Phillip Dale; Williams, Jeffery Thomas; Wouters, Gregg A.; Bacon, Larry Donald; Mar, Alan

    2012-01-01

    The objective of this work was to understand the fundamental physics of extremely high frequency RF effects on electronics. To accomplish this objective, we produced models, conducted simulations, and performed measurements to identify the mechanisms of effects as frequency increases into the millimeter-wave regime. Our purpose was to answer the questions, 'What are the tradeoffs between coupling, transmission losses, and device responses as frequency increases?', and, 'How high in frequency do effects on electronic systems continue to occur?' Using full wave electromagnetics codes and a transmission-line/circuit code, we investigated how extremely high-frequency RF propagates on wires and printed circuit board traces. We investigated both field-to-wire coupling and direct illumination of printed circuit boards to determine the significant mechanisms for inducing currents at device terminals. We measured coupling to wires and attenuation along wires for comparison to the simulations, looking at plane-wave coupling as it launches modes onto single and multiconductor structures. We simulated the response of discrete and integrated circuit semiconductor devices to those high-frequency currents and voltages, using SGFramework, the open-source General-purpose Semiconductor Simulator (gss), and Sandia's Charon semiconductor device physics codes. This report documents our findings.

  19. Tha AGS Booster high frequency rf system

    International Nuclear Information System (INIS)

    Sanders, R.; Cameron, P.; Damn, R.

    1988-01-01

    A high level rf system, including a power amplifier and cavity has been designed for the AGS Booster. It covers a frequency range of 2.4 to 4.2 Mhz and will be used to accelerate high intensity proton, and low intensity polarized proton beams to 1.5 GeV and heavy ions to 0.35 GeV per nucleon. A total accelerating voltage of up to 90kV will be provided by two cavities, each having two gaps. The internally cross-coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate the high beam intensity, up to 0.75 /times/ 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two paralleled cells. The amplifier is a grounded cathode configuration driven by a remotely located solid state amplifier

  20. RF properties of high-T/sub c/ superconductors

    International Nuclear Information System (INIS)

    Bohn, C.L.; Delayen, J.R.; Dos Santos, D.I.; Lanagan, M.T.; Shepard, K.W.

    1988-01-01

    We have investigated the rf properties of high-T/sub c/ superconductors over a wide range of temperature, frequency, and rf field amplitude. We have tested both bulk polycrystalline samples and thick films on silver substrates. At 150 MHz and 4.2 K, we have measured a surface resistance of 18 μ/sup /OMEGA// at low rf field and 3.6 m/sup /OMEGA// at an rf field of 270 gauss. All samples showed a strong dependence of the surface resistance on rf field; however, no breakdown of the superconducting state has been observed up to the highest field achieved (320 gauss). 9 refs., 4 figs., 1 tab

  1. RF Application of High Temperature Single Domain Superconductors

    International Nuclear Information System (INIS)

    Ferendeci, M.

    2004-01-01

    Large single domain YBa2Cu3Ox materials have been successfully fabricated with superb RF properties by employing the seeded-melt growth (SMG) method. Commercially available Y-123 and Y-211 phase precursor powders were mixed thoroughly and pressed into various solid and cavity shapes. The solid pieces were then diced into cylindrical flat plates and polished. Following the growth procedure, the materials were then oxygenated in an oven for at least 7 days. The plates were then used as a part of a dielectric resonator cavity and the surface resistances were measured. The cavities were also tested in a closed cycle cryo cooler. The cavity resonance frequencies for the TM010 and TE111 modes, and the corresponding quality factors (Q values) were measured. From the measured Q values, the surface resistances of the cavity surfaces were calculated. Experimentally measured surface resistance values and various combinations of cavity structures for realizing highly selective RF filters will be presented

  2. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality factors higher than 4 throughout a band of 1-15 GHz and reaching as high as 28 were achieved. Additional benefits that are readily attainable from implementing fractal capacitors in MEMS are discussed, including suppressing residual stress warping, eliminating the need for etching holes, and reducing parasitics. The latter benefits were acquired without any fabrication intervention. © 2011 IEEE.

  3. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.; Emira, Ahmed; Radwan, Ahmed Gomaa; Salama, Khaled N.

    2012-01-01

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality

  4. Series-Tuned High Efficiency RF-Power Amplifiers

    DEFF Research Database (Denmark)

    Vidkjær, Jens

    2008-01-01

    An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits.......An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits....

  5. Low reflectance high power RF load

    Science.gov (United States)

    Ives, R. Lawrence; Mizuhara, Yosuke M.

    2016-02-02

    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  6. The AGS Booster high frequency rf system

    International Nuclear Information System (INIS)

    Sanders, R.T.; Cameron, P.; Eng, W.; Goldman, M.A.; Jablonski, E.; Kasha, D.; Keane, J.; McNerney, A.; Meth, M.; Plotkin, M.; Puglisi, M.; Ratti, A.; Spitz, R.

    1991-01-01

    A high level rf system, including a power amplifier and cavity, has been designed and built for the AGS Booster. It covers a frequency range of 2.4 to 4.2 MHz and will be used to accelerate high intensity protons. Low intensity polarized protons and heavy ions, to the 1.5 GeV level. A total accelerating voltage of up to 90 kV will be provided by two cavities, each having two gaps. The internally cross coupled, pushpull cavities are driven by an adjacently located power amplifier. In order to accommodate beam intensities up to 0.75 x 10 13 protons per bunch, a low plate resistance power tetrode is used. The tube anode is magnetically coupled to one of the cavity's two parallel cells. The amplifier is a grounded cathode configuration driven by a remotely located solid-state amplifier. It has been tested in the laboratory at full gap voltage with satisfactory results. 5 refs., 2 figs., 1 tab

  7. Development and advances in conventional high power RF systems

    International Nuclear Information System (INIS)

    Wilson, P.B.

    1995-06-01

    The development of rf systems capable of producing high peak power (hundreds of megawatts) at relatively short pulse lengths (0.1--5 microseconds) is currently being driven mainly by the requirements of future high energy linear colliders, although there may be applications to industrial, medical and research linacs as well. The production of high peak power rf typically involves four basic elements: a power supply to convert ac from the ''wall plug'' to dc; a modulator, or some sort of switching element, to produce pulsed dc power; an rf source to convert the pulsed dc to pulsed rf power; and possibly an rf pulse compression system to further enhance the peak rf power. Each element in this rf chain from wall plug to accelerating structure must perform with high efficiency in a linear collider application, such that the overall system efficiency is 30% or more. Basic design concepts are discussed for klystrons, modulators and rf pulse compression systems, and their present design status is summarized for applications to proposed linear colliders

  8. High RF Power Production for CLIC

    CERN Document Server

    Syratchev, I; Adli, E; Taborelli, M

    2007-01-01

    The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and excite preferentially the synchronous mode. The RF power produced (several hundred MW) is collected at the downstream end of the structure by means of the Power Extractor and delivered to the main linac structure. The PETS geometry is a result of multiple compromises between beam stability and main linac RF power needs. Another requirement is to provide local RF power termination in case of accelerating structure failure (ON/OFF capability). Surface electric and magnetic fields, power extraction method, HOM damping, ON/OFF capability and fabrication technology were all evaluated to provide a reliable design

  9. High field conditioning of cryogenic RF cavities

    International Nuclear Information System (INIS)

    Cole, M.; Debiak, T.; Lom, C.; Shephard, W.; Sredniawski, J.

    1993-01-01

    Space-based and other related accelerators have conditioning and operation requirements that are not found in most machines. The use of cryogenic copper, relatively poor vacuum, and limited power storage and operating time put unusual demands on the high-field conditioning process and present some concerns. Two CW cryogenic engineering model open-quotes sparkerclose quotes cavities have been fabricated and tested to fairly high field levels. Tests included initial and repeated conditioning as well as sustained RF operations. The two cavities were an engineering model TDL and an engineering model RFQ. Both cavities operated at 425 MHz. The DTL was conditioned to 46 MV/m at 100% duty factor (CW) at cryogenic temperature. This corresponds to a gap voltage of 433 kV and a real estate accelerating gradient (energy gain/total cavity length) of 6.97 MV/m. The authors believe this to be record performance for cryo CW operation. During cryo pulsed operation, the same cavity reached 48 MV/m with 200 μsec pulses at 0.5% DF. The RFQ was conditioned to 30 MV/m CW at cryo, 85 kV gap voltage. During a brief period of cryo pulsed operation, the RFQ operated at 46 MV/m, or 125 kV gap voltage. Reconditioning experiments were performed on both cavities and no problems were encountered. It should be noted that the vacuum levels were not very stringent during these tests and no special cleanliness or handling procedures were followed. The results of these tests indicate that cavities can run CW without difficulty at cryogenic temperatures at normal conservative field levels. Higher field operation may well be possible, and if better vacuums are used and more attention is paid to cleanliness, much higher fields may be attainable

  10. Improving the beam quality of rf guns by correction of rf and space-charge effects

    International Nuclear Information System (INIS)

    Serafini, L.

    1992-01-01

    In this paper we describe two possible strategies to attain ultra-low emittance electron beam generation by laser-driven RF guns. The first one is based on the exploitation of multi-mode resonant cavities to neutralize the emittance degradation induced by RF effects. Accelerating cigar-like (long and thin) electron bunches in multi-mode operated RF guns the space charge induced emittance is strongly decreased at the same time: high charged bunches, as typically requested by future TeV e - e + colliders, can be delivered by the gun at a quite low transverse emittance and good behaviour in the longitudinal phase space, so that they can be magnetically compressed to reach higher peak currents. The second strategy consists in using disk-like electron bunches, produced by very short laser pulses illuminating the photocathode. By means of an analytical study a new regime has been found, where the normalized transverse emittance scales like the inverse of the peak current, provided that the laser pulse intensity distribution is properly shaped in the transverse direction. Preliminary numerical simulations confirm the analytical predictions and show that the minimum emittance achievable is set up, in this new regime, by the wake-field interaction between the bunch and the cathode metallic wall

  11. Embedded control system for high power RF amplifiers

    International Nuclear Information System (INIS)

    Sharma, Deepak Kumar; Gupta, Alok Kumar; Jain, Akhilesh; Hannurkar, P.R.

    2011-01-01

    RF power devices are usually very sensitive to overheat and reflected RF power; hence a protective interlock system is required to be embedded with high power solid state RF amplifiers. The solid state RF amplifiers have salient features of graceful degradation and very low mean time to repair (MTTR). In order to exploit these features in favour of lowest system downtime, a real-time control system is embedded with high power RF amplifiers. The control system is developed with the features of monitoring, measurement and network publishing of various parameters, historical data logging, alarm generation, displaying data to the operator and tripping the system in case of any interlock failure. This paper discusses the design philosophy, features, functions and implementation details of the embedded control system. (author)

  12. High power rf component testing for the NLC

    International Nuclear Information System (INIS)

    Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.

    1998-09-01

    In the Next Linear Collider (NLC), the high power rf components must be capable of handling peak rf power levels in excess of 600 MW. In the current view of the NLC, even the rectangular waveguide components must transmit at least 300 MW rf power. At this power level, peak rf fields can greatly exceed 100 MV/m. The authors present recent results of high power tests performed at the Accelerator Structure Test Area (ASTA) at SLAC. These tests are designed to investigate the rf breakdown limits of several new components potentially useful for the NLC. In particular, the authors tested a new TE 01 --TE 10 circular to rectangular wrap-around mode converter, a modified (internal fin) Magic Tee hybrid, and an upgraded flower petal mode converter

  13. Rf-biasing of highly idealized plasmas

    NARCIS (Netherlands)

    Westermann, R.H.J.; Blauw, M.A.; Goedheer, W.J.; Sanden, van de M.C.M.; Schmidt, J.; Simek, M.; Pekarek, S.; Prukner, V.

    2007-01-01

    Remote plasmas, which are subjected to a radio-frequency (RF) biased surface, have been investigated theoretically and experimentally for decades. The relation between the complex power (DC) voltage characteristics, the ion energy distribution and control losses of the ion bombardment are of

  14. RF system considerations for large high-duty-factor linacs

    International Nuclear Information System (INIS)

    Lynch, M.T.; Ziomek, C.D.; Tallerico, P.J.; Regan, A.H.; Eaton, L.; Lawrence, G.

    1994-01-01

    RF systems are often a major cost item for linacs, but this is especially true for large high-duty-factor linacs (up to and including CW) such as the Accelerator for Production of Tritium (APT) or the Accelerator for Transmutation of nuclear Waste (ATW). In addition, the high energy and high average beam current of these machines (approximately 1 GeV, 100--200 mA) leads to a need for excellent control of the accelerating fields in order to minimize the possibility of beam loss in the accelerator and the resulting activation. This paper will address the key considerations and limitations in the design of the RF system. These considerations impact the design of both the high power RF components and the RF controls. As might be expected, the two concerns sometimes lead to conflicting design requirements. For example minimum RF operating costs lead to a desire for operation near saturation of the high power RF generators in order to maximize the operating efficiency. Optimal control of the RF fields leads to a desire for maximum overdrive capability in those same generators in order to respond quickly to disturbances of the accelerator fields

  15. High time resolution beam-based measurement of the rf-to-laser jitter in a photocathode rf gun

    Directory of Open Access Journals (Sweden)

    Zhen Zhang

    2014-03-01

    Full Text Available Characterizing the rf-to-laser jitter in the photocathode rf gun and its possible origins is important for improving the synchronization and beam quality of the linac based on the photocathode rf gun. A new method based on the rf compression effect in the photocathode rf gun is proposed to measure the rf-to-laser jitter in the gun. By taking advantage of the correlation between the rf compression and the laser injection phase, the error caused by the jitter of the accelerating field in the gun is minimized and thus 10 fs time resolution is expected. Experimental demonstration at the Tsinghua Thomson scattering x-ray source with a time resolution better than 35 fs is reported in this paper. The experimental results are successfully used to obtain information on the possible cause of the jitter and the accompanying drifts.

  16. High temperature stable RF MEMS microwave switches

    OpenAIRE

    Klein, Stefan

    2010-01-01

    Im Rahmen dieser Arbeit wurden elektrostatisch angesteuerte RF-MEMS Schalter mit kapazitiver Kopplung entwickelt, die Prozesstemperaturen von 400°C und darüber hinaus ohne Verlust der Funktionstüchtigkeit überstehen. Als Funktionsmaterial wird einerseits eine AlSiCu und andererseits eine WTi Legierung verwendet. Das Schalterprinzip beruht auf dem Wanderkeileffekt, der einen gekrümmten Biegebalken nutzt. Diese Verbiegung weg von der Substratoberfläche, die durch einen wohldefinierten intri...

  17. Advances in high-power rf amplifiers

    International Nuclear Information System (INIS)

    Tallerico, P.J.

    1979-01-01

    Several powerful accelerators and storage rings are being considered that will require tens or even hundreds of megawatts of continuous rf power. The economics of such large machines can be dictated by the cost and efficiency of the rf amplifiers. The overall design and performance of such narrow-band amplifiers, operating in the 50- to 1500-MHz region, are being theoretically studied as a function of frequency to determine the optimum rf amplifier output power, gain, efficiency, and dc power requirements. The state of the art for three types of amplifiers (gridded tubes, klystrons, and gyrocons) is considered and the development work necessary to improve each is discussed. The gyrocon is a new device, hence its various embodiments are discussed in detail. The Soviet designs are reviewed and the gyrocon's strengths and weaknesses are compared to other types of microwave amplifiers. The primary advantages of the gyrocon are the very large amount of power available from a single device and the excellent efficiency and stable operation. The klystron however, has much greater gain and is simpler mechanically. At very low frequencies, the small size of the gridded tube makes it the optimum choice for all but the most powerful systems

  18. rf coaxial couplers for high-intensity linear accelerators

    International Nuclear Information System (INIS)

    Manca, J.J.; Knapp, E.A.

    1980-02-01

    Two rf coaxial couplers that are particularly suitable for intertank connection of the disk-and-washer accelerating structure for use in high-intensity linear accelerators have been developed. These devices have very high coupling to the accelerating structure and very low rf power loss at the operating frequency, and they can be designed for any relative particle velocity β > 0.4. Focusing and monitoring devices can be located inside these couplers

  19. High power RF test of an 805 MHz RF cavity for a muon cooling channel

    International Nuclear Information System (INIS)

    Li, Derun; Corlett, J.; MacGill, R.; Rimmer, R.; Wallig, J.; Zisman, M.; Moretti, A.; Qian, Z.; Wu, V.; Summers, D.; Norem, J.

    2002-01-01

    We present recent high power RF test results on an 805 MHz cavity for a muon cooling experiment at Lab G in Fermilab. In order to achieve high accelerating gradient for large transverse emittance muon beams, the cavity design has adopted a pillbox like shape with 16 cm diameter beam iris covered by thin Be windows, which are demountable to allow for RF tests of different windows. The cavity body is made from copper with stiff stainless steel rings brazed to the cavity body for window attachments. View ports and RF probes are available for visual inspections of the surface of windows and cavity and measurement of the field gradient. Maximum of three thermo-couples can be attached to the windows for monitoring the temperature gradient on the windows caused by RF heating. The cavity was measured to have Q 0 of about 15,000 with copper windows and coupling constant of 1.3 before final assembling. A 12 MW peak power klystron is available at Lab G in Fermilab for the high power test. The cavity and coupler designs were performed using the MAFIA code in the frequency and the time domain. Numerical simulation results and cold test measurements on the cavity and coupler will be presented for comparisons

  20. High Power RF Transmitters for ICRF Applications on EAST

    International Nuclear Information System (INIS)

    Mao Yuzhou; Yuan Shuai; Zhao Yanping; Zhang Xinjun; Chen Gen; Cheng Yan; Wang Lei; Ju Songqing; Deng Xu; Qin Chengming; Yang Lei; Kumazawa, R.

    2013-01-01

    An Ion Cyclotron Range of Frequency (ICRF) system with a radio frequency (RF) power of 4 × 1.5 MW was developed for the Experimental Advanced Superconducting Tokamak (EAST). High RF power transmitters were designed as a part of the research and development (R and D) for an ICRF system with long pulse operation at megawatt levels in a frequency range of 25 MHz to 70 MHz. Studies presented in this paper cover the following parts of the high power transmitter: the three staged high power amplifier, which is composed of a 5 kW wideband solid state amplifier, a 100 kW tetrode drive stage amplifier and a 1.5 MW tetrode final stage amplifier, and the DC high voltage power supply (HVPS). Based on engineering design and static examinations, the RF transmitters were tested using a matched dummy load where an RF output power of 1.5 MW was achieved. The transmitters provide 6 MW RF power in primary phase and will reach a level up to 12 MW after a later upgrade. The transmitters performed successfully in stable operations in EAST and HT-7 devices. Up to 1.8 MW of RF power was injected into plasmas in EAST ICRF heating experiments during the 2010 autumn campaign and plasma performance was greatly improved.

  1. Superconducting niobium in high rf magnetic fields

    International Nuclear Information System (INIS)

    Mueller, G.

    1988-01-01

    The benefit of superconducting cavities for accelerator applications depends on the field and Q/sub 0/ levels which can be achieved reliably in mass producible multicell accelerating structures. The presently observed field and Q/sub 0/ limitations are caused by anomalous loss mechanisms which are not correlated with the intrinsic properties of the pure superconductor but rather due to defects or contaminants on the superconducting surface. The ultimate performance levels of clean superconducting cavities built from pure Nb will be given by the rf critical field and the surface resistance of the superconductor. In the first part of this paper a short survey is given of the maximum surface magnetic fields achieved in single-cell cavities. The results of model calculations for the thermal breakdown induced by very small defects and for the transition to the defect free case is discussed in part 2. In the last chapter, a discussion is given for the rf critical field of Nb on the basis of the Ginzburg-Landau Theory. It is shown that not only purity but also the homogeneity of the material should become important for the performance of superconducting Nb cavities at field levels beyond 100mT. Measurement results of the upper critical field for different grades of commercially available Nb sheet materials are given. 58 references, 20 figures, 1 table

  2. High power RF window deposition apparatus, method, and device

    Science.gov (United States)

    Ives, Lawrence R.; Lucovsky, Gerald; Zeller, Daniel

    2017-07-04

    A process for forming a coating for an RF window which has improved secondary electron emission and reduced multipactor for high power RF waveguides is formed from a substrate with low loss tangent and desirable mechanical characteristics. The substrate has an RPAO deposition layer applied which oxygenates the surface of the substrate to remove carbon impurities, thereafter has an RPAN deposition layer applied to nitrogen activate the surface of the substrate, after which a TiN deposition layer is applied using Titanium tert-butoxide. The TiN deposition layer is capped with a final RPAN deposition layer of nitridation to reduce the bound oxygen in the TiN deposition layer. The resulting RF window has greatly improved titanium layer adhesion, reduced multipactor, and is able to withstand greater RF power levels than provided by the prior art.

  3. High power RF systems for the BNL ERL project

    Energy Technology Data Exchange (ETDEWEB)

    Zaltsman, A.; Lambiase, R.

    2011-03-28

    The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both.

  4. High power testing of a 17 GHz photocathode RF gun

    International Nuclear Information System (INIS)

    Chen, S.C.; Danly, B.G.; Gonichon, J.

    1995-01-01

    The physics and technological issues involved in high gradient particle acceleration at high microwave (RF) frequencies are under study at MIT. The 17 GHz photocathode RF gun has a 1 1/2 cell (π mode) room temperature cooper cavity. High power tests have been conducted at 5-10 MW levels with 100 ns pulses. A maximum surface electric field of 250 MV/m was achieved. This corresponds to an average on-axis gradient of 150 MeV/m. The gradient was also verified by a preliminary electron beam energy measurement. Even high gradients are expected in our next cavity design

  5. High Power RF Test Facility at the SNS

    CERN Document Server

    Kang, Yoon W; Campisi, Isidoro E; Champion, Mark; Crofford, Mark; Davis, Kirk; Drury, Michael A; Fuja, Ray E; Gurd, Pamela; Kasemir, Kay-Uwe; McCarthy, Michael P; Powers, Tom; Shajedul Hasan, S M; Stirbet, Mircea; Stout, Daniel; Tang, Johnny Y; Vassioutchenko, Alexandre V; Wezensky, Mark

    2005-01-01

    RF Test Facility has been completed in the SNS project at ORNL to support test and conditioning operation of RF subsystems and components. The system consists of two transmitters for two klystrons powered by a common high voltage pulsed converter modulator that can provide power to two independent RF systems. The waveguides are configured with WR2100 and WR1150 sizes for presently used frequencies: 402.5 MHz and 805 MHz. Both 402.5 MHz and 805 MHz systems have circulator protected klystrons that can be powered by the modulator capable of delivering 11 MW peak and 1 MW average power. The facility has been equipped with computer control for various RF processing and complete dual frequency operation. More than forty 805 MHz fundamental power couplers for the SNS superconducting linac (SCL) cavitites have been RF conditioned in this facility. The facility provides more than 1000 ft2 floor area for various test setups. The facility also has a shielded cave area that can support high power tests of normal conducti...

  6. High power RF systems for LEHIPA of ADS

    International Nuclear Information System (INIS)

    Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Rao, B.V.R.; Mishra, J.K.; Patel, Niranjan; Gupta, S.K.

    2011-01-01

    Worldwide accelerator driven sub-critical system (ADS) has generated a huge interest for various reasons. In India, as a part of accelerator driven sub-critical system (ADS) program, a normal conducting, low energy high intensity proton accelerator (LEHIPA) of energy 20 MeV and beam current of 30 mA is being developed in Bhabha Atomic Research Centre (BARC). LEHIPA comprises of Electron Cyclotron Resonance (ECR) ion source (50 KeV), Radio Frequency Quadrupole (RFQ) accelerator (3 MeV) and Drift tube Linac (DTL) 1 and 2 (10 MeV and 20 MeV respectively). As per the accelerator physics design, RFQ requires nearly 530 kW RF power while each of DTL need 900 kW. Each accelerating cavity will be driven by a one- megawatt (CW) klystron based high power RF (HPRF) system at 352.21 MHz. Three such RF systems will be developed. The RF system has been designed around five cavity klystron tube TH2089F (Thales make) capable of delivering 1 MW continuous wave power at 352.21 MHz. The klystron has a gain of 40 dB and efficiency around 62 %. Each of the RF system comprises of a low power solid state driver (∼ 100 W), klystron tube, harmonic filter, directional coupler, Y-junction circulator (AFT make), RF load and WR2300 wave guide based RF transmission line each of 1 MW capacity. It also includes other subsystems like bias supplies (high voltage (HV) and low voltage (LV)), HV interface system, interlock and protection circuits, dedicated low conductivity water-cooling, pulsing circuitry/mechanisms etc. WR 2300 based RF transmission line transmits and feeds the RE power from klystron source to respective accelerating cavity. This transmission line starts from second port of the circulator and consists of straight sections, full height to half height transition, magic Tee, termination load at the centre of magic tee, half height sections, directional couplers and RE windows. For X-ray shielding, klystron will be housed in a lead (3 mm) based shielded cage. This system set up has a

  7. Modeling high-power RF accelerator cavities with SPICE

    International Nuclear Information System (INIS)

    Humphries, S. Jr.

    1992-01-01

    The dynamical interactions between RF accelerator cavities and high-power beams can be treated on personal computers using a lumped circuit element model and the SPICE circuit analysis code. Applications include studies of wake potentials, two-beam accelerators, microwave sources, and transverse mode damping. This report describes the construction of analogs for TM mn0 modes and the creation of SPICE input for cylindrical cavities. The models were used to study continuous generation of kA electron beam pulses from a vacuum cavity driven by a high-power RF source

  8. Eighth CW and High Average Power RF Workshop

    CERN Document Server

    2014-01-01

    We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

  9. Glycol-Substitute for High Power RF Water Loads

    CERN Document Server

    Ebert, Michael

    2005-01-01

    In water loads for high power rf applications, power is dissipated directly into the coolant. Loads for frequencies below approx. 1GHz are ordinarily using an ethylene glycol-water mixture as coolant. The rf systems at DESY utilize about 100 glycol water loads with powers ranging up to 600kW. Due to the increased ecological awareness, the use of glycol is now considered to be problematic. In EU it is forbidden to discharge glycol into the waste water system. In case of cooling system leakages one has to make sure that no glycol is lost. Since it is nearly impossible to avoid any glycol loss in large rf systems, a glycol-substitute was searched for and found. The found sodium-molybdate based substitute is actually a additive for corrosion protection in water systems. Sodium-molybdate is ecologically harmless; for instance, it is also used as fertilizer in agriculture. A homoeopathic dose of 0.4% mixed into deionised water gives better rf absorption characteristics than a 30% glycol mixture. The rf coolant feat...

  10. Study of High Quality Indium Nitride Films Grown on Si(100 Substrate by RF-MOMBE with GZO and AlN Buffer Layers

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chen

    2012-01-01

    Full Text Available Wurtzite structure InN films were prepared on Si(100 substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE system. Ga-doped ZnO (GZO and Amorphous AlN (a-AlN film were used as buffer layers for InN films growth. Structural, surface morphology and optical properties of InN films were investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and photoluminescence (PL. XRD results indicated that all InN films exhibited preferred growth orientation along the c-axis with different intermediate buffers. TEM images exhibit the InN/GZO growth by two-dimensional mode and thickness about 900 nm. Also, the InN films can be obtained by growth rate about ~1.8 μm/h. Optical properties indicated that the band gap of InN/GZO is about 0.79 eV. These results indicate that the control of buffer layer is essential for engineering the growth of InN on silicon wafer.

  11. Comparative Studies of High-Gradient Rf and Dc Breakdowns

    CERN Document Server

    Kovermann, Jan Wilhelm; Wuensch, Walter

    2010-01-01

    The CLIC project is based on normal-conducting high-gradient accelerating structures with an average accelerating gradient of 100 MV/m. The maximum achievable gradient in these structures is limited by the breakdown phenomenon. The physics of breakdowns is not yet fully understood quantitatively. A full knowledge could have strong impact on the design, material choice and construction of rf structures. Therefore, understanding breakdowns has great importance to reaching a gradient of 100MV/m with an acceptable breakdown probability. This thesis addresses the physics underlying the breakdown effect, focusing on a comparison of breakdowns in rf structures and in a dc spark setup. The dc system is simpler, easier to benchmark against simulations, with a faster turnaround time, but the relationship to rf breakdown must be established. To do so, an experimental approach based on optical diagnostics and electrical measurements methods was made. Following an introduction into the CLIC project, a general theoretical ...

  12. High-quality InN grown on KOH wet etched N-polar InN template by RF-MBE

    International Nuclear Information System (INIS)

    Muto, D.; Araki, T.; Kitagawa, S.; Kurouchi, M.; Nanishi, Y.; Naoi, H.; Na, H.

    2006-01-01

    We have succeeded in dramatically decreasing the density of dislocations in InN by regrowing InN films on micro-facetted N-polar InN templates. The micro-facetted N-polar InN templates were formed by wet etching in a 10 mol/l KOH solution. InN films were regrown on the micro-facetted N-polar InN templates and on flat surface N-polar InN templates for comparison by radio-frequency plasma-assisted molecular beam epitaxy. InN regrown on micro-facetted InN had considerably smaller twist distribution than that grown on the flat InN templates. From transmission electron microscopy observation, it was confirmed that the InN grown on the micro-facetted InN template had much lower density of dislocations than that grown on the flat InN template, and moreover the propagation of edge dislocations was almost completely terminated at the interface between the regrown InN and the micro-facetted InN template. Based on the results, we propose that regrowth of InN on micro-facetted InN templates is an effective way to obtain high-quality InN films. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Beam physics design strategy for a high-current rf linac

    Energy Technology Data Exchange (ETDEWEB)

    Reiser, M. [Univ. of Maryland, College Park, MD (United States)

    1995-10-01

    The high average beam power of an rf linac system for transmutation of nuclear waste puts very stringent requirements on beam quality and beam control. Fractional beam losses along the accelerator must be kept at extremely low levels to assure {open_quotes}hands-on{close_quotes} maintenance. Hence, halo formation and large-amplitude tails in the particle distribution due to beam mismatch and equipartitioning effects must be avoided. This implies that the beam should ideally be in near-perfect thermal equilibrium from injection to full energy - in contrast to existing rf linacs in which the transverse temperature, T {sub {perpendicular}}, is higher than the longitudinal temperature, T{sub {parallel}}. The physics and parameter scaling for such a system will be reviewed using the results of recent work on high-intensity bunched beams. A design strategy for a high-current rf linac with equilibrated beam will be proposed.

  14. High power tests of dressed supconducting 1.3 GHz RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hocker, A.; Harms, E.R.; Lunin, A.; Sukhanov, A.; /Fermilab

    2011-03-01

    A single-cavity test cryostat is used to conduct pulsed high power RF tests of superconducting 1.3 GHz RF cavities at 2 K. The cavities under test are welded inside individual helium vessels and are outfitted ('dressed') with a fundamental power coupler, higher-order mode couplers, magnetic shielding, a blade tuner, and piezoelectric tuners. The cavity performance is evaluated in terms of accelerating gradient, unloaded quality factor, and field emission, and the functionality of the auxiliary components is verified. Test results from the first set of dressed cavities are presented here.

  15. High frequency CARM driver for rf linacs

    International Nuclear Information System (INIS)

    Danly, B.G.

    1993-01-01

    This CARM program has successfully demonstrated the first ever long-pulse CARM oscillator operation; these results demonstrate the potential of CARMs as an alternative source of millimeter waves to the gyrotron for ECRH plasma heating. The result of 1.8 MW at 27.8 GHz and 0.5 μs pulse width in the TE 11 mode represent a clear demonstration of the capabilities of the CARM oscillator for the production of high powers with large frequency upshift. It is hoped that this successful proof-of-principle demonstration.will lead to further development of the CARM as an ECRH source by the DOE Office of Fusion Energy, Development and Technology Division. This success is a direct outcome of this support of the Advanced Energy Projects Office of DOE in the form of this program. The CARM amplifier component of the program, although unsuccessful at obtaining CARM amplifier operation at 17 GHz, has succeeded by furthering the understanding of the limitations and difficulties that lie ahead for continued CARM amplifier development. The amplifier component of the program has successfully demonstrated a high power second and third harmonic gyro-TWT amplifier. Up to 5 MW of power at 17.1 GHz and >50dB gain have been obtained. These results should be viewed as an important contribution of this program to the development of viable microwave sources for powering the next linear collider. Indeed, the present gyro-amplifier, which resulted from this program, is presently being used in ongoing high-gradient accelerator research at MIT under a DOE High Energy Physics grant. As a result of both the oscillator and amplifier advances made during this program, the CARM and harmonic gyro-TWT have reached a significantly more mature level; their future role in specific applications of benefit to DOEs OFE and HEP offices may now be pursued

  16. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  17. Application of RF Superconductivity to High-Current Linac

    International Nuclear Information System (INIS)

    Chan, K.C.D.

    1998-01-01

    In 1997, the authors initiated a development program in Los Alamos for high-current superconducting proton-linac technology to build prototypes components of this linac to demonstrate the feasibility. The authors are building 700-MHz niobium cavities with elliptical shapes, as well as power couplers to transfer high RF power to these cavities. The cavities and power couplers will be integrated in cryostats as linac cryomodules. In this paper, they describe the linac design and the status of the development program

  18. Micromachined high-performance RF passives in CMOS substrate

    International Nuclear Information System (INIS)

    Li, Xinxin; Ni, Zao; Gu, Lei; Wu, Zhengzheng; Yang, Chen

    2016-01-01

    This review systematically addresses the micromachining technologies used for the fabrication of high-performance radio-frequency (RF) passives that can be integrated into low-cost complementary metal-oxide semiconductor (CMOS)-grade (i.e. low-resistivity) silicon wafers. With the development of various kinds of post-CMOS-compatible microelectromechanical systems (MEMS) processes, 3D structural inductors/transformers, variable capacitors, tunable resonators and band-pass/low-pass filters can be compatibly integrated into active integrated circuits to form monolithic RF system-on-chips. By using MEMS processes, including substrate modifying/suspending and LIGA-like metal electroplating, both the highly lossy substrate effect and the resistive loss can be largely eliminated and depressed, thereby meeting the high-performance requirements of telecommunication applications. (topical review)

  19. Intermediate quality control tests in the development of a superconducting RF cryomodule for CW operation

    Science.gov (United States)

    Pattalwar, Shrikant; Jones, Thomas; Strachan, John; Bate, Robert; Davies, Phil; McIntosh, Peter

    2012-06-01

    Through an international cryomodule collaboration, ASTeC at Daresbury Laboratory has taken the primary responsibility in leading the development of an optimised Superconducting RF (SRF) cryomodule, operating in CW mode for energy recovery facilities and other high duty cycle accelerators. For high beam current operation, Higher Order Mode (HOM) absorbers are critical components of the SRF Cryomodule, ensuring excessive heating of the accelerating structures and beam instabilities are effectively managed. This paper describes some of the cold tests conducted on the HOM absorbers and other critical components during the construction phase, to ensure that the quality and reliable cryomodule performance is maintained.

  20. RF high voltage performance of RF transmission line components on the DIII-D Fast Wave Current Drive (FWCD) system

    International Nuclear Information System (INIS)

    Ferguson, S.W.; Callis, R.W.; Cary, W.P.; Phelps, D.A.; Ponce, D.; Baity, F.W.; Barber, G.

    1995-01-01

    The performance of the high voltage rf components of the DIII-D Fast Wave Current Drive System (FWCD) have been evaluated under various conditions of insulator configuration, insulator material, insulating gas and gas pressure. The insulator materials that have been investigated are alumina, steatite, pyrex, quartz, and teflon. The results of this evaluation are discussed in this paper. Additionally a rf high potter was developed to aid in the evaluation of rf high voltage components. The high potter consists of a 50 Ω, 1/4 wavelength cavity with a variable position short and a 50 ohm matched tap at one end of the cavity. With this configuration rf voltages were generated in excess of 100 kVp in the frequency range 30 to 60 MHz

  1. RF high voltage performance of RF transmission line components on the DIII-D Fast Wave Current Drive (FWCD) System

    International Nuclear Information System (INIS)

    Ferguson, S.W.; Callis, R.W.; Cary, W.P.; Phelps, D.A.; Ponce, D.; Baity, F.W.; Barber, G.

    1995-12-01

    The performance of the high voltage rf components of the DIII-D Fast Wave Current Drive System (FWCD) have been evaluated under various conditions of insulator configuration, insulator material, insulating gas and gas pressure. The insulator materials that have been investigated are alumina, steatite, pyrex, quartz, and teflon. The results of this evaluation are discussed in this paper. Additionally a rf high potter was developed to aid in the evaluation of rf high voltage components. The high potter consists of a 50 Ω, 1/4 wavelength cavity with a variable position short and a 50 ohm matched tap at one end of the cavity. With this configuration rf voltages were generated in excess of 100 kVp in the frequency range 30 to 60 MHz

  2. Simulation of plasma loading of high-pressure RF cavities

    Science.gov (United States)

    Yu, K.; Samulyak, R.; Yonehara, K.; Freemire, B.

    2018-01-01

    Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have been performed in the range of parameters typical for practical muon cooling channels.

  3. Simulation of plasma loading of high-pressure RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Samulyak, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Stony Brook Univ., NY (United States). Dept. of Applied Mathematics and Statistics; Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Freemire, B. [Northern Illinois Univ., DeKalb, IL (United States)

    2018-01-11

    Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have also been performed in the range of parameters typical for practical muon cooling channels.

  4. Development of a large proton accelerator for innovative researches; development of high power RF source

    Energy Technology Data Exchange (ETDEWEB)

    Chung, K. H.; Lee, K. O.; Shin, H. M.; Chung, I. Y. [KAPRA, Seoul (Korea); Kim, D. I. [Inha University, Incheon (Korea); Noh, S. J. [Dankook University, Seoul (Korea); Ko, S. K. [Ulsan University, Ulsan (Korea); Lee, H. J. [Cheju National University, Cheju (Korea); Choi, W. H. [Korea Advanced Institute of Science and Technology, Taejeon (Korea)

    2002-05-01

    This study was performed with objective to design and develop the KOMAC proton accelerator RF system. For the development of the high power RF source for CCDTL(coupled cavity drift tube linac), the medium power RF system using the UHF klystron for broadcasting was integrated and with this RF system we obtained the basic design data, operation experience and code-validity test data. Based on the medium power RF system experimental data, the high power RF system for CCDTL was designed and its performed was analyzed. 16 refs., 64 figs., 27 tabs. (Author)

  5. Development of new S-band RF window for stable high-power operation in linear accelerator RF system

    Science.gov (United States)

    Joo, Youngdo; Lee, Byung-Joon; Kim, Seung-Hwan; Kong, Hyung-Sup; Hwang, Woonha; Roh, Sungjoo; Ryu, Jiwan

    2017-09-01

    For stable high-power operation, a new RF window is developed in the S-band linear accelerator (Linac) RF systems of the Pohang Light Source-II (PLS-II) and the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The new RF window is designed to mitigate the strength of the electric field at the ceramic disk and also at the waveguide-cavity coupling structure of the conventional RF window. By replacing the pill-box type cavity in the conventional RF window with an overmoded cavity, the electric field component perpendicular to the ceramic disk that caused most of the multipacting breakdowns in the ceramic disk was reduced by an order of magnitude. The reduced electric field at the ceramic disk eliminated the Ti-N coating process on the ceramic surface in the fabrication procedure of the new RF window, preventing the incomplete coating from spoiling the RF transmission and lowering the fabrication cost. The overmoded cavity was coupled with input and output waveguides through dual side-wall coupling irises to reduce the electric field strength at the waveguide-cavity coupling structure and the possibility of mode competitions in the overmoded cavity. A prototype of the new RF window was fabricated and fully tested with the Klystron peak input power, pulse duration and pulse repetition rate of 75 MW, 4.5 μs and 10 Hz, respectively, at the high-power test stand. The first mass-produced new RF window installed in the PLS-II Linac is running in normal operation mode. No fault is reported to date. Plans are being made to install the new RF window to all S-band accelerator RF modules of the PLS-II and PAL-XFEL Linacs. This new RF window may be applied to the output windows of S-band power sources like Klystron as wells as the waveguide windows of accelerator facilities which operate in S-band.

  6. Rf Gun with High-Current Density Field Emission Cathode

    International Nuclear Information System (INIS)

    Jay L. Hirshfield

    2005-01-01

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  7. High-gradient normal-conducting RF structures for muon cooling channels

    International Nuclear Information System (INIS)

    Corlett, J.N.; Green, M.A.; Hartman, N.; Ladran, A.; Li, D.; MacGill, R.; Rimmer, R.; Moretti, A.; Jurgens, T.; Holtkamp, N.; Black, E.; Summers, D.; Booke, M.

    2001-01-01

    We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of muons in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focusing solenoidal magnets, precluding the application of superconducting RF technology [1]. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimize shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R and D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose

  8. MEASUREMENT OF HIGH Q RF CAVITY IMPEDANCE WITH BEAM

    International Nuclear Information System (INIS)

    Limborg, Cecile

    2003-01-01

    An inexpensive method to measure, with beam, the Rs and Q of narrow-band high order resonances in RF cavities was developed on SPEAR. The two main results of this study are: (1) an improved operational stability of SPEAR; and (2) the decision to keep the present cavities for the proposed SPEAR upgrade. SPEAR3 will be run initially at 200 mA, twice the present current. Just beyond the current threshold, and before step loss, there is a regime in which the beam performs large amplitude, low frequency oscillations. Detailed measurements were performed to characterize the frequency, amplitude, growth and damping time of these relaxation oscillations

  9. Crane RF accelerator for high current radiation damage studies

    International Nuclear Information System (INIS)

    Whitham, K.; Anamkath, H.; Evans, K.; Lyons, S.; Palmer, D.; Miller, R.; Treas, P.; Zante, T.

    1992-01-01

    An electron accelerator was designed and built for the Naval Weapons Support Center for transient radiation effects on electronics experiments and testing. The Crane L Band RF Electron Linac was designed to provide high currents over a wide range of pulse widths and energies. The energy extends to 60 MeV and pulse widths vary from a few ns to 10 μsec. Beam currents range from 20 amps in the short pulse case to 1.5 amps in the long pulse case. This paper describes the linac, its architecture, the e-gun and pulser, waveguides, klystrons and modulator, vacuum system, beam transport, and control systems. fig., tab

  10. A brief history of high power RF proton linear accelerators

    International Nuclear Information System (INIS)

    Browne, J.C.

    1996-01-01

    The first mention of linear acceleration was in a paper by G. Ising in 1924 in which he postulated the acceleration of positive ions induced by spark discharges which produced electric fields in gaps between a series of open-quotes drift tubesclose quotes. Ising apparently was not able to demonstrate his concept, most likely due to the limited state of electronic devices. Ising's work was followed by a seminal paper by R. Wideroe in 1928 in which he demonstrated the first linear accelerator. Wideroe was able to accelerate sodium or potassium ions to 50 keV of energy using drift tubes connected alternately to high frequency waves and to ground. Nuclear physics during this period was interested in accelerating protons, deuterons, electrons and alpha particles and not heavy ions like sodium or potassium. To accelerate the light ions required much higher frequencies than available at that time. So linear accelerators were not pursued heavily at that time. Research continued during the 1930s but the development of high frequency RF tubes for radar applications in World War 2 opened the potential for RF linear accelerators after the war. The Berkeley laboratory of E. 0. Lawrence under the leadership of Luis Alvarez developed a new linear proton accelerator concept that utilized drift tubes that required a full RF period to pass through as compared to the earlier concepts. This development resulted in the historic Berkeley 32 MeV proton linear accelerator which incorporated the open-quotes Alvarez drift tubeclose quotes as the basic acceleration scheme using surplus 200 MHz radar components

  11. State-Of High Brightness RF Photo-Injector Design

    Science.gov (United States)

    Ferrario, Massimo; Clendenin, Jym; Palmer, Dennis; Rosenzweig, James; Serafini, Luca

    2000-04-01

    The art of designing optimized high brightness electron RF Photo-Injectors has moved in the last decade from a cut and try procedure, guided by experimental experience and time consuming particle tracking simulations, up to a fast parameter space scanning, guided by recent analytical results and a fast running semi-analytical code, so to reach the optimum operating point which corresponds to maximum beam brightness. Scaling laws and the theory of invariant envelope provide to the designers excellent tools for a first parameters choice and the code HOMDYN, based on a multi-slice envelope description of the beam dynamics, is tailored to describe the space charge dominated dynamics of laminar beams in presence of time dependent space charge forces, giving rise to a very fast modeling capability for photo-injectors design. We report in this talk the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector. During this work a new effective working point for a split RF photoinjector has been discovered by means of the previous mentioned approach. By a proper choice of rf gun and solenoid parameters, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted at the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied.

  12. Spallation Neutron Source High Power RF Installation and Commissioning Progress

    CERN Document Server

    McCarthy, Michael P; Bradley, Joseph T; Fuja, Ray E; Gurd, Pamela; Hardek, Thomas; Kang, Yoon W; Rees, Daniel; Roybal, William; Young, Karen A

    2005-01-01

    The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by four 5.0 MW, 805 MHz klystrons. Eighty-one 550 kW, 805 MHz klystrons each drive a single cavity in the superconducting (SC) section of the linac. The high power radio frequency (HPRF) equipment was specified and procured by LANL and tested before delivery to ensure a smooth transition from installation to commissioning. Installation of RF equipment to support klystron operation in the 350-meter long klystron gallery started in June 2002. The final klystron was set in place in September 2004. Presently, all RF stations have been installed and high power testing has been completed. This paper reviews the progression of the installation and testing of the HPRF Sys...

  13. LCLS-II high power RF system overview and progress

    Energy Technology Data Exchange (ETDEWEB)

    Yeremian, Anahid Dian

    2015-10-07

    A second X-ray free electron laser facility, LCLS-II, will be constructed at SLAC. LCLS-II is based on a 1.3 GHz, 4 GeV, continuous-wave (CW) superconducting linear accelerator, to be installed in the first kilometer of the SLAC tunnel. Multiple types of high power RF (HPRF) sources will be used to power different systems on LCLS-II. The main 1.3 GHz linac will be powered by 280 1.3 GHz, 3.8 kW solid state amplifier (SSA) sources. The normal conducting buncher in the injector will use four more SSAs identical to the linac SSAs but run at 2 kW. Two 185.7 MHz, 60 kW sources will power the photocathode dual-feed RF gun. A third harmonic linac section, included for linearizing the bunch energy spread before the first bunch compressor, will require sixteen 3.9 GHz sources at about 1 kW CW. A description and an update on all the HPRF sources of LCLS-II and their implementation is the subject of this paper.

  14. Development of C-band High-Power Mix-Mode RF Window

    CERN Document Server

    Michizono, S; Matsumoto, T; Nakao, K; Takenaka, T

    2004-01-01

    High power c-band (5712 MHz) rf system (40 MW, 2 μs, 50 Hz) is under consideration for the electron-linac upgrade aimed for the super KEKB project. An rf window, which isolates the vacuum and pass the rf power, is one of the most important components for the rf system. The window consists of a ceramic disk and a pill-box housing. The mix-mode rf window is designed so as to decrease the electric field on the periphery of the ceramic disk. A resonant ring is assembled in order to examine the high-power transmission test. The window was tested up to the transmission power of 160 MW. The rf losses are also measured during the rf operation.

  15. Comprehensive high-accuracy modeling of electromagnetic effects in complete nanoscale RF blocks: CHAMELEON RF

    NARCIS (Netherlands)

    Niehof, J.; Janssen, H.H.J.M.; Schilders, W.H.A.

    2006-01-01

    Next-generation nano-scale RFIC designs have an unprecedented complexity and performance that will inevitably lead to costly re-spins and loss of market opportunities. In order to cope with this, the aim of the European Framework 6 CHAMELEON RF project is to develop methodologies and prototype tools

  16. Advanced high brightness ion rf accelerator applications in the nuclear energy

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1991-01-01

    The capability of modern rf linear accelerators to provide intense high quality beams of protons, deuterons, or heavier ions is opening new possibilities for transmuting existing nuclear wastes, for generating electricity from readily available fuels with minimal residual wastes, for building intense neutron sources for materials research, for inertial confinement fusion using heavy ions, and for other new applications. These are briefly described, couched in a perspective of the advances in the understanding of the high brightness beams that has enabled these new programs. 32 refs., 2 figs

  17. Electron diode oscillators for high-power RF generation

    International Nuclear Information System (INIS)

    Humphries, S.

    1989-01-01

    Feedback oscillators have been used since the invention of the vacuum tube. This paper describes the extension of these familiar circuits to the regime of relativistic electron beam diodes. Such devices have potential application for the generation of high power RF radiation in the range 50-250 MHz, 1-10 GW with 20-60% conversion efficiency. This paper reviews the theory of the oscillator and the results of a design study. Calculations for the four-electrode diode with EGUN and EBQ show that good modulations of 30 kA electron beam at 600 kV can be achieved with moderate field stress on the electrodes. Conditions for oscillation have been studied with an in-house transmission line code. A design for a 7.5 GW oscillator at 200 MHz with 25% conversion efficiency is presented

  18. Material Selection and Characterization for High Gradient RF Applications

    CERN Document Server

    Arnau-Izquierdo, G; Heikkinen, S; Ramsvik, T; Sgobba, Stefano; Taborelli, M; Wuensch, W

    2007-01-01

    The selection of candidate materials for the accelerating cavities of the Compact Linear Collider (CLIC) is carried out in parallel with high power RF testing. The maximum DC breakdown field of copper, copper alloys, refractory metals, aluminium and titanium have been measured with a dedicated setup. Higher maximum fields are obtained for refractory metals and for titanium, which exhibits, however, important damages after conditioning. Fatigue behaviour of copper alloys has been studied for surface and bulk by pulsed laser irradiation and ultrasonic excitation, respectively. The selected copper alloys show consistently higher fatigue resistance than copper in both experiments. In order to obtain the best local properties in the device a possible solution is a bi-metallic assembly. Junctions of molybdenum and copper-zirconium UNS C15000 alloy, achieved by HIP (Hot Isostatic Pressing) diffusion bonding or explosion bonding were evaluated for their mechanical strength. The reliability of the results obtained wit...

  19. RF-MEMS capacitive switches with high reliability

    Science.gov (United States)

    Goldsmith, Charles L.; Auciello, Orlando H.; Carlisle, John A.; Sampath, Suresh; Sumant, Anirudha V.; Carpick, Robert W.; Hwang, James; Mancini, Derrick C.; Gudeman, Chris

    2013-09-03

    A reliable long life RF-MEMS capacitive switch is provided with a dielectric layer comprising a "fast discharge diamond dielectric layer" and enabling rapid switch recovery, dielectric layer charging and discharging that is efficient and effective to enable RF-MEMS switch operation to greater than or equal to 100 billion cycles.

  20. Results of the SLAC LCLS Gun High-Power RF Tests

    International Nuclear Information System (INIS)

    Dowell, D.H.; Jongewaard, E.; Limborg-Deprey, C.; Schmerge, J.F.; Li, Z.; Xiao, L.; Wang, J.; Lewandowski, J.; Vlieks, A.

    2007-01-01

    The beam quality and operational requirements for the Linac Coherent Light Source (LCLS) currently being constructed at SLAC are exceptional, requiring the design of a new RF photocathode gun for the electron source. Based on operational experience at SLAC's GTF and SDL and ATF at BNL as well as other laboratories, the 1.6cell s-band (2856MHz) gun was chosen to be the best electron source for the LCLS, however a significant redesign was necessary to achieve the challenging parameters. Detailed 3-D analysis and design was used to produce near-perfect rotationally symmetric rf fields to achieve the emittance requirement. In addition, the thermo-mechanical design allows the gun to operate at 120Hz and a 140MV/m cathode field, or to an average power dissipation of 4kW. Both average and pulsed heating issues are addressed in the LCLS gun design. The first LCLS gun is now fabricated and has been operated with high-power RF. The results of these high-power tests are presented and discussed

  1. Measurement technology of RF interference current in high current system

    Science.gov (United States)

    Zhao, Zhihua; Li, Jianxuan; Zhang, Xiangming; Zhang, Lei

    2018-06-01

    Current probe is a detection method commonly used in electromagnetic compatibility. With the development of power electronics technology, the power level of power conversion devices is constantly increasing, and the power current of the electric energy conversion device in the electromagnetic launch system can reach 10kA. Current probe conventionally used in EMC (electromagnetic compatibility) detection cannot meet the test requirements on high current system due to the magnetic saturation problem. The conventional high current sensor is also not suitable for the RF (Radio Frequency) interference current measurement in high current power device due to the high noise level in the output of active amplifier. In this paper, a passive flexible current probe based on Rogowski coil and matching resistance is proposed that can withstand high current and has low noise level, to solve the measurement problems of interference current in high current power converter. And both differential mode and common mode current detection can be easily carried out with the proposed probe because of the probe's flexible structure.

  2. Development of low emittance high brightness electron beams and rf accelerating structures

    International Nuclear Information System (INIS)

    Pellegrini, C.

    1991-01-01

    The main goals of this project were the construction of an S-band RF photoinjector for the production of a high brightness electron beam, and the development of a new type of RF accelerator structure; the Plane wave transformer. By the end of October 1991 the photoinjector had been built, its RF characteristics had been measured at low power, and an initial test of the gun at high RF power had been done. The Plane Wave Transformer had also been built and tested at lower power. In both cases the results obtained are mostly in agreement with the expected and calculated behavior

  3. Investigating the effect of electron emission pattern on RF gun beam quality

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, A. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Shokri, B., E-mail: b-shokri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of)

    2016-05-11

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect. - Highlights: • We developed a 3D code to simulate the beam dynamics of thermionic RF gun. • Te impact of the emission pattern on the beam dynamic was investigated. • Different emission pattern results different emittance in the gun exit. • Using a nosecone around the cathode adjacent wall reduces back bombardment effect.

  4. Solid-state high voltage modulator and its application to rf source high voltage power supplies

    International Nuclear Information System (INIS)

    Tooker, J.F.; Huynh, P.; Street, R.W.

    2009-01-01

    A solid-state high voltage modulator is described in which series-connected insulated-gate bipolar transistors (IGBTs) are switched at a fixed frequency by a pulse width modulation (PWM) regulator, that adjusts the pulse width to control the voltage out of an inductor-capacitor filter network. General Atomics proposed the HV power supply (HVPS) topology of multiple IGBT modulators connected to a common HVdc source for the large number of 1 MW klystrons in the linear accelerator of the Accelerator Production of Tritium project. The switching of 24 IGBTs to obtain 20 kVdc at 20 A for short pulses was successfully demonstrated. This effort was incorporated into the design of a -70 kV, 80 A, IGBT modulator, and in a short-pulse test 12 IGBTs regulated -5 kV at 50 A under PWM control. These two tests confirm the practicality of solid-state IGBT modulators to regulate high voltage at reasonable currents. Tokamaks such as ITER require large rf heating and current drive systems with multiple rf sources. A HVPS topology is presented that readily adapts to the three rf heating systems on ITER. To take advantage of the known economy of scale for power conversion equipment, a single HVdc source feeds multiple rf sources. The large power conversion equipment, which is located outside, converts the incoming utility line voltage directly to the HVdc needed for the class of rf sources connected to it, to further reduce cost. The HVdc feeds a set of IGBT modulators, one for each rf source, to independently control the voltage applied to each source, maximizing operational flexibility. Only the modulators are indoors, close to the rf sources, minimizing the use of costly near-tokamak floor space.

  5. Avoiding vacuum arcs in high gradient normal conducting RF structures

    CERN Document Server

    Sjøbæk, Kyrre Ness; Adli, Erik; Grudiev, Alexej; Wuensch, Walter

    In order to build the Compact LInear Collider (CLIC), accelerating structures reaching extremely high accelerating gradients are needed. Such structures have been built and tested using normal-conducting copper, powered by X-band RF power and reaching gradients of 100 MV/m and above. One phenomenon that must be avoided in order to reliably reach such gradients, is vacuum arcs or “breakdowns”. This can be accomplished by carefully designing the structure geometry such that high surface fields and large local power flows are avoided. The research presented in this thesis presents a method for optimizing the geometry of accelerating structures so that these breakdowns are made less likely, allowing the structure to operate reliably at high gradients. This was done primarily based on a phenomenological scaling model, which predicted the maximum gradient as a function of the break down rate, pulse length, and field distribution in the structure. The model is written in such a way that it allows direct comparis...

  6. RF control at transient beamloading for high-duty-factor linacs

    Energy Technology Data Exchange (ETDEWEB)

    Chernogubovsky, M.A.; Sugimoto, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-08-01

    An effective RF control with the transient beamloading is the major issue in the operation of the high-duty-factor linacs to suppress the undesirable beam loss. The RF control method is considered to obtain the control principle and the state equation, under the analysis of electrodynamical properties of the excitation in the resonator of the linac due to the transient beamloading. The concept of the directional selective coupling is applied for the RF system to define the main characteristics and to optimize the RF control parameters. (author)

  7. High voltage power supplies for INDUS-2 RF system

    International Nuclear Information System (INIS)

    Badapanda, M.K.; Hannurkar, P.R.

    2003-01-01

    The RF system of Indus-2 employs klystron amplifiers operating at 505.812 MHz. A precession controlled high voltage DC supply of appropriate rating is needed for each klystron amplifier, as its bias supply. Since internal flashover and arcing are common with the operation of these klystrons and stored energies beyond particular limit inside its bias power supply is detrimental to this device, a properly designed crowbar is incorporated between each klystron and its power supply. This crowbar bypass these stored energies and helps protecting klystron under any of these unfavorable conditions. In either case, power supply sees a near short circuit across its load. So, its power circuit is designed to reduce the fault current level and its various components are also designed to withstand these fault currents, as and when it appears. Finally, operation of these high voltage power supplies (HVPS) generates lot of harmonics on the source side, which distort the input waveform substantially and reduces the input power factor also. Source multiplication between two power supplies are planned to improve upon above parameters and suitable detuned line filters are incorporated to keep the input voltage total harmonics distortion (THD) below 5 % and input power factor (IFF) near unity. (author)

  8. Summary of the 3rd workshop on high power RF-systems for accelerators

    International Nuclear Information System (INIS)

    Sigg, P.K.

    2005-01-01

    The aim of this workshop was to bring together experts from the field of CW and high average power RF systems. The focus was on operational and reliability issues of high-power amplifiers using klystrons and tubes, large power supplies; as well as cavity design and low-level RF and feedback control systems. All these devices are used in synchrotron radiation facilities, high power linacs and collider rings, and cyclotrons. Furthermore, new technologies and their applications were introduced, amongst other: high power solid state amplifiers, IOT amplifiers, and high voltage power supplies employing solid state controllers/crowbars. Numerical methods for complete rf-field modeling of complex RF structures like cyclotrons were presented, as well as integrated RF-cavity designs (electro-magnetic fields and mechanical structure), using numerical methods. (author)

  9. High temperature superconducting films by rf magnetron sputtering

    International Nuclear Information System (INIS)

    Kadin, A.M.; Ballentine, P.H.

    1989-01-01

    The authors have produced sputtered films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O by rf magnetron sputtering from an oxide target consisting of loose reacted powder. The use of a large 8-inch stoichiometric target in the magnetron mode permits films located above the central region to be free of negative-ion resputtering effects, and hence yields reproducible, uniform stoichiometric compositions for a wide range of substrate temperatures. Superconducting YBCO films have been obtained either by sputtering at low temperatures followed by an 850 0 C oxygen anneal, or alternatively by depositing onto substrates heated to ∼600 - 650 0 C and cooling in oxygen. Films prepared by the former method on cubic zirconia substrate consist of randomly oriented crystallites with zero resistance above 83 K. Those deposited on zirconia at medium temperatures without the high-temperature anneal contain smooth partially oriented crystallites, with a slightly depressed T/sub c/ ∼75K. Finally, superconducting films have been deposited on MgO using a BiSrCaCu/sub 2/O/sub x/ powder target

  10. Printable Materials for the Realization of High Performance RF Components: Challenges and Opportunities

    Directory of Open Access Journals (Sweden)

    Eva S. Rosker

    2018-01-01

    Full Text Available Printing methods such as additive manufacturing (AM and direct writing (DW for radio frequency (RF components including antennas, filters, transmission lines, and interconnects have recently garnered much attention due to the ease of use, efficiency, and low-cost benefits of the AM/DW tools readily available. The quality and performance of these printed components often do not align with their simulated counterparts due to losses associated with the base materials, surface roughness, and print resolution. These drawbacks preclude the community from realizing printed low loss RF components comparable to those fabricated with traditional subtractive manufacturing techniques. This review discusses the challenges facing low loss RF components, which has mostly been material limited by the robustness of the metal and the availability of AM-compatible dielectrics. We summarize the effective printing methods, review ink formulation, and the postprint processing steps necessary for targeted RF properties. We then detail the structure-property relationships critical to obtaining enhanced conductivities necessary for printed RF passive components. Finally, we give examples of demonstrations for various types of printed RF components and provide an outlook on future areas of research that will require multidisciplinary teams from chemists to RF system designers to fully realize the potential for printed RF components.

  11. Development of an S-band high-power pillbox-type RF window

    International Nuclear Information System (INIS)

    Miura, A.; Matsumoto, H.

    1992-01-01

    We report on the development of RF windows used to handle a high transmission power up to 110 MW for the Japan Linear Collider. A detailed simulation on multipactoring has been carried out. The results were compared with cathode-luminescence on the surface of alumina RF windows experimentally observed with power transmission up to 200 MW. (Author) 10 refs., 9 figs

  12. RF capacitance-voltage characterization of MOSFETs with high-leakage dielectric

    NARCIS (Netherlands)

    Schmitz, Jurriaan; Cubaynes, F.N; Cubaynes, F.N.; Havens, R.J.; de Kort, R.; Scholten, A.J.; Tiemeijer, L.F.

    2003-01-01

    We present a MOS Capacitance-Voltage measurement methodology that, contrary to present methods, is highly robust against gate leakage current densities up to 1000 A/cm/sup 2/. The methodology features specially designed RF test structures and RF measurement frequencies. It allows MOS parameter

  13. High-powered, solid-state rf systems

    International Nuclear Information System (INIS)

    Reid, D.W.

    1987-01-01

    Over the past two years, the requirement to supply megawatts of rf power for space-based applications at uhf and L-band frequencies has caused dramatic increases in silicon solid-state power capabilities in the frequency range from 10 to 3000 MHz. Radar and communications requirements have caused similar increases in gallium arsenide solid-state power capabilities in the frequency ranges from 3000 to 10,000 MHz. This paper reviews the present state of the art for solid-state rf amplifiers for frequencies from 10 to 10,000 MHz. Information regarding power levels, size, weight, and cost will be given. Technical specifications regarding phase and amplitude stability, efficiency, and system architecture will be discussed. Solid-stage rf amplifier susceptibility to radiation damage will also be examined

  14. Effect of RF Parameters on Breakdown Limits in High-Vacuum X-Band Structures

    International Nuclear Information System (INIS)

    Dolgashev, Valery A.

    2003-01-01

    RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this paper we discuss multi-megawatt operation of X-band rf structures at pulse width on the order of one microsecond. These structures are used in rf systems of high gradient accelerators. Recent experiments at Stanford Linear Accelerator Center (SLAC) have explored the functional dependence of breakdown limit on input power and pulse width. The experimental data covered accelerating structures and waveguides. Another breakdown limit of accelerating structures was associated with high magnetic fields found in waveguide-to-structure couplers. To understand and quantify these limits we simulated 3D structures with the electrodynamics code Ansoft HFSS and the Particle-In-Cell code MAGIC3D. Results of these simulations together with experimental data will be discussed in this paper

  15. Toward High-Power Klystrons With RF Power Conversion Efficiency on the Order of 90%

    CERN Document Server

    Baikov, Andrey Yu; Syratchev, Igor

    2015-01-01

    The increase in efficiency of RF power generation for future large accelerators is considered a high priority issue. The vast majority of the existing commercial high-power RF klystrons operates in the electronic efficiency range between 40% and 55%. Only a few klystrons available on the market are capable of operating with 65% efficiency or above. In this paper, a new method to achieve 90% RF power conversion efficiency in a klystron amplifier is presented. The essential part of this method is a new bunching technique - bunching with bunch core oscillations. Computer simulations confirm that the RF production efficiency above 90% can be reached with this new bunching method. The results of a preliminary study of an L-band, 20-MW peak RF power multibeam klystron for Compact Linear Collider with the efficiency above 85% are presented.

  16. Evidence for preferential flux flow at the grain boundaries of superconducting RF-quality niobium

    Science.gov (United States)

    Sung, Z.-H.; Lee, P. J.; Gurevich, A.; Larbalestier, D. C.

    2018-04-01

    The question of whether grain boundaries (GBs) in niobium can be responsible for lowered operating field (B RF) or quality factor (Q 0) in superconducting radio frequency (SRF) cavities is still controversial. Here, we show by direct DC transport across planar GBs isolated from a slice of very large-grain SRF-quality Nb that vortices can preferentially flow along the grain boundary when the external magnetic field lies in the GB plane. However, increasing the misalignment between the GB plane and the external magnetic field vector markedly reduces preferential flux flow along the GB. Importantly, we find that preferential GB flux flow is more prominent for a buffered chemical polished than for an electropolished bi-crystal. The voltage-current characteristics of GBs are similar to those seen in low angle grain boundaries of high temperature superconductors where there is clear evidence of suppression of the superconducting order parameter at the GB. While local weakening of superconductivity at GBs in cuprates and pnictides is intrinsic, deterioration of current transparency of GBs in Nb appears to be extrinsic, since the polishing method clearly affect the local GB degradation. The dependence of preferential GB flux flow on important cavity preparation and experimental variables, particularly the final chemical treatment and the angle between the magnetic field and the GB plane, suggests two more reasons why real cavity performance can be so variable.

  17. A high-gradient high-duty-factor Rf photo-cathode electron gun

    International Nuclear Information System (INIS)

    Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

    2002-01-01

    We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

  18. A high-gradient high-duty-factor RF photo-cathode electron gun

    International Nuclear Information System (INIS)

    Rimmer, Robert; Hartman, N.; Lidia, S.; Wang, S.H.

    2002-01-01

    We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure

  19. Analytic analysis on asymmetrical micro arcing in high plasma potential RF plasma systems

    International Nuclear Information System (INIS)

    Yin, Y; McKenzie, D R; Bilek, M M M

    2006-01-01

    We report experimental and analytical results on asymmetrical micro arcing in a RF (radio frequency) plasma. Micro arcing, resulting from high plasma potential, in RF plasma was found to occur only on the grounded electrode for a variety of electrode and surface configurations. The analytic derivation was based on a simple RF time-dependent Child-Langmuir sheath model and electric current continuity. We found that the minimum potential difference in one RF period across the grounded electrode sheath depends on the area ratio of the grounded electrode to the powered electrode. As the area ratio increases, the minimum potential difference across a sheath increases for the grounded electrode but not for the RF powered electrode. We showed that discharge time in micro arcing is more than 100 RF periods; thus the presence of a continuous high electric field in one RF cycle results in micro arcing on the grounded electrode. However, the minimum potential difference in one RF period across the powered electrode sheath is always small so that it prevents micro arcing occurring even though the average sheath voltage can be large. This simple analytic model is consistent with particle-in-cell simulation results

  20. Time-resolved measurements of highly-polymerised negative ions in rf silane plasma deposition experiments

    International Nuclear Information System (INIS)

    Howling, A.A.; Sansonnens, L.; Dorier, J.L.; Hollenstein, C.

    1993-07-01

    The time-resolved fluxes of negative polysilicon hydride ions from a power-modulated rf silane plasma have been measured by quadrupole mass spectrometry and modeled using a simple polymerisation scheme. Experiments were performed with plasma parameters suitable for high-quality amorphous silicon deposition. Polysilicon hydride anions diffuse from the plasma with low energy (approximately 0.5 eV) during the afterglow after the electron density has decayed and the sheath fields have collapsed. The mass-dependence of the temporal behavior of the anion loss flux demonstrates that the plasma composition is influenced by the modulation frequency. The negative species attain much higher masses than the positive or neutral species, and anions containing as many as sixteen silicon atoms have been observed, corresponding to the 500 amu limit of the mass spectrometer. This suggests that negative ions could be the precursors to particle formation. Ion-molecule and ion-ion reactions are discussed and a simple negative ion polymerisation scheme is proposed which qualitatively reproduces the experimental results. The model shows that the densities of high mass negative ions in the plasma are strongly reduced by modulation frequencies near 1 kHz. Each plasma period is then too short for the polymerisation chain to propagate to high masses before the elementary anions are lost in each subsequent afterglow period. This explains why modulation of the rf power can reduce particle contamination. We conclude that, for the case of silane rf plasmas, the initiation steps which ultimately lead to particle contamination proceed by negative ion polymerisation. (author) 15 figs., 72 refs

  1. A conceptual design of the RF system for the NSP high intensity proton accelerator at JAERI

    International Nuclear Information System (INIS)

    Chishiro, Etsuji; Kusano, Joichi; Mizumoto, Motoharu; Touchi, Yutaka; Kaneko, Hiroshi; Takado, Hiroshi; Sawada, Junichi

    1999-03-01

    JAERI has been proposing the Neutron Science Project which aims at exploring the fields of basic science and nuclear technology using a high power spallation neutron source. The neutron source will be driven by a high intensity linear accelerator with an energy of 1.5 GeV and an average beam current of 5.33 mA and beam power of 8 MW. The RF system for the accelerator consists of a high-energy accelerator part and a low energy accelerator part. The maximum RF power requirements at the high and low energy accelerator parts are 25 MW and 8.3 MW, respectively. In this report, we describe the conceptual design of the RF system. In the low energy accelerator part, we estimated the requirement for the high-power amplifier tube and made the basis design for RF components. In the high energy accelerator part, we studied the effect of tuning errors, Lorentz forces and microphonics in the superconducting cavity. We calculated the klystron efficiency and supply power in the arrangement of where one klystron distributes the RF power to four cavities. We also considered an IOT RF system. Finally, we describe the electrical capacity and quantity of cooling water in the RF system. (author)

  2. Improving superconducting RF technology for high energy particle accelerators

    International Nuclear Information System (INIS)

    Leconte, P.

    1991-01-01

    A review of the state of the art is given. It shows recent proofs of success of the technology. An important R and D effort remains to be done in order to collect all the expectable benefits of RF superconductivity. (author)

  3. Development of a high-power RF cavity for the PEP-II B factory

    International Nuclear Information System (INIS)

    Rimmer, R.A.; Allen, M.A.; Saba, J.; Schwarz, H.

    1995-03-01

    The authors describe the development and fabrication of the first high-power RF cavity for PEP-II. Design choices and fabrication technologies for the first cavity and subsequent production cavities are described. Conditioning and high-power testing of the first and subsequent cavities are discussed, as well as integration of the cavity into modular RF systems for both high-energy and low-energy rings. Plans for installation of the cavity raft assemblies in the RF sections of the PEP tunnel are also considered

  4. High-Q operation of superconducting rf cavities: Potential impact of thermocurrents on the rf surface resistance

    Directory of Open Access Journals (Sweden)

    J.-M. Vogt

    2015-04-01

    Full Text Available For many new accelerator applications, superconducting radio frequency systems are the enabling technology. In particular for CW applications, much effort is being expended to minimize the power dissipation (surface resistance of niobium cavities. Starting in 2009, we suggested a means of reducing the residual resistance by performing a thermal cycle [O. Kugeler et al., in Proceedings of the 14th International Conference on RF Superconductivity (2009, p. 352], a procedure of warming up a cavity after initial cooldown to about 20 K and cooling it down again. In subsequent studies [J. M. Vogt, O. Kugeler, and J. Knobloch, Phys. Rev. ST Accel. Beams 16, 102002 (2013], this technique was used to manipulate the residual resistance by more than a factor of 2. It was postulated that thermocurrents during cooldown generate additional trapped magnetic flux that impacts the cavity quality factor. Here, we present a more extensive study that includes measurements of two additional passband modes and that confirms the effect. In this paper, we also discuss simulations that support the claim. While the layout of the cavity LHe tank system is cylindrically symmetric, we show that the temperature dependence of the material parameters results in a nonsymmetric current distribution. Hence a significant amount of magnetic flux can be generated at the rf surface.

  5. RF transport

    International Nuclear Information System (INIS)

    Choroba, Stefan

    2013-01-01

    This paper deals with the techniques of transport of high-power radiofrequency (RF) power from a RF power source to the cavities of an accelerator. Since the theory of electromagnetic waves in waveguides and of waveguide components is very well explained in a number of excellent text books it will limit itself on special waveguide distributions and on a number of, although not complete list of, special problems which sometimes occur in RF power transportation systems. (author)

  6. Study of luminous spots observed on metallic surfaces subjected to high RF fields

    International Nuclear Information System (INIS)

    Junquera, T.; Maissa, S.; Fouaidy, M.; Le Goff, A.; Bonin, B.; Luong, M.; Safa, H.; Tan, J.

    1995-01-01

    The performance of high gradient superconducting RF cavities for electron accelerators is mainly limited by field emission. Major improvements have been recently obtained using different surface conditioning techniques confirming the involvement of metallic particles in field emission enhancement. Results obtained with an optical apparatus attached to an RF copper cavity equipped with a removable sample which is subjected to high RF fields are presented. Stable light spots are observed on the sample surface and their intensities and optical spectra are measured as a function of the surface electric field. The total emitted current is simultaneously measured by an isolated hollow electrode facing the sample. (K.A.)

  7. High-power RF cavity R ampersand D for the PEP-II B Factory

    International Nuclear Information System (INIS)

    Rimmer, R.; Lambertson, G.; Hodgson, J.

    1994-06-01

    We describe the development of a high-power test model of the 476 MHz RF cavity for the PEP-II B Factory. This cavity is designed to demonstrate the feasibility of a high-power design with higher-order mode (HOM) damping waveguides and the fabrication technologies involved, and it can also be used to evaluate aperture or loop couplers and various RF windows. Changes to the RF design to reduce peak surface heating are discussed and results of finite-element analyses of temperature and stress are presented. Fabrication methods for the prototype and subsequent production cavities are discussed

  8. Operating experience with high beta superconducting RF cavities

    International Nuclear Information System (INIS)

    Dylla, H.F.; Doolittle, L.R.; Benesch, J.F.

    1993-01-01

    The number of installed and operational β=1 superconducting rf cavities has grown significantly over the last two years in accelerator laboratories in Europe, Japan and the U.S. The total installed acceleration capability as of mid-1993 is approximately 1 GeV at nominal gradients. Major installations at CERN, DESY, KEK and CEBAF have provided large increments to the installed base and valuable operational experience. A selection of test data and operational experience gathered to date is reviewed

  9. Operating experience with high beta superconducting rf cavities

    International Nuclear Information System (INIS)

    Dylla, H.F.; Doolittle, L.R.; Benesch, J.F.

    1993-06-01

    The number of installed and operational β = 1 superconducting rf cavities has grown significantly over the last two years in accelerator laboratories in Europe, Japan and the US. The total installed acceleration capability as of mid-1993 is approximately 1 GeV at nominal gradients. Major installations at CERN, DESY, KEK and CEBAF have provided large increments to the installed base and valuable operational experience. A selection of test data and operational experience gathered to date is reviewed

  10. A high temperature superconductor tape RF receiver coil for a low field magnetic resonance imaging system

    International Nuclear Information System (INIS)

    Cheng, M C; Yan, B P; Lee, K H; Ma, Q Y; Yang, E S

    2005-01-01

    High temperature superconductor (HTS) thin films have been applied in making a low loss RF receiver coil for improving magnetic resonance imaging image quality. However, the application of these coils is severely limited by their limited field of view (FOV). Stringent fabrication environment requirements and high cost are further limitations. In this paper, we propose a simpler method for designing and fabricating HTS coils. Using industrial silver alloy sheathed Bi (2-x) Pb x Sr 2 Ca 2 Cu 3 O 10 (Bi-2223) HTS tapes, a five-inch single-turn HTS solenoid coil has been developed, and human wrist images have been acquired with this coil. The HTS tape coil has demonstrated an enhanced FOV over a six-inch YBCO thin film surface coil at 77 K with comparable signal-to-noise ratio

  11. Effect on antenna structure of high power rf during plasma operation

    International Nuclear Information System (INIS)

    Haste, G.R.; Thomas, C.E.; Fadnek, A.; Carter, M.D.; Beaumont, B.; Becoulet, A.; Kuus, H.; Saoutic, B.

    1993-01-01

    High-power, long-pulse operation on the Tore Supra tokamak results in considerable stress on the plasma-facing components. The ICH antennas must deliver high-power rf(up to 4 MW per antenna) in this environment. The antenna structure is therefore subjected to the power flux resulting from the interaction between rf and the edge plasma. The structure's response during operation is described, as is the condition of the antenna after prolonged use

  12. Study of luminous phenomena observed on contaminated metallic surfaces submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Bonin, B.; Luong, M.; Safa, H.; Tan, J.

    1995-01-01

    The RF field emission from a sample subjected to high RF fields in a copper cavity has been investigated. The study is focused on the luminous emissions occurring on the RF surface simultaneously with the electron emission. The optical apparatus attached to the cavity permits to observe the evolution of the emitters and the direct effects of the surface conditioning. Also, the parameters of the emitted radiation (intensity, glowing duration, spectral distribution) may provide additional informations on the field emission phenomena. Some results concerning samples intentionally contaminated with particles (metallic or dielectric) are presented. (K.A.)

  13. Outgassing studies of lower hybrid antenna module during CW high RF power injection

    International Nuclear Information System (INIS)

    Goniche, M.; Brossaud, J.; Berger-By, G.; Bibet, Ph.; Poli, S.; Rey, G.; Tonon, G.; Seki, M.; Obara, K.; Maebara, S.; Ikeda, Y.; Imai, T.; Nagashima, T.

    1994-01-01

    Outgassing, induced by very long RF waves injection (up to 6000s) at high power density, is studied with a module, able to be used for a lower hybrid frequency antenna. A large outgassing data base is provided by 75 shots cumulating 27 hours of RF injection. Outgassing rate is documented after different thermal pre-treatments, and in various conditions of cooling, RF power level. Relevant parameters are identified and values of outgassing rates are given in order to design pumping system for a large antenna. (author) 4 refs.; 7 figs.; 1 tab

  14. High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

    Directory of Open Access Journals (Sweden)

    J.-M. Wu

    2012-06-01

    Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

  15. Performance test of lower hybrid waveguide under long/high-RF power transmission

    International Nuclear Information System (INIS)

    Seki, Masami; Obara, Kenjiro; Maebara, Sunao

    1996-06-01

    Performance tests of a module for lower hybrid waveguides were carried out at the CEA Cadarache RF Test Facility. For the experiments the test module was fabricated by JAERI, the transmission line of the test bed was modified and the connection waveguides were manufactured by CEA. As the results, the thermal treatment by baking at a higher temperature was the most effective for reducing outgassing during injection of high RF power. The outgassing strongly depended on the temperature of the test module, but was independent to initial temperature. The RF injection reduced outgassing. The outgassing rate decreased to a low level of 10 -6 -10 -5 Pa m 3 /sec m 2 (10 -9 -10 -8 Torr 1/sec cm 2 ) at 400degC after 450degC-baking. The gas injection did not affect outgassing before and during RF injection. The baking under H 2 or D 2 gas atmosphere were not so effective for reducing outgassing rate. The outgassing rate did not depend on input RF power densities. The temperature in central part of the test module saturated to be ∼100degC by using of water cooling at a power level of 150 MW/m 2 RF injection, and a neutral gas pressure decreased gradually. In the water cooling case, the outgassing rate was very low less than 10 -7 Pa m 3 /sec m 2 (10 -10 Torr 1/sec cm 2 ). The steady state RF injection was demonstrated with water cooling. (author)

  16. Study of Electron Swarm in High Pressure Hydrogen Gas Filled RF Cavities

    International Nuclear Information System (INIS)

    Yonehara, K.; Chung, M.; Jansson, A.; Moretti, A.; Popovic, M.; Tollestrup, A.; Alsharo'a, M.; Johnson, R.P.; Notani, M.; Oka, T.; Wang, H.

    2010-01-01

    A high pressure hydrogen gas filled RF cavity has been proposed for use in the muon collection system for a muon collider. It allows for high electric field gradients in RF cavities located in strong magnetic fields, a condition frequently encountered in a muon cooling channel. In addition, an intense muon beam will generate an electron swarm via the ionization process in the cavity. A large amount of RF power will be consumed into the swarm. We show the results from our studies of the HV RF breakdown in a cavity without a beam and present some results on the resulting electron swarm dynamics. This is preliminary to actual beam tests which will take place late in 2010.

  17. Very long pulse high-RF power test of a lower hybrid frequency antenna module

    Energy Technology Data Exchange (ETDEWEB)

    Goniche, M; Brossaud, J; Barral, C; Berger-By, G; Bibet, Ph; Poli, S; Rey, G; Tonon, G [Association Euratom-CEA, Centre d` Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Seki, M; Obara, K [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; and others

    1994-03-01

    Outgassing, induced by very long RF waves injection at high power density was studied in a module, able to be used for a lower hybrid frequency antenna. Good RF properties of the module are reported, however, resonance phenomena with strong absorption of RF power (15%) was observed at high temperature (T>400 deg C). A large outgassing data base is provided by the 75 shots cumulating 27 hours of RF injection. The comparison with previous experiments (Tore Supra and TdV prototype modules) confirm the effect of baking and results are consistent. Outgassing increases exponentially with -1/T, and a desorption model with an activation energy Ed {approx} 0.35 eV fits the data up to 400 deg C. In order to design vacuum pumping system for large lower hybrid frequency antenna, outgassing rates are given for different working temperatures. (author). 11 refs., 55 figs.

  18. Very long pulse high-RF power test of a lower hybrid frequency antenna module

    International Nuclear Information System (INIS)

    Goniche, M.; Brossaud, J.; Barral, C.; Berger-By, G.; Bibet, Ph.; Poli, S.; Rey, G.; Tonon, G.; Seki, M.; Obara, K.

    1994-03-01

    Outgassing, induced by very long RF waves injection at high power density was studied in a module, able to be used for a lower hybrid frequency antenna. Good RF properties of the module are reported, however, resonance phenomena with strong absorption of RF power (15%) was observed at high temperature (T>400 deg C). A large outgassing data base is provided by the 75 shots cumulating 27 hours of RF injection. The comparison with previous experiments (Tore Supra and TdV prototype modules) confirm the effect of baking and results are consistent. Outgassing increases exponentially with -1/T, and a desorption model with an activation energy Ed ∼ 0.35 eV fits the data up to 400 deg C. In order to design vacuum pumping system for large lower hybrid frequency antenna, outgassing rates are given for different working temperatures. (author). 11 refs., 55 figs

  19. High-power RF controls for the NBS-Los Alamos racetrack microtron

    International Nuclear Information System (INIS)

    Young, L.M.; Biddl, R.S.

    1985-01-01

    The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kw cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference

  20. Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

    International Nuclear Information System (INIS)

    Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L; Joshi, L M; Nangru, S C

    2010-01-01

    A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

  1. Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Joshi, L M; Nangru, S C, E-mail: pramod@ipr.res.i [Central Electronics Engineering Research Institute, Pilani, Rajasthan 333 031 (India)

    2010-02-01

    A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

  2. Overview on thermal and mechanical challenges of high power RF electronic packaging

    NARCIS (Netherlands)

    Yuan, C.A.; Kregting, R.; Driel, W. van; Gielen, A.W.J.; Xiao, A.; Zhang, G.Q.

    2011-01-01

    High Power RF electronics is one of the essential parts for wireless communication, including the personal communication, broadcasting, microwave radar, etc. Moreover, high efficient high power electronics has entered the ISM market, such as the power generator of microwave oven. Power electronics

  3. A high-power rf linear accelerator for FELS [free-electron lasers

    International Nuclear Information System (INIS)

    Sheffield, R.L.; Watson, J.M.

    1987-01-01

    This paper describes the design of a high average current rf linear accelerator suitable for driving short-wavelength free-electron lasers (FEL). It is concluded that the design of a room-temperature rf linear acelerator that can meet the stringent requirements of a high-power short-wavelength FEL appears possible. The accelerator requires the use of an advanced photoelectric injector that is under development; the accelerator components, however, do not require appreciable development. At these large beam currents, low-frequency, large-bore room-temperature cavities can be highly efficient and give all specified performance with minimal risk. 20 refs

  4. The Grumman/Brookhaven high-brightness, high-duty factor RF gun

    International Nuclear Information System (INIS)

    Lehrman, I.S.; Birnbaum, I.A.; Cole, M.; Fixler, S.Z.; Heuer, R.L.; Siddiqi, S.; Sheedy, E.; Waren, G.D.

    1992-01-01

    Under a joint collaboration between Brookhaven National Laboratory and the Grumman Corporation, a high-duty (>1%) photocathode RF gun is under construction for use at the ATF facility at BNL. The gun will be capable of producing short ( 300 A (after compression) and a total bunch charge in excess of 3 nC. The gun consists of 3-1/2 cells constructed from GlidCop, an alumina dispersion strengthened copper alloy. Two individually phased waveguides are used to power the first two and final two cells. (Author) 10 refs., 8 figs., 2 tabs

  5. High power tests of X-band RF windows at KEK

    Energy Technology Data Exchange (ETDEWEB)

    Otake, Yuji [Earthquake Research Inst., Tokyo Univ., Tokyo (Japan); Tokumoto, Shuichi; Kazakov, Sergei Yu.; Odagiri, Junichi; Mizuno, Hajime

    1997-04-01

    Various RF windows comprising a short pill-box, a long pill-box, a TW (traveling wave)-mode and three TE11-mode horn types have been developed for an X-band high-power pulse klystron with two output windows for JLC (Japan Linear Collider). The output RF power of the klystron is designed to be 130 MW with the 800 ns pulse duration. Since this X-band klystron has two output windows, the maximum RF power of the window must be over 85 MW. The design principle for the windows is to reduce the RF-power density and/or the electric-field strength at the ceramic part compared with that of an ordinary pill-box-type window. Their reduction is effective to increase the handling RF power of the window. To confirm that the difference among the electric-field strengths depends on their RF structures, High-power tests of the above-mentioned windows were successfully carried out using a traveling-wave resonator (TWR) for the horns and the TW-mode type and, installing them directly to klystron output waveguides for the short and long pill-box type. Based upon the operation experience of S-band windows, two kinds of ceramic materials were used for these tests. The TE11-mode 1/2{lambda}g-1 window was tested up to the RF peak-power of 84 MW with the 700 ns pulse duration in the TWR. (J.P.N)

  6. EXCESS RF POWER REQUIRED FOR RF CONTROL OF THE SPALLATION NEUTRON SOURCE (SNS) LINAC, A PULSED HIGH-INTENSITY SUPERCONDUCTING PROTON ACCELERATOR

    International Nuclear Information System (INIS)

    Lynch, M.; Kwon, S.

    2001-01-01

    A high-intensity proton linac, such as that being planned for the SNS, requires accurate RF control of cavity fields for the entire pulse in order to avoid beam spill. The current design requirement for the SNS is RF field stability within ±0.5% and ±0.5 o [1]. This RF control capability is achieved by the control electronics using the excess RF power to correct disturbances. To minimize the initial capital costs, the RF system is designed with 'just enough' RF power. All the usual disturbances exist, such as beam noise, klystron/HVPS noise, coupler imperfections, transport losses, turn-on and turn-off transients, etc. As a superconducting linac, there are added disturbances of large magnitude, including Lorentz detuning and microphonics. The effects of these disturbances and the power required to correct them are estimated, and the result shows that the highest power systems in the SNS have just enough margin, with little or no excess margin

  7. Feasibility Study for High Power RF – Energy Recovery in Particle Accelerators

    CERN Document Server

    Betz, Michael

    2010-01-01

    When dealing with particle accelerators, especially in systems with travelling wave structures and low beam loading, a substantial amount of RF power is dissipated in 50Ω termination loads. For the Super Proton Synchrotron (SPS) at Cern this is 69 % of the incident RF power or about 1 MW. Different ideas, making use of that otherwise dissipated power, are presented and their feasibility is reviewed. The most feasible one, utilizing an array of semiconductor based RF/DC modules, is used to create a design concept for energy recovery in the SPS. The modules are required to operate at high power, high efficiency and with low harmonic radiation. Besides the actual RF rectifier, they contain additional components to ensure a graceful degradation of the overall system. Different rectifier architectures and semiconductor devices are compared and the most suitable ones are chosen. Two prototype devices were built and operated with up to 400 W of pulsed RF power. Broadband measurements – capturing all harmonics up ...

  8. Performance test of lower hybrid waveguide under long/high-RF power transmission

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Masami; Obara, Kenjiro; Maebara, Sunao [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; and others

    1996-06-01

    Performance tests of a module for lower hybrid waveguides were carried out at the CEA Cadarache RF Test Facility. For the experiments the test module was fabricated by JAERI, the transmission line of the test bed was modified and the connection waveguides were manufactured by CEA. As the results, the thermal treatment by baking at a higher temperature was the most effective for reducing outgassing during injection of high RF power. The outgassing strongly depended on the temperature of the test module, but was independent to initial temperature. The RF injection reduced outgassing. The outgassing rate decreased to a low level of 10{sup -6}-10{sup -5} Pa m{sup 3}/sec m{sup 2} (10{sup -9}-10{sup -8} Torr 1/sec cm{sup 2}) at 400degC after 450degC-baking. The gas injection did not affect outgassing before and during RF injection. The baking under H{sub 2} or D{sub 2} gas atmosphere were not so effective for reducing outgassing rate. The outgassing rate did not depend on input RF power densities. The temperature in central part of the test module saturated to be {approx}100degC by using of water cooling at a power level of 150 MW/m{sup 2} RF injection, and a neutral gas pressure decreased gradually. In the water cooling case, the outgassing rate was very low less than 10{sup -7} Pa m{sup 3}/sec m{sup 2} (10{sup -10} Torr 1/sec cm{sup 2}). The steady state RF injection was demonstrated with water cooling. (author).

  9. Rf system modeling for the high average power FEL at CEBAF

    International Nuclear Information System (INIS)

    Merminga, L.; Fugitt, J.; Neil, G.; Simrock, S.

    1995-01-01

    High beam loading and energy recovery compounded by use of superconducting cavities, which requires tight control of microphonic noise, place stringent constraints on the linac rf system design of the proposed high average power FEL at CEBAF. Longitudinal dynamics imposes off-crest operation, which in turn implies a large tuning angle to minimize power requirements. Amplitude and phase stability requirements are consistent with demonstrated performance at CEBAF. A numerical model of the CEBAF rf control system is presented and the response of the system is examined under large parameter variations, microphonic noise, and beam current fluctuations. Studies of the transient behavior lead to a plausible startup and recovery scenario

  10. Development and simulation of RF components for high power millimeter wave gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Pereyaslavets, M.; Sato, M.; Shimozuma, T.; Takita, Y.; Idei, H.; Kubo, S.; Ohkubo, K.; Hayashi, K.

    1996-11-01

    To test gyrotron RF components, efficient low-power generators for rotating high-order modes of high purity are necessary. Designs of generators for the TE{sub 15,3} mode at 84 GHz and for the TE{sub 31,8} mode at 168 GHz are presented and some preliminary test results are discussed. In addition, Toshiba gyrotron cavities at 168 GHz were analyzed for leakage of RF power in the beam tunnel. To decrease RF power leakage, the declination angle of the cut-off cavity cross section has to be decreased. A TE{sub 15,3} waveguide nonlinear uptaper is analyzed at 84 GHz as well as 168 GHz uptapers. Since the calculated conversion losses are slightly higher than designed value, an optimization of those uptapers may be required. (author)

  11. ADX: a high field, high power density, advanced divertor and RF tokamak

    Science.gov (United States)

    LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

    2015-05-01

    The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept

  12. Aspects of operation of the Fermilab Booster RF System at very high intensity

    International Nuclear Information System (INIS)

    Griffin, J.E.

    1996-04-01

    The purpose of this note is to examine the likelihood and problems associated with operation of the Fermilab Booster rf systems as it presently exists, or with only minor modifications, at beam intensity approaching 5x10 13 protons per pulse. Beam loading of the rf system at such an intensity will be one order of magnitude larger than at the present operation level. It is assumed that the injection energy will be raised to 1 GeV with no major increase in the injected energy spread (longitudinal emittance). The beam will be bunched by adiabatic capture as is presently done although it may be necessary to remove one or two bunches prior to acceleration to allow clean extraction at 8 GeV. At very high intensity the charge in each bunch will interact with the vacuum chamber impedance (and with itself) in such a way as to reduce in some cases the bucket area generated by the rf voltage. Because this decrement must be made up by changes in the rf ring voltage if the required bucket area is to be maintained, these effects must be taken into consideration in any analysis of the capability of the rf system to accelerate very large intensity

  13. Research on DC-RF superconducting photocathode injector for high average power FELs

    International Nuclear Information System (INIS)

    Zhao Kui; Hao Jiankui; Hu Yanle; Zhang Baocheng; Quan Shengwen; Chen Jiaer; Zhuang Jiejia

    2001-01-01

    To obtain high average current electron beams for a high average power Free Electron Laser (FEL), a DC-RF superconducting injector is designed. It consists of a DC extraction gap, a 1+((1)/(2)) superconducting cavity and a coaxial input system. The DC gap, which takes the form of a Pierce configuration, is connected to the 1+((1)/(2)) superconducting cavity. The photocathode is attached to the negative electrode of the DC gap. The anode forms the bottom of the ((1)/(2)) cavity. Simulations are made to model the beam dynamics of the electron beams extracted by the DC gap and accelerated by the superconducting cavity. High quality electron beams with emittance lower than 3 π-mm-mrad can be obtained. The optimization of experiments with the DC gap, as well as the design of experiments with the coaxial coupler have all been completed. An optimized 1+((1)/(2)) superconducting cavity is in the process of being studied and manufactured

  14. High-power, solid-state rf source for accelerator cavities

    International Nuclear Information System (INIS)

    Vaughan, D.R.; Mols, G.E.; Reid, D.W.; Potter, J.M.

    1985-01-01

    During the past few years the Defense and Electronics Center of Westinghouse Electric Corporation has developed a solid-state, 250-kW peak, rf amplifier for use with the SPS-40 radar system. This system has a pulse length of 60 μs and operates across the frequency band from 400 to 450 MHz. Because of the potential use of such a system as an rf source for accelerator applications, a collaborative experiment was initiated between Los Alamos National Laboratory and Westinghouse to simulate the resonant load conditions of an accelerator cavity. This paper describes the positive results of that experiment as well as the solid-state amplifier architecture. It also explores the future of high-power, solid-state amplifiers as rf sources for accelerator structures

  15. Possible role of rf melted microparticles on the operation of high-gradient accelerating structures

    Directory of Open Access Journals (Sweden)

    G. S. Nusinovich

    2009-10-01

    Full Text Available High-gradient accelerating structures should operate reliably for a long time. Therefore studies of various processes which may lead to disruption of such an operation are so important. In the present paper, the dissipation of rf electromagnetic energy in metallic microparticles is analyzed accounting for the temperature dependence of the skin depth. Such particles may appear in structures, for example, due to mechanical fracture of irises in strong rf electric fields. It is shown that such microparticles with dimensions on the order of the skin depth, being immersed in the region of strong rf magnetic field, can absorb enough energy in long-pulse operation to be melted. Then, the melted clumps can impinge on the surface of a structure and create nonuniformities leading to field enhancement and corresponding emission of dark current. Results are given for several geometries and materials of microparticles.

  16. Project outline of high quality electron beam generation at Waseda University

    Energy Technology Data Exchange (ETDEWEB)

    Washio, M.; Hama, Y.; Kashiwagi, S.; Kuroda, R.; Kobuki, T. [Waseda Univ., Advanced Research Institute for Science and Engineering, Shinjuku, Tokyo (Japan); Hirose, T. [Tokyo Metropolitan Univ. (Japan). Dept. of Physics

    2000-03-01

    High quality electron beam generation project has been started at Waseda University under the grant of Ministry of Education, named High-Tech Research Center Project. In the project, we will install a laser photo-cathode RF Gun system with 1.6 accelerating structure cells of s-band and a stabilized RF power source. This RF Gun is expected to produce single electron bunch up to 1 or 2nC with around 10ps pulse duration. (author)

  17. Project outline of high quality electron beam generation at Waseda University

    International Nuclear Information System (INIS)

    Washio, M.; Hama, Y.; Kashiwagi, S.; Kuroda, R.; Kobuki, T.; Hirose, T.

    2000-01-01

    High quality electron beam generation project has been started at Waseda University under the grant of Ministry of Education, named High-Tech Research Center Project. In the project, we will install a laser photo-cathode RF Gun system with 1.6 accelerating structure cells of s-band and a stabilized RF power source. This RF Gun is expected to produce single electron bunch up to 1 or 2nC with around 10ps pulse duration. (author)

  18. High-power RF window design for the PEP-II B Factory

    International Nuclear Information System (INIS)

    Neubauer, M.; Hodgson, J.; Ng, C.; Schwarz, H.; Skarpaas, K.; Kroll, N.; Rimmer, R.

    1994-06-01

    We describe the design of RF windows to transmit up to 500 kW CW to the PEP-II 476 MHz cavities. RF analysis of the windows using high-frequency simulation codes are described. These provide information about the power loss distribution in the ceramic and tim matching properties of the structure. Finite-element analyses of the resulting temperature distribution and thermal stresses are presented. Fabrication methods including a proposed scheme to compensate for thermal expansion s are discussed and hardware tests to validate this approach are described. The effects of surface coatings (intentional and otherwise) and the application of air cooling are considered

  19. Introduction to Superconducting RF Structures and the Effect of High Pressure Rinsing

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, Tsuyoshi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-30

    This presentation begins by describing RF superconductivity and SRF accelerating structures. Then the use of superconducting RF structures in a number of accelerators around the world is reviewed; for example, the International Linear Collider (ILC) will use ~16,000 SRF cavities with ~2,000 cryomodules to get 500 GeV e⁺/e⁻ colliding energy. Field emission control was (and still is) a very important practical issue for SRF cavity development. It has been found that high-pressure ultrapure water rinsing as a final cleaning step after chemical surface treatment resulted in consistent performance of single- and multicell superconducting cavities.

  20. Introduction to Superconducting RF Structures and the Effect of High Pressure Rinsing

    International Nuclear Information System (INIS)

    Tajima, Tsuyoshi

    2016-01-01

    This presentation begins by describing RF superconductivity and SRF accelerating structures. Then the use of superconducting RF structures in a number of accelerators around the world is reviewed; for example, the International Linear Collider (ILC) will use ~16,000 SRF cavities with ~2,000 cryomodules to get 500 GeV e@@@/e@@@ colliding energy. Field emission control was (and still is) a very important practical issue for SRF cavity development. It has been found that high-pressure ultrapure water rinsing as a final cleaning step after chemical surface treatment resulted in consistent performance of single- and multicell superconducting cavities.

  1. RF and microwave microelectronics packaging II

    CERN Document Server

    Sturdivant, Rick

    2017-01-01

    Reviews RF, microwave, and microelectronics assembly process, quality control, and failure analysis Bridges the gap between low cost commercial and hi-res RF/Microwave packaging technologies Engages in an in-depth discussion of challenges in packaging and assembly of advanced high-power amplifiers This book presents the latest developments in packaging for high-frequency electronics. It is a companion volume to “RF and Microwave Microelectronics Packaging” (2010) and covers the latest developments in thermal management, electrical/RF/thermal-mechanical designs and simulations, packaging and processing methods, and other RF and microwave packaging topics. Chapters provide detailed coverage of phased arrays, T/R modules, 3D transitions, high thermal conductivity materials, carbon nanotubes and graphene advanced materials, and chip size packaging for RF MEMS. It appeals to practicing engineers in the electronic packaging and high-frequency electronics domain, and to academic researchers interested in underst...

  2. Compact high efficiency, light weight 200-800 MHz high power RF source

    International Nuclear Information System (INIS)

    Shrader, M.B.; Preist, D.H.

    1985-01-01

    There has long been a need for a new more efficient less bulky high power RF power source to drive accelerators in the 200 to 800 MHz region. Results on a recent 5-year EIMAC sponsored R and D program which have lead to the introduction of the Klystrode for UHF television and troposcatter applications indicate that at power levels of 1MW or more efficiencies in excess of 75% can be obtained at 450 MHz. Efficiencies of this order coupled with potential size and weight parameters which are a fraction of those of existing high power UHF generators open up new applications which heretofore would have been impractical if not impossible. Measurements at 470 MHz on existing Klystrodes are given. Projected operating conditions for a 1MW 450 MHz Klystrode having an overall length of 60 inches and a total tube, circuit, and magnet weight of 250 pounds is presented

  3. Thin-Film layers with Interfaces that reduce RF Losses on High-Resistivity Silicon Substrates

    NARCIS (Netherlands)

    Evseev, S. B.; Milosavljevic, S.; Nanver, L. K.

    2017-01-01

    Radio-Frequency (RF) losses on High-Resistivity Silicon (HRS) substrates were studied for several different surface passivation layers comprising thin-films of SiC, SiN and SiO2 In many combinations, losses from conductive surface channels were reduced and increasing the number of interfaces between

  4. A wideband high-linearity RF receiver front-end in CMOS

    NARCIS (Netherlands)

    Arkesteijn, V.J.; Klumperink, Eric A.M.; Nauta, Bram

    This paper presents a wideband high-linearity RF receiver-front-end, implemented in standard 0.18 μm CMOS technology. The design employs a noise-canceling LNA in combination with two passive mixers, followed by lowpass-filtering and amplification at IF. The achieved bandwidth is >2 GHz, with a noise

  5. Intermodulation Linearity in High-k/Metal Gate 28 nm RF CMOS Transistors

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2015-09-01

    Full Text Available This paper presents experimental characterization, simulation, and Volterra series based analysis of intermodulation linearity on a high-k/metal gate 28 nm RF CMOS technology. A figure-of-merit is proposed to account for both VGS and VDS nonlinearity, and extracted from frequency dependence of measured IIP3. Implications to biasing current and voltage optimization for linearity are discussed.

  6. A highly sensitive RF-to-DC power converter with an extended dynamic range

    KAUST Repository

    Almansouri, Abdullah Saud Mohammed; Ouda, Mahmoud H.; Salama, Khaled N.

    2017-01-01

    This paper proposes a highly sensitive RF-to-DC power converter with an extended dynamic range that is designed to operate at the medical band 433 MHz and simulated using 0.18 μm CMOS technology. Compared to the conventional fully cross

  7. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator

    International Nuclear Information System (INIS)

    Souli, M.

    2007-07-01

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q c in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  8. Design study of a low-emittance high-repetition rate thermionic rf gun

    Directory of Open Access Journals (Sweden)

    A. Opanasenko

    2017-05-01

    Full Text Available We propose a novel gridless continuous-wave radiofrequency (rf thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

  9. New high power 200 MHz RF system for the LANSCE drift tube linac

    International Nuclear Information System (INIS)

    Lyles, J.; Friedrichs, C.; Lynch, M.

    1998-01-01

    The Los Alamos Neutron Science Center (LANSCE) linac provides an 800 MeV direct H + proton beam, and injects H - to the upgraded proton storage ring for charge accumulation for the Short Pulse Spallation Source. Accelerating these interlaced beams requires high average power from the 201.25 MHz drift tube linac (DTL) RF system. Three power amplifiers have operated at up to three Megawatts with 12% duty factor. The total number of electron power tubes in the RF amplifiers and their modulators has been reduced from fifty-two to twenty-four. The plant continues to utilize the original design of a tetrode driving a super power triode. Further increases in the linac duty factor are limited, in part, by the maximum dissipation ratings of the triodes. A description of the system modifications proposed to overcome these limitations includes new power amplifiers using low-level RF modulation for tank field control. The first high power Diacrode reg-sign is being delivered and a new amplifier cavity is being designed. With only eight power tubes, the new system will deliver both peak power and high duty factor, with lower mains power and cooling requirements. The remaining components needed for the new RF system will be discussed

  10. IT-based soil quality evaluation for agroecologically smart land-use planning in RF conditions

    Science.gov (United States)

    Vasenev, Ivan

    2016-04-01

    Activated in the first decades of XXI century global climate, economy and farming changes sharply actualized novel IT-based approaches in soil quality evaluation to address modern agricultural issues with agroecologically smart land-use planning. Despite global projected climate changes will affect a general decline of crop yields (IPCC 2014), RF boreal and subboreal regions will benefit from predicted and already particularly verified temperature warming and increased precipitation (Valentini, Vasenev, 2015) due to essential increasing of growing season length and mild climate conditions favorable for most prospective crops and best available agrotechnologies. However, the essential spatial heterogeneity is mutual feature for most natural and man-changed soils at the Central European region of Russia which is one of the biggest «food baskets» in RF. In these conditions potentially favorable climate circumstances will increase not only soil fertility and workability features but also their dynamics and spatial variability that determine crucial issues of IT-based soil quality evaluation systems development and agroecologically smart farming planning. Developed and verified within the LAMP project (RF Governmental projects #11.G34.31.0079 and #14.120.14.4266) regionally adapted DSS (ACORD-R - RF #2012612944) gives effective informational and methodological support for smart farming agroecological optimization in global climate and farming changes challenges. Information basis for agroecologically smart land-use planning consists of crops and agrotechnologies requirements, regional and local systems of agroecological zoning, local landscape and soil cover patterns, land quality and degradation risk assessments, current and previous farming practices results, agroclimatic predictions and production agroecological models, environmental limitations and planned profitability, fertilizing efficiency DSS ACORD-R. Smart land-use practice refers to sustainable balance

  11. High-resolution simulations of the thermophysiological effects of human exposure to 100 MHz RF energy

    International Nuclear Information System (INIS)

    Nelson, David A; Curran, Allen R; Nyberg, Hans A; Marttila, Eric A; Mason, Patrick A; Ziriax, John M

    2013-01-01

    Human exposure to radio frequency (RF) electromagnetic energy is known to result in tissue heating and can raise temperatures substantially in some situations. Standards for safe exposure to RF do not reflect bio-heat transfer considerations however. Thermoregulatory function (vasodilation, sweating) may mitigate RF heating effects in some environments and exposure scenarios. Conversely, a combination of an extreme environment (high temperature, high humidity), high activity levels and thermally insulating garments may exacerbate RF exposure and pose a risk of unsafe temperature elevation, even for power densities which might be acceptable in a normothermic environment. A high-resolution thermophysiological model, incorporating a heterogeneous tissue model of a seated adult has been developed and used to replicate a series of whole-body exposures at a frequency (100 MHz) which approximates that of human whole-body resonance. Exposures were simulated at three power densities (4, 6 and 8 mW cm −2 ) plus a sham exposure and at three different ambient temperatures (24, 28 and 31 °C). The maximum hypothalamic temperature increase over the course of a 45 min exposure was 0.28 °C and occurred in the most extreme conditions (T amb = 31 °C, PD = 8 mW cm −2 ). Skin temperature increases attributable to RF exposure were modest, with the exception of a ‘hot spot’ in the vicinity of the ankle where skin temperatures exceeded 39 °C. Temperature increases in internal organs and tissues were small, except for connective tissue and bone in the lower leg and foot. Temperature elevation also was noted in the spinal cord, consistent with a hot spot previously identified in the literature. (paper)

  12. Electron beam gun with kinematic coupling for high power RF vacuum devices

    Science.gov (United States)

    Borchard, Philipp

    2016-11-22

    An electron beam gun for a high power RF vacuum device has components joined by a fixed kinematic coupling to provide both precise alignment and high voltage electrical insulation of the components. The kinematic coupling has high strength ceramic elements directly bonded to one or more non-ductile rigid metal components using a high temperature active metal brazing alloy. The ceramic elements have a convex surface that mates with concave grooves in another one of the components. The kinematic coupling, for example, may join a cathode assembly and/or a beam shaping focus electrode to a gun stem, which is preferably composed of ceramic. The electron beam gun may be part of a high power RF vacuum device such as, for example, a gyrotron, klystron, or magnetron.

  13. Passivation of Ge/high-κ interface using RF Plasma nitridation

    Science.gov (United States)

    Dushaq, Ghada; Nayfeh, Ammar; Rasras, Mahmoud

    2018-01-01

    In this paper, plasma nitridation of a germanium surface using NH3 and N2 gases is performed with a standard RF-PECVD method at a substrate temperature of 250 °C. The structural and optical properties of the Ge surface have been investigated using Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), and Variable Angle Spectroscopic Ellipsometery (VASE). Study of the Ge (100) surface revealed that it is nitrated after plasma treatment while the GeO2 regrowth on the surface has been suppressed. Also, stability of the treated surface under air exposure is observed, where all the measurements were performed at room ambient. The electrical characteristics of fabricated Al/Ti/HfO2/GeON/p-Ge capacitors using the proposed surface treatment technique have been investigated. The C-V curves indicated a negligible hysteresis compared to ˜500 mV observed in untreated samples. Additionally, the C-V characteristic is used to extract the high-κ/Ge interface trap density using the most commonly used methods in determining the interface traps. The discussion includes the Dit calculation from the high-low frequency (Castagné-Vapaille) method and Terman (high-frequency) method. The high-low frequency method indicated a low interface trap density of ˜2.5 × 1011 eV-1.cm-2 compared to the Terman method. The J-V measurements revealed more than two orders of magnitude reduction of the gate leakage. This improved Ge interface quality is a promising low-temperature technique for fabricating high-performance Ge MOSFETs.

  14. High-performance RF coil inductors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Malba, V.; Young, D.; Ou, J.J.; Bernhardt, A.F.; Boser, B.E.

    1998-03-01

    Strong demand for wireless communication devices has motivated research directed toward monolithic integration of transceivers. The fundamental electronic component least compatible with silicon integrated circuits is the inductor, although a number of inductors are required to implement oscillators, filters and matching networks in cellular devices. Spiral inductors have been integrated into the silicon IC metallization sequence but have not performed adequately due to coupling to the silicon which results in parasitic capacitance and loss. We have, for the first time, fabricated three dimensional coil inductors on silicon which have significantly lower capacitive coupling and loss and which now exceed the requirements of potential applications. Quality factors of 30 at 1 GHz have been measured in single turn devices and Q > 16 in 2 and 4 turn devices. The reduced Q for multiturn devices appears to be related to eddy currents in outer turns generated by magnetic fields from current in neighboring turns. Higher Q values significantly in excess of 30 are anticipated using modified coil designs.

  15. High-power rf controls for the NBS-Los Alamos racetrack microtron

    International Nuclear Information System (INIS)

    Young, L.M.; Biddle, R.S.

    1985-01-01

    The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kW cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. A block diagram of this system is shown, as is a subset of the complete system on which the measurements reported in this paper were performed. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference. 4 refs., 8 figs

  16. High power test of RF window and coaxial line in vacuum

    International Nuclear Information System (INIS)

    Sun, D.; Champion, M.; Gormley, M.; Kerns, Q.; Koepke, K.; Moretti, A.

    1993-01-01

    Primary rf input couplers for the superconducting accelerating cavities of the TESLA electron linear accelerator test to be performed at DESY, Hamburg, Germany are under development at both DESY and Fermilab. The input couplers consist of a WR650 waveguide to coaxial line transition with an integral ceramic window, a coaxial connection to the superconducting accelerating cavity with a second ceramic window located at the liquid nitrogen heat intercept location, and bellows on both sides of the cold window to allow for cavity motion during cooldown, coupling adjustments and easier assembly. To permit in situ high peak power processing of the TESLA superconducting accelerating cavities, the input couplers are designed to transmit nominally 1 ms long, 2 MW peak, 1.3 GHz rf pulses from the WR650 waveguide at room temperature to the cavities at 1.8 K. The coaxial part of the Fermilab TESLA input coupler design has been tested up to 1.7 MW using the prototype 805 MHz rf source located at the A0 service building of the Tevatron. The rf source, the testing system and the test results are described

  17. Direct high-frequency modulation of VCSELs and applications in fibre optic RF and microwave links

    International Nuclear Information System (INIS)

    Larsson, Anders; Carlsson, Christina; Gustavsson, Johan; Haglund, Asa; Modh, Peter; Bengtsson, Joergen

    2004-01-01

    With the rapid development of wireless communication networks there is an increasing demand for efficient and cost-effective transmission and distribution of RF signals. Fibre optic RF links, employing directly modulated semiconductor lasers, provide many of the desired characteristics for such distribution systems and in the search for cost-effective solutions, the vertical cavity surface emitting laser (VCSEL) is of interest. It has therefore been the purpose of this work to investigate whether 850 nm VCSELs fulfil basic performance requirements for fibre optic RF links operating in the low-GHz range. The performance of single- and multimode oxide confined VCSELs has been compared, in order to pin-point limitations and to find the optimum design. Fibre optic RF links using VCSELs and multimode fibres have been assembled and evaluated with respect to performance characteristics of importance for wireless communication systems. We have found that optimized single-mode VCSELs provide the highest performance and that links using such VCSELs and high-bandwidth multimode fibres satisfy the requirements in a number of applications, including cellular systems for mobile communication and wireless local area networks

  18. HIGH POWER TESTS OF A MULTIMODE X-BAND RF DISTRIBUTION SYSTEMS

    International Nuclear Information System (INIS)

    Tantawi, S

    2004-01-01

    We present a multimode X-band rf pulse compression system suitable for the Next Linear Collider (NLC). The NLC main linacs operate at 11.424 GHz. A single NLC rf unit is required which produce 400 ns pulses with 600 MW of peak power. Each rf unit should power approximately 5 meters of accelerator structures. These rf units consist of two 75 MW klystrons and a dual-moded resonant delay line pulse compression system [1] that produce a flat output pulse. The pulse compression system components are all over moded and most components are design to operate with two modes at the same time. This approach allows increasing the power handling capabilities of the system while maintain a compact inexpensive system. We detail the design of this system and present experimental cold test results. The high power testing of the system is verified using four 50-MW solenoid focused klystrons. These Klystrons should be able to push the system beyond NLC requirements

  19. Final Report for 'Design calculations for high-space-charge beam-to-RF conversion'

    International Nuclear Information System (INIS)

    Smithe, David N.

    2008-01-01

    Accelerator facility upgrades, new accelerator applications, and future design efforts are leading to novel klystron and IOT device concepts, including multiple beam, high-order mode operation, and new geometry configurations of old concepts. At the same time, a new simulation capability, based upon finite-difference 'cut-cell' boundaries, has emerged and is transforming the existing modeling and design capability with unparalleled realism, greater flexibility, and improved accuracy. This same new technology can also be brought to bear on a difficult-to-study aspect of the energy recovery linac (ERL), namely the accurate modeling of the exit beam, and design of the beam dump for optimum energy efficiency. We have developed new capability for design calculations and modeling of a broad class of devices which convert bunched beam kinetic energy to RF energy, including RF sources, as for example, klystrons, gyro-klystrons, IOT's, TWT's, and other devices in which space-charge effects are important. Recent advances in geometry representation now permits very accurate representation of the curved metallic surfaces common to RF sources, resulting in unprecedented simulation accuracy. In the Phase I work, we evaluated and demonstrated the capabilities of the new geometry representation technology as applied to modeling and design of output cavity components of klystron, IOT's, and energy recovery srf cavities. We identified and prioritized which aspects of the design study process to pursue and improve in Phase II. The development and use of the new accurate geometry modeling technology on RF sources for DOE accelerators will help spark a new generational modeling and design capability, free from many of the constraints and inaccuracy associated with the previous generation of 'stair-step' geometry modeling tools. This new capability is ultimately expected to impact all fields with high power RF sources, including DOE fusion research, communications, radar and other

  20. Development of highly qualified UV-laser light source for rf gun

    International Nuclear Information System (INIS)

    Tomizawa, H.; Dewa, H.; Taniuchi, T.

    2004-01-01

    We have been developing stable and highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. In present status, the short pulse energy stability of laser has been improved down to 1.3∼1.5% (rms; 10pps; 10000 shots) at the third harmonic generation. The long stability depends on the stability of modelocking at oscillator. In this improvement we just passively stabilized the system. We considered environmental controls in clean room to reduce optical damage accidents and constructed a new humidity-controlled clean room in 2003. And we re-installed the total laser system in this room in 2004. The relative humidity of this new clean room at room temperature is in a region of 50∼60 % with a stability of less than 2% (p-p). On the other hand, the ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. This laser-shaping project has been started in two steps since 2002. As the first successful test run in 2002, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2π mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run in 2004, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying the both adaptive optics to automatically shape the both spatial and temporal UV-laser profiles with a feedback routine at the same time. We report herein the principle and developing process of our laser beam quality control system. (author)

  1. Rf measurements on high T/sub c/ materials

    International Nuclear Information System (INIS)

    Rubin, D.L.; Gruschus, J.; Kirchgessner, J.

    1988-01-01

    Measurements of the microwave surface resistivity of high T/sub c/ materials were made in a superconducting niobium 6Ghz TE 011 resonant cavity and a niobium 8.6 Ghz TM 010 elliptical cavity. The TE 011 apparatus permits variation of the temperature of the sample independently of that of the niobium cavity. The Q of the host cavity thus remains at a high value while the resistivity of the sample is measured from 4.2 K to above the transition (≅ 100 K). The resistivity of a 1.27 cm diameter ceramic pellet is observed to fall from 1 Omega above transition to 0.02 Omega at 4.2 K. A set of nine single crystals of total area 6.5 mm 2 is measured to have a broad transition near 75 K. The surface resistivity of a single 3 mm 2 crystal is measured in the elliptical cavity to be ≤ 9.8 x 10 -5 Omega at 1.5 K. 4 references, 9 figures

  2. High-power CO laser with RF discharge for isotope separation employing condensation repression

    Science.gov (United States)

    Baranov, I. Ya.; Koptev, A. V.

    2008-10-01

    High-power CO laser can be the effective tool in such applications as isotope separation using the free-jet CRISLA method. The way of transfer from CO small-scale experimental installation to industrial high-power CO lasers is proposed through the use of a low-current radio-frequency (RF) electric discharge in a supersonic stream without an electron gun. The calculation model of scaling CO laser with RF discharge in supersonic stream was developed. The developed model allows to calculate parameters of laser installation and optimize them with the purpose of reception of high efficiency and low cost of installation as a whole. The technical decision of industrial CO laser for isotope separation employing condensation repression is considered. The estimated cost of laser is some hundred thousand dollars USA and small sizes of laser head give possibility to install it in any place.

  3. Development of a high gradient rf system using a nanocrystalline soft magnetic alloy

    Directory of Open Access Journals (Sweden)

    Chihiro Ohmori

    2013-11-01

    Full Text Available The future high intensity upgrade project of the J-PARC (Japan Proton Accelerator Research Complex MR (Main Ring includes developments of high gradient rf cavities and magnet power supplies for high repetition rate. The scenario describing the cavity replacements is reported. By the replacement plan, the total acceleration voltage will be almost doubled, while the number of rf stations remains the same. The key issue is the development of a high gradient rf system using high impedance magnetic alloy, FT3L. The FT3L is produced by the transverse magnetic field annealing although the present cavity for the J-PARC adopts the magnetic alloy, FT3M, which is annealed without magnetic field. After the test production using a large spectrometer magnet in 2011, a dedicated production system for the FT3L cores was assembled in 2012. This setup demonstrated that we can produce material with 2 times higher μ_{p}^{′}Qf product compared to the cores used for present cavities. In this summer, the production system was moved to the company from J-PARC and is used for mass production of 280 FT3L cores for the J-PARC MR. The cores produced in the first test production are already used for standard machine operation. The operation experience shows that the power loss in the cores was reduced significantly as expected.

  4. Study of quality and field limitation of superconducting 1.3 GHz 9-Cell RF-cavities at DESY

    International Nuclear Information System (INIS)

    Schlander, Felix

    2013-01-01

    The European XFEL and the International Linear Collider are based on superconducting rf cavities made of niobium. Their advantages are low ohmic losses which allow high duty cycles and the possibility to use a large beam aperture which is substantial to prevent wake fields at high current accelerators. To reach the theoretical limits of superconducting cavities, it is required to understand the present performance limitations. These are field emission, thermal breakdown (quench) and the ohmic losses dependent on the accelerating field, which are expressed in the quality factor. As the limiting mechanisms themselves are understood in general, the origin of the quench is often unclear. To determine the quench locations, a localisation tool for thermal breakdown using the second sound in superfluid helium has been installed at the cavity test facility at DESY and the results for a sample of about 30 cavities have been examined. The features of the distribution of the quench locations have been analysed and it has been found that the quench locations are in the area of the highest surface magnetic field and not necessarily at the equator of the cells. The data sample has been extended in an attempt to characterise the average behaviour of the quality factor related to the accelerating field. An analysis of the surface resistance of individual cavities shows that a recently developed model for the surface resistance of niobium is not able to describe the measurement in all detail, but the application of an additional mechanism showed promising results.

  5. Study of quality and field limitation of superconducting 1.3 GHz 9-Cell RF-cavities at DESY

    Energy Technology Data Exchange (ETDEWEB)

    Schlander, Felix

    2013-01-15

    The European XFEL and the International Linear Collider are based on superconducting rf cavities made of niobium. Their advantages are low ohmic losses which allow high duty cycles and the possibility to use a large beam aperture which is substantial to prevent wake fields at high current accelerators. To reach the theoretical limits of superconducting cavities, it is required to understand the present performance limitations. These are field emission, thermal breakdown (quench) and the ohmic losses dependent on the accelerating field, which are expressed in the quality factor. As the limiting mechanisms themselves are understood in general, the origin of the quench is often unclear. To determine the quench locations, a localisation tool for thermal breakdown using the second sound in superfluid helium has been installed at the cavity test facility at DESY and the results for a sample of about 30 cavities have been examined. The features of the distribution of the quench locations have been analysed and it has been found that the quench locations are in the area of the highest surface magnetic field and not necessarily at the equator of the cells. The data sample has been extended in an attempt to characterise the average behaviour of the quality factor related to the accelerating field. An analysis of the surface resistance of individual cavities shows that a recently developed model for the surface resistance of niobium is not able to describe the measurement in all detail, but the application of an additional mechanism showed promising results.

  6. Highly ordered amorphous silicon-carbon alloys obtained by RF PECVD

    CERN Document Server

    Pereyra, I; Carreno, M N P; Prado, R J; Fantini, M C A

    2000-01-01

    We have shown that close to stoichiometry RF PECVD amorphous silicon carbon alloys deposited under silane starving plasma conditions exhibit a tendency towards c-Si C chemical order. Motivated by this trend, we further explore the effect of increasing RF power and H sub 2 dilution of the gaseous mixtures, aiming to obtain the amorphous counterpart of c-Si C by the RF-PECVD technique. Doping experiments were also performed on ordered material using phosphorus and nitrogen as donor impurities and boron and aluminum as acceptor ones. For nitrogen a doping efficiency close to device quality a-Si:H was obtained, the lower activation energy being 0,12 eV with room temperature dark conductivity of 2.10 sup - sup 3 (OMEGA.cm). Nitrogen doping efficiency was higher than phosphorous for all studied samples. For p-type doping, results indicate that, even though the attained conductivity values are not device levels, aluminum doping conducted to a promising shift in the Fermi level. Also, aluminum resulted a more efficie...

  7. High voltage power supplies for ITER RF heating and current drive systems

    International Nuclear Information System (INIS)

    Gassmann, T.; Arambhadiya, B.; Beaumont, B.; Baruah, U.K.; Bonicelli, T.; Darbos, C.; Purohit, D.; Decamps, H.; Albajar, F.; Gandini, F.; Henderson, M.; Kazarian, F.; Lamalle, P.U.; Omori, T.; Parmar, D.; Patel, A.; Rathi, D.; Singh, N.P.

    2011-01-01

    The RF heating and current drive (H and CD) systems to be installed for the ITER fusion machine are the electron cyclotron (EC), ion cyclotron (IC) and, although not in the first phase of the project, lower hybrid (LH). These systems require high voltage, high current power supplies (HVPS) in CW operation. These HVPS should deliver around 50 MW electrical power to each of the RF H and CD systems with stringent requirements in terms of accuracy, voltage ripple, response time, turn off time and fault energy. The PSM (Pulse Step Modulation) technology has demonstrated over the past 20 years its ability to fulfill these requirements in many industrial facilities and other fusion reactors and has therefore been chosen as reference design for the IC and EC HVPS systems. This paper describes the technical specifications, including interfaces, the resulting constraints on the design, the conceptual design proposed for ITER EC and IC HVPS systems and the current status.

  8. Progress on the high-current 704 MHz superconducting RF cavity at BNL

    International Nuclear Information System (INIS)

    Xu, W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.

    2012-01-01

    The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.

  9. The UK High Power RF Faraday Partnership Industrial, Academia, and Public Collaboration

    International Nuclear Information System (INIS)

    Phelps, A.D.R.; Carter, R.G.; Clunie, D.; Bowater, S.P.; Ellis, D.; Gamble, D.; Large, T.; Lucas, W.; Pettit, C.; Poole, M. W.; Smith, H.; Smith, P.W.; Wilcox, D.M.

    2003-01-01

    The High Power Radio Frequency (HPRF) Faraday Partnership is a UK technology forum for all users, designers, developers and researchers of RF and microwave devices and systems. High power RF and microwave engineering are key enabling technologies in a wide range of industrial sectors. Formed in October 2001 and funded initially by the UK Department of Trade and Industry and the UK Particle Physics and Astronomy Research Council, the purpose of the HPRF Faraday Partnership is the development of a vibrant research, development and manufacturing base capable of exploiting opportunities in high power radio-frequency engineering. The partnership includes the key UK industrial companies, research laboratories and university research groups. The number of partners is constantly growing and already numbers over thirty. The partnership provides the enabling technology for future high power RF systems and their power supplies through its research programme. It is training people for the sector through PhD studentships and employment as Research Associates. It is planned to develop a Masters Training program. Support and involvement in research for companies in the supply chain is provided through a Partnership Office, a web site and through a range of government funded research schemes. The HPRF Faraday Partnership is seeking to establish more long term international research and development collaborations

  10. High-power RF window and coupler development for the PEP-II B Factory

    International Nuclear Information System (INIS)

    Neubauer, M.; Fant, K.; Hodgson, J.; Judkins, J.; Schwarz, H.; Rimmer, R.A.

    1995-05-01

    We describe the fabrication and testing of the RF windows designed to transmit power to the PEP-II 476 MHz cavities. Design choices to maximize the reliability of the window are discussed. Fabrication technologies for the window are described and finite-element analysis of the assembly process is presented. Conditioning and high-power testing of the window are discussed. Design of the coupler assembly including the integration of the window and other components is reported

  11. Design and Calibration of an RF Actuator for Low-Level RF Systems

    Science.gov (United States)

    Geng, Zheqiao; Hong, Bo

    2016-02-01

    X-ray free electron laser (FEL) machines like the Linac Coherent Light Source (LCLS) at SLAC require high-quality electron beams to generate X-ray lasers for various experiments. Digital low-level RF (LLRF) systems are widely used to control the high-power RF klystrons to provide a highly stable RF field in accelerator structures for beam acceleration. Feedback and feedforward controllers are implemented in LLRF systems to stabilize or adjust the phase and amplitude of the RF field. To achieve the RF stability and the accuracy of the phase and amplitude adjustment, low-noise and highly linear RF actuators are required. Aiming for the upgrade of the S-band Linac at SLAC, an RF actuator is designed with an I/Qmodulator driven by two digital-to-analog converters (DAC) for the digital LLRF systems. A direct upconversion scheme is selected for RF actuation, and an on-line calibration algorithm is developed to compensate the RF reference leakage and the imbalance errors in the I/Q modulator, which may cause significant phase and amplitude actuation errors. This paper presents the requirements on the RF actuator, the design of the hardware, the calibration algorithm, and the implementation in firmware and software and the test results at LCLS.

  12. Development and performance test of a new high power RF window in S-band PLS-II LINAC

    Science.gov (United States)

    Hwang, Woon-Ha; Joo, Young-Do; Kim, Seung-Hwan; Choi, Jae-Young; Noh, Sung-Ju; Ryu, Ji-Wan; Cho, Young-Ki

    2017-12-01

    A prototype of RF window was developed in collaboration with the Pohang Accelerator Laboratory (PAL) and domestic companies. High power performance tests of the single RF window were conducted at PAL to verify the operational characteristics for its application in the Pohang Light Source-II (PLS-II) linear accelerator (Linac). The tests were performed in the in-situ facility consisting of a modulator, klystron, waveguide network, vacuum system, cooling system, and RF analyzing equipment. The test results with Stanford linear accelerator energy doubler (SLED) have shown no breakdown up to 75 MW peak power with 4.5 μs RF pulse width at a repetition rate of 10 Hz. The test results with the current operation level of PLS-II Linac confirm that the RF window well satisfies the criteria for PLS-II Linac operation.

  13. Characterization of a klystrode as a RF source for high-average-power accelerators

    International Nuclear Information System (INIS)

    Rees, D.; Keffeler, D.; Roybal, W.; Tallerico, P.J.

    1995-01-01

    The klystrode is a relatively new type of RF source that has demonstrated dc-to-RF conversion efficiencies in excess of 70% and a control characteristic uniquely different from those for klystron amplifiers. The different control characteristic allows the klystrode to achieve this high conversion efficiency while still providing a control margin for regulation of the accelerator cavity fields. The authors present test data from a 267-MHz, 250-kW, continuous-wave (CW) klystrode amplifier and contrast this data with conventional klystron performance, emphasizing the strengths and weaknesses of the klystrode technology for accelerator applications. They present test results describing that limitation for the 250-kW, CW klystrode and extrapolate the data to other frequencies. A summary of the operating regime explains the clear advantages of the klystrode technology over the klystron technology

  14. MgB_{2} nonlinear properties investigated under localized high rf magnetic field excitation

    Directory of Open Access Journals (Sweden)

    Tamin Tai

    2012-12-01

    Full Text Available The high transition temperature and low surface resistance of MgB_{2} attracts interest in its potential application in superconducting radio frequency accelerating cavities. However, compared to traditional Nb cavities, the viability of MgB_{2} at high rf fields is still open to question. Our approach is to study the nonlinear electrodynamics of the material under localized rf magnetic fields. Because of the presence of the small superconducting gap in the π band, the nonlinear response of MgB_{2} at low temperature is potentially complicated compared to a single-gap s-wave superconductor such as Nb. Understanding the mechanisms of nonlinearity coming from the two-band structure of MgB_{2}, as well as extrinsic sources of nonlinearity, is an urgent requirement. A localized and strong rf magnetic field, created by a magnetic write head, is integrated into our nonlinear-Meissner-effect scanning microwave microscope [T. Tai et al., IEEE Trans. Appl. Supercond. 21, 2615 (2011ITASE91051-822310.1109/TASC.2010.2096531]. MgB_{2} films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor deposition technique on dielectric substrates, are measured at a fixed location and show a strongly temperature-dependent third harmonic response. We propose that several possible mechanisms are responsible for this nonlinear response.

  15. High efficiency RF amplifier development over wide dynamic range for accelerator application

    Science.gov (United States)

    Mishra, Jitendra Kumar; Ramarao, B. V.; Pande, Manjiri M.; Joshi, Gopal; Sharma, Archana; Singh, Pitamber

    2017-10-01

    Superconducting (SC) cavities in an accelerating section are designed to have the same geometrical velocity factor (βg). For these cavities, Radio Frequency (RF) power needed to accelerate charged particles varies with the particle velocity factor (β). RF power requirement from one cavity to other can vary by 2-5 dB within the accelerating section depending on the energy gain in the cavity and beam current. In this paper, we have presented an idea to improve operating efficiency of the SC RF accelerators using envelope tracking technique. A study on envelope tracking technique without feedback is carried out on a 1 kW, 325 MHz, class B (conduction angle of 180 degrees) tuned load power amplifier (PA). We have derived expressions for the efficiency and power output for tuned load amplifier operating on the envelope tracking technique. From the derived expressions, it is observed that under constant load resistance to the device (MOSFET), optimum amplifier efficiency is invariant whereas output power varies with the square of drain bias voltage. Experimental results on 1 kW PA module show that its optimum efficiency is always greater than 62% with variation less than 5% from mean value over 7 dB dynamic range. Low power amplifier modules are the basic building block for the high power amplifiers. Therefore, results for 1 kW PA modules remain valid for the high power solid state amplifiers built using these PA modules. The SC RF accelerators using these constant efficiency power amplifiers can improve overall accelerator efficiency.

  16. Reaffirming normal: the high risk of pathologizing healthy adults when interpreting the MMPI-2-RF.

    Science.gov (United States)

    Odland, Anthony P; Lammy, Andrew B; Perle, Jonathan G; Martin, Phillip K; Grote, Christopher L

    2015-01-01

    Monte Carlo simulations were utilized to determine the proportion of the normal population expected to have scale elevations on the MMPI-2-RF when multiple scores are interpreted. Results showed that when all 40 MMPI-2-RF scales are simultaneously considered, approximately 70% of normal adults are likely to have at least one scale elevation at or above 65 T, and as many as 20% will have five or more elevated scales. When the Restructured Clinical (RC) Scales are under consideration, 34% of normal adults have at least one elevated score. Interpretation of the Specific Problem Scales and Personality Psychopathology Five Scales--Revised also yielded higher than expected rates of significant scores, with as many as one in four normal adults possibly being miscategorized as having features of a personality disorder by the latter scales. These findings are consistent with the growing literature on rates of apparently abnormal scores in the normal population due to multiple score interpretation. Findings are discussed in relation to clinical assessment, as well as in response to recent work suggesting that the MMPI-2-RF's multiscale composition does not contribute to high rates of elevated scores.

  17. Verification of high voltage rf capacitive sheath models with particle-in-cell simulations

    Science.gov (United States)

    Wang, Ying; Lieberman, Michael; Verboncoeur, John

    2009-10-01

    Collisionless and collisional high voltage rf capacitive sheath models were developed in the late 1980's [1]. Given the external parameters of a single-frequency capacitively coupled discharge, plasma parameters including sheath width, electron and ion temperature, plasma density, power, and ion bombarding energy can be estimated. One-dimensional electrostatic PIC codes XPDP1 [2] and OOPD1 [3] are used to investigate plasma behaviors within rf sheaths and bulk plasma. Electron-neutral collisions only are considered for collisionless sheaths, while ion-neutral collisions are taken into account for collisional sheaths. The collisionless sheath model is verified very well by PIC simulations for the rf current-driven and voltage-driven cases. Results will be reported for collisional sheaths also. [1] M. A. Lieberman, IEEE Trans. Plasma Sci. 16 (1988) 638; 17 (1989) 338 [2] J. P. Verboncoeur, M. V. Alves, V. Vahedi, and C. K. Birdsall, J. Comp. Phys. 104 (1993) 321 [3] J. P. Verboncoeur, A. B. Langdon and N. T. Gladd, Comp. Phys. Comm. 87 (1995) 199

  18. High RF power test of a CFC antenna module for lower hybrid current drive

    International Nuclear Information System (INIS)

    Maebara, S.; Seki, M.; Ikeda, Y.; Kiyono, K.; Suganuma, K.; Imai, T.; Goniche, M.; Bibet, Ph.; Brossaud, J.; Cano, V.; Kazarian-Vibert, F.; Froissard, P.; Rey, G.

    1998-01-01

    A mock-up of a 3.7 GHz Lower Hybrid Current Drive (LHCD) antenna module was fabricated from Carbon Fibre Composite (CFC) for the development of heat resistive low Z front facing the plasma. This 2 divided waveguide module is made from CFC plates and rods which are Cu-plated to reduce the RF losses. The withstand-voltage, the RF properties and the outgassing rates for long pulses and high RF power were tested at the Lower Hybrid test bed facility of Cadarache. A reference module made from Dispersion Strengthened Copper (DSC) was also fabricated. After the short pulse conditioning, long pulses with a power density ranging between 50 and 150 MW/m 2 were performed with no breakdowns on the CFC module. It was also checked that the highest power density, up to 150 MW/m 2 , could be transmitted when the waveguides are filled with H2 at a pressure of 5 x 10 -2 Pa. During a long pulse, the power reflection coefficient remains low in the 0.8-1.3 % range and no significant change in the reflection coefficient is measured after the thermal cycling provided by the long pulse operation. From thermocouple measurements, RF losses of the copper coated CFC and the DSC modules were compared. No significant differences were measured. From pressure measurements, it was found that the outgassing rate of Cu-plated CFC is about 6-7 times larger than of DSC at 300 deg.C. It is concluded that a CFC module is an attractive candidate for the hardening of the tip of the LHCD antenna. (author)

  19. A differential low-voltage high gain current-mode integrated RF receiver front-end

    Energy Technology Data Exchange (ETDEWEB)

    Wang Chunhua; Ma Minglin; Sun Jingru; Du Sichun; Guo Xiaorong; He Haizhen, E-mail: wch1227164@sina.com [School of Information Science and Technology, Hunan University, Changsha 410082 (China)

    2011-02-15

    A differential low-voltage high gain current-mode integrated RF front end for an 802.11b WLAN is proposed. It contains a differential transconductance low noise amplifier (G{sub m}-LNA) and a differential current-mode down converted mixer. The single terminal of the G{sub m}-LNA contains just one MOS transistor, two capacitors and two inductors. The gate-source shunt capacitors, C{sub x1} and C{sub x2}, can not only reduce the effects of gate-source C{sub gs} on resonance frequency and input-matching impedance, but they also enable the gate inductance L{sub g1,2} to be selected at a very small value. The current-mode mixer is composed of four switched current mirrors. Adjusting the ratio of the drain channel sizes of the switched current mirrors can increase the gain of the mixer and accordingly increase the gain of RF receiver front-end. The RF front-end operates under 1 V supply voltage. The receiver RFIC was fabricated using a chartered 0.18 {mu}m CMOS process. The integrated RF receiver front-end has a measured power conversion gain of 17.48 dB and an input referred third-order intercept point (IIP3) of -7.02 dBm. The total noise figure is 4.5 dB and the power is only 14 mW by post-simulations. (semiconductor integrated circuits)

  20. High power rf amplifiers for accelerator applications: The large orbit gyrotron and the high current, space charge enhanced relativistic klystron

    International Nuclear Information System (INIS)

    Stringfield, R.M.; Fazio, M.V.; Rickel, D.G.; Kwan, T.J.T.; Peratt, A.L.; Kinross-Wright, J.; Van Haaften, F.W.; Hoeberling, R.F.; Faehl, R.; Carlsten, B.; Destler, W.W.; Warner, L.B.

    1991-01-01

    Los Alamos is investigating a number of high power microwave (HPM) sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics (to allow injection of a suitable fraction of the electron beam born in the gun into the amplifier structure), and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3-5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device than has been converted to-date in the extractor

  1. Sparking limits, cavity loading, and beam breakup instability associated with high-current rf linacs

    International Nuclear Information System (INIS)

    Faehl, R.J.; Lemons, D.S.; Thode, L.E.

    1982-01-01

    The limitations on high-current rf linacs due to gap sparking, cavity loading, and the beam breakup instability are studied. It appears possible to achieve cavity accelerating gradients as high as 35 MV/m without sparking. Furthermore, a linear analysis, as well as self-consistent particle simulations of a multipulsed 10 kA beam, indicated that only a negligible small fraction of energy is radiated into nonfundamental cavity modes. Finally, the beam breakup instability is analyzed and found to be able to magnify initial radial perturbations by a factor of no more than about 20 during the beam transit time through a 1 GeV accelerator

  2. High current electron beam acceleration in dielectric-filled RF cavities

    International Nuclear Information System (INIS)

    Faehl, R.J.; Keinigs, R.K.

    1996-01-01

    The acceleration of charged particles in radio frequency (RF) cavities is a widely used mode in high energy accelerators. Advantages include very high accelerating gradients and very stable phase control. A traditional limitation for such acceleration has been their use for intense, high current beam generation. This constraint arises from the inability to store a large amount of electromagnetic energy in the cavity and from loading effects of the beam on the cavity. The authors have studied a simple modification to transcend these limitations. Following Humphries and Huang, they have conducted analytic and numerical investigations of RF accelerator cavities in which a high dielectric constant material, such as water, replaces most of the cavity volume. This raises the stored energy in a cavity of given dimensions by a factor var-epsilon/var-epsilon 0 . For a water fill, var-epsilon/var-epsilon 0 ∼ 80, depending on the frequency. This introduction of high dielectric constant material into the cavity reduces the resonant frequencies by a factor of (var-epsilon/var-epsilon 0 ) 1/2 . This reduced operating frequency mans that existing high efficiency power supplies, at lower frequencies, can be used for an accelerator

  3. Recent developments in the application of rf superconductivity to high-brightness and high-gradient ion beam accelerators

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Nichols, G.L.; Roche, C.T.; Sagalovsky, L.

    1991-01-01

    A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high- brightness ion beams. Since the last workshop, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm 2 ) surface areas. Theoretical studies of beam impingement and cumulative beam breakup have also yielded encouraging results. Consequently, a section of superconducting resonators and focusing elements has been designed for tests with high-current deuteron beams. In addition, considerable data pertaining to the rf properties of high-T c superconductors has been collected at rf-field amplitudes and frequencies of interest in connection with accelerator operation. This paper summarizes the recent progress and identifies current and future work in the areas of accelerator technology and superconducting materials which will build upon it

  4. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    International Nuclear Information System (INIS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

    2010-01-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

  5. Analysis of RF section of 250 kW CW C-Band high power klystron

    International Nuclear Information System (INIS)

    Badola, Richa; Kaushik, Meenu; Baloda, Suman; Kirti; Vrati; Lamba, O.S.; Joshi, L.M.

    2012-01-01

    Klystron is a microwave tube which is used as a power amplifier in various applications like radar, particle accelerators and thermonuclear reactors. The paper deals with the analysis of RF section of 250 kW CW C band high power klystron for 50 to 60 kV beam voltage The simulation is done using Poisson's superfish and AJ disk software's Design of cavity is done using superfish. The result of superfish is used to decide the dimensions of the geometry of the cavity and AJ disk is used to determined the centre to centre distances between the cavities in order to obtain the desired powers. (author)

  6. Modelling of pulsed RF corona discharges in high-pressure air

    International Nuclear Information System (INIS)

    Auzas, F; Makarov, M; Naidis, G V

    2012-01-01

    An approach to description of pulsed RF corona discharges in high-pressure air is developed, based on the model of a filamentary discharge sustained by an electromagnetic wave guided along the plasma filament. Results of numerical simulation of spatial-temporal discharge dynamics at the quasi-stationary stage are obtained for various values of gas pressure and wave frequency. Experimental data on the discharge length versus the power absorbed by the discharge are presented. Their comparison with simulation results is given. (paper)

  7. High plasma rotation velocity and density transitions by biased electrodes in RF produced, magnetized plasma

    International Nuclear Information System (INIS)

    Matsuyama, Shoichiro; Shinohara, Shunjiro

    2001-01-01

    A large density profile modification was successfully obtained by voltage biasing to electrodes inserted in a RF (radio frequency) produced, magnetized plasma, and formation of strong shear of azimuthal plasma rotation velocity in a supersonic regime was found. For the case of biasing to an electrode near the central plasma region, two types of density transitions were observed in the outer plasma region: one was an oscillatory transition between two states, and the other was a transition from high to low density states with a large reduction of density fluctuations. (author)

  8. High plasma rotation velocity and density transitions by biased electrodes in RF produced, magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Shoichiro; Shinohara, Shunjiro [Kyushu Univ., Interdisciplinary Graduate School of Engineering Sciences, Fukuoka (Japan)

    2001-07-01

    A large density profile modification was successfully obtained by voltage biasing to electrodes inserted in a RF (radio frequency) produced, magnetized plasma, and formation of strong shear of azimuthal plasma rotation velocity in a supersonic regime was found. For the case of biasing to an electrode near the central plasma region, two types of density transitions were observed in the outer plasma region: one was an oscillatory transition between two states, and the other was a transition from high to low density states with a large reduction of density fluctuations. (author)

  9. Ka-Band Rf Transmission Line Components for a High-Gradient Linear Accelerator. Final report

    International Nuclear Information System (INIS)

    Hirshfield, Jay L.

    2005-01-01

    High-power, high-vacuum prototypes of a variety of components for use at 34 GHz were developed. These include waveguide tapers, right-angle miter bends, windows, mode converters, power combiners, mode launchers, phase shifters, dual directional couplers, and loads. High-power, high-vacuum prototypes of all the components were built and tested up to 45 MW, using the Omega-P 34-GHz magnicon. Peak power limits for the components were determined using a quasi-optical rf pulse compressor, developed under a companion project. The components and the magnicon were configured into a user's facility for research and development by others on high-gradient accelerator structures for a future high-energy electron-positron collider.

  10. Developments and directions in 200 MHz very high power RF at LAMPF

    International Nuclear Information System (INIS)

    Cliff, R.; Bush, E.D.; DeHaven, R.A.; Harris, H.W.; Parsons, M.

    1991-01-01

    The Los Alamos Meson Physics Facility (LAMPF), is a linear particle accelerator a half-mile long. It produces an 800 million electron- volt hydrogen-ion beam at an average current of more than one milliamp. The first RF section of the accelerator consists of four Alvarez drift-tube structures. Each of these structures is excited by an amplifier module at a frequency of 201.25 MHz. These amplifiers operate at a duty of 13 percent or more and at peak pulsed power levels of about 2.5 million watts. The second RF accelerator section consists of forty-four side-coupled-cavity structures. Each of these is excited by an amplifier module at a frequency of 805 MHz. These amplifiers operate at a duty of up to 12 percent and at peak pulsed power levels of about 1.2 million watts. The relatively high average beam current in the accelerator places a heavy demand upon components in the RF systems. The 201-MHz modules have always required a large share of maintenance efforts. In recent years, the four 201.25 MHz modules have been responsible for more than twice as much accelerator down-time as have the forty-four 805 MHz modules. This paper reviews recent, ongoing, and planned improvements in the 201-MHz systems. The Burle Industries 7835 super power triode is used in the final power amplifiers of each of the 201-MHz modules. This tube has been modified for operation at LAMPF by the addition of Penning ion vacuum''pumps.'' This has enabled more effective tube conditioning and restarting. A calorimetry system of high accuracy is in development to monitor tube plate-power dissipation

  11. High RF power test of a lower hybrid module mock-up in carbon fiber composite

    International Nuclear Information System (INIS)

    Goniche, M.; Bibet, P.; Brossaud, J.; Cano, V.; Froissard, P.; Kazarian, F.; Rey, G.; Maebara, S.; Kiyono, K.; Seki, M.; Suganuma, K.; Ikeda, Y.; Imai, T.

    1999-02-01

    A mock-up module of a Lower Hybrid Current Drive antenna module of a Carbon Fiber Composite (CFC) was fabricated for the development of heat resistive front facing the plasma. This module is made from CFC plates and rods which are copper coated to reduce the RF losses. The withstand-voltage, the RF properties and outgassing rates for long pulses and high RF power were tested at the Lower Hybrid test bed facility of Cadarache. After the short pulse conditioning, long pulses with a power density ranging between 50 and 150 MW/m 2 were performed with no breakdowns. During these tests, the module temperature was increasing from 100-200 deg. C to 400-500 deg. C. It was also checked that high power density, up to 150 MW/m 2 , could be transmitted when the waveguides are filled with H 2 at a pressure of 5 x 10 -2 Pa. No significant change in the reflection coefficient is measured after the long pulse operation. During a long pulse, the power reflection increases during the pulse typically from 0.8% to 1.3%. It is concluded that the outgassing rate of Cu-plated CFC is about 6 times larger than of Dispersion Strengthened Copper (DSC) module at the module temperature of 300 deg. C. No significant increase of the global outgassing of the CFC module was measured after hydrogen pre-filling. After the test, visual inspection revealed that peeling of the copper coating occurred at one end of the module only on a very small area (0.2 cm 2 ). It is assessed that a CFC module is an attractive candidate for the hardening of the tip of the LHCD antenna. (authors)

  12. High RF power test of a lower hybrid module mock-up in Carbon Fiber Composite

    International Nuclear Information System (INIS)

    Maebara, Sunao; Kiyono, Kimihiro; Seki, Masami

    1997-11-01

    A mock-up module of a Lower Hybrid Current Drive antenna module of a Carbon Fiber Composite (CFC) was fabricated for the development of heat resistive front facing the plasma. This module is made from CFC plates and rods which are copper coated to reduce the RF losses. The withstand-voltage, the RF properties and outgassing rates for long pulses and high RF power were tested at the Lower Hybrid test bed facility of Cadarache. After the short pulse conditioning, long pulses with a power density ranging between 50 and 150 MW/m 2 were performed with no breakdowns. During these tests, the module temperature was increasing from 100-200degC to 400-500degC. It was also checked that high power density, up to 150 MW/m 2 , could be transmitted when the waveguides are filled with H 2 at a pressure of 5 x 10 -2 Pa. No significant change in the reflection coefficient is measured after the long pulse operation. During a long pulse, the power reflection increases during the pulse typically from 0.8 % to 1.3 %. It is concluded that the outgassing rate of Cu-plated CFC is about 6-7 times larger than of Dispersion Strengthened Copper (DSC) module at the module temperature of 300degC. No significant increase of the global outgassing of the CFC module was measured after hydrogen prefilling. After the test, visual inspection revealed that peeling of the copper coating occurred at one end of the module only on a very small area (0.2 cm 2 ). It is assessed that a CFC module is an attractive candidate for the hardening of the tip of the LHCD antenna. (author)

  13. Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

    Science.gov (United States)

    Lin, James C; Wang, Zhangwei

    2010-04-01

    The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

  14. Active high-power RF pulse compression using optically switched resonant delay lines

    International Nuclear Information System (INIS)

    Tantawi, S.G.; Ruth, R.D.; Vlieks, A.E.

    1996-11-01

    The authors present the design and a proof of principle experimental results of an optically controlled high power rf pulse compression system. The design should, in principle, handle few hundreds of Megawatts of power at X-band. The system is based on the switched resonant delay line theory. It employs resonant delay lines as a means of storing rf energy. The coupling to the lines is optimized for maximum energy storage during the charging phase. To discharge the lines, a high power microwave switch increases the coupling to the lines just before the start of the output pulse. The high power microwave switch, required for this system, is realized using optical excitation of an electron-hole plasma layer on the surface of a pure silicon wafer. The switch is designed to operate in the TE 01 mode in a circular waveguide to avoid the edge effects present at the interface between the silicon wafer and the supporting waveguide; thus, enhancing its power handling capability

  15. A Novel Technique for Design of Ultra High Tunable Electrostatic Parallel Plate RF MEMS Variable Capacitor

    Science.gov (United States)

    Baghelani, Masoud; Ghavifekr, Habib Badri

    2017-12-01

    This paper introduces a novel method for designing of low actuation voltage, high tuning ratio electrostatic parallel plate RF MEMS variable capacitors. It is feasible to achieve ultra-high tuning ratios way beyond 1.5:1 barrier, imposed by pull-in effect, by the proposed method. The proposed method is based on spring strengthening of the structure just before the unstable region. Spring strengthening could be realized by embedding some dimples on the spring arms with the precise height. These dimples shorten the spring length when achieved to the substrate. By the proposed method, as high tuning ratios as 7.5:1 is attainable by only considering four dimple sets. The required actuation voltage for this high tuning ratio is 14.33 V which is simply achievable on-chip by charge pump circuits. Brownian noise effect is also discussed and mechanical natural frequency of the structure is calculated.

  16. High-charge s-band photocathode RF-gun and linac system for radiation research

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Tetsuya; Uesaka, Mitsuru; Katsumura, Yousuke [Univ. of Tokyo, Graduate School of Engineering, Nuclear Engineering Research Laboratory, Tokai, Ibaraki (JP)] (and others)

    2002-01-01

    For sub-picosecond pump-and-prove-type radiation chemistry work, a new synchronized electron linac and laser system was installed in the Nuclear Engineering Research Laboratory (NERL) of University of Tokyo. The new laser system, with a Ti:Sapphire oscillator (795 nm) and amplifiers, generates 300 ps pulses at 10 Hz. The laser is transported through the vacuum chamber and then split into two beams. The first is compressed and converted to the third harmonics (265 nm, <250 {mu}J, 4-11 ps) so as to drive the photocathode RF-gun and generate a pump-electron beam. The second is compressed to 100 fs and used for the probe light. The high-power RF, which is provided by a new 15 MW klystron, is divided into the gun and the accelerating section. Finally, a time jitter of 330 fs (rms) was achieved between the pump-electron beam and the probe laser, which is equivalent to the design value of 320 fs. A charge of 7 nC/bunch was observed at the exit of the gun from this new laser system. Improvement of the vacuum in the gun (<10{sup -9} Torr) is the most effective way to obtain such a high-charge beam. After about three years of operation, the Cu photocathode has shown no degradation of quantum efficiency. (author)

  17. Multi-service highly sensitive rectifier for enhanced RF energy scavenging.

    Science.gov (United States)

    Shariati, Negin; Rowe, Wayne S T; Scott, James R; Ghorbani, Kamran

    2015-05-07

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478-496 and 852-869 MHz) and exhibits favorable impedance matching over a broad input power range (-40 to -10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of -10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments.

  18. Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging

    Science.gov (United States)

    Shariati, Negin; Rowe, Wayne S. T.; Scott, James R.; Ghorbani, Kamran

    2015-01-01

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478–496 and 852–869 MHz) and exhibits favorable impedance matching over a broad input power range (−40 to −10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of −10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

  19. Wireless Capacitive Pressure Sensor With Directional RF Chip Antenna for High Temperature Environments

    Science.gov (United States)

    Scardelletti, M. C.; Jordan, J. L.; Ponchak, G. E.; Zorman, C. A.

    2015-01-01

    This paper presents the design, fabrication and characterization of a wireless capacitive pressure sensor with directional RF chip antenna that is envisioned for the health monitoring of aircraft engines operating in harsh environments. The sensing system is characterized from room temperature (25 C) to 300 C for a pressure range from 0 to 100 psi. The wireless pressure system consists of a Clapp-type oscillator design with a capacitive MEMS pressure sensor located in the LC-tank circuit of the oscillator. Therefore, as the pressure of the aircraft engine changes, so does the output resonant frequency of the sensing system. A chip antenna is integrated to transmit the system output to a receive antenna 10 m away.The design frequency of the wireless pressure sensor is 127 MHz and a 2 increase in resonant frequency over the temperature range of 25 to 300 C from 0 to 100 psi is observed. The phase noise is less than minus 30 dBcHz at the 1 kHz offset and decreases to less than minus 80 dBcHz at 10 kHz over the entire temperature range. The RF radiation patterns for two cuts of the wireless system have been measured and show that the system is highly directional and the MEMS pressure sensor is extremely linear from 0 to 100 psi.

  20. Rf systems for high-energy e/sup /minus//e/sup /plus// storage rings

    International Nuclear Information System (INIS)

    Allen, M.A.; Wilson, P.B.

    1974-01-01

    Electron or positron beams in a storage ring radiate electromagnetic energy at a rate proportional to the fourth power of the recirculating energy, and this loss must be supplied by an rf system. Furthermore, a substantial overvoltage is required to contain the stored beam against losses due to quantum fluctuations in the emitted photons. As an example, an improvement program, SPEAR II, is now underway to increase the energy of the SPEAR ring to 4.5 GeV. At this energy, the radiation loss per turn is 2.8 MeV, and to maintain a reasonable lifetime against quantum fluctuations, a peak voltage of 7.5 MeV is required. Thus, the SPEAR II rf system is similar to a continuously-operating 7.5 MeV linear accelerator. Furthermore, the available straight-section space in the ring which is suitable for containing the accelerating structures is limited, and this means that a cavity design must be sought with a high shunt impedance per losses will be held to a reasonable level. In the case of SPEAR, about 9 meters of straight section space is available for accelerating cavities, requiring a gradient of close to 1 MV per meter. The PEP 15-GeV ring would require peak accelerating voltages of around 50 MV, with about 60 meters of straight-section space available for accelerating structures. 8 refs

  1. High-power rf pulse compression with SLED-II at SLAC

    International Nuclear Information System (INIS)

    Nantista, C.

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE 01 mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator)

  2. High power RF performance test of an improved SiC load

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, W.H.; Kim, S.H.; Park, Y.J. [Pohang Accelerator Lab., Pohang Inst. of Sceince and Technology, Pohang (KR)] [and others

    1998-11-01

    Two prototypes of SiC loads sustaining a maximum peak power of 50 MW were fabricated by Nihon Koshuha Co. in Japan. The PAL conducted the high power RF performance tests of SiC loads to verify the operation characteristics for the application to the PLS Linac. The in-situ facility for the K 12 module was used for the test, which consists of a modulator and klystron system, waveguide network, vacuum and cooling system, and RF analyzing equipment. As the test results, no breakdown appeared up to 50 MW peak power of 1 {mu}s pulse width at a repetition rate of 50 Hz. However, as the peak power increased above 20 MW at 4 {mu}s with 10 Hz, the breakdown phenomena has been observed. Analysing the test results with the current operation power level of PLS Linac, it is confirmed that the SiC loads well satisfy the criteria of the PLS Linac operation. (author)

  3. Design and development of power supplies for high power IOT based RF amplifier

    International Nuclear Information System (INIS)

    Kumar, Yashwant; Kumari, S.; Ghosh, M.K.; Bera, A.; Sadhukhan, A.; Pal, S.S.; Khare, V.K.; Tiwari, T.P.; Thakur, S.K.; Saha, S.

    2013-01-01

    Design, development, circuit topology, function of system components and key system specifications of different power supplies for biasing electrodes of Thales Inductive Output Tube (IOT) based high power RF amplifier are presented in this paper. A high voltage power supply (-30 kV, 3.2A dc) with fast (∼microsecond) crowbar protection circuit is designed, developed and commissioned at VECC for testing the complete setup. Other power supplies for biasing grid electrode (300V, 0.5A dc) and Ion Pump (3 kV, 0.1mA dc) of IOT are also designed, developed and tested with actual load. A HV Deck (60kV Isolation) is specially designed in house to place these power supplies which are floating at 30 kV. All these power supplies are powered by an Isolation Transformer (5 kVA, 60 kV isolation) designed and developed in VECC. (author)

  4. A highly sensitive RF-to-DC power converter with an extended dynamic range

    KAUST Repository

    Almansouri, Abdullah Saud Mohammed

    2017-10-24

    This paper proposes a highly sensitive RF-to-DC power converter with an extended dynamic range that is designed to operate at the medical band 433 MHz and simulated using 0.18 μm CMOS technology. Compared to the conventional fully cross-coupled rectifier, the proposed design offers 3.2× the dynamic range. It is also highly sensitive and requires −18 dBm of input power to produce a 1 V-output voltage when operating with a 100 kΩ load. Furthermore, the proposed design offers an open circuit sensitivity of −23.4 dBm and a peak power conversion efficiency of 67%.

  5. SiGe HBT linear-in-dB high dynamic range RF envelope detectors and wideband high linearity amplifiers

    OpenAIRE

    Pan, Hsuan-yu

    2010-01-01

    This research work aims on exploiting SiGe HBT technologies in high dynamic range wideband RF linear-in- dB envelope detectors and linear amplifiers. First, an improved all-npn broadband highly linear SiGe HBT differential amplifier is presented based on a variation of Caprio's Quad. A broadband linear amplifier with 46dBm OIP₃ at 20MHz, 34dBm OIP₃ at 1GHz, 6dB noise figure and 10.3dBm P₁dB is demonstrated. Second, an improved exact dynamic model of a fast-settling linear-in-dB Automatic Gain...

  6. Quasi-Optical Network Analyzers and High-Reliability RF MEMS Switched Capacitors

    Science.gov (United States)

    Grichener, Alexander

    The thesis first presents a 2-port quasi-optical scalar network analyzer consisting of a transmitter and receiver both built in planar technology. The network analyzer is based on a Schottky-diode mixer integrated inside a planar antenna and fed differentially by a CPW transmission line. The antenna is placed on an extended hemispherical high-resistivity silicon substrate lens. The LO signal is swept from 3-5 GHz and high-order harmonic mixing in both up- and down- conversion mode is used to realize the 15-50 GHz RF bandwidth. The network analyzer resulted in a dynamic range of greater than 40 dB and was successfully used to measure a frequency selective surface with a second-order bandpass response. Furthermore, the system was built with circuits and components for easy scaling to millimeter-wave frequencies which is the primary motivation for this work. The application areas for a millimeter and submillimeter-wave network analyzer include material characterization and art diagnostics. The second project presents several RF MEMS switched capacitors designed for high-reliability operation and suitable for tunable filters and reconfigurable networks. The first switched-capacitor resulted in a digital capacitance ratio of 5 and an analog capacitance ratio of 5-9. The analog tuning of the down-state capacitance is enhanced by a positive vertical stress gradient in the the beam, making it ideal for applications that require precision tuning. A thick electroplated beam resulted in Q greater than 100 at C to X-band frequencies, and power handling of 0.6-1.1 W. The design also minimized charging in the dielectric, resulting in excellent reliability performance even under hot-switched and high power (1 W) conditions. The second switched-capacitor was designed without any dielectric to minimize charging. The device was hot-switched at 1 W of RF power for greater than 11 billion cycles with virtually no change in the C-V curve. The final project presents a 7-channel

  7. High Pressure Gas Filled RF Cavity Beam Test at the Fermilab MuCool Test Area

    Energy Technology Data Exchange (ETDEWEB)

    Freemire, Ben [Illinois Inst. of Technology, Chicago, IL (United States)

    2013-05-01

    The high energy physics community is continually looking to push the limits with respect to the energy and luminosity of particle accelerators. In the realm of leptons, only electron colliders have been built to date. Compared to hadrons, electrons lose a large amount of energy when accelerated in a ring through synchrotron radiation. A solution to this problem is to build long, straight accelerators for electrons, which has been done with great success. With a new generation of lepton colliders being conceived, building longer, more powerful accelerators is not the most enticing option. Muons have been proposed as an alternative particle to electrons. Muons lose less energy to synchrotron radiation and a Muon Collider can provide luminosity within a much smaller energy range than a comparable electron collider. This allows a circular collider to be built with higher attainable energy than any present electron collider. As part of the accelerator, but separate from the collider, it would also be possible to allow the muons to decay to study neutrinos. The possibility of a high energy, high luminosity muon collider and an abundant, precise source of neutrinos is an attractive one. The technological challenges of building a muon accelerator are many and diverse. Because the muon is an unstable particle, a muon beam must be cooled and accelerated to the desired energy within a short amount of time. This requirement places strict requisites on the type of acceleration and focusing that can be used. Muons are generated as tertiary beams with a huge phase space, so strong magnetic fields are required to capture and focus them. Radio frequency (RF) cavities are needed to capture, bunch and accelerate the muons. Unfortunately, traditional vacuum RF cavities have been shown to break down in the magnetic fields necessary for capture and focusing.

  8. Time Dependent Quantum Efficiency and Dark Current Measurements in an RF Photocathode Injector with a High Quantum Efficiency Cathode

    CERN Document Server

    Fliller, Raymond P; Hartung, Walter

    2005-01-01

    A system was developed at INFN Milano for preparing cesium telluride photo-cathodes and transferring them into an RF gun under ultra-high vacuum. This system has been in use at the Fermilab NICADD Photo-Injector Laboratory (FNPL) since 1997. A similar load-lock system is used at the TeSLA Test Facility at DESY-Hamburg. Two 1.625-cell high duty cycle RF guns have been fabricated for the project. Studies of the photo-emission and field emission ("dark current") behavior of both RF guns have been carried out. Unexpected phenomena were observed in one of the RF guns. In situ changes in the cathode's quantum efficiency and dark current with time were seen during operation of the photo-injector. These changes were correlated with the magnetostatic field at the cathode.* In addition, multipacting is observed in the RF guns under certain conditions. Recent measurements indicate a correlation between multipacting, anomalous photo-emission behavior, and anomalous field emission behavior. Results will be presented.

  9. Development of L-band niobium superconducting RF cavities with high accelerating field

    International Nuclear Information System (INIS)

    Saito, Kenji; Noguchi, Shuichi; Ono, Masaaki; Kako, Eiji; Shishido, Toshio; Matsuoka, Masanori; Suzuki, Takafusa; Higuchi, Tamawo.

    1994-01-01

    Superconducting RF cavity is a candidate for the TeV energy e + /e - linear collider of next generation if the accelerating field is improved to 25-30 MV/m and much cost down is achieved in cavity fabrication. Since 1990, KEK has continued R and D of L-band niobium superconducting cavities focusing on the high field issue. A serious problem like Q-degradation due to vacuum discharge came out on the way, however, it has been overcome and presently all of cavities which were annealed at 1400degC achieved the accelerating field of >25 MV/m with enough Qo value. Recent results on single cell cavities are described in this paper. (author)

  10. The production of high poloidal tokamak equilibria in Versator II by means of RF current drive

    International Nuclear Information System (INIS)

    Luckhardt, S.C.; Chen, K.-I.; Kesner, J.; Kirkwood, R.; Lane, B.; Porkolab, M.; Squire, J.

    1989-01-01

    Experiments on the Versator II device have been carried out in a regime of low plasma current with the aim of reaching high poloidal beta, β p . Lower-Hybrid RF current drive is used to produce an energetic electron population which carries the plasma current and pressure. In this mode of operation, plasmas with εβ p approaching unity appear attainable. Data from equilibrium magnetic analysis, hard x-ray, and density profiles display an outward magnetic axis shift in agreement with equilibrium theory, and further indicate that q(O) is in the range of 4-6. PEST code modeling of these experiments suggests that some of these plasmas may be near or beyond the transition to the second stability region for ballooning modes. (author)

  11. Low Cost SU8 Based Above IC Process for High Q RF Power Inductors Integration

    International Nuclear Information System (INIS)

    Ghannam, A.; Bourrier, D.; Viallon, Ch.; Parra, Th.

    2011-01-01

    This paper presents a new process for integration of high-Q RF power inductors above low resistivity silicon substrates. The process uses the SU8 resin as a dielectric layer. The aim of using the SU8 is to form thick dielectric layer that can enhance the performance of the inductors. The flexibility of the process enables the possibility to realize complex shaped planar inductors with various dielectric and metal thicknesses to meet the requirements of the application. Q values of 55 at 5 GHz has been demonstrated for an inductance value of 0.8 nH using a 60 μm thick SU8 layer and 30 μm thick copper ribbons. (author)

  12. Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

    Directory of Open Access Journals (Sweden)

    Hikaru Akahoshi

    2018-03-01

    Full Text Available High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

  13. Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

    Science.gov (United States)

    Akahoshi, Hikaru; Takahashi, Kazunori; Ando, Akira

    2018-03-01

    High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf) inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

  14. RF-MEMS Technology for High-Performance Passives; The challenge of 5G mobile applications

    Science.gov (United States)

    Iannacci, Jacopo

    2017-11-01

    Commencing with a review of the characteristics of RF-MEMS in relation to 5G, the book proceeds to develop practical insight concerning the design and development of RF-MEMS including case studies of design concepts. Including multiphysics simulation and animated figures, the book will be essential reading for both academic and industrial researchers and engineers.

  15. Design and RF test result of High Power Hybrid Combiner for Helicon Wave Current Drive in KSTAR Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)

    2016-05-15

    200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.

  16. Investigation of the influence of growth parameters on self-catalyzed ITO nanowires by high RF-power sputtering

    Science.gov (United States)

    Li, Qiang; Zhang, Yuantao; Feng, Lungang; Wang, Zuming; Wang, Tao; Yun, Feng

    2018-04-01

    Tin-doped indium oxide (ITO) nanowires are successfully fabricated using a radio frequency (RF) sputtering technique with a high RF power of 250 W. The fabrication of the ITO nanowires is optimized through the study of oxygen flow rates, temperatures and RF power. The difference in the morphology of the ITO nanowires prepared by using a new target and a used target is observed and the mechanism for the difference is discussed in detail. A hollow structure and air voids within the nanowires are formed during the process of the nanowire growth. The ITO nanowires fabricated by this method demonstrated good conductivity (15 Ω sq-1) and a transmittance of more than 64% at a wavelength longer than 550 nm after annealing. Furthermore, detailed microstructure studies show that the ITO nanowires exhibit a large number of oxygen vacancies. As a result, it is expected that they can be useful for the fabrication of gas sensor devices.

  17. Development of high pressure rinsing set up for 650 MHz, 5- cell superconducting RF cavity cleaning

    International Nuclear Information System (INIS)

    Suhane, S.K.; Chauhan, S.K.; Bose, A.; Kokil, S.V.; Rajput, D.S.; Oraon, B.; Md Hussain; Sahu, A.; Raghavendra, S.; Joshi, S.C.

    2015-01-01

    High pressure rinsing (HPR) is an ultra-cleanliness process for the surface preparation of high field superconducting RF cavities. Any dust particle or chemical residue on the interior of cavity causes field emission. Jets of high pressure (80-100 bar) ultra pure water dislodge surface contaminants that normally resist removal with conventional rinsing procedures, leading to substantial reduction in field emission and better cavity performance. For cleaning of 650 MHz, 5-cell SRF cavities, a high pressure rinsing set up has been developed at RRCAT. The HPR tool has a rotating wand coaxial with the vertically mounted SRF cavity that is moving up and down. Fan style spray nozzles are attached to the end of the rotating wand and the water jets emerging from spray nozzles scan the entire internal surface of the cavity. The set-up was installed in a specially built clean area meeting cleanliness class 100 standards. The ultrapure water with resistivity 2 ≥ 18 MΩ-cm required for rinsing is obtained from a dedicated water purification system installed for this purpose. The paper describes the salient design and constructional details of the high pressure rinsing set up. Characterization of water jet parameters based on the momentum transfer between the water jet and a load cell is also presented. (author)

  18. Development of high power CW and pulsed RF test facility based on 1 MW, 352.2 MHz klystron amplifier

    International Nuclear Information System (INIS)

    Badapanda, M.K.; Tripathi, Akhilesh; Upadhyay, Rinki; Rao, J.N.; Tiwari, Ashish; Jain, Akhilesh; Lad, M.R.; Hannurkar, P.R.

    2013-01-01

    A high power 1 MW, 352.2 MHz RF Test facility having CW and Pulse capability is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for performance evaluation of various RF components, accelerating structures and related subsystems. Thales make 1 MW, 352.2 MHz klystron amplifier (TH 2089) will be employed in this high power test facility, which is thoroughly tested for its performance parameters at rated operating conditions. Auxiliary power supplies like filament, electromagnet, ion pump and mod anode power supply as well as 200 W solid state driver amplifier necessary for this high power test facility have been developed. A high voltage floating platform is created for floating filament and mod anode power supplies. Interconnection of various power supplies and other subsystems of this test facility are being carried out. A high voltage 100 kV, 25 Amp DC crowbar less power supply and low conductivity water (LCW) plant required for this klystron amplifier are in advanced stage of development. NI make cRIO 9081 real time (RT) controller based control and interlock system has been developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test facility. This RF test facility will provide confidence for development of RF System of future accelerators like SNS and ADSS. (author)

  19. Characterization and evaluation of a flexible MRI receive coil array for radiation therapy MR treatment planning using highly decoupled RF circuits

    Science.gov (United States)

    McGee, Kiaran P.; Stormont, Robert S.; Lindsay, Scott A.; Taracila, Victor; Savitskij, Dennis; Robb, Fraser; Witte, Robert J.; Kaufmann, Timothy J.; Huston, John, III; Riederer, Stephen J.; Borisch, Eric A.; Rossman, Phillip J.

    2018-04-01

    The growth in the use of magnetic resonance imaging (MRI) data for radiation therapy (RT) treatment planning has been facilitated by scanner hardware and software advances that have enabled RT patients to be imaged in treatment position while providing morphologic and functional assessment of tumor volumes and surrounding normal tissues. Despite these advances, manufacturers have been slow to develop radiofrequency (RF) coils that closely follow the contour of a RT patient undergoing MR imaging. Instead, relatively large form surface coil arrays have been adapted from diagnostic imaging. These arrays can be challenging to place on, and in general do not conform to the patient’s body habitus, resulting in sub optimal image quality. The purpose of this study is to report on the characterization of a new flexible and highly decoupled RF coil for use in MR imaging of RT patients. Coil performance was evaluated by performing signal-to-noise ratio (SNR) and noise correlation measurements using two coil (SNR) and four coil (noise correlation) element combinations as a function of coil overlap distance and comparing these values to those obtained using conventional coil elements. In vivo testing was performed in both normal volunteers and patients using a four and 16 element RF coil. Phantom experiments demonstrate the highly decoupled nature of the new coil elements when compared to conventional RF coils, while in vivo testing demonstrate that these coils can be integrated into extremely flexible and form fitting substrates that follow the exact contour of the patient. The new coil design addresses limitations imposed by traditional surface coil arrays and have the potential to significantly impact MR imaging for both diagnostic and RT applications.

  20. Design and modeling of a 17 GHz photocathode RF gun

    International Nuclear Information System (INIS)

    Lin, C.L.; Chen, S.C.; Wurtele, J.S.; Temkin, R.; Danly, B.

    1991-01-01

    The performance of a high-frequency (17 GHz), high accelerating gradient (250 MV/m) photocathode RF gun is studied with the particle-in-cell code MAGIC. For the parameter regime of interest, i.e. bunch charge smaller than 1 nC and bunch length shorter than 2 ps, space-charge forces and finite bunch length effects are less significant in determining the beam quality than nonlinear RF forces are. The cavity geometry, RF phase for photoemission, cathode size, and current density are being optimized to obtain high quality beams. Preliminary results are presented

  1. Design development and testing of high voltage power supply with crowbar protection for IOT based RF amplifier system in VECC

    Science.gov (United States)

    Thakur, S. K.; Kumar, Y.

    2018-05-01

    This paper described the detailed design, development and testing of high voltage power supply (‑30 kV, 3.2 A) and different power supplies for biasing electrodes of Inductive Output Tube (IOT) based high power Radio Frequency (RF) amplifier. This IOT based RF amplifier is further used for pursuing research and development activity in superconducting RF cavity project at Variable Energy Cyclotron Centre (VECC) Kolkata. The state-of-the-art technology of IOT-based high power RF amplifier is designed, developed, and tested at VECC which is the first of its kind in India. A high voltage power supply rated at negative polarity of 30 kV dc/3.2 A is required for biasing cathode of IOT with crowbar protection circuit. This power supply along with crowbar protection system is designed, developed and tested at VECC for testing the complete setup. The technical difficulties and challenges occured during the design of cathode power supply, its crowbar protection techniques along with other supported power supplies i.e. grid and ion pump power supplies are discussed in this paper.

  2. Reduction of field emission in superconducting cavities with high power pulsed RF

    International Nuclear Information System (INIS)

    Graber, J.; Crawford, C.; Kirchgessner, J.; Padamsee, H.; Rubin, D.; Schmueser, P.

    1994-01-01

    A systematic study is presented of the effects of pulsed high power RF processing (HPP) as a method of reducing field emission (FE) in superconducting radio frequency (SRF) cavities to reach higher accelerating gradients for future particle accelerators. The processing apparatus was built to provide up to 150 kW peak RF power to 3 GHz cavities, for pulse lengths from 200 μs to 1 ms. Single-cell and nine-cell cavities were tested extensively. The thermal conductivity of the niobium for these cavities was made as high as possible to ensure stability against thermal breakdown of superconductivity. HPP proves to be a highly successful method of reducing FE loading in nine-cell SRF cavities. Attainable continuous wave (CW) fields increase by as much as 80% from their pre-HPP limits. The CW accelerating field achieved with nine-cell cavities improved from 8-15 MV/m with HPP to 14-20 MV/m. The benefits are stable with subsequent exposure to dust-free air. More importantly, HPP also proves effective against new field emission subsequently introduced by cold and warm vacuum ''accidents'' which admitted ''dirty'' air into the cavities. Clear correlations are obtained linking FE reduction with the maximum surface electric field attained during processing. In single cells the maximums reached were E peak =72 MV/m and H peak =1660 Oe. Thermal breakdown, initiated by accompanying high surface magnetic fields is the dominant limitation on the attainable fields for pulsed processing, as well as for final CW and long pulse operation. To prove that the surface magnetic field rather than the surface electric fields is the limitation to HPP effectiveness, a special two-cell cavity with a reduced magnetic to electric field ratio is successfully tested. During HPP, pulsed fields reach E peak =113 MV/m (H peak =1600 Oe) and subsequent CW low power measurement reached E peak =100 MV/m, the highest CW field ever measured in a superconducting accelerator cavity. ((orig.))

  3. A compact high-gradient 25 MeV 17 GHz RF linac for free-electron laser research

    International Nuclear Information System (INIS)

    Danly, B.G.; Chen, S.C.; Kreischer, K.E.

    1995-01-01

    A new compact high-gradient (60 MeV/m) high-frequency (17.136 GHz) RF linac is presently under construction by Haimson Research Corp. (HRC) for installation at the MIT Plasma Fusion Center in the High-Gradient Accelerator and High Power Microwave Laboratory. This accelerator will utilize an existing traveling-wave relativistic klystron (TWRK) which is now operation at MIT with 25 MW power, 67 dB gain, and 52% efficiency at 17.136 GHz

  4. SQIF Arrays as RF Sensors (Briefing Charts)

    National Research Council Canada - National Science Library

    Yukon, Stanford P

    2007-01-01

    ... (Superconducting Quantum Interference Filter) arrays may be employed as sensitive RF sensors. RF SQIF arrays fabricated with high Tc Josephson junctions can be cooled with small Sterling microcoolers...

  5. Look at energy compression as an assist for high power rf production

    International Nuclear Information System (INIS)

    Birx, D.L.; Farkas, Z.D.; Wilson, P.B.

    1984-01-01

    The desire to construct electron linacs of higher and higher energies, coupled with the realities of available funding and real estate, has forced machine designers to reassess the limitations in both accelerator gradient (MeV/m) and energy. The gradients achieved in current radio-frequency (RF) linacs are sometimes set by electrical breakdown in the accelerating structure, but are in most cases determined by the RF power level available to drive the linac. In this paper we will not discuss RF power sources in general, but rather take a brief look at several energy compression schemes which might be of service in helping to make better use of the sources we employ. We will, however, diverge for a bit and discuss what the RF power requirements are. 12 references, 21 figures, 3 tables

  6. Very Low NF, High DR Heterodyne RF Lightwave Links Using a Simple, Versatile Photonic Integration Technology

    National Research Council Canada - National Science Library

    Forrest, Stephen R

    2006-01-01

    ...: Demonstration of a versatile integration technology based on the asymmetric twin waveguide platform that allowed for the realization of a broad range of components useful in RF photonic components...

  7. RF Noise Generation in High-Pressure Short-Arc DC Xenon Lamps

    Science.gov (United States)

    Minayeva, Olga; Doughty, Douglas

    2007-10-01

    Continuous direct current xenon arcs will generate RF noise under certain circumstance, which can lead to excessive electro- magnetic interference in systems that use these arcs as light sources. Phenomenological observations are presented for xenon arcs having arc gaps ˜1 mm, cold fill pressures of ˜2.5 MPa, and currents up to 30 amps. Using a loop antenna in the vicinity of an operating lamp, it is observed that as the current to the arc is lowered there is a reproducible threshold at which the RF noise generation begins. This threshold is accompanied by a small abrupt drop in voltage (˜0.2 volts). The RF emission appears in pulses ˜150 nsec wide separated by ˜300 nec - the pulse interval decreases with decreasing current. The properties of the RF emission as a function of arc parameters (such as pressure, arc gap, electrode design) will be discussed and a semi-quantitative model presented.

  8. High field side launch of RF waves: A new approach to reactor actuators

    Science.gov (United States)

    Wallace, G. M.; Baek, S. G.; Bonoli, P. T.; Faust, I. C.; LaBombard, B. L.; Lin, Y.; Mumgaard, R. T.; Parker, R. R.; Shiraiwa, S.; Vieira, R.; Whyte, D. G.; Wukitch, S. J.

    2015-12-01

    Launching radio frequency (RF) waves from the high field side (HFS) of a tokamak offers significant advantages over low field side (LFS) launch with respect to both wave physics and plasma material interactions (PMI). For lower hybrid (LH) waves, the higher magnetic field opens the window between wave accessibility (n∥≡c k∥/ω >√{1 -ωpi 2/ω2+ωpe 2/ωce 2 }+ωp e/|ωc e| ) and the condition for strong electron Landau damping (n∥˜√{30 /Te } with Te in keV), allowing LH waves from the HFS to penetrate into the core of a burning plasma, while waves launched from the LFS are restricted to the periphery of the plasma. The lower n∥ of waves absorbed at higher Te yields a higher current drive efficiency as well. In the ion cyclotron range of frequencies (ICRF), HFS launch allows for direct access to the mode conversion layer where mode converted waves absorb strongly on thermal electrons and ions, thus avoiding the generation of energetic minority ion tails. The absence of turbulent heat and particle fluxes on the HFS, particularly in double null configuration, makes it the ideal location to minimize PMI damage to the antenna structure. The quiescent SOL also eliminates the need to couple LH waves across a long distance to the separatrix, as the antenna can be located close to plasma without risking damage to the structure. Improved impurity screening on the HFS will help eliminate the long-standing issues of high Z impurity accumulation with ICRF. Looking toward a fusion reactor, the HFS is the only possible location for a plasma-facing RF antenna that will survive long-term. By integrating the antenna into the blanket module it is possible to improve the tritium breeding ratio compared with an antenna occupying an equatorial port plug. Blanket modules will require remote handling of numerous cooling pipes and electrical connections, and the addition of transmission lines will not substantially increase the level of complexity. The obvious engineering

  9. RF heating and current drive on NSTX with high harmonic fast waves

    International Nuclear Information System (INIS)

    Ryan, P.M.; Swain, D.W.; Rosenberg, A.L.

    2003-01-01

    NSTX is a small aspect ratio tokamak (R = 0.85 m, a = 0.65 m). The High Harmonic Fast Wave (HHFW) system is a 30 MHz, 12-element array capable of launching both symmetric and directional wave spectra for plasma heating and non-inductive current drive. It has delivered up to 6 MW for short pulses and has routinely operated at ∼3 MW for 100-400 ms pulses. Results include strong, centrally-peaked electron heating in both D and He plasmas for both high and low phase velocity spectra. H-modes were obtained with application of HHFW power alone, with stored energy doubling after the L-H transition. Beta poloidal as large as unity has been obtained with significant fractions (0.4) of bootstrap current. Differences in the loop voltage are observed depending on whether the array is phased to drive current in the co- or counter-current directions. A fast ion tail with energies extending up to 140 keV has been observed when HHFW interacts with 80 keV neutral beams; neutron rate and lost ion measurements, as well as modeling, indicate significant power absorption by the fast ions. Radial rf power deposition and driven current profiles have been calculated with ray tracing and kinetic full-wave codes and compared with measurements. (author)

  10. A High-Intensity, RF Plasma-Sputter Negative Ion Source

    International Nuclear Information System (INIS)

    Alton, G.D.; Bao, Y.; Cui, B.; Lohwasser, R.; Reed, C.A.; Zhang, T.

    1999-01-01

    A high-intensity, plasma-sputter negative-ion source based on the use of RF power for plasma generation has been developed that can be operated in either pulsed or dc modes. The source utilizes a high-Q, self-igniting, inductively coupled antenna system, operating at 80 MHz that has been optimized to generate Cs-seeded plasmas at low pressures (typically, - (610 microA); F - (100 microA); Si - (500 microA); S - (500 microA); P - (125 microA); Cl - (200 microA); Ni - (150 microA); Cu - (230 microA); Ge - (125 microA); As - (100 microA); Se - (200 microA); Ag - (70 microA); Pt - (125 microA); Au - (250 microA). The normalized emittance var e psilon n of the source at the 80% contour is: var e psilon n = 7.5 mm.mrad.(MeV) 1/2 . The design principles of the source, operational parameters, ion optics, emittance and intensities for a number of negative-ion species will be presented in this report

  11. Performance enhancement of high-field asymmetric waveform ion mobility spectrometry by applying differential-RF-driven operation mode.

    Science.gov (United States)

    Zeng, Yue; Tang, Fei; Zhai, Yadong; Wang, Xiaohao

    2017-09-01

    The traditional operation mode of high-field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) uses a one-way radio frequency (RF) voltage input as the dispersion voltage. This requires a high voltage input and limits power consumption reduction and miniaturization of instruments. With higher dispersion voltages or larger compensation voltages, there also exist problems such as low signal intensity or the fact that the dispersion voltage is no longer much larger than the compensation voltage. In this paper, a differential-RF-driven operation mode of FAIMS is proposed. The two-way RF is used to generate the dispersion field, and a phase difference is added between the two RFs to generate a single step waveform field. Theoretical analysis, and experimental results from an ethanol sample, showed that the peak positions of the ion spectra changed linearly (R 2 = 0.9992) with the phase difference of the two RFs in the differential-RF-driven mode and that the peak intensity of the ion spectrum could be enhanced by more than eight times for ethanol ions. In this way, it is possible to convert the ion spectrum peaks outside the separation or compensation voltage range into a detectable range, by changing the phase difference. To produce the same separation electric field, the high-voltage direct current input voltage can be maximally reduced to half of that in the traditional operation mode. Without changing the drift region size or drift condition, the differential-RF-driven operation mode can reduce power consumption, increase signal-to-noise ratio, extend the application range of the dispersion voltage and compensation voltage, and improve FAIMS detection performance.

  12. Hearthfire design base for the high current low velocity rf linac

    International Nuclear Information System (INIS)

    Burke, R.J.; Khoe, T.K.; Kustom, R.L.; Martin, R.L.; Moretti, A.

    1977-01-01

    The particle beam parameters needed for inertial fusion can be achieved with conventional accelerator technology if heavy ion machines attain the level of performance of the most intense high energy proton machines. Many of the problems posed by this goal pertain to the low energy portions of the accelerator system. In particular, the implied particle current in the rf linac is 10 3 --10 4 times the values achieved with existing heavy ion machines. Much of this discrepancy is simply attributable to the great differences between the design considerations relevant to accelerators for fusion and those which have determined the performance of the existing machines. The basic concept chosen at Argonne National Laboratory is cavities containing single drift tubes mounted on lambda/4 supports. Such structures pose the least problem for the beam transport system, and one cavity is placed between adjacent quadrupole magnets. The average voltage gain of the first cells of the low velocity section is moderate; and, although probably acceptable and improved by the end of the 10 MV section, the low initial gain adds to the motivation provided by the transport problem to increase the preinjector voltage substantially above 750 kV

  13. RF plasma cleaning of silicon substrates with high-density polyethylene contamination

    Science.gov (United States)

    Cagomoc, Charisse Marie D.; De Leon, Mark Jeffry D.; Ebuen, Anna Sophia M.; Gilos, Marlo Nicole R.; Vasquez, Magdaleno R., Jr.

    2018-01-01

    Upon contact with a polymeric material, microparticles from the polymer may adhere to a silicon (Si) substrate during device processing. The adhesion contaminates the surface and, in turn, leads to defects in the fabricated Si-based microelectronic devices. In this study, Si substrates with artificially induced high-density polyethylene (HDPE) contamination was exposed to 13.56 MHz radio frequency (RF) plasma utilizing argon and oxygen gas admixtures at a power density of 5.6 W/cm2 and a working pressure of 110 Pa for up to 6 min of treatment. Optical microscopy studies revealed the removal of up to 74% of the polymer contamination upon plasma exposure. Surface free energy (SFE) increased owing to the removal of contaminants as well as the formation of polar groups on the Si surface after plasma treatment. Atomic force microscopy scans showed a decrease in surface roughness from 12.25 nm for contaminated samples to 0.77 nm after plasma cleaning. The smoothening effect can be attributed to the removal of HDPE particles from the surface. In addition, scanning electron microscope images showed that there was a decrease in the amount of HDPE contaminants adhering onto the surface after plasma exposure.

  14. Low Voltage, High-Q SOI MEMS Varactors for RF Applications

    DEFF Research Database (Denmark)

    Yalcinkaya, Arda Deniz; Jensen, Søren; Hansen, Ole

    2003-01-01

    A micro electromechanical tunable capacitor with a low control voltage, a wide tuning range and high electrical quality factor is presented with detailed characterizations. A 50μm thick single-crystalline silicon layer was etched using deep reactive ion etching (DRIE) for obtaining high-aspect ra...... is a suitable passive component to be used in band-pass filtering, voltage controlled oscillator or impedance matching applications on the very high frequency(VHF) and ultra high frequency (UHF) bands....

  15. Formation of a quasi-hollow beam of high-energy heavy ions using a multicell resonance RF deflector

    Science.gov (United States)

    Minaev, S. A.; Sitnikov, A. L.; Golubev, A. A.; Kulevoy, T. V.

    2012-09-01

    The generation of matter in an extreme state with precisely measurable parameters is of great interest for contemporary physics. One way of obtaining such a state is to irradiate the end of a hollow cylindrical shell at the center of which a test material is kept at a temperature of several Kelvin by an annular beam of high-energy heavy ions. Under the action of the beam, the shell starts explosively expanding both outwards and inwards, compressing the material to an extremely high pressure without subjecting it to direct heating. A method of producing a hollow cylindrical beam of high-energy heavy ions using a resonance rf deflector is described. The deflection of the beam in two transverse directions by means of an rf electric field allows it to rotate about the longitudinal axis and irradiate an annular domain on the end face of the target.

  16. Rf power sources

    International Nuclear Information System (INIS)

    Allen, M.A.

    1988-01-01

    In this paper, the author reports on RF power sources for accelerator applications. The approach will be with particular customers in mind. These customers are high energy physicists who use accelerators as experimental tools in the study of the nucleus of the atom, and synchrotron light sources derived from electron or positron storage rings. The author pays close attention to electron- positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. Circular machines, cyclotrons, synchrotrons, etc. have usually not been limited by the RF power available and the machine builders have usually had their RF power source requirements met off the shelf. The main challenge for the RF scientist has been then in the areas of controls. An interesting example of this is in the Conceptual Design Report of the Superconducting Super Collider (SSC) where the RF system is described in six pages of text in a 700-page report. Also, the cost of that RF system is about one-third of a percent of the project's total cost. The RF system is well within the state of the art and no new power sources need to be developed. All the intellectual effort of the system designer would be devoted to the feedback systems necessary to stabilize beams during storage and acceleration, with the main engineering challenges (and costs) being in the superconducting magnet lattice

  17. RF MEMS

    Indian Academy of Sciences (India)

    At the bare die level the insertion loss, return loss and the isolation ... ing and packaging of a silicon on glass based RF MEMS switch fabricated using DRIE. ..... follows the power law based on the asperity deformation model given by Pattona & ... Surface mount style RF packages (SMX series 580465) from Startedge Corp.

  18. Origin of high carrier mobility and low residual stress in RF superimposed DC sputtered Al doped ZnO thin film for next generation flexible devices

    Science.gov (United States)

    Kumar, Naveen; Dubey, Ashish; Bahrami, Behzad; Venkatesan, S.; Qiao, Qiquan; Kumar, Mukesh

    2018-04-01

    In this work, the energy and flux of high energetic ions were controlled by RF superimposed DC sputtering process to increase the grain size and suppress grain boundary potential with minimum residual stress in Al doped ZnO (AZO) thin film. AZO thin films were deposited at different RF/(RF + DC) ratios by keeping total power same and were investigated for their electrical, optical, structural and nanoscale grain boundaries potential. All AZO thin film showed high crystallinity and orientation along (002) with peak shift as RF/(RF + DC) ratio increased from 0.0, pure DC, to 1.0, pure RF. This peak shift was correlated with high residual stress in as-grown thin film. AZO thin film grown at mixed RF/(RF + DC) of 0.75 showed high electron mobility, low residual stress and large crystallite size in comparison to other AZO thin films. The nanoscale grain boundary potential was mapped using Kelvin Probe Force Microscopy in all AZO thin film and it was observed that carrier mobility is controlled not only by grains size but also by grain boundary potential. The XPS analysis confirms the variation in oxygen vacancies and zinc interstitials which explain the origin of low grain boundaries potential and high carrier mobility in AZO thin film deposited at 0.75 RF/(RF + DC) ratio. This study proposes a new way to control the grain size and grain boundary potential to further tune the optoelectronic-mechanical properties of AZO thin films for next generation flexible and optoelectronic devices.

  19. Fast protection circuit for 1 MW Klystron based RF system of Low Energy High Intensity Proton Accelerator (LEHIPA)

    International Nuclear Information System (INIS)

    Shrotriya, Sandip; Shiju, A.; Patel, N.R.; Pande, Manjiri; Singh, P.

    2014-01-01

    This paper describes the details of a hardwired protection circuit designed and developed for 1 MW Klystron based Radio Frequency (RF) System. The hardwired protection circuit protects the klystron from fault conditions occurring in high power DC supplies, other bias supplies and inside the klystron itself. Fast response of the order of 1-2 microseconds is necessary in case of critical signals for the protection of such a high power system. The system needs to handle around 10 critical signals comprising of optical signals and different digital signals. In case of malfunction in the existing controller based interlock and protection system, klystron will be protected by this hardwired protection circuit. The hardwired circuit will provide redundant protection and protect the klystron from damage. This circuit and controller based protection system are operating in parallel. This paper describes details of a purely hardwired protection circuit developed for critical signals for achieving reliability and faster response time requirements of the RF system. (author)

  20. Design of an RF Antenna for a Large-Bore, High Power, Steady State Plasma Processing Chamber for Material Separation

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Freeman, R.L.

    2001-01-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC, (Contractor), and Archimedes Technology Group, (Participant) is to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure. The project objectives are to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure

  1. RF processing of an S-band high gradient accelerator unit

    International Nuclear Information System (INIS)

    Morita, S.

    1994-01-01

    A 3m-long S-band accelerating structure is used in 1.54 GeV Linac of Accelerator Test Facility. The accelerating structure should be processed up to 200 MW which produce 52 MV/m accelerating gradient. The process of RF processing is described. (author)

  2. Foreword in "RF imperfections in high-rate wireless systems: impact and digital compensation"

    NARCIS (Netherlands)

    Linnartz, J.P.M.G.; Schenk, Tim

    2008-01-01

    Foreword This book takes a modern, multidisciplinary view on radio system design: the advantages of digital signal processing are exploited to satisfy the ever increasing demands on better performing, flexible radio frequency (RF) circuits. By accepting that analog circuits are inherently imperfect,

  3. RF imperfections in high-rate wireless systems : impact and digital compensation

    NARCIS (Netherlands)

    Schenk, T.C.W.

    2008-01-01

    Wireless communication systems are persistently applying wider bandwidths, larger signal dynamics and higher carrier frequencies to fulfil the demand for higher data rates. This results in an ever increasing demand on the performance of low-cost and power-efficient radio frequency (RF) front-ends.

  4. Assessment and Monitoring of RF Safety for Ultra-High Field MRI

    NARCIS (Netherlands)

    Restivo, MC

    2017-01-01

    The radio frequency (RF) energy deposited in a human subject undergoing a 7T MRI scan has the potential to cause localized tissue heating. The use of parallel transmit MRI at 7T increases the risk of localized heating due interference effects among the simultaneously transmitting channels. The

  5. A High-Precision RF Time-of-Flight Measurement Method based on Vernier Effect for Localization of Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sang-il KO

    2011-12-01

    Full Text Available This paper presents the fundamental principles of a high-precision RF time-of-flight (ToF measurement method based on the vernier effect, which enables the improvement of time measurement resolution, for accurate distance measurement between sensor nodes in wireless sensor networks. Similar to the two scales of the vernier caliper, two heterogeneous clocks are employed to induce a new virtual time resolution that is much finer than clocks’ intrinsic time resolution. Consecutive RF signal transmission and sensing using two heterogeneous clocks generates a unique sensing pattern for the RF ToF, so that the size of the RF ToF can be estimated by comparing the measured sensing pattern with the predetermined sensing patterns for the RF ToF. RF ToF measurement experiments using this heterogeneous clock system, which has low operating frequencies of several megahertz, certify the proposed RF ToF measurement method through the evaluation of the measured sensing patterns with respect to an RF round-trip time of several nanoseconds.

  6. High Isolation Single-Pole Four-Throw RF MEMS Switch Based on Series-Shunt Configuration

    Directory of Open Access Journals (Sweden)

    Tejinder Singh

    2014-01-01

    Full Text Available This paper presents a novel design of single-pole four-throw (SP4T RF-MEMS switch employing both capacitive and ohmic switches. It is designed on high-resistivity silicon substrate and has a compact area of 1.06 mm2. The series or ohmic switches have been designed to provide low insertion loss with good ohmic contact. The pull-in voltage for ohmic switches is calculated to be 7.19 V. Shunt or capacitive switches have been used in each port to improve the isolation for higher frequencies. The proposed SP4T switch provides excellent RF performances with isolation better than 70.64 dB and insertion loss less than 0.72 dB for X-band between the input port and each output port.

  7. Visible luminescence from highly textured Tb{sup 3+} doped RF sputtered zinc oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Sreedharan, R. Sreeja; Krishnan, R. Reshmi; Bose, R. Jolly; Kavitha, V.S.; Suresh, S. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Vinodkumar, R. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Department of Physics, University College, Thiruvananthapuram, Kerala (India); Sudheer, S.K. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Pillai, V.P. Mahadevan, E-mail: vpmpillai9@gmail.com [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India)

    2017-04-15

    Highly transparent, luminescent, c-axis oriented Tb{sup 3+} doped ZnO films are prepared by RF magnetron sputtering technique. The structural, morphological, optical and luminescence properties of these films are investigated as a function of Tb{sup 3+} doping concentration by X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), spectroscopic ellipsometry, UV-Visible spectroscopy and photoluminescence spectroscopy. The as-deposited films are found to be highly crystalline with wurtzite hexagonal phase of ZnO. The characteristic features of hexagonal wurtzite structure of ZnO, particularly the appearance of non-polar E{sub 2} modes are easily identified from the Raman spectra of the films. The surface morphology of the films revealed by FESEM and AFM images present a dense distribution of grains. The elemental analysis carried out using energy dispersive X-ray (EDX) spectra confirms the incorporation of Tb{sup 3+} ions in the ZnO lattice. The films are highly transparent in the visible region. Using ellipsometric analysis, the variation of refractive index, dielectric constant and thickness of the films are studied as a function of Tb{sup 3+} doping concentration. The photoluminescence spectra of the Tb{sup 3+} doped ZnO films recorded using an excitation radiation of wavelength 325 nm from a He-Cd laser exhibit visible luminescence ~430, 490, 516 and 542 nm. The origin of visible emissions ~490 and 542 nm in the doped films can be attributed to 5D{sub 4}→7F{sub 6} and 5D{sub 4}→7F{sub 5} transition of Tb{sup 3+} ion respectively. The intensity of the emission at 542 nm is found to be decreasing at higher doping concentration due to concentration quenching effect. The blue emission in the films can be attributed to the electron transition from shallow donor level formed by interstitial Zn atoms to the top of the valence band. The origin of the visible emission ~516 nm is attributed

  8. Underreporting on the MMPI-2-RF in a high-demand police officer selection context: an illustration.

    Science.gov (United States)

    Detrick, Paul; Chibnall, John T

    2014-09-01

    Positive response distortion is common in the high-demand context of employment selection. This study examined positive response distortion, in the form of underreporting, on the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF). Police officer job applicants completed the MMPI-2-RF under high-demand and low-demand conditions, once during the preemployment psychological evaluation and once without contingencies after completing the police academy. Demand-related score elevations were evident on the Uncommon Virtues (L-r) and Adjustment Validity (K-r) scales. Underreporting was evident on the Higher-Order scales Emotional/Internalizing Dysfunction and Behavioral/Externalizing Dysfunction; 5 of 9 Restructured Clinical scales; 6 of 9 Internalizing scales; 3 of 4 Externalizing scales; and 3 of 5 Personality Psychopathology 5 scales. Regression analyses indicated that L-r predicted demand-related underreporting on behavioral/externalizing scales, and K-r predicted underreporting on emotional/internalizing scales. Select scales of the MMPI-2-RF are differentially associated with different types of underreporting among police officer applicants. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  9. New results of development on high efficiency high gradient superconducting rf cavities

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Li, Z. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hao, Z. K. [Peking Univ., Beijing (China); Liu, K. X. [Peking Univ., Beijing (China); Zhao, H. Y. [OTIC, Ningxia (China); Adolphsen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-09-01

    We report on the latest results of development on high-efficiency high-gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.

  10. A wideband large dynamic range and high linearity RF front-end for U-band mobile DTV

    International Nuclear Information System (INIS)

    Liu Rongjiang; Liu Shengyou; Guo Guiliang; Cheng Xu; Yan Yuepeng

    2013-01-01

    A wideband large dynamic range and high linearity U-band RF front-end for mobile DTV is introduced, and includes a noise-cancelling low-noise amplifier (LNA), an RF programmable gain amplifier (RFPGA) and a current communicating passive mixer. The noise/distortion cancelling structure and RC post-distortion compensation are employed to improve the linearity of the LNA. An RFPGA with five stages provides large dynamic range and fine gain resolution. A simple resistor voltage network in the passive mixer decreases the gate bias voltage of the mixing transistor, and optimum linearity and symmetrical mixing is obtained at the same time. The RF front-end is implemented in a 0.25 μm CMOS process. Tests show that it achieves an IIP3 (third-order intercept point) of −17 dBm, a conversion gain of 39 dB, and a noise figure of 5.8 dB. The RFPGA achieves a dynamic range of −36.2 to 23.5 dB with a resolution of 0.32 dB. (semiconductor integrated circuits)

  11. High total dose proton irradiation effects on silicon NPN rf power transistors

    International Nuclear Information System (INIS)

    Bharathi, M. N.; Praveen, K. C.; Prakash, A. P. Gnana; Pushpa, N.

    2014-01-01

    The effects of 3 MeV proton irradiation on the I-V characteristics of NPN rf power transistors were studied in the dose range of 100 Krad to 100 Mrad. The different electrical characteristics like Gummel, current gain and output characteristics were systematically studied before and after irradiation. The recovery in the I-V characteristics of irradiated NPN BJTs were studied by isochronal and isothermal annealing methods

  12. High total dose proton irradiation effects on silicon NPN rf power transistors

    Energy Technology Data Exchange (ETDEWEB)

    Bharathi, M. N.; Praveen, K. C.; Prakash, A. P. Gnana, E-mail: gnanaprakash@physics.uni-mysore.ac.in [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore-570006, Karnataka (India); Pushpa, N. [Department of PG Studies in Physics, JSS College, Ooty Road, Mysore-570025, Karnataka (India)

    2014-04-24

    The effects of 3 MeV proton irradiation on the I-V characteristics of NPN rf power transistors were studied in the dose range of 100 Krad to 100 Mrad. The different electrical characteristics like Gummel, current gain and output characteristics were systematically studied before and after irradiation. The recovery in the I-V characteristics of irradiated NPN BJTs were studied by isochronal and isothermal annealing methods.

  13. Suppression of multipacting in high power RF couplers operating with superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ostroumov, P.N., E-mail: ostroumov@frib.msu.edu [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States); Kazakov, S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Morris, D.; Larter, T.; Plastun, A.S.; Popielarski, J.; Wei, J.; Xu, T. [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States)

    2017-06-01

    Capacitive input couplers based on a 50 Ω coaxial transmission line are frequently used to transmit RF power to superconducting (SC) resonators operating in CW mode. It is well known that coaxial transmission lines are prone to multipacting phenomenon in a wide range of RF power level and operating frequency. The Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University includes two types of quarter wave SC resonators (QWR) operating at 80.5 MHz and two types of half wave SC resonators (HWR) operating at 322 MHz. As was reported in ref. [1] a capacitive input coupler used with HWRs was experiencing strong multipacting that resulted in a long conditioning time prior the cavity testing at design levels of accelerating fields. We have developed an insert into 50 Ω coaxial transmission line that provides opportunity to bias the RF coupler antenna and protect the amplifier from the bias potential in the case of breakdown in DC isolation. Two of such devices have been built and are currently used for the off-line testing of 8 HWRs installed in the cryomodule.

  14. Performance of the Crowbar of the LHC High Power RF System

    CERN Document Server

    Ravidà, G; Valuch, D

    2012-01-01

    The counter-rotating proton beams in the Large Hadron Collider (LHC) are captured and accelerated to their final energies by two identical 400 MHz Radio Frequency (RF) systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell superconducting (SC) cavity. Each unit of four klystrons is powered by a -100kV/40A AC/DC power converter. A fast protection system (crowbar) protects the four klystrons in each of these units. Although the LHC RF system has shown has very good performance, operational experience has shown that the five-gap double-ended thyratrons used in the crowbar system suffer, from time to time, from auto-firing, which result in beam dumps. This paper presents the recent results obtained with an alternative solution based on solid state thyristors. Comparative measurements with the thyratron are shown.

  15. Design of RF chopper system for improving beam quality in FEL injector with thermionic gun

    International Nuclear Information System (INIS)

    Chen, Q.; Qin, B.; Tan, P.; Hu, T.; Pei, Y.; Zhang, F.

    2014-01-01

    For a linac-based Free Electron Laser (FEL), good beam quality largely contributes to the success of the final radiation. An imperfection confronted with the HUST THz-FEL facility is the long beam tail that emerges in the electron gun and exists through the whole beam line. This paper proposes to deploy a chopper system after the electron gun to truncate the beam tails before they enter into the linac. Physical dimensions of the chopper cavity are discussed in detail and we have developed and derived new analytical expressions applying to all frequencies for the optimal design. Also, technical issues of the cavity are considered. Beam dynamic simulation is performed to examine the truncation effect and the results show that more than 78% of the beam tail can be removed effectively, while preserving the emittance and energy spread in acceptable level

  16. Microbunching and RF Compression

    International Nuclear Information System (INIS)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-01-01

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  17. Rf power sources

    International Nuclear Information System (INIS)

    Allen, M.A.

    1988-05-01

    This paper covers RF power sources for accelerator applications. The approach has been with particular customers in mind. These customers are high energy physicists who use accelerators as experimental tools in the study of the nucleus of the atom, and synchrotron light sources derived from electron or positron storage rings. This paper is confined to electron-positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. 11 refs., 13 figs

  18. Present status of high quality beam facility at Waseda University

    International Nuclear Information System (INIS)

    Washio, M.; Kawai, H.; Hama, Y.; Kudo, N.; Kobayashi, M.; Kuribayasi, T.; Kawaguchi, M.; Kuroda, R.; Maeda, K.; Nagasawa, F.; Ueyama, D.; Hizume, K.; Wang, X.J.; Hayano, H.; Urakawa, J.; Kashiwagi, S.

    2004-01-01

    A research project named High-Tech Research Center Project has been conducted at Waseda University. In this project, an RF gun system has been used for production of low emittance and short bunched electron beam. The experiments for the electron beam quality measurement have been carried out by slit scan techniques, etc. Short pulsed x-ray with the energy range of so-called water window has been generation by the inverse compton scattering. Further, the pulse radiolysis system has been constructed, and the stroboscopic pulse radiolysis has been applied for the detection of hydrated electron in picosecond time region. (author)

  19. High quality ZnO layers with adjustable refractive indices for integrated optics applications

    NARCIS (Netherlands)

    Heideman, Rene; Lambeck, Paul; Gardeniers, Johannes G.E.

    1995-01-01

    Thin (approx. 1 μm) crystalline ZnO films with a good optical quality and a good (0002) texture are grown under two considerably different process parameter sets using a r.f. planar magnetron sputtering unit. The optical parameters of the two corresponding ZnO layers are distinctly different: high

  20. A low-frequency high-voltage rf-barrier-bunching system for high-intensity neutron source compressor rings

    International Nuclear Information System (INIS)

    Hardek, T.W.; Ziomek, C.; Rees, D.

    1995-01-01

    A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an rf-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in this case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured retrode amplifiers incorporating local rf feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with rf feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated

  1. High-precision laser and rf spectroscopy of atomic, molecular, and slow ion beams

    International Nuclear Information System (INIS)

    Childs, W.J.; Steimle, T.C.; Sen, A.; Azuma, Y.

    1988-01-01

    We have obtained extensive new structural information on the light diatomic radical ScO since the last report in this series. The new studies complete our systematic investigation of the fine and hyperfine structure (hfs) of the group IIIa monoxides LaO, YO, and ScO. The studies of the molecular X 2 Σ + electronic ground state were carried out using the molecular-beam laser-rf double-resonance method, and the excited electronic state information was obtained by complementing this data with Doppler-free laser fluorescence studies

  2. High-precision hyperfine structure measurement in slow atomic ion beams by collinear laser-rf double resonance

    International Nuclear Information System (INIS)

    Amarjit Sen; Childs, W.J.; Goodman, L.S.

    1987-01-01

    A new collinear laser-ion beam apparatus for slow ions (1 to 1.5 keV) has been built for measuring the hyperfine structure of metastable levels of ions with laser-rf double resonance technique. Narrow linewidths of ∼60 kHz (FWHM) have been observed for the first time in such systems. As a first application the hyperfine structure of the 4f 7 ( 8 S 0 )5d 9 D/sub J/ 0 metastable levels of /sup 151,153/Eu + has been measured with high precision. 10 refs., 8 figs

  3. High-Bandwidth, High-Efficiency Envelope Tracking Power Supply for 40W RF Power Amplifier Using Paralleled Bandpass Current Sources

    DEFF Research Database (Denmark)

    Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a high-performance power conversion scheme for power supply applications that require very high output voltage slew rates (dV/dt). The concept is to parallel 2 switching bandpass current sources, each optimized for its passband frequency space and the expected load current....... The principle is demonstrated with a power supply, designed for supplying a 40 W linear RF power amplifier for efficient amplification of a 16-QAM modulated data stream...

  4. Association of acute adverse effects with high local SAR induced in the brain from prolonged RF head and neck hyperthermia

    International Nuclear Information System (INIS)

    Adibzadeh, F; Verhaart, R F; Rijnen, Z; Franckena, M; Van Rhoon, G C; Paulides, M M; Verduijn, G M; Fortunati, V

    2015-01-01

    To provide an adequate level of protection for humans from exposure to radio-frequency (RF) electromagnetic fields (EMF) and to assure that any adverse health effects are avoided. The basic restrictions in terms of the specific energy absorption rate (SAR) were prescribed by IEEE and ICNIRP. An example of a therapeutic application of non-ionizing EMF is hyperthermia (HT), in which intense RF energy is focused at a target region. Deep HT in the head and neck (H and N) region involves inducing energy at 434 MHz for 60 min on target. Still, stray exposure of the brain is considerable, but to date only very limited side-effects were observed. The objective of this study is to investigate the stringency of the current basic restrictions by relating the induced EM dose in the brain of patients treated with deep head and neck (H and N) HT to the scored acute health effects. We performed a simulation study to calculate the induced peak 10 g spatial-averaged SAR (psSAR 10g ) in the brains of 16 selected H and N patients who received the highest SAR exposure in the brain, i.e. who had the minimum brain-target distance and received high forwarded power during treatment. The results show that the maximum induced SAR in the brain of the patients can exceed the current basic restrictions (IEEE and ICNIRP) on psSAR 10g for occupational environments by 14 times. Even considering the high local SAR in the brain, evaluation of acute effects by the common toxicity criteria (CTC) scores revealed no indication of a serious acute neurological effect. In addition, this study provides pioneering quantitative human data on the association between maximum brain SAR level and acute adverse effects when brains are exposed to prolonged RF EMF. (paper)

  5. Extraction of High Charge Electron Bunch from the ELSA RF Injector Comparison Between Simulation and Experiment

    CERN Document Server

    Lemaire, J; Binet, A; Lagniel, J M; Le Flanchec, V; Pichoff, N

    2004-01-01

    A new scheme based on a photoinjector and a RF linear accelerator operating at 352 MHz has been recently proposed as a versatile radiographic facility. Beam pulses of 60 ns duration contain 20 succesive electron bunches which will be extracted at 2.5 MeV from a photoinjector then accelerated through the next structure to the final energy of 51 MeV. Bunches carrying 100 nC are required for this purpose. As a first demonstrating step, 50 nC electron bunches have been produced and accelerated to 2.5 MeV with the 144 MHz ELSA photoinjector at Bruyères le Chatel. For this experiment, we compare the results and the numerical simulations made with PARMELA, MAGIC and MAFIA codes.

  6. Investigation of High Voltage Breakdown and Arc Localization in RF Structures

    International Nuclear Information System (INIS)

    Bigelow, T.S.; Goulding, R.H.; Swain, D.W.

    1999-01-01

    An effort is underway to improve the voltage standoff capabilities of ion cyclotron range of frequencies (ICRF) heating and current drive systems. One approach is to develop techniques for determining the location of an electrical breakdown (arc) when it occurs. A technique is described which uses a measurement of the reflection coefficient of a swept frequency signal to determine the arc location. The technique has several advantages including a requirement for only a small number of sensors and very simple data interpretation. In addition a test stand is described which will be used for studies of rf arc behavior. The device uses a quarter-wave resonator to produce voltages to 90 kV in the frequency range of 55-80 MHz

  7. Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R & D

    Science.gov (United States)

    Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.

    2009-01-01

    A preliminary design is presented for a two-cavity harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.

  8. High-efficiency resonant rf spin rotator with broad phase space acceptance for pulsed polarized cold neutron beams

    Directory of Open Access Journals (Sweden)

    P.-N. Seo

    2008-08-01

    Full Text Available High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating γ-ray asymmetry A_{γ} in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5  cm×9.5  cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized ^{3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8±0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPDGamma experiment are considered.

  9. Fast High-Quality Noise

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Wyvill, Geoff

    2007-01-01

    At the moment the noise functions available in a graphics programmer's toolbox are either slow to compute or they involve grid-line artifacts making them of lower quality. In this paper we present a real-time noise computation with no grid-line artifacts or other regularity problems. In other words......, we put a new tool in the box that computes fast high-quality noise. In addition to being free of artifacts, the noise we present does not rely on tabulated data (everything is computed on the fly) and it is easy to adjust quality vs. quantity for the noise. The noise is based on point rendering (like...... spot noise), but it extends to more than two dimensions. The fact that it is based on point rendering makes art direction of the noise much easier....

  10. Characterization of Cs-Sb cathodes for high charge RF photoinjectors

    CERN Document Server

    AUTHOR|(CDS)2082505; Beghi, Marco

    Future accelerators such as CLIC (Compact LInear Collider), require high brightness electron beams that could be produced with a photoinjector (laser-driven electron source). Cs2Te photocathodes in combination with ultra-violet (UV) laser beams are currently used in many photoinjector facilities, but requirements to the electron sources for future accelerators like CLIC are more demanding. The main challenge for the CLIC drive beam photoinjector is to achieve high bunch charges (8.4 nC), high bunch repetition rates (500 MHz) within long trains (140 s) and with suciently long cathode lifetimes. In particular the laser pulse energy in UV, for such long pulse trains, is currently limited due to a degradation of the beam quality during the 4th harmonic frequency conversion process. Using the 2nd harmonic (green laser beam), provided it is matched with a low photoemission threshold photocathode material, would overcome this limitation. Cesium antimonide (Cs3Sb), being a photoemissive material in the visible range,...

  11. Investigation of growth parameters influence on self-catalyzed ITO nanowires by high RF-power sputtering.

    Science.gov (United States)

    Li, Qiang; Zhang, Yuantao; Feng, Lungang; Wang, Zuming; Wang, Tao; Yun, Feng

    2018-02-15

    ITO nanowires have been successfully fabricated using a radio-frequency sputtering technique with a high RF-power of 250W. The fabrication of the ITO nanowires has been optimized through the study of oxygen flow rates, temperatures and RF-power. The difference in the morphology of the ITO nanowires prepared by using a new target and a used target has been first observed and the mechanism for the difference has been discussed in detail. A hollow structure and air voids within the nanowires are formed during the process of the nanowire growth. The ITO nanowires fabricated by this method has demonstrated good conductivity (15Ω/sq) and a transmittance of more than 64% at a wavelength longer than 550nm after annealing. Furthermore, detailed microstructure studies show that the ITO nanowires exhibit a large number of oxygen vacancies. As a result, it is expected that they can be useful for the fabrication of gas sensor devices. © 2018 IOP Publishing Ltd.

  12. Interaction between beam control and rf feedback loops for high Q cavities an heavy beam loading. Revision A

    International Nuclear Information System (INIS)

    Mestha, L.K.; Kwan, C.M.; Yeung, K.S.

    1994-04-01

    An open-loop state space model of all the major low-level rf feedback control loops is derived. The model has control and state variables for fast-cycling machines to apply modern multivariable feedback techniques. A condition is derived to know when exactly we can cross the boundaries between time-varying and time-invariant approaches for a fast-cycling machine like the Low Energy Booster (LEB). The conditions are dependent on the Q of the cavity and the rate at which the frequency changes with time. Apart from capturing the time-variant characteristics, the errors in the magnetic field are accounted in the model to study the effects on synchronization with the Medium Energy Booster (MEB). The control model is useful to study the effects on beam control due to heavy beam loading at high intensities, voltage transients just after injection especially due to time-varying voltages, instability thresholds created by the cavity tuning feedback system, cross coupling between feedback loops with and without direct rf feedback etc. As a special case we have shown that the model agrees with the well known Pedersen model derived for the CERN PS booster. As an application of the model we undertook a detailed study of the cross coupling between the loops by considering all of them at once for varying time, Q and beam intensities. A discussion of the method to identify the coupling is shown. At the end a summary of the identified loop interactions is presented

  13. An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T.

    Science.gov (United States)

    Rietsch, Stefan H G; Pfaffenrot, Viktor; Bitz, Andreas K; Orzada, Stephan; Brunheim, Sascha; Lazik-Palm, Andrea; Theysohn, Jens M; Ladd, Mark E; Quick, Harald H; Kraff, Oliver

    2017-12-01

    In this work, we present an 8-channel transceiver (Tx/Rx) 7-channel receive (Rx) radiofrequency (RF) coil setup for 7 T ultrahigh-field MR imaging of the shoulder. A C-shaped 8-channel Tx/Rx coil was combined with an anatomically close-fitting 7-channel Rx-only coil. The safety and performance parameters of this coil setup were evaluated on the bench and in phantom experiments. The 7 T MR imaging performance of the shoulder RF coil setup was evaluated in in vivo measurements using a 3D DESS, a 2D PD-weighted TSE sequence, and safety supervision based on virtual observation points. Distinct SNR gain and acceleration capabilities provided by the additional 7-channel Rx-only coil were demonstrated in phantom and in vivo measurements. The power efficiency indicated good performance of each channel and a maximum B 1 + of 19 μT if the hardware RF power limits of the MR system were exploited. MR imaging of the shoulder was demonstrated with clinically excellent image quality and submillimeter spatial resolution. The presented 8-channel transceiver 7-channel receive RF coil setup was successfully applied for in vivo 7 T MRI of the shoulder providing a clear SNR gain vs the transceiver array without the additional receive array. Homogeneous images across the shoulder region were obtained using 8-channel subject-specific phase-only RF shimming. © 2017 American Association of Physicists in Medicine.

  14. Soft X-ray generation via inverse compton scattering between high quality electron beam and high power laser

    International Nuclear Information System (INIS)

    Masakazu Washio; Kazuyuki Sakaue; Yoshimasa Hama; Yoshio Kamiya; Tomoko Gowa; Akihiko Masuda; Aki Murata; Ryo Moriyama; Shigeru Kashiwagi; Junji Urakawa

    2007-01-01

    High quality beam generation project based on High-Tech Research Center Project, which has been approved by Ministry of Education, Culture, Sports, Science and Technology in 1999, has been conducted by advance research institute for science and engineering, Waseda University. In the project, laser photo-cathode RF-gun has been selected for the high quality electron beam source. RF cavities with low dark current, which were made by diamond turning technique, have been successfully manufactured. The low emittance electron beam was realized by choosing the modified laser injection technique. The obtained normalized emmitance was about 3 m.mrad at 100 pC of electron charge. The soft x-ray beam generation with the energy of 370 eV, which is in the energy region of so-called water window, by inverse Compton scattering has been performed by the collision between IR laser and the low emmitance electron beams. (Author)

  15. RF transformer

    Science.gov (United States)

    Smith, James L.; Helenberg, Harold W.; Kilsdonk, Dennis J.

    1979-01-01

    There is provided an improved RF transformer having a single-turn secondary of cylindrical shape and a coiled encapsulated primary contained within the secondary. The coil is tapered so that the narrowest separation between the primary and the secondary is at one end of the coil. The encapsulated primary is removable from the secondary so that a variety of different capacity primaries can be utilized with one secondary.

  16. Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    Energy Technology Data Exchange (ETDEWEB)

    Lu, D.F.; Fan, C.; Ruan, J.Z. [Midwest Superconductivity Inc., Lawrence, KS (United States)] [and others

    1994-12-31

    A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology.

  17. Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-Gradient Accelerating Structures

    CERN Document Server

    Tecker, F; Kelisani, M; Doebert, S; Grudiev, A; Quirante, J; Riddone, G; Syratchev, I; Wuensch, W; Kononenko, O; Solodko, A; Lebet, S

    2013-01-01

    RF breakdown is a key issue for the multi-TeV highluminosity e+e- Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

  18. Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    International Nuclear Information System (INIS)

    Lu, D.F.; Fan, C.; Ruan, J.Z.

    1994-01-01

    A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology

  19. Outage Performance of Hybrid FSO/RF System with Low-Complexity Power Adaptation

    KAUST Repository

    Rakia, Tamer

    2016-02-26

    Hybrid free-space optical (FSO) / radio-frequency (RF) systems have emerged as a promising solution for high data- rate wireless communication systems. We consider truncated channel inversion based power adaptation strategy for coherent and non- coherent hybrid FSO/RF systems, employing an adaptive combining scheme. Specifically, we activate the RF link along with the FSO link when FSO link quality is unacceptable, and adaptively set RF transmission power to ensure constant combined signal-to-noise ratio at receiver terminal. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are derived. Numerical examples show that, the hybrid FSO/RF systems with power adaptation achieve considerable outage performance improvement over conventional hybrid FSO/RF systems without power adaptation. © 2015 IEEE.

  20. Rf system specifications for a linear accelerator

    International Nuclear Information System (INIS)

    Young, A.; Eaton, L.E.

    1992-01-01

    A linear accelerator contains many systems; however, the most complex and costly is the RF system. The goal of an RF system is usually simply stated as maintaining the phase and amplitude of the RF signal within a given tolerance to accelerate the charged particle beam. An RF system that drives a linear accelerator needs a complete system specification, which should contain specifications for all the subsystems (i.e., high-power RF, low-level RF, RF generation/distribution, and automation control). This paper defines a format for the specifications of these subsystems and discusses each RF subsystem independently to provide a comprehensive understanding of the function of each subsystem. This paper concludes with an example of a specification spreadsheet allowing one to input the specifications of a subsystem. Thus, some fundamental parameters (i.e., the cost and size) of the RF system can be determined

  1. Minimum beam-energy spread of a high-current rf linac

    International Nuclear Information System (INIS)

    Chan, K.C.D.; Fraser, J.S.

    1987-01-01

    Energy spread is an important parameter of an electron linac and, usually, is determined by the time dependence of the external rf accelerating field. By using a combination of fundamental and higher harmonic frequencies, the accelerating field can be maintained approximately constant over a beam bunch with the resultant energy spread approximately zero. This technique is no longer adequate when the longitudinal wake field of the beam bunch is taken into account. The wake-field variation along the bunch length introduces an energy spread that cannot be exactly compensated for with the use of fundamental and higher harmonic frequencies. The achievable minimum energy spread including the wake-field effect is therefore limited. In this paper, we report the minimum energy spreads achievable using the fundamental and third-harmonic frequencies, calculated using a least-squares algorithm, for some typical structures in use at Los Alamos National Laboratory. The dependence of these results on bunch shape, bunch charge, and structure frequency is discussed. Also included are discussions of schemes for implementing the third-harmonic frequency and their effectiveness

  2. A new hybrid scheme for simulations of highly collisional RF-driven plasmas

    International Nuclear Information System (INIS)

    Eremin, Denis; Hemke, Torben; Mussenbrock, Thomas

    2016-01-01

    This work describes a new 1D hybrid approach for modeling atmospheric pressure discharges featuring complex chemistry. In this approach electrons are described fully kinetically using particle-in-cell/Monte-Carlo (PIC/MCC) scheme, whereas the heavy species are modeled within a fluid description. Validity of the popular drift-diffusion approximation is verified against a ‘full’ fluid model accounting for the ion inertia and a fully kinetic PIC/MCC code for ions as well as electrons. The fluid models require knowledge of the momentum exchange frequency and dependence of the ion mobilities on the electric field when the ions are in equilibrium with the latter. To this end an auxiliary Monte-Carlo scheme is constructed. It is demonstrated that the drift-diffusion approximation can overestimate ion transport in simulations of RF-driven discharges with heavy ion species operated in the γ mode at the atmospheric pressure or in all discharge simulations for lower pressures. This can lead to exaggerated plasma densities and incorrect profiles provided by the drift-diffusion models. Therefore, the hybrid code version featuring the full ion fluid model should be favored against the more popular drift-diffusion model, noting that the suggested numerical scheme for the former model implies only a small additional computational cost. (paper)

  3. Design and development of embedded control system for high power RF test facility

    International Nuclear Information System (INIS)

    Nageswara Rao, J.; Badapanda, M.K.; Upadhyay, Rinki; Tripathi, Akhilesh; Hannurkar, P.R.

    2013-01-01

    Design and development of an embedded control system for the control, interlock and operation of 1MW, 352.2 MHz TH2089 klystron based RF test facility. The key components of the control system are NI compact Re configurable Input Output (cRIO) system and Windows based PC. The cRIO system's rugged hardware architecture includes a 1.06 GHz Dual-Core embedded controller with Real Time (RT) Operating System, a reconfigurable Field Programmable Gate Array (FPGA) chassis for custom I/O timing, control and processing; and I/O modules. Windows based Graphical User Interface (GUI) has been developed to guide the user through start-up procedure, to set the operating parameters and also to display the status information of all the signals. The application software for data logging and publishing of the acquired data namely set, read back and status signals of auxiliary power supplies and machine safety interlocks has been developed in LabVIEW RT module and is running on embedded controller. Machine safety interlock logic has been implemented in FPGA to meet the time criticality. (author)

  4. Review of pulsed rf power generation

    International Nuclear Information System (INIS)

    Lavine, T.L.

    1992-04-01

    I am going to talk about pulsed high-power rf generation for normal-conducting electron and positron linacs suitable for applications to high-energy physics in the Next Linear Collider, or NLC. The talk will cover some basic rf system design issues, klystrons and other microwave power sources, rf pulse-compression devices, and test facilities for system-integration studies

  5. RF and feedback systems

    International Nuclear Information System (INIS)

    Boussard, D.

    1994-01-01

    The radiofrequency system of the Tau Charm Factory accelerating 10 11 particles per bunch and a circulating current of 0.5 A is presented. In order to produce the very short bunches required, the RF system of TCF must provide a large RF voltage (8 MV) at a frequency in the neighbourhood of 400-500 MHz. It appears very attractive to produce the high voltage required with superconducting cavities, for which wall losses are negligible. A comparison between the sc RF system proposed and a possible copper system run at an average 1 MV/m, shows the clear advantage of sc cavities for TCF. (R.P.). 2 figs,. 1 tab

  6. Frontier applications of rf superconductivity for high energy physics in the TeV range

    International Nuclear Information System (INIS)

    Tigner, M.; Padamsee, H.

    1988-01-01

    The authors present understanding of the fundamental nature of matter is embodied in the standard theory. This theory views all matter as composed of families of quarks and leptons with their interactions mediated by the family of force-carrying particles. Progress in particle accelerators has been a vital element in bringing about this level of understanding. Although the standard theory is successful in relating a wide range of phenomena, it raises deeper questions about the basic nature of matter and energy. Among these are: why are the masses of the various elementary particles and the strengths of the basic forces what they are? It is expected that over the next decade a new generation of accelerators spanning the 100 Gev mass range will shed light on some of these questions. These accelerators, will provide the means to thoroughly explore the energy regime corresponding to the mass scale of the weak interactions to reveal intimate details of the force carrying particles, the weak bosons, Z0 and W+-. Superconducting rf technology will feature in a major way in the electron storage rings. Current theoretical ideas predict that to make further progress towards a more fundamental theory of matter, it will be necessary to penetrate the TeV energy regime. At this scale a whole new range of phenomena will manifest the nature of the symmetry breaking mechanism that must be responsible for the differences they observe in the familiar weak and electromagnetic forces. History has shown that unexpected discoveries made in a new energy regime have proven to be the main engine of progress. The experimental challenge to accelerator designers and builders is clear. 11 references, 3 figures, 1 table

  7. CAS Accelerator Physics (RF for Accelerators) in Denmark

    CERN Multimedia

    Barbara Strasser

    2010-01-01

    The CERN Accelerator School (CAS) and Aarhus University jointly organised a specialised course on RF for Accelerators, at the Ebeltoft Strand Hotel, Denmark from 8 to 17 June 2010.   Caption The challenging programme focused on the introduction of the underlying theory, the study and the performance of the different components involved in RF systems, the RF gymnastics and RF measurements and diagnostics. This academic part was supplemented with three afternoons dedicated to practical hands-on exercises. The school was very successful, with 100 participants representing 25 nationalities. Feedback from the participants was extremely positive, praising the expertise and enthusiasm of the lecturers, as well as the high standard and excellent quality of their lectures. In addition to the academic programme, the participants were able to visit a small industrial exhibition organised by Aarhus University and take part in a one-day excursion consisting of a visit of the accelerators operated ...

  8. Beyond the RF photogun

    NARCIS (Netherlands)

    Luiten, O.J.; Rozenzweig, J.; Travish, G.

    2003-01-01

    Laser-triggered switching of MV DC voltages enables acceleration gradients an order of magnitude higher than in state-of-the-art RF photoguns. In this way ultra-short, high-brightness electron bunches may be generated without the use of magnetic compression. The evolution of the bunch during the

  9. RF properties of 700 MHz, β = 0.42 elliptical cavity for high current ...

    Indian Academy of Sciences (India)

    Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, ... has been taken up as a part of the accelerator-driven subcritical system project. ... cavity's peak electric and magnetic fields, power dissipation Pc, quality factor Q and.

  10. Recoupling and decoupling of nuclear spin interactions at high MAS frequencies: numerical design of CNnν symmetry-based RF pulse schemes

    International Nuclear Information System (INIS)

    Herbst, Christian; Herbst, Jirada; Kirschstein, Anika; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

    2009-01-01

    The CN n ν class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning solid state NMR studies of biological systems, involves the application of a basic 'C' element corresponding to an RF cycle with unity propagator. In this study, the design of CN n ν symmetry-based RF pulse sequences for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated 13 C- 13 C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated basic 'C' elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by an RF phase value. The phase-modulation profile of the 'C' element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were evaluated via numerical simulations and experimental measurements and are presented here

  11. Sources of Emittance in RF Photocathode Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-12-11

    Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of the electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.

  12. A low-jitter RF PLL frequency synthesizer with high-speed mixed-signal down-scaling circuits

    International Nuclear Information System (INIS)

    Tang Lu; Wang Zhigong; Xue Hong; He Xiaohu; Xu Yong; Sun Ling

    2010-01-01

    A low-jitter RF phase locked loop (PLL) frequency synthesizer with high-speed mixed-signal down-scaling circuits is proposed. Several techniques are proposed to reduce the design complexity and improve the performance of the mixed-signal down-scaling circuit in the PLL. An improved D-latch is proposed to increase the speed and the driving capability of the DMP in the down-scaling circuit. Through integrating the D-latch with 'OR' logic for dual-modulus operation, the delays associated with both the 'OR' and D-flip-flop (DFF) operations are reduced, and the complexity of the circuit is also decreased. The programmable frequency divider of the down-scaling circuit is realized in a new method based on deep submicron CMOS technology standard cells and a more accurate wire-load model. The charge pump in the PLL is also realized with a novel architecture to improve the current matching characteristic so as to reduce the jitter of the system. The proposed RF PLL frequency synthesizer is realized with a TSMC 0.18-μm CMOS process. The measured phase noise of the PLL frequency synthesizer output at 100 kHz offset from the center frequency is only -101.52 dBc/Hz. The circuit exhibits a low RMS jitter of 3.3 ps. The power consumption of the PLL frequency synthesizer is also as low as 36 mW at a 1.8 V power supply. (semiconductor integrated circuits)

  13. Development of a movable plunger tuner for the high-power RF cavity for the PEP-II B-factory

    International Nuclear Information System (INIS)

    Schwarz, H.D.; Fant, K.; Judkins, J.G.

    1997-05-01

    A 10 cm diameter by 5 cm travel plunger tuner was developed for the PEP-II RF copper cavity system. The single cell cavity including the tuner is designed to operate up to 150 kW of dissipated RF power are specially placed 8.5 cm away from the inside wall of the cavity to avoid fundamental and higher order mode resonances. The spring fingers are made of dispersion-strengthened copper to accommodate relatively high heating. The design, alignment, testing and performance of the tuner is described

  14. RF gun using laser-triggered photocathode

    International Nuclear Information System (INIS)

    Akiyama, H.; Otake, Y.; Naito, T.; Takeuchi, Y.; Yoshioka, M.

    1992-01-01

    An RF gun using laser-triggered photocathode has many advantages as an injector of the linear colliders since it can generate a low emittance and high current pulsed beam. The experimental facility for the RF gun, such as an RF system, a laser system and a photocathode have been fabricated to study the fundamental characteristics. The dynamics of the RF gun has also studied by the 1D sheet beam model. (author)

  15. Compression and radiation of high-power short rf pulses. II. A novel antenna array design with combined compressor/radiator elements

    KAUST Repository

    Sirenko, Kostyantyn; Pazynin, Vadim L.; Sirenko, Yu K.; Bagci, Hakan

    2011-01-01

    The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a

  16. Theory of RF superconductivity for resonant cavities

    Science.gov (United States)

    Gurevich, Alex

    2017-03-01

    An overview of a theory of electromagnetic response of superconductors in strong radio-frequency (RF) electromagnetic fields is given with the emphasis on applications to superconducting resonant cavities for particle accelerators. The paper addresses fundamentals of the BCS surface resistance, the effect of subgap states and trapped vortices on the residual surface resistance at low RF fields, and a nonlinear surface resistance at strong fields, particularly the effect of the RF field suppression of the surface resistance. These issues are essential for the understanding of the field dependence of high quality factors Q({B}a)˜ {10}10{--}{10}11 achieved on the Nb cavities at 1.3-2 K in strong RF fields B a close to the depairing limit, and the extended Q({B}a) rise which has been observed on Ti and N-treated Nb cavities. Possible ways of further increase of Q({B}a) and the breakdown field by optimizing impurity concentration at the surface and by multilayer nanostructuring with materials other than Nb are discussed.

  17. RF Gun Optimization Study

    International Nuclear Information System (INIS)

    Alicia Hofler; Pavel Evtushenko

    2007-01-01

    Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. A genetic algorithm (GA) has been successfully used to optimize DC photo injector designs at Cornell University [1] and Jefferson Lab [2]. We propose to apply GA techniques to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize a system that has been benchmarked with beam measurements and simulation

  18. A high-efficiency, low-noise power solution for a dual-channel GNSS RF receiver

    International Nuclear Information System (INIS)

    Shi Jian; Mo Taishan; Gan Yebing; Ma Chengyan; Ye Tianchun; Le Jianlian

    2012-01-01

    A high-efficiency low-noise power solution for a dual-channel GNSS RF receiver is presented. The power solution involves a DC—DC buck converter and a followed low-dropout regulator (LDO). The pulse-width-modulation (PWM) control method is adopted for better noise performance. An improved low-power high-frequency PWM control circuit is proposed, which halves the average quiescent current of the buck converter to 80 μA by periodically shutting down the OTA. The size of the output stage has also been optimized to achieve high efficiency under a light load condition. In addition, a novel soft-start circuit based on a current limiter has been implemented to avoid inrush current. Fabricated with commercial 180-nm CMOS technology, the DC—DC converter achieves a peak efficiency of 93.1% under a 2 MHz working frequency. The whole receiver consumes only 20.2 mA from a 3.3 V power supply and has a noise figure of 2.5 dB. (semiconductor integrated circuits)

  19. Experimental study on the luminous radiation associated to the field emission of samples submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Luong, M.; Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    Nowadays the accelerating gradient of the RF cavities is limited by the strong field emission (FE) of electrons stemming from the metallic walls. Previous experiments evidenced luminous radiations associated with electron emission on cathodes subjected to intense DC electric field. These observations led these authors to propose new theoretical models of the field emission phenomenon. The presented experimental study extends these previous DC works to the RF case. A special copper RF cavity has been developed equipped with an optical window and a removable sample. It has been designed for measuring both electron current and luminous radiation emitted by the sample, subjected to maximum RF electric field. The optical apparatus attached to the cavity permits to characterize the radiation in terms of intensity, glowing duration and spectral distribution. The results concerning different niobium or copper samples, whom top was either scratched or intentionally contaminated with metallic or dielectric particles are summarized. (author)

  20. Experimental study on the luminous radiation associated to the field emission of samples submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Luong, M.; Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    The accelerating gradient of the RF cavities is limited by the strong field emission (FE) of electrons stemming from the metallic walls. Previous experiments evidenced luminous radiations associated with electron emission of cathodes subjected to intense DC electric field. These observations invoked the proposal of new theoretical models of the field emission phenomenon. This experimental study extends the previous DC works to the RF case. A special copper RF cavity has been developed equipped with an optical window and a removable sample. It has been designed for measuring both electron current and luminous radiation emitted by the sample, subjected to maximum RF electric field. The optical apparatus attached to the cavity permits to characterize the radiation in terms of intensity, glowing duration and spectral distribution. The results concerning different niobium or copper samples, whom top was either scratched or intentionally contaminated with metallic or dielectric particles are summarized. (author)

  1. Microscopic investigation of RF surfaces of 3 GHz niobium accelerator cavities following RF processing

    International Nuclear Information System (INIS)

    Graber, J.; Barnes, P.; Flynn, T.; Kirchgessner, J.; Knobloch, J.; Moffat, D.; Muller, H.; Padamsee, H.; Sears, J.

    1993-01-01

    RF processing of Superconducting accelerating cavities is achieved through a change in the electron field emission (FE) characteristics of the RF surface. The authors have examined the RF surfaces of several single-cell 3 GHz cavities, following RF processing, in a Scanning Electron Microscope (SEM). The RF processing sessions included both High Peak Power (P ≤ 50 kW) pulsed processing, and low power (≤ 20 W) continuous wave processing. The experimental apparatus also included a thermometer array on the cavity outer wall, allowing temperature maps to characterize the emission before and after RF processing gains. Multiple sites have been located in cavities which showed improvements in cavity behavior due to RF processing. Several SEM-located sites can be correlated with changes in thermometer signals, indicating a direct relationship between the surface site and emission reduction due to RF processing. Information gained from the SEM investigations and thermometry are used to enhance the theoretical model of RF processing

  2. ADX: A high Power Density, Advanced RF-Driven Divertor Test Tokamak for PMI studies

    Science.gov (United States)

    Whyte, Dennis; ADX Team

    2015-11-01

    The MIT PSFC and collaborators are proposing an advanced divertor experiment, ADX; a divertor test tokamak dedicated to address critical gaps in plasma-material interactions (PMI) science, and the world fusion research program, on the pathway to FNSF/DEMO. Basic ADX design features are motivated and discussed. In order to assess the widest range of advanced divertor concepts, a large fraction (>50%) of the toroidal field volume is purpose-built with innovative magnetic topology control and flexibility for assessing different surfaces, including liquids. ADX features high B-field (>6 Tesla) and high global power density (P/S ~ 1.5 MW/m2) in order to access the full range of parallel heat flux and divertor plasma pressures foreseen for reactors, while simultaneously assessing the effect of highly dissipative divertors on core plasma/pedestal. Various options for efficiently achieving high field are being assessed including the use of Alcator technology (cryogenic cooled copper) and high-temperature superconductors. The experimental platform would also explore advanced lower hybrid current drive and ion-cyclotron range of frequency actuators located at the high-field side; a location which is predicted to greatly reduce the PMI effects on the launcher while minimally perturbing the core plasma. The synergistic effects of high-field launchers with high total B on current and flow drive can thus be studied in reactor-relevant boundary plasmas.

  3. High Power, Pulsed, RF Generation from Nonlinear Lumped Element Transmission Lines (NLETLs)

    Science.gov (United States)

    2011-02-05

    in order to focus on the primary technology tinder consideration. Their practicality at very high powers and frequencies is questionable due to...also possessed suitably large CXL ratios. Measuring capacitive nonlinearity tinder high voltage proved to be more tricky than first imagi- ned

  4. 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)

  5. Overview of superconducting RF technology and its application to high-current linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.

    1994-01-01

    Superconducting linacs may be a viable option for high-current applications such as copious neutron production like that needed for transmutation of radioactive waste. These linacs must run reliably for many years and allow easy routine maintenance. superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs. However, cost effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement

  6. Development of RF-linac and storage ring system for high-current experiments at GSI

    International Nuclear Information System (INIS)

    Hofmann, I.

    1986-08-01

    The heavy ion facility under construction at GSI is suitable for the generation of high-current beams. It consists of a new high-current injector into the Unilac and a synchrotron and storage ring. We discuss the capability of this system to produce short pulses of heavy ions with a specific energy of the order of 0.1 MJ/g. Under these conditions the system allows to perform a first generation of heavy ion driven target experiments and to test most of the critical issues of a large scale heavy ion fusion driver facility. (orig.)

  7. Design of a high-power test model of the PEP-II rf cavity

    International Nuclear Information System (INIS)

    Schwarz, H.D.; Bell, R.A.; Hodgson, J.A.

    1993-05-01

    The design of a normal-conducting high-power test cavity (HPTC) for PEP-II is described. The cavity includes HOM loading waveguides and provisions for testing two alternate input coupling schemes. 3-D electromagnetic field simulations provided input information for the surface power deposition. Finite element codes were utilized for thermal and stress analyses of the cavity to arrive at a suitable mechanical design capable of handling the high power dissipation. The mechanical design approach with emphasis on the cooling channel layout and mechanical stress reduction is described

  8. Charge distributions of fission fragments of low- and high-energy fission of Fm, No, and Rf isotopes

    Science.gov (United States)

    Paşca, H.; Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.

    2018-03-01

    The charge (mass) distributions of fission fragments resulting from low- and high-energy fission of the even-even nuclei 254 -260 ,264Fm , 258 -264No , and 262 -266Rf are studied with the statistical scission-point model. The calculated results are compared with the available experimental data. In contrast to the experimental data, the calculated mass distribution for 258Fm (s.f.) is strikingly similar to the experimental one for 257Fm (s.f.). The transformation of the shape of charge distribution with increasing isospin and excitation energy occurs gradually and in a similar fashion like that of the mass distribution, but slower. For 254Fm(i.f.), 257Fm(nt h,f), and 260Fm (s.f.), the unexpected difference (symmetric or asymmetric) between the shapes of charge and mass distributions is predicted for the first time. At some critical excitation energy, the saturation of the symmetric component of charge (mass) yields is demonstrated.

  9. Analysis and design of a high-linearity receiver RF front-end with an improved 25%-duty-cycle LO generator for WCDMA/GSM applications

    International Nuclear Information System (INIS)

    Hu Song; Li Weinan; Huang Yumei; Hong Zhiliang

    2012-01-01

    A fully integrated receiver RF front-end that meets WCDMA/GSM system requirements is presented. It supports SAW-less operation for WCDMA. To improve the linearity in terms of both IP3 and IP2, the RF front-end is comprised of multiple-gated LNAs with capacitive desensitization, current-mode passive mixers with the proposed IP2 calibration circuit and reconfigurable Tow-Thomas-like biquad TIAs. A new power-saving multi-mode divider with low phase noise is proposed to provide the 4-phase 25%-duty-cycle LO. In addition, a constant-g m biasing with a non-chip resistor is adopted to make the conversion gain invulnerable to the process and temperature variations of the transimpedance. This RF front-end is integrated in a receiver with an on-chip frequency synthesizer in 0.13 μm CMOS. The measurement results show that owing to this high-linearity RF front-end, the receiver achieves −6 dBm IIP3 and better than +60 dBm IIP2 for all modes and bands. (semiconductor integrated circuits)

  10. Design, Fabrication and High Power RF Test of a C-band Accelerating Structure for Feasibility Study of the SPARC photo-injector energy upgrade

    CERN Document Server

    Alesini, D.; Di Pirro, G.; Di Raddo, R.; Ferrario, M.; Gallo, A.; Lollo, V.; Marcellini, F.; Higo, T.; Kakihara, K.; Matsumoto, S.; Campogiani, G.; Mostacci, A.; Palumbo, L.; Persichelli, S.; Spizzo, V.; Verdú-Andrés, S.

    2011-01-01

    The energy upgrade of the SPARC photo-injector from 160 to more than 260 MeV will be done by replacing a low gradient 3m S-Band structure with two 1.4m high gradient C-band structures. The structures are travelling wave, constant impedance sections, have symmetric waveguide input couplers and have been optimized to work with a SLED RF input pulse. A prototype with a reduced number of cells has been fabricated and tested at high power in KEK (Japan) giving very good performances in terms of breakdown rates (10^6 bpp/m) at high accelerating gradient (>50 MV/m). The paper illustrates the design criteria of the structures, the fabrication procedure and the high power RF test results.

  11. Generation of high intensity rf pulses in the ionosphere by means of in situ compression

    International Nuclear Information System (INIS)

    Cowley, S.C.; Perkins, F.W.; Valeo, E.J.

    1993-04-01

    We demonstrate, using a simple model, that high intensity pulses can be generated from a frequency-chirped modifier of much lower intensity by making use of the dispersive properties of the ionosphere. We show that a frequency-chirped pulse can be constructed so that its various components overtake each other at a prescribed height, resulting in large (up to one hundred times) transient intensity enhancements as compared to those achievable from a steady modifier operating at the same power. We examine briefly one possible application: the enhancement of plasma wave amplitudes which occurs as a result of the interaction of such a compressed pulse with pre-generated turbulence

  12. RF heating and current drive on NSTX with high harmonic fast waves

    International Nuclear Information System (INIS)

    Ryan, P.M.

    2002-01-01

    NSTX is a small aspect ratio tokamak with a large dielectric constant (50-100); under these conditions high harmonic fast waves (HHFW) will readily damp on electrons via Landau damping and TTMP. The HHFW system is a 30 MHz, 12-element array capable of launching both symmetric and directional wave spectra for plasma heating and non-inductive current drive. It has delivered up to 6 MW for short pulses and has routinely operated at ∼3-4 MW for 100-200 ms pulses. Results include strong, centrally-peaked electron heating in both D and He plasmas, for both high and low phase velocity spectra. H-modes were obtained with application of HHFW power alone, with stored energy doubling after the L-H transition. Beta poloidal as large as unity has been obtained with large fractions (0.4) of bootstrap current. A fast ion tail with energies extending up to 140 keV has been observed when HHFW interacts with 80 keV neutral beams; neutron rate and lost ion measurements, as well as modeling, indicate significant power absorption by the fast ions. Radial power deposition profiles are being calculated with ray tracing and kinetic full-wave codes and benchmarked against measurements. (author)

  13. High temperature electrons exhausted from rf plasma sources along a magnetic nozzle

    Science.gov (United States)

    Takahashi, Kazunori; Akahoshi, Hikaru; Charles, Christine; Boswell, Rod W.; Ando, Akira

    2017-08-01

    Two dimensional profiles of electron temperature are measured inside and downstream of a radiofrequency plasma thruster source having a magnetic nozzle and being immersed in vacuum. The temperature is estimated from the slope of the fully swept I-V characteristics of a Langmuir probe acquired at each spatial position and with the assumption of a Maxwellian distribution. The results show that the peripheral high temperature electrons in the magnetic nozzle originate from the upstream antenna location and are transported along the "connecting" magnetic field lines. Two-dimensional measurements of electron energy probability functions are also carried out in a second simplified laboratory device consisting of the source contiguously connected to the diffusion chamber: again the high temperature electrons are detected along the magnetic field lines intersecting the wall at the antenna location, even when the antenna location is shifted along the main axis. These results demonstrate that the peripheral energetic electrons in the magnetic nozzle mirror those created in the source tube.

  14. Power Adaptation Based on Truncated Channel Inversion for Hybrid FSO/RF Transmission With Adaptive Combining

    KAUST Repository

    Rakia, Tamer

    2015-07-23

    Hybrid free-space optical (FSO)/radio-frequency (RF) systems have emerged as a promising solution for high-data-rate wireless communications. In this paper, we consider power adaptation strategies based on truncated channel inversion for the hybrid FSO/RF system employing adaptive combining. Specifically, we adaptively set the RF link transmission power when FSO link quality is unacceptable to ensure constant combined signal-to-noise ratio (SNR) at the receiver. Two adaptation strategies are proposed. One strategy depends on the received RF SNR, whereas the other one depends on the combined SNR of both links. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are obtained. Numerical examples show that the hybrid FSO/RF system with power adaptation achieves a considerable outage performance improvement over the conventional system.

  15. Power Adaptation Based on Truncated Channel Inversion for Hybrid FSO/RF Transmission With Adaptive Combining

    KAUST Repository

    Rakia, Tamer; Hong-Chuan Yang; Gebali, Fayez; Alouini, Mohamed-Slim

    2015-01-01

    Hybrid free-space optical (FSO)/radio-frequency (RF) systems have emerged as a promising solution for high-data-rate wireless communications. In this paper, we consider power adaptation strategies based on truncated channel inversion for the hybrid FSO/RF system employing adaptive combining. Specifically, we adaptively set the RF link transmission power when FSO link quality is unacceptable to ensure constant combined signal-to-noise ratio (SNR) at the receiver. Two adaptation strategies are proposed. One strategy depends on the received RF SNR, whereas the other one depends on the combined SNR of both links. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are obtained. Numerical examples show that the hybrid FSO/RF system with power adaptation achieves a considerable outage performance improvement over the conventional system.

  16. Highly transparent conductive ITO/Ag/ITO trilayer films deposited by RF sputtering at room temperature

    Directory of Open Access Journals (Sweden)

    Ningyu Ren

    2017-05-01

    Full Text Available ITO/Ag/ITO (IAI trilayer films were deposited on glass substrate by radio frequency magnetron sputtering at room temperature. A high optical transmittance over 94.25% at the wavelength of 550 nm and an average transmittance over the visual region of 88.04% were achieved. The calculated value of figure of merit (FOM reaches 80.9 10-3 Ω-1 for IAI films with 15-nm-thick Ag interlayer. From the morphology and structural characterization, IAI films could show an excellent correlated electric and optical performance if Ag grains interconnect with each other on the bottom ITO layer. These results indicate that IAI trilayer films, which also exhibit low surface roughness, will be well used in optoelectronic devices.

  17. Superconducting linac beam dynamics with high-order maps for RF resonators

    CERN Document Server

    Geraci, A A; Pardo, R C; 10.1016/j.nima.2003.11.177

    2004-01-01

    The arbitrary-order map beam optics code COSY Infinity has recently been adapted to calculate accurate high-order ion-optical maps for electrostatic and radio-frequency accelerating structures. The beam dynamics of the superconducting low-velocity positive-ion injector linac for the ATLAS accelerator at Argonne National Lab is used to demonstrate some advantages of the new simulation capability. The injector linac involves four different types of superconducting accelerating structures and has a total of 18 resonators. The detailed geometry for each of the accelerating cavities is included, allowing an accurate representation of the on- and off-axis electric fields. The fields are obtained within the code from a Poisson-solver for cylindrically symmetric electrodes of arbitrary geometry. The transverse focusing is done with superconducting solenoids. A detailed comparison of the transverse and longitudinal phase space is made with the conventional ray-tracing code LINRAY. The two codes are evaluated for ease ...

  18. RF Pulsed Heating

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2002-01-03

    RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  19. Atomistic self-sputtering mechanisms of rf breakdown in high-gradient linacs

    International Nuclear Information System (INIS)

    Insepov, Z.; Norem, J.; Veitzer, S.

    2010-01-01

    Molecular dynamics (MD) models of sputtering solid and liquid surfaces - including the surfaces charged by interaction with plasma, Coulomb explosion, and Taylor cone formation - were developed. MD simulations of self-sputtering of a crystalline (1 0 0) copper surface by Cu + ions in a wide range of ion energies (50 eV-50 keV) were performed. In order to accommodate energetic ion impacts on a target, a computational model was developed that utilizes MD to simulate rapid atomic collisions in the central impact zone, and a finite-difference method to absorb the energy and shock wave for the collisional processes occurring at a longer time scales. The sputtering yield increases if the surface temperature rises and the surface melts as a result of heat from plasma. Electrostatic charging of the surface under bombardment with plasma ions is another mechanism that can dramatically increase the sputtering yield because it reduces the surface binding energy and the surface tension. An MD model of Taylor cone formation at a sharp tip placed in a high electric field was developed, and the model was used to simulate Taylor cone formation for the first time. Good agreement was obtained between the calculated Taylor cone angle (104.3 deg.) and the experimental one (98.6 deg.). A Coulomb explosion (CE) was proposed as the main surface failure mechanism triggering breakdown, and the dynamics of CE was studied by MD.

  20. Status on RF superconductivity at the institute for high energy physics

    International Nuclear Information System (INIS)

    Sevryukova, L.M.

    2003-01-01

    The development of SC cavities started at the Institute for High Energy Physics in September 1980 when the group of technology and study of SC cavities of the Research Institute of Nuclear Physics at Tomsk Polytechnic Institute moved there. At first the group worked at the Linear Accelerator Division, then later, in March 1993 the Federate Problem Laboratory for Technology and Study of the superconducting cavities of the Russian Atomic Ministry was founded at IHEP. The main goal of the SC cavity investigation is to study and develop the suppression methods for emission effects and conditions for thermomagnetic breakdown creation to increase the accelerating fields at SC cavities; also developing the experimental equipment to answer this goal. In this report the following items are enlightened in short: 1. Study and development of methods to suppress emission effects in SC cavities; 2. Study and development of methods to increase the threshold of the thermomagnetic breakdown. 3. Study of new materials and technologies. 4. SVAAP (SC accelerator for the applied purposes) project development. (author)

  1. Performance of RF sputtered p-Si/n-ZnO nanoparticle thin film heterojunction diodes in high temperature environment

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Satyendra Kumar, E-mail: satyndra.singh.eee09@itbhu.ac.in [Department of Electronics and Communication Engineering, Model Institute of Engineering and Technology, Jammu, 181122 (India); Department of Electronics and Communication Engineering, Motilal Nehru National Institute of Technology, Allahabad, Uttar Pradesh, 211004 (India); Hazra, Purnima, E-mail: purnima.hazra@smvdu.ac.in [Department of Electronics and Communication Engineering, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, 182320 (India)

    2017-04-01

    Highlights: • Synthesize ZnO nanoparticle thin film on p-Si substrate using RF sputtering method. • I–V and C–V characteristics of Si/ZnO heterojunction diode are studied. • High temperature performance is analyzed accounting barrier height inhomogeneities. • Gaussian distribution of BH inhomogeneities is considered to modify Richardson plot. • Modified R constant is 33.06 Acm{sup −2}K{sup −2}, i.e. nearer to theoretical value 32 Acm{sup −2}K{sup −2}. - Abstract: In this article, temperature-dependent current-voltage characteristics of n-ZnO/p-Si nanoparticle thin film heterojunction diode grown by RF sputtering technique are analyzed in the temperature range of 300–433 k to investigate the performance of the device in high temperature environment. The microstructural, morphological, optical and temptrature dependent electrical properties of as-grown nanoparticle thin film were characterized by X-ray diffractometer (XRD), atomic force microscopy (AFM), field emmision scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), variable angle ellipsometer and semiconductor device analyzer. XRD spectra of as-grown ZnO films are exhibited that highly c-axis oriented ZnO nanostructures are grown on p- Si〈100〉 substrate whereas AFM and FESEM images confirm the homogeneous deposition of ZnO nanoparticles on surface of Si substratewith minimum roughness.The optical propertiesof as-grown ZnO nanoparticles have been measured in the spectral range of 300–800 nm using variable angle ellipsometer.To measure electrical parameters of the device prototype in the temperature range of room temperature (300 K) to 433 K, large area ohmic contacts were fabricated on both side of the ZnO/Si heterostructure. From the current-voltage charcteristics of ZnO/Si heterojunction device, it is observed that the device exhibits rectifing nature at room temperature. However, with increase in temperature, reverse saturation current and barrier

  2. Availability of high quality weather data measurements

    DEFF Research Database (Denmark)

    Andersen, Elsa; Johansen, Jakob Berg; Furbo, Simon

    In the period 2016-2017 the project “Availability of high quality weather data measurements” is carried out at Department of Civil Engineering at the Technical University of Denmark. The aim of the project is to establish measured high quality weather data which will be easily available...... for the building energy branch and the solar energy branch in their efforts to achieve energy savings and for researchers and students carrying out projects where measured high quality weather data are needed....

  3. Compression and radiation of high-power short rf pulses. II. A novel antenna array design with combined compressor/radiator elements

    KAUST Repository

    Sirenko, Kostyantyn

    2011-01-01

    The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a radiator. The studies on the monopole antenna demonstrate the possibility of a high power short RF pulse\\'s efficient radiation even using simple antennas. The studies on the novel array design demonstrate that a reduced size array with lower pulse distortion and power decay can be constructed by assembling the array from elements each of which integrates a compressor and a radiator. This design idea can be used with any type of antenna array; in this work it is applied to a phased array.

  4. Arcing and rf signal generation during target irradiation by a high-energy, pulsed neutral particle beam

    International Nuclear Information System (INIS)

    Robiscoe, R.T.

    1988-02-01

    We present a theory describing the dynamics of arc discharges in bulk dielectric materials on board space-based vehicles. Such ''punch-through'' arcs can occur in target satellites irradiated by high-energy (250 MeV), pulsed (100 mA x 10 ms) neutral particle beams. We treat the arc as a capacitively limited avalanche current in the target dielectric material, and we find expressions for the arc duration, charge transport, currents, and discharge energy. These quantities are adjusted to be consistent with known scaling laws for the area of charge depleted by the arc. After a brief account of the statistical distribution of voltages at which the arc starts and stops, we calculate the signal strength and frequency spectrum of the electromagnetic radiation broadcast by the arc. We find that arcs from thick (/similar to/1 cm) targets can generate rf signals detectable up to 1000 km from the target, bu a radio receiver operating at frequency 80 MHz, bandwidth 100 kHz, and detection threshold -105 dBm. These thick-target arc signals are 10 to 20 dB above ambient noise at the receiver, and they provide target hit assessment if the signal spectrum can be sampled at several frequencies in the nominal range 30-200 MHz. Thin-target (/similar to/1 mm) arc signals are much weaker, but when they are detecable in conjunction with thick-target signals, target discrimination is possible by comparing the signal frequency spectra. 24 refs., 12 figs

  5. Device quality InO{sub x}:Sn and InO{sub x} thin films deposited at room temperature with different rf-power densities

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, A., E-mail: ana.de.amaral@ist.utl.pt [Dept. de Fisica and ICEMS, Instituto Superior Tecnico/Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Brogueira, P. [Dept. de Fisica and ICEMS, Instituto Superior Tecnico/Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Conde, O. [Universidade de Lisboa, Dept. de Fisica and ICEMS, Campo Grande, 1749-016 Lisboa (Portugal); Lavareda, G. [Dept. de Ciencia dos Materiais and CTS, FCT-UNL, 2829-516 Caparica (Portugal); Nunes de Carvalho, C. [Dept. de Ciencia dos Materiais, FCT-UNL and ICEMS, 2829-516 Caparica (Portugal)

    2012-12-30

    The influence of tin doping on the electrical, optical, structural and morphological properties of indium oxide films produced by radio-frequency plasma enhanced reactive thermal evaporation is studied, as transport properties are expected to improve with doping. Undoped and tin doped indium oxide thin films are deposited at room temperature using both pure In rods and (95-80) % In:(5-20) % Sn alloys as evaporation sources and 19.5 mW/cm{sup 2} and 58.6 mW/cm{sup 2} as rf-power densities. The two most important macroscopic properties - visible transparency and electrical resistivity - are relatively independent of tin content (0-20%). Visible transmittance of about 75% and electrical resistivity around 5 Multiplication-Sign 10{sup -4} {Omega}{center_dot}cm can be observed in the films. The structural features are similar for all samples. Nevertheless, the surface morphology characterization shows that the homogeneity of the films varies according to the tin content. Moreover this variation is a balance between the rf-power and the tin content in the alloy: i) films with small and compact grains are produced at 58.6 mW/cm{sup 2} from a 5% Sn alloy or at 19.5 mW/cm{sup 2} from a 15% Sn alloy and consequently, smooth surfaces with reduced roughness and similar grain size and shape are obtained; ii) films showing the presence of aggregates randomly distributed above a tissue formed of thinner grains and higher roughness are produced at the other deposition conditions. - Highlights: Black-Right-Pointing-Pointer InO{sub x}:Sn and InO{sub x} thin films were deposited at room temperature. Black-Right-Pointing-Pointer Transparency and electrical resistivity are relatively independent of Sn content. Black-Right-Pointing-Pointer Device quality material was obtained. Black-Right-Pointing-Pointer The surface morphology homogeneity of the films varies with tin content.

  6. Device quality InOx:Sn and InOx thin films deposited at room temperature with different rf-power densities

    International Nuclear Information System (INIS)

    Amaral, A.; Brogueira, P.; Conde, O.; Lavareda, G.; Nunes de Carvalho, C.

    2012-01-01

    The influence of tin doping on the electrical, optical, structural and morphological properties of indium oxide films produced by radio-frequency plasma enhanced reactive thermal evaporation is studied, as transport properties are expected to improve with doping. Undoped and tin doped indium oxide thin films are deposited at room temperature using both pure In rods and (95–80) % In:(5–20) % Sn alloys as evaporation sources and 19.5 mW/cm 2 and 58.6 mW/cm 2 as rf-power densities. The two most important macroscopic properties – visible transparency and electrical resistivity – are relatively independent of tin content (0–20%). Visible transmittance of about 75% and electrical resistivity around 5 × 10 −4 Ω·cm can be observed in the films. The structural features are similar for all samples. Nevertheless, the surface morphology characterization shows that the homogeneity of the films varies according to the tin content. Moreover this variation is a balance between the rf-power and the tin content in the alloy: i) films with small and compact grains are produced at 58.6 mW/cm 2 from a 5% Sn alloy or at 19.5 mW/cm 2 from a 15% Sn alloy and consequently, smooth surfaces with reduced roughness and similar grain size and shape are obtained; ii) films showing the presence of aggregates randomly distributed above a tissue formed of thinner grains and higher roughness are produced at the other deposition conditions. - Highlights: ► InO x :Sn and InO x thin films were deposited at room temperature. ► Transparency and electrical resistivity are relatively independent of Sn content. ► Device quality material was obtained. ► The surface morphology homogeneity of the films varies with tin content.

  7. Recovery in dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors with thermal annealing

    International Nuclear Information System (INIS)

    Kim, Byung-Jae; Hwang, Ya-Hsi; Ahn, Shihyun; Zhu, Weidi; Dong, Chen; Lu, Liu; Ren, Fan; Holzworth, M. R.; Jones, Kevin S.; Pearton, Stephen J.; Smith, David J.; Kim, Jihyun; Zhang, Ming-Lan

    2015-01-01

    The recovery effects of thermal annealing on dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors were investigated. After stress, reverse gate leakage current and sub-threshold swing increased and drain current on-off ratio decreased. However, these degradations were completely recovered after thermal annealing at 450 °C for 10 mins for devices stressed either once or twice. The trap densities, which were estimated by temperature-dependent drain-current sub-threshold swing measurements, increased after off-state step-stress and were reduced after subsequent thermal annealing. In addition, the small signal rf characteristics of stressed devices were completely recovered after thermal annealing

  8. Zerodur polishing process for high surface quality and high efficiency

    International Nuclear Information System (INIS)

    Tesar, A.; Fuchs, B.

    1992-08-01

    Zerodur is a glass-ceramic composite importance in applications where temperature instabilities influence optical and mechanical performance, such as in earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Polished surface quality of substrates affects performance of high reflection coatings. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing. With the proper control of polishing parameters, such surfaces exhibit roughnesses of < l Angstrom rms. Zerodur polishing was studied to recommend a high surface quality polishing process which could be easily adapted to standard planetary continuous polishing machines and spindles. This summary contains information on a polishing process developed at LLNL which reproducibly provides high quality polished Zerodur surfaces at very high polishing efficiencies

  9. Numerical design of an rf-coupling Iris

    International Nuclear Information System (INIS)

    Hanaki, H.

    1991-07-01

    For an rf coupler of an rf system in high-quality transmission an analytical method may be applied to treat the design problem, if a coupling hole between cavities or waveguides is small enough. However, in most cases of accelerator engineering the dimensions of the coupling slots are not so small compared with the size of a cavity and a waveguide. Numerical design of rf coupling slots for a few cases is tried basically according to Henke's method using an equivalent circuit to treat the matching of microwave components, but taking account of beam loading expressed by the coupling coefficient β. The MAFIA code has been applied for the design. (R.P.) 5 refs., 10 figs., 3 tabs

  10. Tunable Q-Factor RF Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Balcazar, Mario D. [Fermilab; Yonehara, Katsuya [Fermilab; Moretti, Alfred [Fermilab; Kazakevitch, Gregory [Fermilab

    2018-01-01

    Intense neutrino beam is a unique probe for researching beyond the standard model. Fermilab is the main institution to produce the most powerful and widespectrum neutrino beam. From that respective, a radiation robust beam diagnostic system is a critical element in order to maintain the quality of the neutrino beam. Within this context, a novel radiation-resistive beam profile monitor based on a gasfilled RF cavity is proposed. The goal of this measurement is to study a tunable Qfactor RF cavity to determine the accuracy of the RF signal as a function of the quality factor. Specifically, measurement error of the Q-factor in the RF calibration is investigated. Then, the RF system will be improved to minimize signal error.

  11. Engineering high quality medical software

    CERN Document Server

    Coronato, Antonio

    2018-01-01

    This book focuses on high-confidence medical software in the growing field of e-health, telecare services and health technology. It covers the development of methodologies and engineering tasks together with standards and regulations for medical software.

  12. Computation of External Quality Factors for RF Structures by Means of Model Order Reduction and a Perturbation Approach

    CERN Document Server

    Flisgen, Thomas; van Rienen, Ursula

    2016-01-01

    External quality factors are significant quantities to describe losses via waveguide ports in radio frequency resonators. The current contribution presents a novel approach to determine external quality factors by means of a two-step procedure: First, a state-space model for the lossless radio frequency structure is generated and its model order is reduced. Subsequently, a perturbation method is applied on the reduced model so that external losses are accounted for. The advantage of this approach results from the fact that the challenges in dealing with lossy systems are shifted to the reduced order model. This significantly saves computational costs. The present paper provides a short overview on existing methods to compute external quality factors. Then, the novel approach is introduced and validated in terms of accuracy and computational time by means of commercial software.

  13. Computer simulation for improving radio frequency (RF) heating uniformity of food products: A review.

    Science.gov (United States)

    Huang, Zhi; Marra, Francesco; Subbiah, Jeyamkondan; Wang, Shaojin

    2018-04-13

    Radio frequency (RF) heating has great potential for achieving rapid and volumetric heating in foods, providing safe and high-quality food products due to deep penetration depth, moisture self-balance effects, and leaving no chemical residues. However, the nonuniform heating problem (usually resulting in hot and cold spots in the heated product) needs to be resolved. The inhomogeneous temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms or insects may not be controlled in the cold spots. The mathematical modeling for RF heating processes has been extensively studied in a wide variety of agricultural products recently. This paper presents a comprehensive review of recent progresses in computer simulation for RF heating uniformity improvement and the offered solutions to reduce the heating nonuniformity. It provides a brief introduction on the basic principle of RF heating technology, analyzes the applications of numerical simulation, and discusses the factors influencing the RF heating uniformity and the possible methods to improve heating uniformity. Mathematical modeling improves the understanding of RF heating of food and is essential to optimize the RF treatment protocol for pasteurization and disinfestation applications. Recommendations for future research have been proposed to further improve the accuracy of numerical models, by covering both heat and mass transfers in the model, validating these models with sample movement and mixing, and identifying the important model parameters by sensitivity analysis.

  14. Endoluminal ultrasound applicator with an integrated RF coil for high-resolution magnetic resonance imaging-guided high-intensity contact ultrasound thermotherapy

    International Nuclear Information System (INIS)

    Rata, Mihaela; Salomir, Rares; Lafon, Cyril; Umathum, Reiner; Jenne, Juergen; Bock, Michael; Cotton, Francois

    2008-01-01

    High-intensity contact ultrasound (HICU) under MRI guidance may provide minimally invasive treatment of endocavitary digestive tumors in the esophagus, colon or rectum. In this study, a miniature receive-only coil was integrated into an endoscopic ultrasound applicator to offer high-resolution MRI guidance of thermotherapy. A cylindrical plastic support with an incorporated single element flat transducer (9.45 MHz, water cooling tip) was made and equipped with a rectangular RF loop coil surrounding the active element. The integrated coil provided significantly higher sensitivity than a four-element extracorporeal phased array coil, and the standard deviation of the MR thermometry (SDT) improved up to a factor of 7 at 10 mm depth in tissue. High-resolution morphological images (T1w-TFE and IR-T1w-TSE with a voxel size of 0.25 x 0.25 x 3 mm 3 ) and accurate thermometry data (the PRFS method with a voxel size of 0.5 x 0.5 x 5 mm 3 , 2.2 s/image, 0.3 deg. C voxel-wise SDT) were acquired in an ex vivo esophagus sample, on a clinical 1.5T scanner. The endoscopic device was actively operated under automatic temperature control, demonstrating a high level of accuracy (1.7% standard deviation, 1.1% error of mean value), which indicates that this technology may be suitable for HICU therapy of endoluminal cancer.

  15. Endoluminal ultrasound applicator with an integrated RF coil for high-resolution magnetic resonance imaging-guided high-intensity contact ultrasound thermotherapy

    Science.gov (United States)

    Rata, Mihaela; Salomir, Rares; Umathum, Reiner; Jenne, Jürgen; Lafon, Cyril; Cotton, François; Bock, Michael

    2008-11-01

    High-intensity contact ultrasound (HICU) under MRI guidance may provide minimally invasive treatment of endocavitary digestive tumors in the esophagus, colon or rectum. In this study, a miniature receive-only coil was integrated into an endoscopic ultrasound applicator to offer high-resolution MRI guidance of thermotherapy. A cylindrical plastic support with an incorporated single element flat transducer (9.45 MHz, water cooling tip) was made and equipped with a rectangular RF loop coil surrounding the active element. The integrated coil provided significantly higher sensitivity than a four-element extracorporeal phased array coil, and the standard deviation of the MR thermometry (SDT) improved up to a factor of 7 at 10 mm depth in tissue. High-resolution morphological images (T1w-TFE and IR-T1w-TSE with a voxel size of 0.25 × 0.25 × 3 mm3) and accurate thermometry data (the PRFS method with a voxel size of 0.5 × 0.5 × 5 mm3, 2.2 s/image, 0.3 °C voxel-wise SDT) were acquired in an ex vivo esophagus sample, on a clinical 1.5T scanner. The endoscopic device was actively operated under automatic temperature control, demonstrating a high level of accuracy (1.7% standard deviation, 1.1% error of mean value), which indicates that this technology may be suitable for HICU therapy of endoluminal cancer.

  16. Computer control of rf at SLAC

    International Nuclear Information System (INIS)

    Schwarz, H.D.

    1985-03-01

    The Stanford Linear Accelerator is presently upgraded for the SLAC Linear Collider project. The energy is to be increased from approximately 31 GeV to 50 GeV. Two electron beams and one positron beam are to be accelerated with high demands on the quality of the beams. The beam specifications are shown. To meet these specifications, all parameters influencing the beams have to be under tight control and continuous surveillance. This task is accomplished by a new computer system implemented at SLAC which has, among many other functions, control over rf accelerating fields. 13 refs., 8 figs., 2 tabs

  17. Numerical design of RNnν symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies

    International Nuclear Information System (INIS)

    Herbst, Christian; Herbst, Jirada; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

    2009-01-01

    An approach for the efficient implementation of RN n ν symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN n ν symmetry involve the repeated application of the pulse sandwich {R φ R -φ }, corresponding to a propagator U RF = exp(-i4φI z ), where φ = πν/N and R is typically a pulse that rotates the nuclear spins through 180 o about the x-axis. In this study, broadband, phase-modulated 180 o pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN n ν symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here

  18. Development of Localized Arc Filament RF Plasma Actuators for High-Speed and High Reynolds Number Flow Control

    Science.gov (United States)

    2010-01-01

    high-speed flows is problematic due to their low forcing frequency (for mechanical actuators) and low forcing amplitude (for piezo actuators...very low fraction of DC power is coupled to the actuators (5-10%), with the rest of the power dissipated in massive ballast resistors acting as heat... resistors . The use of high-power resistors also significantly increases the weight and size of the plasma generator and makes scaling to a large number of

  19. Computer-aided design of the RF-cavity for a high-power S-band klystron

    Science.gov (United States)

    Kant, D.; Bandyopadhyay, A. K.; Pal, D.; Meena, R.; Nangru, S. C.; Joshi, L. M.

    2012-08-01

    This article describes the computer-aided design of the RF-cavity for a S-band klystron operating at 2856 MHz. State-of-the-art electromagnetic simulation tools SUPERFISH, CST Microwave studio, HFSS and MAGIC have been used for cavity design. After finalising the geometrical details of the cavity through simulation, it has been fabricated and characterised through cold testing. Detailed results of the computer-aided simulation and cold measurements are presented in this article.

  20. Imaging RF Phased Array Receivers using Optically-Coherent Up-conversion for High Beam-Bandwidth Processing

    Science.gov (United States)

    2017-03-01

    It does so by using an optical lens to perform an inverse spatial Fourier Transform on the up-converted RF signals, thereby rendering a real-time... simultaneous beams or other engineered beam patterns. There are two general approaches to array-based beam forming: digital and analog. In digital beam...of significantly limiting the number of beams that can be formed simultaneously and narrowing the operational bandwidth. An alternate approach that

  1. Analog techniques in CEBAF's RF control system

    International Nuclear Information System (INIS)

    Hovater, C.; Fugitt, J.

    1989-01-01

    Recent developments in high-speed analog technology have progressed into the areas of traditional RF technology. Diode related devices are being replaced by analog IC's in the CEBAF RF control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. RF signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

  2. Analog techniques in CEBAF'S RF control system

    International Nuclear Information System (INIS)

    Hovater, C.; Fugitt, J.

    1989-01-01

    Recent developments in high-speed analog technology have progressed into the areas of traditional rf technology. Diode-related devices are being replaced by analog IC's in the CEBAF rf control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. Rf signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

  3. Practical use of the amplitude and phase modulation of a high-power RF pulse via feed-forward control

    International Nuclear Information System (INIS)

    Kawase, Keigo; Kato, Ryukou; Irizawa, Akinori; Isoyama, Goro; Kashiwagi, Shigeru

    2013-01-01

    A new feed-forward control system to precisely control the amplitude and phase of the pulsed RF power in an electron linear accelerator (linac) is developed to make the accelerating field constant. Fast variations and ripples in the amplitude and phase in the RF pulses are compensated by modulating the amplitude and phase in the low-level system with a variable attenuator and phase shifter. The system is innovated the overdrive technique, which is commonly used in analog circuits, to speed up the slow response of the phase shifter, while the control signals are digitally processed; thus, the method is a hybrid of analog and digital techniques. By using the new control system, we find that the peak-to-peak variations in the amplitude and phase are reduced from 11.6% to 0.4% and from 6.1 degrees to 0.3 degrees, respectively, in 7.6-μs-long RF pulses for the L-band electron linac at Osaka University. (author)

  4. Longitudinal beam instabilities in a double RF system

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00229208; Gazis, Evangelos

    Operation with a double RF system is essential for many accelerators in order to increase beam stability, to change the bunch shape or to perform various RF manipulations. This is also the case for the operation of the CERN SPS as the LHC proton injector, where in addition to the main RF system, a fourth harmonic RF system is used in bunch shortening mode in order to increase the synchrotron frequency spread inside the bunch and thus to enhance Landau damping of the collective instabilities. In fact the double RF system operation in the SPS is one of the essential means, together with the controlled longitudinal emittance blow-up to significantly increase the longitudinal instability thresholds (single and multi-bunch) and deliver a good quality beam for the LHC. However, for the HiLumi-LHC (HL-LHC) and LHC injector upgrade (LIU) projects higher beam intensities are required. After all upgrades are in place, the main performance limitations of the LHC injector complex are beam instabilities and high intensity...

  5. RF Loads for Energy Recovery

    CERN Document Server

    Federmann, S; Caspers, F

    2012-01-01

    Different conceptional designs for RF high power loads are presented. One concept implies the use of solid state rectifier modules for direct RF to DC conversion with efficiencies beyond 80%. In addition, robust metallic low-Q resonant structures, capable of operating at high temperatures (>150 ◦C) are discussed. Another design deals with a very high temperature (up to 800 ◦C) air cooled load using a ceramic foam block inside a metal enclosure. This porous ceramic block is the microwave absorber and is not brazed to the metallic enclosure.

  6. HUMAN RESOURCES MANAGEMENT AND ASSESSMENT OF ITS QUALITY BY THE EXAMPLE OF ARCHIVES OF THE RF REGION

    OpenAIRE

    Molotkov Y.I.; Romanenko E.V.

    2012-01-01

    The purpose of the research conducted in state archives was to define the level of human resources and estimate the possibility of its further growth and development. The human resources assessment has been performed using the Adizes method. In accordance with the results, professionally important qualities of archive personnel have been defined at the level of the Russian Federation substitute. Issues of the improvement of the performance of the use of human resources using the research and ...

  7. RF linacs for FELs

    International Nuclear Information System (INIS)

    Schwettman, H.A.

    1992-01-01

    There are twenty rf linac-driven Free Electron Lasers (FELs) existing or under construction throughout the world and proposals for several more. A number of these FELs have recently been established as facilities to produce coherent optical beams for materials and biomedical research. Both short pulse low duty factor and long pulse high duty factor linac-driven FELs will be discussed. Accelerator issues that influence the performance of an FEL as a scientific instrument will be indicated. (Author) 6 refs., 6 figs., 2 tabs

  8. Quality management manual for production of high quality cassava flour

    DEFF Research Database (Denmark)

    Dziedzoave, Nanam Tay; Abass, Adebayo Busura; Amoa-Awua, Wisdom K.

    The high quality cassava flour (HQCF) industry has just started to evolve in Africa and elsewhere. The sustainability of the growing industry, the profitability of small- and medium-scale enterprises (SMEs) that are active in the industry and good-health of consumers can best be guaranteed through...... the adoption of proper quality and food safety procedures. Cassava processing enterprises involved in the productionof HQCF must therefore be commited to the quality and food safety of the HQCF. They must have the right technology, appropriate processing machhinery, standard testing instruments...... and the necessary technical expertise. This quality manual was therefore developed to guide small- to medium-scale cassava in the design and implematation of Hazard Analysis Critical Control Point (HACCP) system and Good manufacturing Practices (GMP) plans for HQCF production. It describes the HQCF production...

  9. High quality-factor optical resonators

    International Nuclear Information System (INIS)

    Henriet, Rémi; Salzenstein, Patrice; Coillet, Aurélien; Saleh, Khaldoun; Chembo, Yanne K; Ristic, Davor; Ferrari, Maurizio; Mortier, Michel; Rasoloniaina, Alphonse; Dumeige, Yannick; Féron, Patrice; Cibiel, Gilles; Llopis, Olivier

    2014-01-01

    Various resonators are investigated for microwave photonic applications. Micro-sphere, disk and fiber ring resonators were designed, realized and characterized. Obtained quality factors are as high as Q = 10 10 . (paper)

  10. Improving the quality factor of an RF spiral inductor with non-uniform metal width and non-uniform coil spacing

    International Nuclear Information System (INIS)

    Shen Pei; Zhang Wanrong; Huang Lu; Jin Dongyue; Xie Hongyun

    2011-01-01

    An improved inductor layout with non-uniform metal width and non-uniform spacing is proposed to increase the quality factor (Q factor). For this inductor layout, from outer coil to inner coil, the metal width is reduced by an arithmetic-progression step, while the metal spacing is increased by a geometric-progression step. An improved layout with variable width and changed spacing is of benefit to the Q factor of RF spiral inductor improvement (approximately 42.86%), mainly due to the suppression of eddy-current loss by weakening the current crowding effect in the center of the spiral inductor. In order to increase the Q factor further, for the novel inductor, a patterned ground shield is used with optimized layout together. The results indicate that, in the range of 0.5 to 16 GHz, the Q factor of the novel inductor is at an optimum, which improves by 67% more than conventional inductors with uniform geometry dimensions (equal width and equal spacing), is enhanced by nearly 23% more than a PGS inductor with uniform geometry dimensions, and improves by almost 20% more than an inductor with an improved layout. (semiconductor devices)

  11. Impact of self-assembled monolayer assisted surface dipole modulation of PET substrate on the quality of RF-sputtered AZO film

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Thieu Thi Tien [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Faculty of Chemical Engineering and Food Technology, Ba Ria-Vung Tau University, Vung Tau (Viet Nam); Mahesh, K.P.O. [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Lin, Pao-Hung [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Tai, Yian, E-mail: ytai@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2017-05-01

    Highlights: • We use SAMs functionalizing the PET substrates to generate different surface dipoles. • We deposited AZO film on pristine and SAMs-modified PET substrate. • The positive dipole moment of PET surface promotes the crystallinity of AZO film. • The negative dipole moment of PET surface deteriorates the crystallinity of AZO film. • The electrical properties of AZO/PET changes upon the variation of the crystallinity. - Abstract: In this study, we fabricated the electron donating/withdrawing group functionalized organosilane self-assembled monolayers (SAMs) on transparent polyethylene terephthalate (PET) flexible substrate followed by the deposition of aluminum doped zinc oxide (AZO) using RF magnetron sputtering at room temperature. The effect of different SAMs on transparent PET substrates and AZO films were studied by contact angle (CA), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), X-ray diffraction (XRD), Field-Emission scanning electron microscope (FE-SEM), Hall measurement and UV–vis spectroscopy (UV–vis). The results presented that the surface dipole (i.e. electron-donating/withdrawing) of different SAMs functionalized PET substrates affected the quality of the AZO films which deposited on top of them. The crystallinity, the charge mobility, and the carrier concentration of the AZO improved when the film was deposited on the PET functionalized with electron donating group, which was possibly due to favored interaction between electron donating group and Al ions.

  12. Impact of self-assembled monolayer assisted surface dipole modulation of PET substrate on the quality of RF-sputtered AZO film

    International Nuclear Information System (INIS)

    Vo, Thieu Thi Tien; Mahesh, K.P.O.; Lin, Pao-Hung; Tai, Yian

    2017-01-01

    Highlights: • We use SAMs functionalizing the PET substrates to generate different surface dipoles. • We deposited AZO film on pristine and SAMs-modified PET substrate. • The positive dipole moment of PET surface promotes the crystallinity of AZO film. • The negative dipole moment of PET surface deteriorates the crystallinity of AZO film. • The electrical properties of AZO/PET changes upon the variation of the crystallinity. - Abstract: In this study, we fabricated the electron donating/withdrawing group functionalized organosilane self-assembled monolayers (SAMs) on transparent polyethylene terephthalate (PET) flexible substrate followed by the deposition of aluminum doped zinc oxide (AZO) using RF magnetron sputtering at room temperature. The effect of different SAMs on transparent PET substrates and AZO films were studied by contact angle (CA), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), X-ray diffraction (XRD), Field-Emission scanning electron microscope (FE-SEM), Hall measurement and UV–vis spectroscopy (UV–vis). The results presented that the surface dipole (i.e. electron-donating/withdrawing) of different SAMs functionalized PET substrates affected the quality of the AZO films which deposited on top of them. The crystallinity, the charge mobility, and the carrier concentration of the AZO improved when the film was deposited on the PET functionalized with electron donating group, which was possibly due to favored interaction between electron donating group and Al ions.

  13. High-quality compressive ghost imaging

    Science.gov (United States)

    Huang, Heyan; Zhou, Cheng; Tian, Tian; Liu, Dongqi; Song, Lijun

    2018-04-01

    We propose a high-quality compressive ghost imaging method based on projected Landweber regularization and guided filter, which effectively reduce the undersampling noise and improve the resolution. In our scheme, the original object is reconstructed by decomposing of regularization and denoising steps instead of solving a minimization problem in compressive reconstruction process. The simulation and experimental results show that our method can obtain high ghost imaging quality in terms of PSNR and visual observation.

  14. Liquid Metal Droplet and Micro Corrugated Diaphragm RF-MEMS for reconfigurable RF filters

    Science.gov (United States)

    Irshad, Wasim

    detail and have proved pivotal to this work. The second part of the dissertation focuses on the Liquid Metal Droplet RF-MEMS. A novel tunable RF MEMS resonator that is based upon electrostatic control over the morphology of a liquid metal droplet (LMD) is conceived. We demonstrate an LMD evanescent-mode cavity resonator that simultaneously achieves wide analog tuning from 12 to 18 GHz with a measured quality factor of 1400-1840. A droplet of 250-mum diameter is utilized and the applied bias is limited to 100 V. This device operates on a principle called Electro-Wetting On Dielectric (EWOD). The liquid metal employed is a non-toxic eutectic alloy of Gallium, Indium and Tin known as Galinstan. This device also exploits interfacial surface energy and viscous body forces that dominate at nanoliter scale. We then apply our Liquid Metal Droplet (LMD) RF-MEMS architecture to demonstrate a continuously tunable electrostatic Ku-Band Filter. A 2-pole bandpass filter with measured insertion loss of less than 0.4dB and 3dB FBW of 3.4% is achieved using a Galinstan droplet of 250mum diameter and bias limited to 100V. We demonstrate that the LMD is insensitive to gravity by performing inversion and tilt experiments. In addition, we study its thermal tolerance by subjecting the LMD up to 150° C. The third part of the dissertation is dedicated to the Micro-Corrugated Diaphragm (MCD) RF-MEMS. We present an evanescent-mode cavity bandpass filter with state-of-the-art RF performance metrics like 4:1 tuning ratio from 5 to 20 GHz with less than 2dB insertion loss and 2-6% 3dB bandwidth. Micro-Corrugated Diaphragm (MCD) is a novel electrostatic MEMS design specifically engineered to provide large-scale analog deflections necessary for such continuous and wide tunable filtering with very high quality factor. We demonstrate a 1.25mm radius and 2mum thick Gold MCD which provides 30mum total deflection with nearly 60% analog range. We also present a detailed and systematic MCD design

  15. Epitaxial ZnO gate dielectrics deposited by RF sputter for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

    Science.gov (United States)

    Yoon, Seonno; Lee, Seungmin; Kim, Hyun-Seop; Cha, Ho-Young; Lee, Hi-Deok; Oh, Jungwoo

    2018-01-01

    Radio frequency (RF)-sputtered ZnO gate dielectrics for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were investigated with varying O2/Ar ratios. The ZnO deposited with a low oxygen content of 4.5% showed a high dielectric constant and low interface trap density due to the compensation of oxygen vacancies during the sputtering process. The good capacitance-voltage characteristics of ZnO-on-AlGaN/GaN capacitors resulted from the high crystallinity of oxide at the interface, as investigated by x-ray diffraction and high-resolution transmission electron microscopy. The MOS-HEMTs demonstrated comparable output electrical characteristics with conventional Ni/Au HEMTs but a lower gate leakage current. At a gate voltage of -20 V, the typical gate leakage current for a MOS-HEMT with a gate length of 6 μm and width of 100 μm was found to be as low as 8.2 × 10-7 mA mm-1, which was three orders lower than that of the Ni/Au Schottky gate HEMT. The reduction of the gate leakage current improved the on/off current ratio by three orders of magnitude. These results indicate that RF-sputtered ZnO with a low O2/Ar ratio is a good gate dielectric for high-performance AlGaN/GaN MOS-HEMTs.

  16. Characteristics of a high-power RF source of negative hydrogen ions for neutral beam injection into controlled fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Abdrashitov, G. F.; Belchenko, Yu. I.; Gusev, I. A.; Ivanov, A. A.; Kondakov, A. A.; Sanin, A. L.; Sotnikov, O. Z., E-mail: O.Z.Sotnikov@inp.nsk.su; Shikhovtsev, I. V. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2017-01-15

    An injector of hydrogen atoms with an energy of 0.5–1 MeV and equivalent current of up to 1.5 A for purposes of controlled fusion research is currently under design at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. Within this project, a multiple-aperture RF surface-plasma source of negative hydrogen ions is designed. The source design and results of experiments on the generation of a negative ion beam with a current of >1 A in the long-pulse mode are presented.

  17. On scaling and optimization of high-intensity, low-beam-loss RF linacs for neutron source drivers

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1992-01-01

    RF linacs providing cw proton beams of 30--250 mA at 800--1600 MeV, and cw deuteron beams of 100--250 mA at 35--40 MeV, are needed as drivers for factory neutron sources applied to radioactive waste transmutation, advanced energy production, materials testing facilities, and spallation neutron sources. The maintenance goals require very low beam loss along the linac. Optimization of such systems is complex; status of beam dynamics aspects presently being investigated is outlined

  18. rhoCentralRfFoam: An OpenFOAM solver for high speed chemically active flows - Simulation of planar detonations -

    Science.gov (United States)

    Gutiérrez Marcantoni, L. F.; Tamagno, J.; Elaskar, S.

    2017-10-01

    A new solver developed within the framework of OpenFOAM 2.3.0, called rhoCentralRfFoam which can be interpreted like an evolution of rhoCentralFoam, is presented. Its use, performing numerical simulations on initiation and propagation of planar detonation waves in combustible mixtures H2-Air and H2-O2-Ar, is described. Unsteady one dimensional (1D) Euler equations coupled with sources to take into account chemical activity, are numerically solved using the Kurganov, Noelle and Petrova second order scheme in a domain discretized with finite volumes. The computational code can work with any number of species and its corresponding reactions, but here it was tested with 13 chemically active species (one species inert), and 33 elementary reactions. A gaseous igniter which acts like a shock-tube driver, and powerful enough to generate a strong shock capable of triggering exothermic chemical reactions in fuel mixtures, is used to start planar detonations. The following main aspects of planar detonations are here, treated: induction time of combustible mixtures cited above and required mesh resolutions; convergence of overdriven detonations to Chapman-Jouguet states; detonation structure (ZND model); and the use of reflected shocks to determine induction times experimentally. The rhoCentralRfFoam code was verified comparing numerical results and it was validated, through analytical results and experimental data.

  19. Plasma edge cooling during RF heating

    International Nuclear Information System (INIS)

    Suckewer, S.; Hawryluk, R.J.

    1978-01-01

    A new approach to prevent the influx of high-Z impurities into the core of a tokamak discharge by using RF power to modify the edge plasma temperature profile is presented. This concept is based on spectroscopic measurements on PLT during ohmic heating and ATC during RF heating. A one dimensional impurity transport model is used to interpret the ATC results

  20. Fabrication of high-quality brazed joints

    International Nuclear Information System (INIS)

    Orlov, A.V.

    1980-01-01

    Problem of ensuring of joint high-quality when brazing different parts in power engineering is considered. To obtain high-quality joints it is necessary to correctly design brazed joint and to choose a gap width, overlap length and fillet radius; to clean up carefully the surfaces to be brazed and fix them properly one relative to another; to apply a solder so as to provide its flowing into the gap and sticking in it; to exactly regulate thermal conditions of brazing. High quality and reliability of brazed joints are ensured by the application of solders based on noble metals, and cheap solders based on nickel, manganese and copper. Joints brazed with nickel base solders may operate at temperatures as high as 888 deg C

  1. RF design and tests on a broadband, high-power coaxial quadrature hybrid applicable to ITER ICRF transmission line system for load-resilient operations

    International Nuclear Information System (INIS)

    Kim, Hae Jin; Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu; Hillairet, Julien; Choi, Jin Joo

    2015-01-01

    Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.

  2. RF design and tests on a broadband, high-power coaxial quadrature hybrid applicable to ITER ICRF transmission line system for load-resilient operations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hae Jin, E-mail: haejin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu [National Fusion Research Institute, Daejeon (Korea, Republic of); Hillairet, Julien [CEA/IRFM, Saint-lez-Durance (France); Choi, Jin Joo [Kwangwoon University, Seoul (Korea, Republic of)

    2015-10-15

    Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.

  3. TOTAL QUALITY MANAGEMENT IN HIGH EDUCATION

    Directory of Open Access Journals (Sweden)

    Hasan SERİN, Alper AYTEKİN

    2009-01-01

    Full Text Available The approach of Total Quality Management (TQM has been even more common and most recently its use in high education has been discussed. Likewise the enterprises producing various products, universities have also inputs, processes, and outputs. Due to conditions of competition, universities have to improve the qualities of these inputs, processes, and outputs, according to satisfaction, demands, and expectations of internal and external customers. If the TQM has been implemented in the universities with a manner that aims for customer satisfaction (students, lecturers, public and private establishments, and families, supports constant development, ensures participatory approach, and encourages working in groups, it will provide universities with effectiveness, efficiency, dynamics, and economics. In this study, common problems of universities, definitions of quality and TQM in high education, customer concept at universities, and factors affecting the quality of education have been explained. Besides, in order TQM approach to be successfully implemented in the universities, various suggestions have been presented.

  4. rf experiments on PLT

    International Nuclear Information System (INIS)

    Hosea, J.; Wilson, J.R.; Hooke, W.

    1986-01-01

    A variety of rf experiments are being conducted on PLT in order to explore rf techniques which could improve tokamak performance parameters. Of special importance are the studies of ion Bernstein wave (IBW) heating, lower hybrid MHD stabilization and electron heating, down-shifted electron cyclotron heating, and fast wave current drive. Ion Bernstein wave heating results at modest power indicate that the particle confinement time could be enhanced relative to that for fast wave heating in the ion cyclotron range of frequencies (ICRF) and neutral beam heating. At these power levels a conclusive determination of energy confinement scaling with power cannot yet be given. Central sawtooth and m = 1 MHD stabilization is being obtained with centrally peaked lower hybrid (LH) current drive and the central electron temperature is peaking to values (approx.5 keV) well outside the bounds of ''profile consistency.'' In this case the electron energy confinement is apparently increased relative to the ohmic value. The production of relativistic electrons via heating at the down-shifted electron cyclotron (EC) frequency is found to be consistent with theoretical predictions and lends support to the use of this method for heating in relatively high magnetic field devices

  5. Tagging of four Rf genes with selective genotyping analysis in rice (Oryza sativa L.

    Directory of Open Access Journals (Sweden)

    Yarahmadi Saeid

    2017-01-01

    Full Text Available Wild abortive type of cytoplasmic male sterility (WA-CMS is commercially used for hybrid rice seed production. The linked markers can be used for selection of plants with desirable traits. Tagging of Rf genes was carried out using recessive and dominant class analysis in a large F2 population from the cross IR58025A×IR42686R. Pollen fertility and seed setting were evaluated at the flowering and maturity stages, respectively. Forty-seven highly sterile and 23 fertile homozygous plants were selected from F2 population for molecular marker assay. Four Rf genes identified in a good restorer line with high-quality derived from a random mating composite population at the International Rice Research Institute (IRRI. The genetic distance from Rf3 locus with flanking markers RM443 and RM315 on chromosome 1 was 3.7 and 21.2 cM, respectively. RM258, RM591, RM271 and RM6737 on the long arm of chromosome 10 were linked with the Rf6 gene with distance of 7.4, 22.6, 6 and 2.9 cM, respectively. Rf6 was flanked by RM6737 and RM591. The Rf4 gene located on chromosome 7 was linked with RM6344 at a genetic distance of 10.6 cM. RM519 and RM7003 were linked with other Rf gene on chromosome 12 at a genetic distance of 8.5 and 20.8 cM, respectively. Closely linked markers identified in this study could be used for marker assisted selection in a hybrid rice breeding program. A new Rf locus on chromosome 12 that designated Rf7 was linked with RM7003 and RM519.

  6. Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistor and Its RF Power Efficiency Optimization with Source-Bridged Field-Plate Structure.

    Science.gov (United States)

    Kwak, Hyeon-Tak; Chang, Seung-Bo; Jung, Hyun-Gu; Kim, Hyun-Seok

    2018-09-01

    In this study, we consider the relationship between the temperature in a two-dimensional electron gas (2-DEG) channel layer and the RF characteristics of an AlGaN/GaN high-electron-mobility transistor by changing the geometrical structure of the field-plate. The final goal is to achieve a high power efficiency by decreasing the channel layer temperature. First, simulations were performed to compare and contrast the experimental data of a conventional T-gate head structure. Then, a source-bridged field-plate (SBFP) structure was used to obtain the lower junction temperature in the 2-DEG channel layer. The peak electric field intensity was reduced, and a decrease in channel temperature resulted in an increase in electron mobility. Furthermore, the gate-to-source capacitance was increased by the SBFP structure. However, under the large current flow condition, the SBFP structure had a lower maximum temperature than the basic T-gate head structure, which improved the device electron mobility. Eventually, an optimum position of the SBFP was used, which led to higher frequency responses and improved the breakdown voltages. Hence, the optimized SBFP structure can be a promising candidate for high-power RF devices.

  7. Impact of cool-down conditions at T_{c} on the superconducting rf cavity quality factor

    Directory of Open Access Journals (Sweden)

    J.-M. Vogt

    2013-10-01

    Full Text Available Many next-generation, high-gradient accelerator applications, from energy-recovery linacs to accelerator-driven systems (ADS rely on continuous wave (CW operation for which superconducting radio-frequency (SRF systems are the enabling technology. However, while SRF cavities dissipate little power, they must be cooled by liquid helium and for many CW accelerators the complexity as well as the investment and operating costs of the cryoplant can prove to be prohibitive. We investigated ways to reduce the dynamic losses by improving the residual resistance (R_{res} of niobium cavities. Both the material treatment and the magnetic shielding are known to have an impact. In addition, we found that R_{res} can be reduced significantly when the cool-down conditions during the superconducting phase transition of the niobium are optimized. We believe that not only do the cool-down conditions impact the level to which external magnetic flux is trapped in the cavity but also that thermoelectric currents are generated which in turn create additional flux that can be trapped. Therefore, we investigated the generation of flux and the dynamics of flux trapping and release in a simple model niobium-titanium system that mimics an SRF cavity in its helium tank. We indeed found that thermal gradients along the system during the superconducting transition can generate a thermoelectric current and magnetic flux, which subsequently can be trapped. These effects may explain the observed variation of the cavity’s R_{res} with cool-down conditions.

  8. RF power generation for future linear colliders

    International Nuclear Information System (INIS)

    Fowkes, W.R.; Allen, M.A.; Callin, R.S.; Caryotakis, G.; Eppley, K.R.; Fant, K.S.; Farkas, Z.D.; Feinstein, J.; Ko, K.; Koontz, R.F.; Kroll, N.; Lavine, T.L.; Lee, T.G.; Miller, R.H.; Pearson, C.; Spalek, G.; Vlieks, A.E.; Wilson, P.B.

    1990-06-01

    The next linear collider will require 200 MW of rf power per meter of linac structure at relatively high frequency to produce an accelerating gradient of about 100 MV/m. The higher frequencies result in a higher breakdown threshold in the accelerating structure hence permit higher accelerating gradients per meter of linac. The lower frequencies have the advantage that high peak power rf sources can be realized. 11.42 GHz appears to be a good compromise and the effort at the Stanford Linear Accelerator Center (SLAC) is being concentrated on rf sources operating at this frequency. The filling time of the accelerating structure for each rf feed is expected to be about 80 ns. Under serious consideration at SLAC is a conventional klystron followed by a multistage rf pulse compression system, and the Crossed-Field Amplifier. These are discussed in this paper

  9. First plasma experiments in Tore Supra with a new generation of high heat flux limiters for RF antennas

    International Nuclear Information System (INIS)

    Agarici, G.; Beaumont, B.; Bibet, Ph.; Bremond, S.; Bucalossi, J.; Colas, L.; Durocher, A.; Gargiulo, L.; Ladurelle, L.; Lombard, G.; Martin, G.; Mollard, P.

    2000-01-01

    During the 1997 and 1998 Tore Supra shutdown, a first set of new antenna guard limiters was installed on one of the three ion cyclotron resonance heating (ICRH) antennas of Tore Supra. This limiter, which was one of the main technological studies of the 1998 campaign, was widely experimented in real plasma conditions, thus allowing the validation in situ, for the first time, of the technology of active metal casting (AMC) for plasma facing components. The huge improvement in the thermal response of the new limiter generation, compared to the old one, is shown on plasma pulses made identical in terms of antenna position and injected RF power profile. By using the infrared cameras installed inside Tore Supra and viewing the antennas front, the power density fluxes received by the carbon fibre composite (CFC) surface of the limiter were evaluated by correlation with the heat load tests made on the electrons beam facility of CEA/Framatome

  10. Design of high reliability RF-LDMOS by suppressing the parasitic bipolar effect using enhanced p-well and double epitaxy

    Science.gov (United States)

    Xiangming, Xu; Jingfeng, Huang; Han, Yu; Wensheng, Qian; Zhengliang, Zhou; Bo, Han; Yong, Wang; Pengfei, Wang; Zhang, David Wei

    2015-06-01

    A laterally diffused metal-oxide-semiconductor (LDMOS) device design with an enhanced p-well and double p-epitaxial structure is investigated for device ruggedness improvement while keeping its high device performance under high frequency. Based upon the device design, radio-frequency (RF) LDMOS transistors for GSM (global system for mobile communication) application have been fabricated by using 0.35 μm CMOS technologies. Experimental data show that the proposed device achieves a breakdown voltage of 70 V, output power of 180 W. The RF linear gain is over 20 dB and the power added efficiency (PAE) is over 70% with the frequency of 920 MHz. In particular, it can pass the 20 : 1 voltage standing wave ratio (VSWR) load mismatch biased at drain DC supply voltage of 32 V and output power at 10-dB gain compression point (P10dB). The device ruggedness has been remarkably improved by using the proposed device structure. Project supported by the Chinese National Key Project (No. 2012ZX02502).

  11. Design of high reliability RF-LDMOS by suppressing the parasitic bipolar effect using enhanced p-well and double epitaxy

    International Nuclear Information System (INIS)

    Xu Xiangming; Wang Yong; Wang Pengfei; David Wei Zhang; Huang Jingfeng; Yu Han; Qian Wensheng; Zhou Zhengliang; Han Bo

    2015-01-01

    A laterally diffused metal–oxide–semiconductor (LDMOS) device design with an enhanced p-well and double p-epitaxial structure is investigated for device ruggedness improvement while keeping its high device performance under high frequency. Based upon the device design, radio-frequency (RF) LDMOS transistors for GSM (global system for mobile communication) application have been fabricated by using 0.35 μm CMOS technologies. Experimental data show that the proposed device achieves a breakdown voltage of 70 V, output power of 180 W. The RF linear gain is over 20 dB and the power added efficiency (PAE) is over 70% with the frequency of 920 MHz. In particular, it can pass the 20 : 1 voltage standing wave ratio (VSWR) load mismatch biased at drain DC supply voltage of 32 V and output power at 10-dB gain compression point (P 10dB ). The device ruggedness has been remarkably improved by using the proposed device structure. (paper)

  12. 30 nm T-gate enhancement-mode InAlN/AlN/GaN HEMT on SiC substrates for future high power RF applications

    Science.gov (United States)

    Murugapandiyan, P.; Ravimaran, S.; William, J.

    2017-08-01

    The DC and RF performance of 30 nm gate length enhancement mode (E-mode) InAlN/AlN/GaN high electron mobility transistor (HEMT) on SiC substrate with heavily doped source and drain region have been investigated using the Synopsys TCAD tool. The proposed device has the features of a recessed T-gate structure, InGaN back barrier and Al2O3 passivated device surface. The proposed HEMT exhibits a maximum drain current density of 2.1 A/mm, transconductance {g}{{m}} of 1050 mS/mm, current gain cut-off frequency {f}{{t}} of 350 GHz and power gain cut-off frequency {f}\\max of 340 GHz. At room temperature the measured carrier mobility (μ), sheet charge carrier density ({n}{{s}}) and breakdown voltage are 1580 cm2/(V \\cdot s), 1.9× {10}13 {{cm}}-2, and 10.7 V respectively. The superlatives of the proposed HEMTs are bewitching competitor or future sub-millimeter wave high power RF VLSI circuit applications.

  13. RF feedback for KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Ezura, Eizi; Yoshimoto, Shin-ichi; Akai, Kazunori [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    This paper describes the present status of the RF feedback development for the KEK B-Factory (KEKB). A preliminary experiment concerning the RF feedback using a parallel comb-filter was performed through a choke-mode cavity and a klystron. The RF feedback has been tested using the beam of the TRISTAN Main Ring, and has proved to be effective in damping the beam instability. (author)

  14. RF guns: a review

    International Nuclear Information System (INIS)

    Travier, C.

    1990-06-01

    Free Electron Lasers and future linear colliders require very bright electron beams. Conventional injectors made of DC guns and RF bunchers have intrinsic limitations. The recently proposed RF guns have already proven their capability to produce bright beams. The necessary effort to improve further these performances and to gain reliability is now undertaken by many laboratories. More than twenty RF gun projects both thermionic and laser-driven are reviewed. Their specific characteristics are outlined and their nominal performances are given

  15. Effect of forage quality in faeces from different ruminant species fed high and low quality forage

    DEFF Research Database (Denmark)

    Jalali, A R; Nørgaard, P; Nielsen, M O

    2010-01-01

    Effect of forage quality in faeces from different ruminant species fed high and low quality forage......Effect of forage quality in faeces from different ruminant species fed high and low quality forage...

  16. Assuring quality in high-consequence engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, Marcey L.; Kolb, Rachel R.

    2014-03-01

    In high-consequence engineering organizations, such as Sandia, quality assurance may be heavily dependent on staff competency. Competency-dependent quality assurance models are at risk when the environment changes, as it has with increasing attrition rates, budget and schedule cuts, and competing program priorities. Risks in Sandia's competency-dependent culture can be mitigated through changes to hiring, training, and customer engagement approaches to manage people, partners, and products. Sandia's technical quality engineering organization has been able to mitigate corporate-level risks by driving changes that benefit all departments, and in doing so has assured Sandia's commitment to excellence in high-consequence engineering and national service.

  17. New developments in RF power sources

    International Nuclear Information System (INIS)

    Miller, R.H.

    1994-06-01

    The most challenging rf source requirements for high-energy accelerators presently being studied or designed come from the various electron-positron linear collider studies. All of these studies except TESLA (the superconducting entry in the field) have specified rf sources with much higher peak powers than any existing tubes at comparable high frequencies. While circular machines do not, in general, require high peak power, the very high luminosity electron-positron rings presently being designed as B factories require prodigious total average rf power. In this age of energy conservation, this puts a high priority on high efficiency for the rf sources. Both modulating anodes and depressed collectors are being investigated in the quest for high efficiency at varying output powers

  18. Electrical degradation on DC and RF characteristics of short channel AlGaN/GaN-on-Si hemt with highly doped carbon buffer

    Science.gov (United States)

    Kim, Dong-Hwan; Jeong, Jun-Seok; Eom, Su-Keun; Lee, Jae-Gil; Seo, Kwang-Seok; Cha, Ho-Young

    2017-11-01

    In this study, we investigated the effects of highly doped carbon (C) buffer on the microwave performance of AlGaN/GaN-on-Si high electron mobility transistor (HEMT).We fabricated AlGaN/GaN-on-Si HEMTs with two different buffer structures. One structure had an un-doped buffer layer and the other structure had C-doped buffer layer with the doping concentration of 1 × 1019 cm -3 with GaN channel thickness of 350 nm. Despite higher leakage current, the device fabricated on the un-doped buffer structure exhibited better transfer and current collapse characteristics which, in turn, resulted in superior small-signal characteristics and radio frequency (RF) output power. Photoluminescence and secondary ion mass spectrometry measurements were carried out to investigate the effects of the highly-doped C buffer on microwave characteristics.

  19. Producing high-quality slash pine seeds

    Science.gov (United States)

    James Barnett; Sue Varela

    2003-01-01

    Slash pine is a desirable species. It serves many purposes and is well adapted to poorly drained flatwoods and seasonally flooded areas along the lower Coastal Plain of the Southeastern US. The use of high-quality seeds has been shown to produce uniform seedlings for outplanting, which is key to silvicultural success along the Coastal Plain and elsewhere. We present...

  20. Endorectal high dose rate brachytherapy quality assurance

    International Nuclear Information System (INIS)

    Devic, S.; Vuong, T.; Evans, M.; Podgorsak, E.

    2008-01-01

    We describe our quality assurance method for preoperative high dose rate (HDR) brachytherapy of endorectal tumours. Reproduction of the treatment planning dose distribution on a daily basis is crucial for treatment success. Due to the cylindrical symmetry, two types of adjustments are necessary: applicator rotation and dose distribution shift along the applicator axis. (author)

  1. The Bohm criterion for rf discharges

    International Nuclear Information System (INIS)

    Meijer, P.M.; Goedheer, W.J.

    1991-01-01

    The well-known dc Bohm criterion is extended to rf discharges. Both low- (ω rf much-lt ω pi ) and high-(ω pi much-lt ω rf ) frequency regimes are considered. For low frequencies, the dc Bohm criterion holds. This criterion states that the initial energy of the ions entering the sheath must exceed a limit in order to obtain a stable sheath. For high frequencies, a modified limit is derived, which is somewhat lower than that of the dc Bohm criterion. The resulting ion current density in a high-frequency sheath is only a few percent lower than that for the dc case

  2. The LHC Low Level RF

    CERN Document Server

    Baudrenghien, Philippe; Molendijk, John Cornelis; Olsen, Ragnar; Rohlev, Anton; Rossi, Vittorio; Stellfeld, Donat; Valuch, Daniel; Wehrle, Urs

    2006-01-01

    The LHC RF consists of eight 400 MHz superconducting cavities per ring, with each cavity independently powered by a 300 kW klystron, via a circulator. The challenge for the Low Level is to cope with very high beam current (more than 1 A RF component) and achieve excellent beam lifetime (emittance growth time in excess of 25 hours). Each cavity has an associated Cavity Controller rack consisting of two VME crates which implement high gain RF Feedback, a Tuner Loop with a new algorithm, a Klystron Ripple Loop and a Conditioning system. In addition each ring has a Beam Control system (four VME crates) which includes a Frequency Program, Phase Loop, Radial Loop and Synchronization Loop. A Longitudinal Damper (dipole and quadrupole mode) acting via the 400 MHz cavities is included to reduce emittance blow-up due to filamentation from phase and energy errors at injection. Finally an RF Synchronization system implements the bunch into bucket transfer from the SPS into each LHC ring. When fully installed in 2007, the...

  3. RF Energy Compressor

    International Nuclear Information System (INIS)

    Farkas, Z.D.

    1980-02-01

    The RF Energy Compressor, REC described here, transforms cw rf into periodic pulses using an energy storage cavity, ESC, whose charging is controlled by 180 0 bi-phase modulation, PSK, and external Q switching, βs. Compression efficiency, C/sub e/, of 100% can be approached at any compression factor C/sub f/

  4. High Quality Virtual Reality for Architectural Exhibitions

    DEFF Research Database (Denmark)

    Kreutzberg, Anette

    2016-01-01

    This paper will summarise the findings from creating and implementing a visually high quality Virtual Reality (VR) experiment as part of an international architecture exhibition. It was the aim to represent the architectural spatial qualities as well as the atmosphere created from combining natural...... and artificial lighting in a prominent not yet built project. The outcome is twofold: Findings concerning the integration of VR in an exhibition space and findings concerning the experience of the virtual space itself. In the exhibition, an important aspect was the unmanned exhibition space, requiring the VR...... experience to be self-explanatory. Observations of different visitor reactions to the unmanned VR experience compared with visitor reactions at guided tours with personal instructions are evaluated. Data on perception of realism, spatial quality and light in the VR model were collected with qualitative...

  5. Practical RF system design

    CERN Document Server

    Egan, William F

    2003-01-01

    he ultimate practical resource for today's RF system design professionals Radio frequency components and circuits form the backbone of today's mobile and satellite communications networks. Consequently, both practicing and aspiring industry professionals need to be able to solve ever more complex problems of RF design. Blending theoretical rigor with a wealth of practical expertise, Practical RF System Design addresses a variety of complex, real-world problems that system engineers are likely to encounter in today's burgeoning communications industry with solutions that are not easily available in the existing literature. The author, an expert in the field of RF module and system design, provides powerful techniques for analyzing real RF systems, with emphasis on some that are currently not well understood. Combining theoretical results and models with examples, he challenges readers to address such practical issues as: * How standing wave ratio affects system gain * How noise on a local oscillator will affec...

  6. Compact rf polarizer and its application to pulse compression systems

    Directory of Open Access Journals (Sweden)

    Matthew Franzi

    2016-06-01

    Full Text Available We present a novel method of reducing the footprint and increasing the efficiency of the modern multi-MW rf pulse compressor. This system utilizes a high power rf polarizer to couple two circular waveguide modes in quadrature to a single resonant cavity in order to replicate the response of a traditional two cavity configuration using a 4-port hybrid. The 11.424 GHz, high-Q, spherical cavity has a 5.875 cm radius and is fed by the circularly polarized signal to simultaneously excite the degenerate TE_{114} modes. The overcoupled spherical cavity has a Q_{0} of 9.4×10^{4} and coupling factor (β of 7.69 thus providing a loaded quality factor Q_{L} of 1.06×10^{4} with a fill time of 150 ns. Cold tests of the polarizer demonstrated good agreement with the numerical design, showing transmission of -0.05  dB and reflection back to the input rectangular WR 90 waveguide less than -40  dB over a 100 MHz bandwidth. This novel rf pulse compressor was tested at SLAC using XL-4 Klystron that provided rf power up to 32 MW and generated peak output power of 205 MW and an average of 135 MW over the discharged signal. A general network analysis of the polarizer is discussed as well as the design and high power test of the rf pulse compressor.

  7. Technology development of solid state rf systems at 350 MHz and 325 MHz for RF accelerator

    International Nuclear Information System (INIS)

    Rama Rao, B.V.; Mishra, J.K.; Pande, Manjiri; Gupta, S.K.

    2011-01-01

    For decades vacuum tubes and klystrons have been used in high power application such as RF accelerators and broadcast transmitters. However, now, the solid-state technology can give power output in kilowatt regime. Higher RF power output can be achieved by combining several solid-state power amplifier modules using power combiners. This technology presents several advantages over traditional RF amplifiers, such as simpler start-up procedure, high modularity, high redundancy and flexibility, elimination of high voltage supplies and high power circulators, low operational cost, online maintenance without shut down of RF power station and no warm up time. In BARC, solid state amplifier technology development is being done both at 350 MHz and 325 MHz using RF transistors such as 1 kW LDMOS and 350 Watt VDMOS. Topology of input and output matching network in RF modules developed, consist of two L type matching sections with each section having a combination of series micro-strip line and parallel capacitor. The design is of equal Q for both the sections and of 25 ohm characteristics impedance of micro strip lines. Based on this, lengths of micro strips lines and values of shunt capacitors have been calculated. The calculated and simulated values of network elements have been compared. Similarly power combiners have been designed and developed based on Wilkinson techniques without internal resistors and using coaxial technology. This paper presents design and development of RF power amplifier modules, associated power combiner technologies and then integrated RF power amplifier. (author)

  8. A Micromechanical RF Channelizer

    Science.gov (United States)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  9. High quality transportation fuels from renewable feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Lindfors, Lars Peter

    2010-09-15

    Hydrotreating of vegetable oils is novel process for producing high quality renewable diesel. Hydrotreated vegetable oils (HVO) are paraffinic hydrocarbons. They are free of aromatics, have high cetane numbers and reduce emissions. HVO can be used as component or as such. HVO processes can also be modified to produce jet fuel. GHG savings by HVO use are significant compared to fossil fuels. HVO is already in commercial production. Neste Oil is producing its NExBTL diesel in two plants. Production of renewable fuels will be limited by availability of sustainable feedstock. Therefore R and D efforts are made to expand feedstock base further.

  10. Boiling curve in high quality flow boiling

    International Nuclear Information System (INIS)

    Shiralkar, B.S.; Hein, R.A.; Yadigaroglu, G.

    1980-01-01

    The post dry-out heat transfer regime of the flow boiling curve was investigated experimentally for high pressure water at high qualities. The test section was a short round tube located downstream of a hot patch created by a temperature controlled segment of tubing. Results from the experiment showed that the distance from the dryout point has a significant effect on the downstream temperatures and there was no unique boiling curve. The heat transfer coefficients measured sufficiently downstream of the dryout point could be correlated using the Heineman correlation for superheated steam, indicating that the droplet deposition effects could be neglected in this region

  11. Microfluidic stretchable RF electronics.

    Science.gov (United States)

    Cheng, Shi; Wu, Zhigang

    2010-12-07

    Stretchable electronics is a revolutionary technology that will potentially create a world of radically different electronic devices and systems that open up an entirely new spectrum of possibilities. This article proposes a microfluidic based solution for stretchable radio frequency (RF) electronics, using hybrid integration of active circuits assembled on flex foils and liquid alloy passive structures embedded in elastic substrates, e.g. polydimethylsiloxane (PDMS). This concept was employed to implement a 900 MHz stretchable RF radiation sensor, consisting of a large area elastic antenna and a cluster of conventional rigid components for RF power detection. The integrated radiation sensor except the power supply was fully embedded in a thin elastomeric substrate. Good electrical performance of the standalone stretchable antenna as well as the RF power detection sub-module was verified by experiments. The sensor successfully detected the RF radiation over 5 m distance in the system demonstration. Experiments on two-dimensional (2D) stretching up to 15%, folding and twisting of the demonstrated sensor were also carried out. Despite the integrated device was severely deformed, no failure in RF radiation sensing was observed in the tests. This technique illuminates a promising route of realizing stretchable and foldable large area integrated RF electronics that are of great interest to a variety of applications like wearable computing, health monitoring, medical diagnostics, and curvilinear electronics.

  12. Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

    OpenAIRE

    Zhuhao Gong; Yulong Zhang; Xin Guo; Zewen Liu

    2018-01-01

    A radio-frequency micro-electro-mechanical system (RF MEMS) wafer-level packaging (WLP) method using pre-patterned benzo-cyclo-butene (BCB) polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to gener...

  13. Breeding and maintaining high-quality insects

    DEFF Research Database (Denmark)

    Jensen, Kim; Kristensen, Torsten Nygård; Heckmann, Lars-Henrik

    2017-01-01

    Insects have a large potential for sustainably enhancing global food and feed production, and commercial insect production is a rising industry of high economic value. Insects suitable for production typically have fast growth, short generation time, efficient nutrient utilization, high...... reproductive potential, and thrive at high density. Insects may cost-efficiently convert agricultural and industrial food by-products into valuable protein once the technology is finetuned. However, since insect mass production is a new industry, the technology needed to efficiently farm these animals is still...... in a starting phase. Here, we discuss the challenges and precautions that need to be considered when breeding and maintaining high-quality insect populations for food and feed. This involves techniques typically used in domestic animal breeding programs including maintaining genetically healthy populations...

  14. Versatile rf controller

    International Nuclear Information System (INIS)

    Howard, D.

    1985-05-01

    The low level rf system developed for the new Bevatron local injector provides precise control and regulation of the rf phase and amplitude for three 200 MHz linac cavities. The main features of the system are: extensive use of inexpensive, off-the-shelf components, ease of maintenance, and adaptability to a wide range of operation frequencies. The system utilizes separate function, easily removed rf printed circuit cards interconnected via the edge connectors. Control and monitoring are available both locally and through the computer. This paper will describe these features as well as the few component changes that would be required to adapt the techniques to other operating frequencies. 2 refs

  15. Bunch Compression Stability Dependence on RF Parameters

    CERN Document Server

    Limberg, T

    2005-01-01

    In present designs for FEL's with high electron peak currents and short bunch lengths, higher harmonic RF systems are often used to optimize the final longitudinal charge distributions. This opens degrees of freedom for the choice of RF phases and amplitudes to achieve the necessary peak current with a reasonable longitudinal bunch shape. It had been found empirically that different working points result in different tolerances for phases and amplitudes. We give an analytical expression for the sensitivity of the compression factor on phase and amplitude jitter for a bunch compression scheme involving two RF systems and two magnetic chicanes as well numerical results for the case of the European XFEL.

  16. Exploring the genetics of fertility restoration controlled by Rf1 in common wheat (Triticum aestivum L.) using high-density linkage maps.

    Science.gov (United States)

    Geyer, Manuel; Albrecht, Theresa; Hartl, Lorenz; Mohler, Volker

    2018-04-01

    Hybrid wheat breeding has the potential to significantly increase wheat productivity compared to line breeding. The induction of male sterility by the cytoplasm of Triticum timopheevii Zhuk. is a widely discussed approach to ensure cross-pollination between parental inbred lines in hybrid wheat seed production. As fertility restoration in hybrids with this cytoplasm is often incomplete, understanding the underlying genetics is a prerequisite to apply this technology. A promising component for fertility restoration is the restorer locus Rf1, which was first detected on chromosome 1A of the restorer accession R3. In the present study, we performed quantitative trait locus (QTL) analyses to locate Rf1 and estimate its effect in populations involving the restorer lines R3, R113 and L19. Molecular markers linked to Rf1 in these populations were used to analyse the genomic target region in T. timopheevii accessions and common wheat breeding lines. The QTL analyses revealed that Rf1 interacted with a modifier locus on chromosome 1BS and the restorer locus Rf4 on chromosome 6B. The modifier locus significantly influenced both the penetrance and expressivity of Rf1. Whereas Rf1 exhibited expressivity higher than that of Rf4, the effects of these loci were not additive. Evaluating the marker haplotype for the Rf1 region, we propose that the restoring Rf1 allele may be derived exclusively from T. timopheevii. The present study demonstrates that interactions between restorer and modifier loci play a critical role in fertility restoration of common wheat with the cytoplasm of T. timopheevii.

  17. Characteristic performance of radio-frequency(RF) plasma heating using inverter RF power supplies

    International Nuclear Information System (INIS)

    Imai, Takahiro; Uesugi, Yoshihiko; Takamura, Shuichi; Sawada, Hiroyuki; Hattori, Norifumi

    2000-01-01

    High heat flux plasma are produced by high powe (∼14 kW) ICRF heating using inverter power supplies in the linear divertor simulator NAGDIS-II. The power flow of radiated rf power is investigated by a calorimetric method. Conventional power calculation using antenna voltage and current gives that about 70% of the rf power is radiated into the plasma. But increase of the heat load at the target and anode is about 10% of the rf power. Through this experiment, we find that about half of the rf power is lost at the antenna surface through the formation of rf induced sheath. And about 30% of the power is lost into the vacuum vessel through the charge exchange and elastic collision of ions with neutrals. (author)

  18. Rheumatoid factor (RF)

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003548.htm Rheumatoid factor (RF) To use the sharing features on this ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  19. RF radiation safety handbook

    International Nuclear Information System (INIS)

    Kitchen, Ronald.

    1993-01-01

    Radio frequency radiation can be dangerous in a number of ways. Hazards include electromagnetic compatibility and interference, electro-explosive vapours and devices, and direct effects on the human body. This book is a general introduction to the sources and nature of RF radiation. It describes the ways in which our current knowledge, based on relevant safety standards, can be used to safeguard people from any harmful effects of RF radiation. The book is designed for people responsible for, or concerned with, safety. This target audience will primarily be radio engineers, but includes those skilled in other disciplines including medicine, chemistry or mechanical engineering. The book covers the problems of RF safety management, including the use of measuring instruments and methods, and a review of current safety standards. The implications for RF design engineers are also examined. (Author)

  20. RF Measurement Concepts

    CERN Document Server

    Caspers, F

    2014-01-01

    For the characterization of components, systems and signals in the radiofrequency (RF) and microwave ranges, several dedicated instruments are in use. In this article the fundamentals of the RF signal techniques are discussed. The key element in these front ends is the Schottky diode which can be used either as a RF mixer or as a single sampler. The spectrum analyser has become an absolutely indispensable tool for RF signal analysis. Here the front end is the RF mixer as the RF section of modern spectrum analyses has a ra ther complex architecture. The reasons for this complexity and certain working principles as well as limitations are discussed. In addition, an overview of the development of scalar and vector signal analysers is given. For the determination of the noise temperature of a one-port and the noise figure of a two-port, basic concepts and relations are shown as well as a brief discussion of commonly used noise-measurement techniques. In a further part of this article the operating principles of n...

  1. High quality electron beams from a plasma channel guided laser wakefield accelerator

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2004-01-01

    Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10 9 electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources

  2. A no-load RF calorimeter

    Science.gov (United States)

    Chernoff, R. C.

    1975-01-01

    The described device can be used to measure the output of any dc powered RF source. No dummy load is required for the measurements. The device is, therefore, called the 'no-load calorimeter' (NLC). The NLC measures the power actually fed to the antenna or another useful load. It is believed that the NLC can compete successfully with directional coupler type systems in measuring the output of high-power RF sources.

  3. Superconductors for pulsed rf accelerators

    International Nuclear Information System (INIS)

    Campisi, I.E.; Farkas, Z.D.

    1985-04-01

    The choice of superconducting materials for accelerator rf cavities has been determined in the past only in part by basic properties of the superconductors, such as the critical field, and to a larger extent by criteria which include fabrication processes, surface conditions, heat transfer capabilities and so on. For cw operated cavities the trend has been toward choosing materials with higher critical temperatures and lower surface resistance, from Lead to Niobium, from Niobium to Nb 3 Sn. This trend has been dictated by the specific needs of storage ring cw system and by the relatively low fields which could be reached without breakdown. The work performed at SLAC on superconducting cavities using microsecond long high power rf pulses has shown that in Pb, Nb, and Nb 3 Sn fields close to the critical magnetic fields can be reached without magnetic breakdown

  4. Generation and application of soft-X-ray by means of inverse compton scattering between high quality election beam and IR laser

    International Nuclear Information System (INIS)

    Washio, M.; Sakaue, K.; Hama, Y.; Kamiya, Y.; Moriyama, R.; Hezume, K.; Saito, T.; Kuroda, R.; Kashiwagi, S.; Ushida, K.; Hayano, H.; Urakawa, J.

    2006-01-01

    High quality beam generation project based on High-Tech Research Center Project, which has been approved by Ministry of Education, Culture, Sports, Science and Technology in 1999, has been conducted by advance research institute for science and engineering, Waseda University. In the project, laser photo-cathode RF-gun has been selected for the high quality electron beam source. RF cavities with low dark current, which were made by diamond turning technique, have been successfully manufactured. The low emittance electron beam was realized by choosing the modified laser injection technique. The obtained normalized emittance was about 3 mm·mrad at 100 pC of electron charge. The soft X-ray beam generation with the energy of 370 eV, which is in the energy region of so-called 'water window', by inverse Compton scattering has been performed by the collision between IR laser and the low emittance electron beams. (authors)

  5. Superconducting RF activities at Cornell University

    International Nuclear Information System (INIS)

    Kirchgessner, J.; Moffat, D.; Padamsee, H.; Rubin, D.; Sears, J.; Shu, Q.S.

    1990-01-01

    This paper outlines the RF superconductivity research and development work that has taken place at Cornell Laboratory of Nuclear Studies over the past years. The work that has been performed since the last RF superconductivity workshop is emphasized together with a discussion of the direction of future efforts. Past work is summarized first, focusing on research and development activities in the area of RF superconductivity. Superconducting TeV linear collider is then discussed focusing on the application of superconducting RF to a future TeV linear collider. Linear collider structure development is then described centering on the development of a simpler (thereby cheaper) structure for a TeV linear collider. B-factory with superconducting RF is outlined focusing on the formulation of a conceptual design for a B-factory. B-factory structure development is discussed in relation to the advancement in the capability of SC cavities to carry beam currents of several amperes necessary for a high luminosity storage ring. High gradients are discussed as the key to the realization of a high energy superconducting linac or a superconducting RF B-factory. (N.K.)

  6. Adaptive RF front-ends for hand-held applications

    CERN Document Server

    van Bezooijen, Andre; van Roermund, Arthur

    2010-01-01

    The RF front-end - antenna combination is a vital part of a mobile phone because its performance is very relevant to the link quality between hand-set and cellular network base-stations. The RF front-end performance suffers from changes in operating environment, like hand-effects, that are often unpredictable. ""Adaptive RF Front-Ends for Hand-Held Applications"" presents an analysis on the impact of fluctuating environmental parameters. In order to overcome undesired behavior two different adaptive control methods are treated that make RF frond-ends more resilient: adaptive impedance control,

  7. FinFET and UTBB for RF SOI communication systems

    Science.gov (United States)

    Raskin, Jean-Pierre

    2016-11-01

    Performance of RF integrated circuit (IC) is directly linked to the analog and high frequency characteristics of the transistors, the quality of the back-end of line process as well as the electromagnetic properties of the substrate. Thanks to the introduction of the trap-rich high-resistivity Silicon-on-Insulator (SOI) substrate on the market, the ICs requirements in term of linearity are fulfilled. Today partially depleted SOI MOSFET is the mainstream technology for RF SOI systems. Future generations of mobile communication systems will require transistors with better high frequency performance at lower power consumption. The advanced MOS transistors in competition are FinFET and Ultra Thin Body and Buried oxide (UTBB) SOI MOSFETs. Both devices have been intensively studied these last years. Most of the reported data concern their digital performance. In this paper, their analog/RF behavior is described and compared. Both show similar characteristics in terms of transconductance, Early voltage, voltage gain, self-heating issue but UTBB outperforms FinFET in terms of cutoff frequencies thanks to their relatively lower fringing parasitic capacitances.

  8. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator; Etude et developpement d'un coupleur de puissance pour les cavites supraconductrices destinees aux accelerateurs de protons de haute intensite

    Energy Technology Data Exchange (ETDEWEB)

    Souli, M

    2007-07-15

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q{sub c} in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  9. Prototype rf cavity for the HISTRAP accelerator

    International Nuclear Information System (INIS)

    Mosko, S.W.; Dowling, D.T.; Olsen, D.K.

    1989-01-01

    HISTRAP, a proposed synchrotron-cooling-storage ring designed to both accelerate and decelerate very highly charged very heavy ions for atomic physics research, requires an rf accelerating system to provide /+-/2.5 kV of peak accelerating voltage per turn while tuning through a 13.5:1 frequency range in a fraction of a second. A prototype half-wave, single gap rf cavity with biased ferrite tuning was built and tested over a continuous tuning range of 200 kHz through 2.7 MHz. Initial test results establish the feasibility of using ferrite tuning at the required rf power levels. The resonant system is located entirely outside of the accelerator's 15cm ID beam line vacuum enclosure except for a single rf window which serves as an accelerating gap. Physical separation of the cavity and the beam line permits in situ vacuum baking of the beam line at 300/degree/C

  10. Superconducting RF for energy-recovery linacs

    International Nuclear Information System (INIS)

    Liepe, M.; Knobloch, J.

    2006-01-01

    Since superconducting RF for particle accelerators made its first appearance in the 1970s, it has found highly successful application in a variety of machines. Recent progress in this technology has made so-called Energy-Recovery Linacs (ERLs)-originally proposed in 1965-feasible, and interest in this type of machine has increased enormously. A superconducting linac is the driving heart of ERLs, and emittance preservation and cost efficiency is of utmost importance. The resulting challenges for the superconducting cavity technology and RF field control are manifold. In March 2005 the first international workshop on ERLs was held at Newport News, VA, to explore the potential of ERLs and to discuss machine-physics and technology challenges and their solutions. This paper reviews the state-of-the-art in superconducting RF and RF control for ERLs, and summarizes the discussions of the SRF working group on this technology during the ERL2005 workshop

  11. Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

    Science.gov (United States)

    Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

    2014-08-29

    Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

  12. The Development of the Linac Coherent Light Source RF Gun

    International Nuclear Information System (INIS)

    Dowell, D

    2008-01-01

    The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron laser (FEL) requiring extraordinary beam quality to saturate at 1.5 angstroms within a 100 meter undulator.[1] This new type of light source is using the last kilometer of the three kilometer linac at SLAC to accelerate the beam to an energy as high as 13.6 GeV and required a new electron gun and injector to produce a very bright beam for acceleration. At the outset of the project it was recognized that existing RF guns had the potential to produce the desired beam but none had demonstrated it. Therefore a new RF gun or at least the modification of an existing gun was necessary. The parameters listed in Table 1 illustrate the unique characteristics of LCLS which drive the requirements for the electron gun as given in Table 2. The gun beam quality needs to accommodate emittance growth as the beam is travels through approximately one kilometer of linac and two bunch compressors before reaching the undulator. These beam requirements were demonstrated during the recent commissioning runs of the LCLS injector and linac [2] due to the successful design, fabrication, testing and operation of the LCLS gun. The goal of this paper is to relate the technical background of how the gun was able to achieve and in some cases exceed these requirements by understanding and correcting the deficiencies of the prototype s-band RF photocathode gun, the BNL/SLAC/UCLA Gun III. This paper begins with a brief history and technical description of Gun III and the Gun Test Facility (GTF) at SLAC, and studies of the gun's RF and emittance compensation solenoid. The work at the GTF identified the gun and solenoid deficiencies, and helped to define the specifications for the LCLS gun. Section 1.1.5 describes the modeling used to compute and correct the gun RF fields and Section 1.1.6 describes the use of these fields in the electron beam simulations. The magnetic design and measurements of

  13. High gradient RF test results of S-band and C-band cavities for medical linear accelerators

    Science.gov (United States)

    Degiovanni, A.; Bonomi, R.; Garlasché, M.; Verdú-Andrés, S.; Wegner, R.; Amaldi, U.

    2018-05-01

    TERA Foundation has proposed and designed hadrontherapy facilities based on novel linacs, i.e. high gradient linacs which accelerate either protons or light ions. The overall length of the linac, and therefore its cost, is almost inversely proportional to the average accelerating gradient. With the scope of studying the limiting factors for high gradient operation and to optimize the linac design, TERA, in collaboration with the CLIC Structure Development Group, has conducted a series of high gradient experiments. The main goals were to study the high gradient behavior and to evaluate the maximum gradient reached in 3 and 5.7 GHz structures to direct the design of medical accelerators based on high gradient linacs. This paper summarizes the results of the high power tests of 3.0 and 5.7 GHz single-cell cavities.

  14. Measurement of RF characteristics of magnetic alloys for an RF cavity of the accumulator cooler ring

    International Nuclear Information System (INIS)

    Watanabe, M.; Chiba, Y.; Katayama, T.; Koseki, T.; Ohtomo, K.; Tsutsui, H.

    2004-01-01

    The magnetic alloy (MA)-loaded RF cavity has been studied for an RF stacking system of the accumulator cooler ring (ACR). RF characteristics of several high-permeability MA cores were measured in the frequency range between 1 and 50 MHz. The effects of the cut-core configuration, cutting the core and leaving air gaps between two circular halves, were also investigated. The results show that the shunt impedance remains high and the appropriate inductance and Q-value can be obtained by increasing the gap width of the cut core in the frequency region of the ACR cavity

  15. Oak Ridge rf Test Facility

    International Nuclear Information System (INIS)

    Gardner, W.L.; Hoffman, D.J.; McCurdy, H.C.; McManamy, T.J.; Moeller, J.A.; Ryan, P.M.

    1985-01-01

    The rf Test Facility (RFTF) of Oak Ridge National Laboratory (ORNL) provides a national facility for the testing and evaluation of steady-state, high-power (approx.1.0-MW) ion cyclotron resonance heating (ICRH) systems and components. The facility consists of a vacuum vessel and two fully tested superconducting development magnets from the ELMO Bumpy Torus Proof-of-Principle (EBT-P) program. These are arranged as a simple mirror with a mirror ratio of 4.8. The axial centerline distance between magnet throat centers is 112 cm. The vacuum vessel cavity has a large port (74 by 163 cm) and a test volume adequate for testing prototypic launchers for Doublet III-D (DIII-D), Tore Supra, and the Tokamak Fusion Test Reactor (TFTR). Attached to the internal vessel walls are water-cooled panels for removing the injected rf power. The magnets are capable of generating a steady-state field of approx.3 T on axis in the magnet throats. Steady-state plasmas are generated in the facility by cyclotron resonance breakdown using a dedicated 200-kW, 28-GHz gyrotron. Available rf sources cover a frequency range of 2 to 200 MHz at 1.5 kW and 3 to 18 MHz at 200 kW, with several sources at intermediate parameters. Available in July 1986 will be a >1.0-MW, cw source spanning 40 to 80 MHz. 5 figs

  16. Method for synthesis of high quality graphene

    Science.gov (United States)

    Lanzara, Alessandra [Piedmont, CA; Schmid, Andreas K [Berkeley, CA; Yu, Xiaozhu [Berkeley, CA; Hwang, Choonkyu [Albany, CA; Kohl, Annemarie [Beneditkbeuern, DE; Jozwiak, Chris M [Oakland, CA

    2012-03-27

    A method is described herein for the providing of high quality graphene layers on silicon carbide wafers in a thermal process. With two wafers facing each other in close proximity, in a first vacuum heating stage, while maintained at a vacuum of around 10.sup.-6 Torr, the wafer temperature is raised to about 1500.degree. C., whereby silicon evaporates from the wafer leaving a carbon rich surface, the evaporated silicon trapped in the gap between the wafers, such that the higher vapor pressure of silicon above each of the wafers suppresses further silicon evaporation. As the temperature of the wafers is raised to about 1530.degree. C. or more, the carbon atoms self assemble themselves into graphene.

  17. High quality data: An evaluation of AIM data quality and data quality procedures

    Science.gov (United States)

    The goal of every monitoring program is to collect high-quality data which can then be used to provide information to decision makers. The Bureau of Land Management (BLM) Assessment, Inventory, and Monitoring (AIM) program is one such data set which provides rangeland status, condition, and trend in...

  18. High-picture quality industrial CT scanner

    International Nuclear Information System (INIS)

    Shoji, Takao; Nishide, Akihiko; Fujii, Masashi.

    1989-01-01

    Industrial X-ray-CT-scanners, which provide cross-sectional images of a tested sample without destroying it, are attracting attention as a new nondestructive inspection device. In 1982, Toshiba commenced the development of industrial CT scanners, and introduced the 'TOSCANER' -3000 and-4000 series. Now, the state of the art 'TOSCANER'-20000 series of CT systems has been developed incorporating the latest computer tomography and image processing technology, such as the T9506 image processor. One of the advantages of this system is its applicability to a wide range of X-ray energy . The 'TOSCANER'-20000 series can be utilized for inspecting castings and other materials with relatively low-transparency to X-rays, as well as ceramics, composite materials and other materials with high X-ray transparency. A further feature of the new system is its high-picture quality, with a high-spatial resolution resulting from a pixel size of 0.2x0.2(mm). (author)

  19. [Quality management is associated with high quality services in health care].

    Science.gov (United States)

    Nielsen, Tenna Hassert; Riis, Allan; Mainz, Jan; Jensen, Anne-Louise Degn

    2013-12-09

    In these years, quality management has been the focus in order to meet high quality services for the patients in Danish health care. This article provides information on quality management and quality improvement and it evaluates its effectiveness in achieving better organizational structures, processes and results in Danish health-care organizations. Our findings generally support that quality management is associated with high quality services in health care.

  20. Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Volfbeyn, P.; Bekefi, G. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-12-31

    We report the results of temporal and spatial measurements of phase of a pulsed free electron laser amplifier (FEL) operating in combined wiggler and axial guide magnetic fields. The 33 GHz FEL is driven by a mildly relativistic electron beam (750 kV, 90-300 A, 30 ns) and generates 61 MW of radiation with a high power magnetron as the input source. The phase is measured by an interferometric technique from which frequency shifting is determined. The results are simulated with a computer code. Experimental studies on a CERN-CLIC 32.98 GHz 26-cell high gradient accelerating section (HGA) were carried out for input powers from 0.1 MW to 35 MW. The FEL served as the r.f. power source for the HGA. The maximum power in the transmitted pulse was measured to be 15 MW for an input pulse of 35 MW. The theoretically calculated shunt impedance of 116 M{Omega}/m predicts a field gradient of 65 MeV/m inside the HGA. For power levels >3MW the pulse transmitted through the HGA was observed to be shorter than the input pulse and pulse shortening became more serious with increasing power input. At the highest power levels the output pulse length (about 5 nsec) was about one quarter of the input pulse length. Various tests suggest that these undesirable effects occur in the input coupler to the HGA. Light and X-ray production inside the HGA have been observed.

  1. Highly textured Sr, Nb co-doped BiFeO3 thin films grown on SrRuO3/Si substrates by rf- sputtering

    International Nuclear Information System (INIS)

    Ostos, C.; Raymond, O.; Siqueiros, J. M.; Suarez-Almodovar, N.; Bueno-Baques, D.; Mestres, L.

    2011-01-01

    In this study, (011)-highly oriented Sr, Nb co-doped BiFeO 3 (BFO) thin films were successfully grown on SrRuO 3 /Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of ≅5.3 nm and average grain sizes of ≅65-70 nm for samples with different thicknesses. Remanent polarization values (2P r ) of 54 μC cm -2 at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe 3+ /Fe 2+ trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO 3 /Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.

  2. Optical studies of high quality synthetic diamond

    International Nuclear Information System (INIS)

    Sharp, S.J.

    1999-01-01

    This thesis is concerned with the study of fundamental and defect induced optical properties of synthetic diamond grown using high pressure, high temperature (HPHT) synthesis or chemical vapour deposition (CVD). The primary technique used for investigation is cathodoluminescence (including imaging and decay-time measurements) in addition to other forms of optical spectroscopy. This thesis is timely in that the crystallinity and purity of synthetic diamond has increased ten fold over the last few years. The diamond exciton emission, which is easily quenched by the presence of defects, is studied in high quality samples in detail. In addition the ability now exists to engineer the isotopic content of synthetic diamond to a high degree of accuracy. The experimental chapters are divided as follows: Chapter 2: High resolution, low temperature spectra reveal a splitting of the free-exciton phonon recombination emission peaks and the bound-exciton zero phonon line. Included are measurements of the variation in intensity and decay-time as a function of temperature. Chapter 3: The shift in energy of the phonon-assisted free-exciton phonon replicas with isotopic content has been measured. The shift is in agreement with the results of interatomic force model for phonon scattering due to isotope disorder. Chapter 4: A study of the shift in energy with isotopic content of the diamond of the GR1 band due to the neutral vacancy has allowed a verification of the theoretical predictions due to the Jahn Teller effect. Chapter 5: The spatial distribution of the free-exciton luminescence is studied in HPHT synthetic and CVD diamond. A variation in intensity with distance from the surface is interpreted as a significant non-radiative loss of excitons to the surface. Chapter 6: The decay-times of all known self-interstitial related centres have been measured in order to calculate the concentration of these centres present in electron irradiated diamond. (author)

  3. High Quality Data for Grid Integration Studies

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, Andrew; Draxl, Caroline; Sengupta, Manajit; Hodge, Bri-Mathias

    2017-01-22

    As variable renewable power penetration levels increase in power systems worldwide, renewable integration studies are crucial to ensure continued economic and reliable operation of the power grid. The existing electric grid infrastructure in the US in particular poses significant limitations on wind power expansion. In this presentation we will shed light on requirements for grid integration studies as far as wind and solar energy are concerned. Because wind and solar plants are strongly impacted by weather, high-resolution and high-quality weather data are required to drive power system simulations. Future data sets will have to push limits of numerical weather prediction to yield these high-resolution data sets, and wind data will have to be time-synchronized with solar data. Current wind and solar integration data sets are presented. The Wind Integration National Dataset (WIND) Toolkit is the largest and most complete grid integration data set publicly available to date. A meteorological data set, wind power production time series, and simulated forecasts created using the Weather Research and Forecasting Model run on a 2-km grid over the continental United States at a 5-min resolution is now publicly available for more than 126,000 land-based and offshore wind power production sites. The National Solar Radiation Database (NSRDB) is a similar high temporal- and spatial resolution database of 18 years of solar resource data for North America and India. The need for high-resolution weather data pushes modeling towards finer scales and closer synchronization. We also present how we anticipate such datasets developing in the future, their benefits, and the challenges with using and disseminating such large amounts of data.

  4. Study of RF flux penetration on Nb for SRF Applications

    Science.gov (United States)

    Oripov, Bakhrom; Anlage, Steven

    Superconducting Radio Frequency (SRF) cavities are being widely used in new generation particle accelerators. Based on the needs of the SRF community to identify defects on Nb surfaces, a novel near-field magnetic field microwave microscope was successfully built using a magnetic writer from a conventional perpendicular magnetic recording hard-disk drive. Using our probe, we performed microwave measurement of both third P3f\\ (Pf,T) and fifth P5f (Pf,T) harmonic responses and its dependence on temperature and rf input power by applying a strong and localized RF magnetic field on high quality Nb films. Our preliminary results show significant difference in low-field and high-field harmonic responses. Above a temperature-dependent onset field H1 periodic structures in the harmonic response vs rf field amplitude data emerges. Similar behavior is observed in both bulk Nb and thin film Nb samples. We attribute this periodic response to vortex nonlinearity. Using our microscope, we are able to measure a local lower critical field for vortex formation Hc,v (in arbitrary units), and compare the Hc,v's of samples produced with different techniques and chemical treatments. This work is funded by US Department of Energy through Grant # DE-SC0012036T and CNAM.

  5. The FELIX RF system

    International Nuclear Information System (INIS)

    Manintveld, P.; Delmee, P.F.M.; Geer, C.A.J. van der; Meddens, B.J.H.; Meer, A.F.G. van der; Amersfoort, P.W. van

    1992-01-01

    The performance of the RF system for the Free Electron Laser for Infrared eXperiments (FELIX) is discussed. The RF system provides the input power for a triode gun (1 GHz, 100 W), a prebuncher (1 GHz, 10 kW), a buncher (3 GHz, 20 MW), and two linacs (3 GHz, 8 MW each). The pulse length in the system is 20 μs. The required electron beam stability imposes the following demands on the RF system: a phase stability better than 0.3 deg for the 1 GHz signals and better than 1 deg for the 3 GHz signals; the amplitude stability has to be better than 1% for the 1 GHz and better than 0.2% for the 3 GHz signals. (author) 3 refs.; 6 figs

  6. Experiments on the rf surface resistance of the perovskite superconductors at 3 GHz

    International Nuclear Information System (INIS)

    Hein, M.; Klein, N.; Mueller, G.; Piel, H.; Roeth, R.W.

    1988-01-01

    Since the discovery of the perovskite superconductors many experiments to explore their physical properties have been performed and various potential applications have been considered. The high critical temperature of more than 90 K obtained with Y 1 Ba 2 Cu 3 O/sub 7-δ/ (Y may be substituted by other rare earth elements) makes these superconductors interesting for applications in microwave technology. This has focused the authors interest on the investigation of their rf properties. Due to the sensitivity of the rf surface resistance to surface impurities and remaining non superconducting phases rf measurements are a good means to provide useful information about the quality of sample preparation and about physical properties of the superconductor itself. This contribution reports on the experimental determination of the rf surface resistance of Y 1 Ba 2 Cu 3 O/sub 7-δ/ and Eu 1 Ba 2 Cu 3 O/sub 7-δ/ in the normal and superconducting state at 3 GHz. In the first chapter the preparation of the ceramic samples and initial dc experiments are described. The main part of the paper describes the rf measurements which are performed in a superconducting niobium host cavity. The obtained results for both the surface resistance and the high field performance are discussed with respect to the preparation of the samples and regarding possible applications. 7 references, 7 figures, 2 tables

  7. ISR RF cavities

    CERN Multimedia

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  8. Conventional RF system design

    International Nuclear Information System (INIS)

    Puglisi, M.

    1994-01-01

    The design of a conventional RF system is always complex and must fit the needs of the particular machine for which it is planned. It follows that many different design criteria should be considered and analyzed, thus exceeding the narrow limits of a lecture. For this reason only the fundamental components of an RF system, including the generators, are considered in this short seminar. The most common formulas are simply presented in the text, while their derivations are shown in the appendices to facilitate, if desired, a more advanced level of understanding. (orig.)

  9. A noncontact wireless passive radio frequency (RF) resonant pressure sensor with optimized design for applications in high-temperature environments

    International Nuclear Information System (INIS)

    Li, Chen; Tan, Qiulin; Xiong, Jijun; Jia, Pinggang; Hong, Yingping; Ren, Zhong; Luo, Tao; Liu, Jun; Xue, Chenyang; Zhang, Wendong

    2014-01-01

    A noncontact wireless passive pressure sensor based on alumina ceramic for pressure measurement is presented in this paper. A faithful pressure signal in harsh environment is captured through wireless sensing, and a novel antenna design method is developed to increase the measurement distance between the antenna and the sensor. The sensor is fabricated using a novel no-co-fired technology, and the properties of the alumina ceramic and platinum ensure the feasibility of the sensor in high-temperature environments. The experimental results show that the coupled distance between the antenna and the sensor can be up to 5.5 cm, and the designed sensor, featuring improved structural parameters, has a high responsivity (15.5 kHz kPa −1 ) in a pressure environment at room temperature. The sensor can be coupled with the antenna at 850 °C, which verifies the feasibility in high-temperature environments. (paper)

  10. Compression and radiation of high-power short rf pulses. I. Energy accumulation in direct-flow waveguide compressors

    KAUST Repository

    Sirenko, Kostyantyn; Pazynin, Vadim L.; Sirenko, Yu K.; Bagci, Hakan

    2011-01-01

    Proper design of efficient requires precise understanding of the physics pertinent to energy accumulation and exhaust processes in resonant waveguide cavities. In this paper, practically for the first time these highly non-monotonic transient processes are studied in detail using a rigorous time-domain approach. Additionally, influence of the geometrical design and excitation parameters on the compressor's performance is quantified in detail.

  11. Direct observation of 0.57 eV trap-related RF output power reduction in AlGaN/GaN high electron mobility transistors

    Science.gov (United States)

    Arehart, A. R.; Sasikumar, A.; Rajan, S.; Via, G. D.; Poling, B.; Winningham, B.; Heller, E. R.; Brown, D.; Pei, Y.; Recht, F.; Mishra, U. K.; Ringel, S. A.

    2013-02-01

    This paper reports direct evidence for trap-related RF output power loss in GaN high electron mobility transistors (HEMTs) grown by metal organic chemical vapor deposition (MOCVD) through increased concentration of a specific electron trap at EC-0.57 eV that is located in the drain access region, as a function of accelerated life testing (ALT). The trap is detected by constant drain current deep level transient spectroscopy (CID-DLTS) and the CID-DLTS thermal emission time constant precisely matches the measured drain lag. Both drain lag and CID-DLTS measurements show this state to already exist in pre-stressed devices, which coupled with its strong increase in concentration as a function of stress in the absence of significant increases in concentrations of other detected traps, imply its role in causing degradation, in particular knee walkout. This study reveals EC-0.57 eV trap concentration tracks degradation induced by ALT for MOCVD-grown HEMTs supplied by several commercial and university sources. The results suggest this defect has a common source and may be a key degradation pathway in AlGaN/GaN HEMTs and/or an indicator to predict device lifetime.

  12. Status of the C-band RF System for the SPARC-LAB high brightness photo-injector

    CERN Document Server

    Boni, R.; Bellaveglia, M.; Di Pirro, G.; Ferrario, M.; Gallo, A.; Spataro, B.; Mostacci, A.; Palumbo, L.

    2013-01-01

    The high brightness photo-injector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy so improving the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.

  13. Conceptual design of compact heavy-ion inertial fusion driver with an r.f. LINAC with high acceleration rate

    International Nuclear Information System (INIS)

    Hattori, T.; Sasa, K.; Okamura, M.; Ito, T.; Tomizawa, H.; Katayose, T.; Hayashizaki, N.; Yoshida, T.; Isokawa, K.; Aoki, M.; Fujita, N.; Okada, M.

    1996-01-01

    The interdigital-H-type (IH) linear accelerator (LINAC) is well known for its high shunt impedance at low and medium particle velocities. Therefore, it can be used to operate efficiently with a high acceleration gradient. The IH LINAC cavity is able to generate 10 MV m -1 (average acceleration gradient) with focusing of the particles by a superconducting solenoid and quadrupole. The LINAC can accelerate particles with a charge to mass ratio (q/A) greater than 1/250 from 0.3 MeV a.m.u. -1 . In a compact heavy-ion inertial fusion driver design, the total effective length of the IH LINAC cavities is about 1250 m. (orig.)

  14. Development and contribution of rf heating and current drive systems to long pulse, high performance experiments in JT-60U

    International Nuclear Information System (INIS)

    Moriyama, Shinichi; Seki, Masami; Terakado, Masayuki; Shimono, Mitsugu; Ide, Shunsuke; Isayama, Akihiko; Suzuki, Takahiro; Fujii, Tsuneyuki

    2005-01-01

    To contribute to high performance long pulse (∼65 s) experiments in JT-60U, the target of the electron cyclotron (EC) operation in long pulse is 0.6 MW for 30 s with four gyrotrons, though 10 MJ (2.8 MW and 3.6 s) was achieved in high power operation before 2003. One of the critical issues for the long pulse operation is detuning due to decay in beam current of the gyrotron. This decay comes from the cathode cooling by continuous electron emission. As a countermeasure for this issue, active adjustments for the heater current and anode voltage during the pulse have successfully extended the duration of a good oscillation condition for the gyrotron. As a result, 0.4 MW for 16 s with one gyrotron to the dummy load and for 8.7 s to the plasma have been achieved up to now

  15. Compression and radiation of high-power short rf pulses. I. Energy accumulation in direct-flow waveguide compressors

    KAUST Repository

    Sirenko, Kostyantyn

    2011-01-01

    Proper design of efficient requires precise understanding of the physics pertinent to energy accumulation and exhaust processes in resonant waveguide cavities. In this paper, practically for the first time these highly non-monotonic transient processes are studied in detail using a rigorous time-domain approach. Additionally, influence of the geometrical design and excitation parameters on the compressor\\'s performance is quantified in detail.

  16. Highly accelerated acquisition and homogeneous image reconstruction with rotating RF coil array at 7T-A phantom based study.

    Science.gov (United States)

    Li, Mingyan; Zuo, Zhentao; Jin, Jin; Xue, Rong; Trakic, Adnan; Weber, Ewald; Liu, Feng; Crozier, Stuart

    2014-03-01

    Parallel imaging (PI) is widely used for imaging acceleration by means of coil spatial sensitivities associated with phased array coils (PACs). By employing a time-division multiplexing technique, a single-channel rotating radiofrequency coil (RRFC) provides an alternative method to reduce scan time. Strategically combining these two concepts could provide enhanced acceleration and efficiency. In this work, the imaging acceleration ability and homogeneous image reconstruction strategy of 4-element rotating radiofrequency coil array (RRFCA) was numerically investigated and experimental validated at 7T with a homogeneous phantom. Each coil of RRFCA was capable of acquiring a large number of sensitivity profiles, leading to a better acceleration performance illustrated by the improved geometry-maps that have lower maximum values and more uniform distributions compared to 4- and 8-element stationary arrays. A reconstruction algorithm, rotating SENSitivity Encoding (rotating SENSE), was proposed to provide image reconstruction. Additionally, by optimally choosing the angular sampling positions and transmit profiles under the rotating scheme, phantom images could be faithfully reconstructed. The results indicate that, the proposed technique is able to provide homogeneous reconstructions with overall higher and more uniform signal-to-noise ratio (SNR) distributions at high reduction factors. It is hoped that, by employing the high imaging acceleration and homogeneous imaging reconstruction ability of RRFCA, the proposed method will facilitate human imaging for ultra high field MRI. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Phase calibration strategies for synchrotron RF signals

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, Aleksandr [TEMF, Technische Universitaet Darmstadt (Germany); Klingbeil, Harald [TEMF, Technische Universitaet Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Lens, Dieter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

    2016-07-01

    For the FAIR facility that is currently under construction, the beam quality requirements impose several demands on the low-level RF (LLRF) systems. For example the phase error of the gap voltage of a specific RF cavity must be less than 1 . The RF reference signals for the FAIR synchrotron RF cavity systems are generated by direct digital synthesis modules (DDS) mounted in one crate called Group-DDS. In order to allow performing various multi-harmonic operations, each DDS unit operates at a certain mode defined by the harmonic number that can be changed during the operation. Since the DDS modules generate reference RF signals for different LLRF systems, the precise calibration of units to compensate the different phase response is of importance. The currently used calibration procedure is done with a fixed harmonic number for each module and uses the DDS module configured to the highest harmonic number as a reference. If the harmonic number of the DDS module is changed, one then has to repeat the calibration for the new values. Therefore, a new calibration method with respect to the absolute phases of DDS modules is under development and will be presented.

  18. RF Characterization of Niobium Films for Superconducting Cavities

    CERN Document Server

    Aull† , S; Doebert, S; Junginger, T; Ehiasarian, AP; Knobloch, J; Terenziani, G

    2013-01-01

    The surface resistance RS of superconductors shows a complex dependence on the external parameters such as temperature, frequency or radio-frequency (RF) field. The Quadrupole Resonator modes of 400, 800 and 1200 MHz allow measurements at actual operating frequencies of superconducting cavities. Niobium films on copper substrates have several advantages over bulk niobium cavities. HIPIMS (High-power impulse magnetron sputtering) is a promising technique to increase the quality and therefore the performance of niobium films. This contribution will introduce CERNs recently developed HIPIMS coating apparatus. Moreover, first results of niobium coated copper samples will be presented, revealing the dominant loss mechanisms.

  19. Design of an rf quadrupole for Landau damping

    Science.gov (United States)

    Papke, K.; Grudiev, A.

    2017-08-01

    The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC) with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM) spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.

  20. The TESLA RF System

    International Nuclear Information System (INIS)

    Choroba, S.

    2003-01-01

    The TESLA project proposed by the TESLA collaboration in 2001 is a 500 to 800GeV e+/e- linear collider with integrated free electron laser facility. The accelerator is based on superconducting cavity technology. Approximately 20000 superconducting cavities operated at 1.3GHz with a gradient of 23.4MV/m or 35MV/m will be required to achieve the energy of 500GeV or 800GeV respectively. For 500GeV ∼600 RF stations each generating 10MW of RF power at 1.3GHz at a pulse duration of 1.37ms and a repetition rate of 5 or 10Hz are required. The original TESLA design was modified in 2002 and now includes a dedicated 20GeV electron accelerator in a separate tunnel for free electron laser application. The TESLA XFEL will provide XFEL radiation of unprecedented peak brilliance and full transverse coherence in the wavelength range of 0.1 to 6.4nm at a pulse duration of 100fs. The technology of both accelerators, the TESLA linear collider and the XFEL, will be identical, however the number of superconducting cavities and RF stations for the XFEL will be reduced to 936 and 26 respectively. This paper describes the layout of the entire RF system of the TESLA linear collider and the TESLA XFEL and gives an overview of its various subsystems and components

  1. Remote RF Battery Charging

    NARCIS (Netherlands)

    Visser, H.J.; Pop, V.; Op het Veld, J.H.G.; Vullers, R.J.M.

    2011-01-01

    The design of a remote RF battery charger is discussed through the analysis and design of the subsystems of a rectenna (rectifying antenna): antenna, rectifying circuit and loaded DC-to-DC voltage (buck-boost) converter. Optimum system power generation performance is obtained by adopting a system

  2. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G [Jefferson Lab (United States)

    2014-07-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  3. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  4. Correction of inhomogeneous RF field using multiple SPGR signals for high-field spin-echo MRI

    International Nuclear Information System (INIS)

    Ishimori, Yoshiyuki; Monma, Masahiko; Yamada, Kazuhiro; Kimura, Hirohiko; Uematsu, Hidemasa; Fujiwara, Yasuhiro; Yamaguchi, Isao

    2007-01-01

    The purpose of this study was to propose a simple and useful method for correcting nonuniformity of high-field (3 Tesla) T 1 -weighted spin-echo (SE) images based on a B1 field map estimated from gradient recalled echo (GRE) signals. The method of this study was to estimate B1 inhomogeneity, spoiled gradient recalled echo (SPGR) images were collected using a fixed repetition time of 70 ms, flip angles of 45 and 90 degrees, and echo times of 4.8 and 10.4 ms. Selection of flip angles was based on the observation that the relative intensity changes in SPGR signals were very similar among different tissues at larger flip angles than the Ernst angle. Accordingly, spatial irregularity that was observed on a signal ratio map of the SPGR images acquired with these 2 flip angles was ascribed to inhomogeneity of the B1 field. Dual echo time was used to eliminate T 2 * effects. The ratio map that was acquired was scaled to provide an intensity correction map for SE images. Both phantom and volunteer studies were performed using a 3T magnetic resonance scanner to validate the method. In the phantom study, the uniformity of the T 1 -weighted SE image improved by 23%. Images of human heads also showed practically sufficient improvement in the image uniformity. The present method improves the image uniformity of high-field T 1 -weighted SE images. (author)

  5. The RF Design of an HOM Polarized RF Gun for the ILC

    International Nuclear Information System (INIS)

    Wang, J.W.; Clendenin, J.E.; Colby, E.R.; Miller, R.A.; Lewellen, J.W.

    2006-01-01

    The ILC requires a polarized electron beam. While a highly polarized beam can be produced by a GaAs-type cathode in a DC gun of the type currently in use at SLAC, JLAB and elsewhere, the ILC injector system can be simplified and made more efficient if a GaAs-type cathode can be combined with a low emittance RF gun. Since this type of cathode is known to be extremely sensitive to vacuum contamination including back bombardment by electrons and ions, any successful polarized RF gun must have a significantly improved operating vacuum compared to existing RF guns. We present a new RF design for an L-Band normal conducting (NC) RF gun for the ILC polarized electron source. This design incorporates a higher order mode (HOM) structure, whose chief virtue in this application is an improved conductance for vacuum pumping on the cathode. Computer simulation models have been used to optimize the RF parameters with two principal goals: first to minimize the required RF power; second to reduce the peak surface field relative to the field at the cathode in order to suppress field emitted electron bombardment. The beam properties have been simulated initially using PARMELA. Vacuum and other practical issues for implementing this design are discussed

  6. Electron-beam direct drive for rf accelerator cavities

    International Nuclear Information System (INIS)

    Nahemow, M.D.; Humphries, S. Jr.

    1987-01-01

    This paper describes a Program to Demonstrate Electron-Beam Direct Drive for Radio Frequency (RF) Linear Accelerators at the Westinghouse R and D Center. The experimental program was undertaken using an existing electron beam facility at the Westinghouse R and C Center to demonstrate the potential of the Direct Drive RF Cavities for High Power Beams concept discussed as part of a program to develop a viable alternate concept for driving RF linear accelerators

  7. RF Processing Experience with the GTF Prototype RF Gun

    International Nuclear Information System (INIS)

    Schmerge, J.F.

    2010-01-01

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. A total of five different metal cathodes (4 Cu and 1 Mg) have been installed on the GTF gun. The rf processing history with the different cathodes will be presented including peak field achieved at the cathode. The LCLS gun is intended to operate at 120 MV/m and fields up to 140 MV/m have been achieved in the GTF gun. After installing a new cathode the number of rf pulses required to reach 120 MV/m is approximately 5-10 million. Total emitted dark current and Fowler Nordheim plots are also shown over the life of the cathode. The GTF photo-injector gun is an S-band standing-wave structure, with two resonant cavities and an intervening thick washer (Figure 1). The flat, back wall of the first cavity is a copper plate that serves as photocathode when illuminated with ultraviolet light from a pulsed, high-power laser. RF power enters the gun through an iris on the outer wall of the second cavity, and is coupled to the first through the axial opening of the washer. The first cavity is often referred to as a half cell, because its full-cell length has been truncated by the cathode plate and the second cavity is called the full cell. The gun is designed to operate in a π mode, with the peak field on axis in each cell approximately equal. The maximum in the half cell occurs at the cathode, and in the full cell near the center of the cavity. The field profile and tuning procedures are discussed in a separate tech note (1).

  8. Digital base-band rf control system for the superconducting Darmstadt electron linear accelerator

    Directory of Open Access Journals (Sweden)

    M. Konrad

    2012-05-01

    Full Text Available The accelerating field in superconducting cavities has to be stabilized in amplitude and phase by a radio-frequency (rf control system. Because of their high loaded quality factor superconducting cavities are very susceptible for microphonics. To meet the increased requirements with respect to accuracy, availability, and diagnostics, the previous analog rf control system of the superconducting Darmstadt electron linear accelerator S-DALINAC has been replaced by a digital rf control system. The new hardware consists of two components: An rf module that converts the signal from the cavity down to the base-band and a field-programmable gate array board including a soft CPU that carries out the signal processing steps of the control algorithm. Different algorithms are used for normal-conducting and superconducting cavities. To improve the availability of the control system, techniques for automatic firmware and software deployment have been implemented. Extensive diagnostic features provide the operator with additional information. The architecture of the rf control system as well as the functionality of its components will be presented along with measurements that characterize the performance of the system, yielding, e.g., an amplitude stabilization down to (ΔA/A_{rms}=7×10^{-5} and a phase stabilization of (Δϕ_{rms}=0.8° for superconducting cavities.

  9. Beam Dynamics Simulation of Photocathode RF Electron Gun at the PBP-CMU Linac Laboratory

    Science.gov (United States)

    Buakor, K.; Rimjaem, S.

    2017-09-01

    Photocathode radio-frequency (RF) electron guns are widely used at many particle accelerator laboratories due to high quality of produced electron beams. By using a short-pulse laser to induce the photoemission process, the electrons are emitted with low energy spread. Moreover, the photocathode RF guns are not suffered from the electron back bombardment effect, which can cause the limited electron current and accelerated energy. In this research, we aim to develop the photocathode RF gun for the linac-based THz radiation source. Its design is based on the existing gun at the PBP-CMU Linac Laboratory. The gun consists of a one and a half cell S-band standing-wave RF cavities with a maximum electric field of about 60 MV/m at the centre of the full cell. We study the beam dynamics of electrons traveling through the electromagnetic field inside the RF gun by using the particle tracking program ASTRA. The laser properties i.e. transverse size and injecting phase are optimized to obtain low transverse emittance. In addition, the solenoid magnet is applied for beam focusing and emittance compensation. The proper solenoid magnetic field is then investigated to find the optimum value for proper emittance conservation condition.

  10. A new measurement tool for characterization of superconducting rf accelerator cavities using high-performance LTS SQUIDs

    Energy Technology Data Exchange (ETDEWEB)

    Vodel, W [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Neubert, R [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Nietzsche, S [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Seidel, P [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Knaack, K [DESY Hamburg (Germany); Wittenburg, K [DESY Hamburg (Germany); Peters, A [Heidelberger Ionenstrahl-Therapiezentrum, Heidelberg (Germany)

    2007-11-15

    This paper presents a new system to measure very low currents in an accelerator environment, using a cryogenic current comparator (CCC). In principle a CCC is a conventional current transformer using the high-performance SQUID technology to sense the magnetic fields caused by the beam current. Since the system is sensitive on a pA level, it is an optimum device to detect dark currents of superconducting cavities. The system presented here is designed for the test facilities of the superconducting accelerator modules for the European XFEL at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Measurements in a quiet environment showed that an intrinsic noise level of the CCC of 40 pA Hz{sup -1/2} could be achieved.

  11. Fundamentals of RF and microwave transistor amplifiers

    CERN Document Server

    Bahl, Inder J

    2009-01-01

    A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read

  12. Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

    Energy Technology Data Exchange (ETDEWEB)

    Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de; Lindemann, Maike E. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147 (Germany); Lanz, Titus [Rapid Biomedical GmbH, Rimpar 97222 (Germany); Kinner, Sonja [Institute for Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen 45147 (Germany); Quick, Harald H. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147, Germany and Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen 45141 (Germany)

    2016-08-15

    positions closer to attenuating hardware structures of the RF coil. The position accuracy of the RF coil on the patient table when using the positioning frame was determined well below 1 mm for all three spatial dimensions. This ensures perfect position match between the RF coil and its three-dimensional attenuation template during the PET data reconstruction process. When applying the CT-based AC of the RF coil, the global attenuation bias was mostly compensated to ±0.5% across the entire breast imaging volume. The patient study revealed high quality MR, PET, and combined PET/MR imaging of breast cancer. Quantitative activity measurements in all 11 breast cancer lesions of the ten patients resulted in increased mean difference values of SUV{sub max} 11.8% (minimum 3.2%; maximum 23.2%) between nonAC images and images when AC of the RF breast coil was applied. This supports the quantitative results of the phantom study as well as successful attenuation correction of the RF coil. Conclusions: A 16-channel breast RF coil was designed for optimized MR imaging performance and PET transparency and was successfully integrated with its dedicated attenuation correction template into a whole-body PET/MR system. Systematic PET/MR imaging evaluation with phantoms and an initial study on patients with breast cancer provided excellent MR and PET image quality and accurate PET quantification.

  13. Ensuring High-Quality Learning for All

    Science.gov (United States)

    Núñez, Elsa M.

    2018-01-01

    The Association of American Colleges and Universities (AAC&U) has embarked on a sustained program to enhance the quality of student learning on campuses, while also supporting AAC&U members' efforts to bring liberal education to all sectors of society. This commitment to quality and equity in service to democracy forms the basis for…

  14. RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland

    2014-09-21

    Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Part of the problem is that RF breakdown in an evacuated cavity involves a complex mixture of effects, which include the geometry, metallurgy, and surface preparation of the accelerating structures and the make-up and pressure of the residual gas in which plasmas form. Studies showed that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas, as needed for muon cooling channels, without the need for long conditioning times, even in the presence of strong external magnetic fields. This positive result was expected because the dense gas can practically eliminate dark currents and multipacting. In this project we used this high pressure technique to suppress effects of residual vacuum and geometry that are found in evacuated cavities in order to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. One of the interesting and useful outcomes of this project was the unanticipated collaborations with LANL and Fermilab that led to new insights as to the operation of evacuated normal-conducting RF cavities in high external magnetic fields. Other accomplishments included: (1) RF breakdown experiments to test the effects of SF6 dopant in H2 and He gases with Sn, Al, and Cu electrodes were carried out in an 805 MHz cavity and compared to calculations and computer simulations. The heavy corrosion caused by the SF6 components led to the suggestion that a small admixture of oxygen, instead of SF6, to the hydrogen would allow the same advantages without the corrosion in a practical muon beam line. (2) A

  15. Nanoparticle manipulation in the near-substrate areas of low-temperature, high-density rf plasmas

    International Nuclear Information System (INIS)

    Rutkevych, P.P.; Ostrikov, K.; Xu, S.

    2005-01-01

    Manipulation of a single nanoparticle in the near-substrate areas of high-density plasmas of low-temperature glow discharges is studied. It is shown that the nanoparticles can be efficiently manipulated by the thermophoretic force controlled by external heating of the substrate stage. Particle deposition onto or repulsion from nanostructured carbon surfaces critically depends on the values of the neutral gas temperature gradient in the near-substrate areas, which is directly measured in situ in different heating regimes by originally developed temperature gradient probe. The measured values of the near-surface temperature gradient are used in the numerical model of nanoparticle dynamics in a variable-length presheath. Specific conditions enabling the nanoparticle to overcome the repulsive potential and deposit on the substrate during the discharge operation are investigated. The results are relevant to fabrication of various nanostructured films employing structural incorporation of the plasma-grown nanoparticles, in particular, to nanoparticle deposition in the plasma-enhanced chemical-vapor deposition of carbon nanostructures in hydrocarbon-based plasmas

  16. Effects of annealing temperature on the structural, mechanical and electrical properties of flexible bismuth telluride thin films prepared by high-pressure RF magnetron sputtering

    Science.gov (United States)

    Singkaselit, Kamolmad; Sakulkalavek, Aparporn; Sakdanuphab, Rachsak

    2017-09-01

    In this work Bi x Te y thin films were deposited on polyimide substrate by a high-pressure RF magnetron sputtering technique. The deposited condition was maintained using a high pressure of 1.3  ×  10-2 mbar. The as-deposited films show Bi2Te3 structure with Te excess phase (Te-rich Bi2Te3). After that, as-deposited films were annealed in the vacuum chamber under the N2 flow at temperatures from 250 to 400 °C for one hour. The microstructure, cross-section, [Bi]:[Te] content, and the mechanical, electrical and thermoelectric properties of as-deposited and different annealed films were investigated. It was found that the annealing temperature enhanced the crystallinity and film density for the temperature range 250-300 °C. However, the crystal structure of Bi2Te3 almost changed to the BiTe structure after annealing the films above 350 °C, due to the re-evaporation of Te. Nano-indentation results and cross-section images indicated that the hardness of the films related to the film density. The maximum hardness of 2.30 GPa was observed by annealing the films at 300 °C. As a result of an improvement in crystallinity and phase changes, the highest power factor of 11.45  ×  10-4 W m-1K-2 at 300 °C with the carrier concentration and mobility of 6.15  ×  1020 cm-3 and 34.03 cm2 V-1 s-1, respectively, was achieved for the films annealed at 400 °C. Contribution at the 4th Southeast Asia Conference on Thermoelectrics 2016 (SACT 2016), 15-18 December 2016, Da Nang City, Vietnam.

  17. High power beam test and measurement of emittance evolution of a 1.6-cell photocathode RF gun at Pohang Accelerator Laboratory

    International Nuclear Information System (INIS)

    Park, Jang-Ho; Park, Sung-Ju; Kim, Changbum; Huang, Jung-Yun; Ko, In Soo; Parc, Yong-Woon; Hong, Ju-Ho; Xiang Dao; Wang, Xijie

    2007-01-01

    A Brookhaven National Laboratory (BNL) GUN-IV type photocathode rf gun has been fabricated to use in femtosecond electron diffraction (FED), femtosecond far infrared radiation (fs-FIR) facility, and X-ray free electron laser (XFEL) facilities at the Pohang Accelerator Laboratory (PAL). The gun consists of a 1.6-cell cavity with a copper cathode, a solenoid magnet, beam diagnostic components and auxiliary systems. We report here the measurement of the basic beam parameters which confirm a successful fabrication of the photocathode RF gun system. The emittance evolution is measured by an emittance meter and compared with the PARMELA simulation, which shows a good agreement. (author)

  18. Reduced dose uncertainty in MRI-based polymer gel dosimetry using parallel RF transmission with multiple RF sources

    International Nuclear Information System (INIS)

    Sang-Young Kim; Jung-Hoon Lee; Jin-Young Jung; Do-Wan Lee; Seu-Ran Lee; Bo-Young Choe; Hyeon-Man Baek; Korea University of Science and Technology, Daejeon; Dae-Hyun Kim; Jung-Whan Min; Ji-Yeon Park

    2014-01-01

    In this work, we present the feasibility of using a parallel RF transmit with multiple RF sources imaging method (MultiTransmit imaging) in polymer gel dosimetry. Image quality and B 1 field homogeneity was statistically better in the MultiTransmit imaging method than in conventional single source RF transmission imaging method. In particular, the standard uncertainty of R 2 was lower on the MultiTransmit images than on the conventional images. Furthermore, the MultiTransmit measurement showed improved dose resolution. Improved image quality and B 1 homogeneity results in reduced dose uncertainty, thereby suggesting the feasibility of MultiTransmit MR imaging in gel dosimetry. (author)

  19. Geometry Optimization of DC/RF Photoelectron Gun

    CERN Document Server

    Chen Ping; Yu, David

    2005-01-01

    Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

  20. RF pulse compression in the NLC test accelerator at SLAC

    International Nuclear Information System (INIS)

    Lavine, T.L.

    1995-01-01

    At the Stanford Linear Accelerator Center (SLAC), the authors are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test - the Next Linear Collider Test Accelerator (NLCTA) - which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy

  1. Status of RF superconductivity at Argonne

    International Nuclear Information System (INIS)

    Shepard, K.W.

    1990-01-01

    Development of a superconducting slow-wave structures began at Argonne National Laboratory (ANL) in 1971, and led to the first superconducting heavy-ion linac (ATLAS - the Argonne Tandem-Linac Accelerator System). The Physics Division at ANL has continued to develop superconducting RF technology for accelerating heavy-ions, with the result that the linac has been in an almost continuous process of upgrade and expansion. In 1987, the Engineering Physics Division at ANL began developing of superconducting RF components for the acceleration of high-brightness proton and deuterium beams. The two divisions collaborate in work on several applications of RF superconductivity, and also in work to develop the technology generally. The present report briefly describes major features of the superconducting heavy-ion linac (very-low-velocity superconducting linac, positive ion injector), proton accelerating structures (superconducting resonant cavities for acceleration of high-current proton and deuteron beams, RF properties of oxide superconductors), and future work. Both divisions expect to continue a variety of studies, frequently in collaboration, to advance the basic technology of RF superconductivity. (N.K.)

  2. PEP-II RF System Operation and Performance

    International Nuclear Information System (INIS)

    McIntosh, P.

    2005-01-01

    The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured. The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured

  3. Barrier rf systems in synchrotrons

    International Nuclear Information System (INIS)

    Bhat, Chandra M.

    2004-01-01

    Recently, many interesting applications of the barrier RF system in hadron synchrotrons have been realized. A remarkable example of this is the development of longitudinal momentum mining and implementation at the Fermilab Recycler for extraction of low emittance pbars for the Tevatron shots. At Fermilab, we have barrier RF systems in four different rings. In the case of Recycler Ring, all of the rf manipulations are carried out using a barrier RF system. Here, the author reviews various uses of barrier rf systems in particle accelerators including some new schemes for producing intense proton beam and possible new applications

  4. rf driven multicusp H- ion source

    International Nuclear Information System (INIS)

    Leung, K.N.; DeVries, G.J.; DiVergilio, W.F.; Hamm, R.W.; Hauck, C.A.; Kunkel, W.B.; McDonald, D.S.; Williams, M.D.

    1991-01-01

    An rf driven multicusp source capable of generating 1-ms H - beam pulses with a repetition rate as high as 150 Hz has been developed. This source can be operated with a filament or other types of starter. There is almost no lifetime limitation and a clean plasma can be maintained for a long period of operation. It is demonstrated that rf power as high as 25 kW could be coupled inductively to the plasma via a glass-coated copper-coil antenna. The extracted H - current density achieved is about 200 mA/cm 2

  5. X-Band RF Gun Development

    International Nuclear Information System (INIS)

    Vlieks, A.E.

    2012-01-01

    In support of the MEGa-ray program at LLNL and the High Gradient research program at SLAC, a new X-band multi-cell RF gun is being developed. This gun, similar to earlier guns developed at SLAC for Compton X-ray source program, will be a standing wave structure made of 5.5 cells operating in the pi mode with copper cathode. This gun was designed following criteria used to build SLAC X-band high gradient accelerating structures. It is anticipated that this gun will operate with surface electric fields on the cathode of 200 MeV/m with low breakdown rate. RF will be coupled into the structure through a final cell with symmetric duel feeds and with a shape optimized to minimize quadrupole field components. In addition, geometry changes to the original gun, operated with Compton X-ray source, will include a wider RF mode separation, reduced surface electric and magnetic fields.

  6. Effects of Si3N4 passivation on the dc and RF characteristics of metamorphic high-electron-mobility transistors depending on the gate-recess structures

    International Nuclear Information System (INIS)

    Oh, J H; Han, M; Baek, Y H; Moon, S W; Rhee, J K; Kim, S D

    2009-01-01

    Effects of the Si 3 N 4 passivation on the dc and RF characteristics of a 0.1 µm metamorphic high-electron-mobility transistor (HEMT) are investigated for narrow and wide gate-recess structures. Maximum drain-source saturation current (I dss,max ) and maximum extrinsic transconductance (g m,max ) are reduced by ∼14.8 and ∼11.6%, respectively, in the wide gate-recess structure after the passivation; on the other hand, only ∼5.7 and ∼4.9% reductions are measured from I dss,max and g m,max , respectively, in the narrow gate-recess structure. We examine the passivation-induced degradation by using a modified charge control model assuming the charged surface states on the Si 3 N 4 interface and a comparative study of the hydrodynamic device simulation with the experimental measurement. From the analysis, it is proposed that the difference of degradation in two different gate structures is due to an approximately three times higher charged surface state density of ∼4.5 × 10 11 cm −2 in the wide gate-recess structure than ∼1.6 × 10 11 cm −2 in the narrow gate-recess structure. The cut-off frequency (f T ) of the wide gate-recess structure also exhibits a greater reduction of ∼14.5%, while the f T of the narrow gate-recess structure is reduced by only ∼6.6% after the passivation. This is mainly due to the passivation-induced surface states of a higher density in the wide gate-recess structure. A great increase of the gate-to-drain parasitic capacitance in the wide gate-recess structure makes a major contribution to ∼13.5% degradation of the maximum frequency of oscillation

  7. Racetrack microtron rf system

    International Nuclear Information System (INIS)

    Tallerico, P.J.; Keffeler, D.R.

    1985-01-01

    The rf system for the National Bureau of Standards (NBS)/Los Alamos cw racetrack microtron is described. The low-power portion consists of five 75-W amplifers that drive two input ports in each of two chopper deflection cavities and one port in the prebuncher cavity. A single 500-kW klystron drives four separate 2380-MHz cavity sections: the two main accelerator sections, a capture section, and a preaccelerator section. The phases and amplitudes in all cavities are controlled by electronic or electromechanical controls. The 1-MW klystron power supply and crowbar system were purchased as a unit; several modifications are described that improve power-supply performance. The entire rf system has been tested and shipped to the NBS, and the chopper-buncher system has been operated with beam at the NBS. 5 refs., 2 figs

  8. Lasers for RF guns: Proceedings

    International Nuclear Information System (INIS)

    Srinivasan-Rao, T.

    1994-01-01

    In the past decade, laser driven RF guns have matured from a device under development to a proven source for high brightness and low emittance electron beams. The reliability of the electron beam from these sources is dictated by the laser system that drives it. In addition, capabilities of the laser systems play a vital role in the design of the electron source for future machines such as the TESLA and NLC. The purpose of this workshop was to provide a forum for discussing the design criteria for the laser systems so that the reliability of the existing sources could be improved and the future machines could be serviced. The Workshop brought together experts in RF Guns, accelerators, and lasers, from both the commercial and academic community. Most of the presentations, discussions and conclusions at the workshop are included in these proceedings. The contents are divided into three sections, Section I contains the invited talks that outline the requirements of the RF Guns and the capabilities of the laser systems to meet these requirements. Section II includes most of the papers presented in the poster session. These papers describe various laser systems used with electron guns, schemes to modify the laser beam profile to optimize the electron bunch, and computer simulations of electron trajectories. Section III contains the summaries of the working groups. As the summary section indicates, with sufficient feed back systems, the electron gun could be made to operate reliably with minimum downtime, using commercial lasers currently available. The design of laser systems for future colliders depend critically on the choice of the cathode m the gun and its efficiency. Tentative designs of laser systems for the TESLA test facility and LCLS had been drawn assuming a copper cathode. Using a more efficient cathode will ease the energy requirement of the laser and simplify the design. The individual papers have been cataloged separately elsewhere

  9. High Efficiency, Illumination Quality OLEDs for Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

    2008-03-31

    The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown

  10. Pulsed rf operation analysis

    International Nuclear Information System (INIS)

    Puglisi, M.; Cornacchia, M.

    1981-01-01

    The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated

  11. RF pulse compression development

    International Nuclear Information System (INIS)

    Farkas, Z.D.; Weaver, J.N.

    1987-10-01

    The body of this paper discusses the theory and some rules for designing a multistage Binary Energy Compressor (BEC) including its response to nonstandard phase coding, describes some proof-of-principle experiments with a couple of low power BECs, presents the design parameters for some sample linear collider rf systems that could possibly use a BEC to advantage and outlines in the conclusion some planned R and D efforts. 8 refs., 26 figs., 4 tabs

  12. Microwave and RF engineering

    CERN Document Server

    Sorrentino, Roberto

    2010-01-01

    An essential text for both students and professionals, combining detailed theory with clear practical guidance This outstanding book explores a large spectrum of topics within microwave and radio frequency (RF) engineering, encompassing electromagnetic theory, microwave circuits and components. It provides thorough descriptions of the most common microwave test instruments and advises on semiconductor device modelling. With examples taken from the authors' own experience, this book also covers:network and signal theory;electronic technology with guided electromagnetic pr

  13. Investigation of MIM Diodes for RF Applications

    KAUST Repository

    Khan, Adnan

    2015-05-01

    Metal Insulator Metal (MIM) diodes that work on fast mechanism of tunneling have been used in a number of very high frequency applications such as (Infra-Red) IR detectors and optical Rectennas for energy harvesting. Their ability to operate under zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF use is the requirement of a very thin oxide layer essential for the tunneling operation that requires sophisticated nano-fabrication processes. Another issue is that the reliability and stable performance of MIM diodes is highly dependent on the surface roughness of the metallic electrodes. Finally, comprehensive RF characterization has not been performed for MIM diodes reported in the literature, particularly from the perspective of their integration with antennas as well as their rectification abilities. In this thesis, various metal deposition methods such as sputtering, electron beam evaporation, and Atomic Layer Deposition (ALD) are compared in pursuit of achieving low surface roughness. It is worth mentioning here that MIM diodes realized through ALD method have been presented for the first time in this thesis. Amorphous metal alloy have also been investigated in terms of their low surface roughness. Zinc-oxide has been investigated for its suitability as a thin dielectric layer for MIM diodes. Finally, comprehensive RF characterization of MIM diodes has been performed in two ways: 1) by standard S-parameter methods, and 2) by investigating their rectification ability under zero bias operation. It is concluded from the Atomic Force Microscopy (AFM) imaging that surface roughness as low as sub 1 nm can be achieved reliably from crystalline metals such as copper and platinum. This value is comparable to surface roughness achieved from amorphous alloys, which are non

  14. Superconducting rf and beam-cavity interactions

    International Nuclear Information System (INIS)

    Bisognano, J.J.

    1987-01-01

    Beam-cavity interactions can limit the beam quality and current handling capability of linear and circular accelerators. These collective effects include cumulative and regenerative transverse beam breakup (BBU) in linacs, transverse multipass beam breakup in recirculating linacs and microtrons, longitudinal and transverse coupled-bunch instabilities in storage rings, and a variety of transverse and longitudinal single-bunch phenomena (instabilities, beam breakup, and energy deposition). The superconducting radio frequency (SRF) environment has a number of features which distinguish it from room temperature configuration with regard to these beam-cavity interactions. Typically the unloaded Qs of the lower higher order modes (HOM) are at the 10 9 level and require significant damping through couplers. High gradient CW operation, which is a principal advantage of SRF, allows for better control of beam quality, which for its preservation requires added care which respect to collective phenomena. Gradients are significantly higher than those attainable with copper in CW operation but remain significantly lower than those obtainable with pulsed copper cavities. Finally, energy deposition by the beam into the cavity can occur in a cryogenic environment. In this note those characteristics of beam-cavity interactions which are of particular importance for superconducting RF cavities are highlighted. 6 refs., 4 figs

  15. Binary rf pulse compression experiment at SLAC

    International Nuclear Information System (INIS)

    Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

    1990-06-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here

  16. Radiofrequency (RF) radiation measurement for diathermy machine

    International Nuclear Information System (INIS)

    Rozaimah Abdul Rahim; Roha Tukimin; Mohd Amirul Nizam; Ahmad Fadzli; Mohd Azizi

    2010-01-01

    Full-text: Diathermy machine is one of medical device that use widely in hospital and clinic. During the diathermy treatment, high radiofrequency (RF) currents (shortwave and microwave) are used to heat deep muscular tissues through electromagnetic energy to body tissues. The heat increases blood flow, relieve pain and speeding up recovery. The stray RF radiation from the machine can exposes to unintended tissue of the patient, to the operator (physical therapist) and also can cause electromagnetic interference (EMI) effect to medical devices around the machine. The main objective of this study is to establish a database of the RF radiation exposure levels experienced by the operator and patient during the treatments. RF radiation (electric and magnetic field) produced by the diathermy machines were measured using special RF survey meters. The finding of this study confirms that radiation levels on the surface and near the applicator of the diathermy machine much more elevated due to the much closer distance to the source and they exceeding the occupational and general public exposure limit. The results also shows the field strengths drop very significantly when the distance of measurement increase. (author)

  17. Analysis of high-quality modes in open chaotic microcavities

    International Nuclear Information System (INIS)

    Fang, W.; Yamilov, A.; Cao, H.

    2005-01-01

    We present a numerical study of the high-quality modes in two-dimensional dielectric stadium microcavities. Although the classical ray mechanics is fully chaotic in a stadium billiard, all of the high-quality modes show a 'strong scar' around unstable periodic orbits. When the deformation (ratio of the length of the straight segments over the diameter of the half circles) is small, the high-quality modes correspond to whispering-gallery-type trajectories and their quality factors decrease monotonically with increasing deformation. At large deformation, each high-quality mode is associated with multiple unstable periodic orbits. Its quality factor changes nonmonotonically with the deformation, and there exists an optimal deformation for each mode at which its quality factor reaches a local maximum. This unusual behavior is attributed to the interference of waves propagating along different constituent orbits that could minimize light leakage out of the cavity

  18. Experimental investigations on the influence of the photocathode laser pulse parameters on the electron bunch quality in an RF-photoelectron source

    International Nuclear Information System (INIS)

    Haenel, Marc

    2010-06-01

    Free Electron Lasers based on the SASE principle like the European XFEL require electron bunches having peak currents of several kiloamperes as well as very low transverse emittance. While high peak currents can be generated using longitudinal bunch compression techniques, the transverse emittance must have values as low as 1mmmrad already at the source. The development of electron sources fulfilling these demanding specifications is the goal of the Photo Injector Test Facility (PITZ) in DESY, Zeuthen site. The key component of a photoinjector is the electron gun cavity where the electrons bunches are generated and immediately accelerated. The extraction of the electrons is based on the photoelectric effect of the cathode which requires a laser system having special capabilities. In the first part of the thesis, measurements are presented which were performed to investigate whether the laser and the laser transport system fulfill these requirements. The second part of the thesis is dedicated to simulations as well as experimental studies on the impact of the temporal and spatial parameters of the laser pulses on the electron bunch quality. This influence is possible because the response time of the Cs 2 Te photocathode is short compared to the laser pulse duration. Based on these investigations, suggestions for improvements are given and tolerances for the laser pulse properties are defined. (orig.)

  19. Experimental investigations on the influence of the photocathode laser pulse parameters on the electron bunch quality in an RF-photoelectron source

    Energy Technology Data Exchange (ETDEWEB)

    Haenel, Marc

    2010-07-15

    Free Electron Lasers based on the SASE principle like the European XFEL require electron bunches having peak currents of several kiloamperes as well as very low transverse emittance. While high peak currents can be generated using longitudinal bunch compression techniques, the transverse emittance must have values as low as 1mmmrad already at the source. The development of electron sources fulfilling these demanding specifications is the goal of the Photo Injector Test Facility (PITZ) in DESY, Zeuthen site. The key component of a photoinjector is the electron gun cavity where the electrons bunches are generated and immediately accelerated. The extraction of the electrons is based on the photoelectric effect of the cathode which requires a laser system having special capabilities. In the first part of the thesis, measurements are presented which were performed to investigate whether the laser and the laser transport system fulfill these requirements. The second part of the thesis is dedicated to simulations as well as experimental studies on the impact of the temporal and spatial parameters of the laser pulses on the electron bunch quality. This influence is possible because the response time of the Cs{sub 2}Te photocathode is short compared to the laser pulse duration. Based on these investigations, suggestions for improvements are given and tolerances for the laser pulse properties are defined. (orig.)

  20. A design and performance analysis tool for superconducting RF systems

    International Nuclear Information System (INIS)

    Schilcher, T.; Simrock, S.N.; Merminga, L.; Wang, D.X.

    1997-01-01

    Superconducting rf systems are usually operated with continuous rf power or with rf pulse lengths exceeding 1 ms to maximize the overall wall plug power efficiency. Typical examples are CEBAF at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) and the TESLA Test Facility at DESY. The long pulses allow for effective application of feedback to stabilize the accelerating field in presence of microphonics, Lorentz force detuning, and fluctuations of the beam current. In this paper the authors describe a set of tools to be used with MATLAB and SIMULINK, which allow to analyze the quality of field regulation for a given design. The tools include models for the cavities, the rf power source, the beam, sources of field perturbations, and the rf feedback system. The rf control relevant electrical and mechanical characteristics of the cavity are described in form of time-varying state space models. The power source is modeled as a current generator and includes saturation characteristics and noise.An arbitrary time structure can be imposed on the beam current to reflect a macro-pulse structure and bunch charge fluctuations. For rf feedback several schemes can be selected: Traditional amplitude and phase control as well as I/Q control. The choices for the feedback controller include analog or digital approaches and various choices of frequency response. Feed forward can be added to further suppress repetitive errors. The results of a performance analysis of the CEBAF and the TESLA Linac rf system using these tools are presented

  1. High quality steel casting for energy technics

    International Nuclear Information System (INIS)

    Schuster, F.; Koefler, G.

    1982-01-01

    The casting of several chromium-molybdenum steels for steam and hydraulic turbines is discussed. Non-destructive testing of the castings is performed demonstrating the safety for use in nuclear technology. The effect of metallurgical parameters on steel casting quality, the heat treatment, and the effect of construction design on costs for fettling and repair weldings are considered. (Auth.)

  2. Application to the conservation of RF tags in the radiation environment

    International Nuclear Information System (INIS)

    Teraura, Nobuyuki; Ito, Kunio; Takahashi, Naoki; Sakurai, Kouichi

    2011-01-01

    RF tags that are implemented RFID technology as tag has been used in various fields. Tags have been developed, such as resistance to chemicals and high temperature resistant RF tags are also used in specialized fields. The RF tag apply to the existing nuclear field, had been concerned about the effects of radiation to the RF tags. Now, since the RF tag with a goal to develop radiation-proof, we have examined, such as applying for maintenance of nuclear facilities under radiation environment. We report the results and RF tags to be radiation resistant. (author)

  3. Automotive RF immunity test set-up analysis

    NARCIS (Netherlands)

    Coenen, M.J.; Pues, H.; Bousquet, T.; Gillon, R.; Gielen, G.; Baric, A.

    2011-01-01

    Though the automotive RF emission and RF immunity requirements are highly justifiable, the application of those requirements in an non-intended manner leads to false conclusions and unnecessary redesigns for the electronics involved. When the test results become too dependent upon the test set-up

  4. Development of L-band pillbox RF window

    International Nuclear Information System (INIS)

    Takeuchi, Y.; Fukuda, S.; Hisamatsu, H.; Saito, Y.; Takahashi, A.

    1994-01-01

    A pillbox RF output window was developed for the L-band pulsed klystron for the Japanese Hadron Project (JHP) 1-GeV proton linac. The window was designed to withstand a peak RF power of 6 MW, where the pulse width is 600 μsec and the repetition rate is 50 Hz. A high power model was fabricated using an alumina ceramic which has a low loss tangent of 2.5x10 -5 . A high power test was successfully performed up to a 113 kW RF average power with a 4 MW peak power, a 565 μsec pulse width and a 50 Hz repetition rate. By extrapolating the data of this high power test, the temperature rise of the ceramic is estimated low enough at the full RF power of 6 MW. Thus this RF window is expected to satisfy the specifications of the L-band Klystron. (author)

  5. Pulsed rf superconductivity program at SLAC

    International Nuclear Information System (INIS)

    Campisi, I.E.; Farkas, Z.D.

    1984-08-01

    Recent tests performed at SLAC on superconducting TM 010 caavities using short rf pulses (less than or equal to 2.5 μs) have established that at the cavity surface magnetic fields can be reached in the vicinity of the theoretical critical fields without an appreciable increase in average losses. Tests on niobium and lead cavities are reported. The pulse method seems to be best suited to study peak field properties of superconductors in the microwave band, without the limitations imposed by defects. The short pulses also seem to be more effective in decreasing the causes of field emission by rf processing. Applications of the pulsed rf superconductivity to high-gradient linear accelerators are also possible

  6. Performance of the Brookhaven photocathode rf gun

    International Nuclear Information System (INIS)

    Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fischer, J.; Fisher, A.S.; Gallardo, J.; Ingold, G.; Kirk, H.G.; Leung, K.P.; Malone, R.; Pogorelsky, I.; Srinivasan-Rao, T.; Rogers, J.; Tsang, T.; Sheehan, J.; Ulc, S.; Woodle, M.; Xie, J.; Zhang, R.S.; Lin, L.Y.; McDonald, K.T.; Russell, D.P.; Hung, C.M.; Wang, X.J.

    1991-01-01

    The Brookhaven Accelerator Test Facility (ATF) uses a photocathode rf gun to provide a high-brightness electron beam intended for FEL and laser-acceleration experiments. The rf gun consists of 1 1/2 cells driven at 2856 MHz in π-mode with a maximum cathode field of 100 MV/m. To achieve long lifetimes, the photocathode development concentrates on robust metals such as copper, yttrium and samarium. We illuminate these cathodes with a 10-ps, frequency-quadrupled Nd:YAG laser. We describe the initial operation of the gun, including measurements of transverse and longitudinal emittance, quantum efficiencies, and peak current. The results are compared to models

  7. SSRL photocathode RF gun test stand

    International Nuclear Information System (INIS)

    Hernandez, M.; Baltay, M.; Boyce, A.

    1995-01-01

    A photocathode RF gun test stand designed for the production and study of high brightness electron beams will be constructed at SSRL. The beam will be generated from a laser driven third generation photocathode RF gun being developed in collaboration with BNL, LBL, and UCLA. The 3-5 [MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section, in order to achieve the desired low emittance beam, emittance compensation with solenoidal focusing will be employed

  8. RF control system of the HIMAC synchrotron

    International Nuclear Information System (INIS)

    Kanazawa, M.; Sato, K.; Itano, A.

    1992-01-01

    An RF control system of the HIMAC synchrotron has been constructed. In this control system we have adopted a digital feed back system with a digital synthesizer (DS). Combining a high power system, performance of the control system have been tested in a factory (Toshiba) with a simulator circuit of the synchrotron oscillation. Following this test, We had beam acceleration test with this control system at TARN-II in INS (Institute for Nuclear Study, University of Tokyo). This paper describes the RF control system and its tested results. (author)

  9. Emittance investigation of RF photo-injector

    CERN Document Server

    Yang Mao Rong; Li Zheng; Li Ming; Xu Zhou

    2002-01-01

    A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF find in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. The author analyzes the factors which lead the transverse emittance growth and method how to resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show these results are coincident

  10. Amorphous NEA Silicon Photocathodes - A Robust RF Gun Electron Source. Final Report

    International Nuclear Information System (INIS)

    Mulhollan, Gregory A.

    2009-01-01

    Amorphous silicon (a-Si) has been shown to have great promise as a negative electron affinity visible wavelength photocathode suitable for radio frequency (RF) gun systems. The specific operating wavelength can be shifted by growing it as a germanium alloy (a-Si(1-x)Ge(x)) rather than as pure silicon. This class of photoemitters has been shown to possess a high degree of immunity to charged particle flux. Such particle flux can be a significant problem in the operation of other photocathodes in RF gun systems. Its emission characteristics in the form of current per unit area, or current density, and emission angle, or beam spread are well matched for use in RF guns. Photocathodes made of a-Si can be fabricated on a variety of substrates including those most commonly employed in RF gun systems. Such photocathodes can be made for operation in either transmission or reflection mode. By growing them utilizing radio frequency plasma enhanced chemical vapor deposition, the unit cost is quite low, the quality is high and it is straightforward to grow custom size substrates and full or limited regions to confine the electron emission to the desired area. Quality emitters have been fabricated on tantalum, molybdenum, tungsten, titanium, copper, stainless steel, float glass, borosilicate glass and gallium arsenide. In addition to performing well in dedicated test chambers, a-Si photocathodes have been shown to function well in self-contained vacuum tubes. In this employment, they are subjected to a strenuous environment. Successful operation in this configuration provides additional confidence in their application to high energy linac photoinjectors and potentially as part of reliable, low cost photocathode driven RF gun systems that could become ready replacements for the diode and triode guns used on medical accelerators. Their applications in stand-alone vacuum tubes is just beginning to be explored.

  11. RF Power Generation in LHC

    CERN Document Server

    Brunner, O C; Valuch, D

    2003-01-01

    The counter-rotating proton beams in the Large Hadron Collider (LHC) will be captured and then accelerated to their final energies of 2 x 7 TeV by two identical 400 MHz RF systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell super-conducting (SC) cavity. Four klystrons are powered by a 100 kV, 40A AC/DC power converter, previously used for the operation of the LEP klystrons. A five-gap thyratron crowbar protects the four klystrons in each of these units. The technical specification and measured performance of the various high-power elements are discussed. These include the 400MHz/300kW klystrons with emphasis on their group delay and the three-port circulators, which have to cope with peak reflected power levels up to twice the simultaneously applied incident power of 300 kW. In addition, a novel ferrite loaded waveguide absorber, used as termination for port No...

  12. The RF system of FELI

    International Nuclear Information System (INIS)

    Morii, Y.; Miyauchi, Y.; Koga, A.; Abe, H.; Keishi, T.; Bessho, I.; Tomimasu, T.

    1994-01-01

    FELI (Free Electron Laser Research Institute, Inc.) is constructing a Free Electron Laser facility covering from 20 μm (infra red region) to 0.35 μm (ultra violet region), using an S-band linac. The building will be completed in November 1993 and installation of the linac will start in December 1993. The linac consists of a thermoionic 0.5ns-pulse triggered gun, a 714 MHz SHB (subharmonic buncher), a 2856 MHz standing wave type buncher, and 7 ETL (Electrotechnical Laboratory) type accelerating sections. An RF system of the linac for FELs is required of long pulse duration and high stability. S-band klystrons (TOSHIBA E3729) are operated in three pulse operation modes (pulse width and peak RF power); 24 μs - 24 MW, 12.5 μs - 34 MW, 0.5 μs - 70 MW. Each klystron modulator has the PFN consisting of 4 parallel networks of 24 capacitors and 24 inductors, and it has a line switch of an optical thyristor stack. These equipments are manufactured now, and an S-band klystron and modulator will be combined to test their performance at the works of NISSIN ELECTRIC Co. in October 1993. (author)

  13. Indoor Air Quality in High Performance Schools

    Science.gov (United States)

    High performance schools are facilities that improve the learning environment while saving energy, resources, and money. The key is understanding the lifetime value of high performance schools and effectively managing priorities, time, and budget.

  14. High-Fidelity RF Gun Simulations with the Parallel 3D Finite Element Particle-In-Cell Code Pic3P

    Energy Technology Data Exchange (ETDEWEB)

    Candel, A; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Schussman, G.; Ko, K.; /SLAC

    2009-06-19

    SLAC's Advanced Computations Department (ACD) has developed the first parallel Finite Element 3D Particle-In-Cell (PIC) code, Pic3P, for simulations of RF guns and other space-charge dominated beam-cavity interactions. Pic3P solves the complete set of Maxwell-Lorentz equations and thus includes space charge, retardation and wakefield effects from first principles. Pic3P uses higher-order Finite Elementmethods on unstructured conformal meshes. A novel scheme for causal adaptive refinement and dynamic load balancing enable unprecedented simulation accuracy, aiding the design and operation of the next generation of accelerator facilities. Application to the Linac Coherent Light Source (LCLS) RF gun is presented.

  15. RF sources for recent linear accelerator projects

    International Nuclear Information System (INIS)

    Terrien, J.C.; Faillon, G.; Guidee, P.

    1992-01-01

    We present the state of the art of high power klystrons at Thomson Tubes Electroniques, along with the main technological limitations for peak power and pulse width. Then we describe the work that is under way to upgrade performance and some of the alternative RF sources that have been developed. (Author) 3 refs., 4 figs., 2 tabs

  16. Study of HV Dielectrics for High Frequency Operation in Linear & Nonlinear Transmission Lines & Simulation & Development of Hybrid Nonlinear Lines for RF Generation

    Science.gov (United States)

    2015-08-27

    As shown in [4], [5], the capacitors based on PZT (lead-zirconate- titanate) and BT dielectrics have dielectric BD strength of the order of 50 kV/cm...results. Depending on the nonlinearity properties of the capacitor dielectric , input pulse rise time, output pulse sharpening and or RF soliton... capacitors in a frequency range up to 2 MHz, below the resonant frequency of the both dielectrics . As seen in Fig. 1, PZTs have better performance than

  17. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  18. Low frequency rf current drive

    International Nuclear Information System (INIS)

    Hershkowitz, N.

    1992-01-01

    An unshielded antenna for rf heating has been developed and tested during this report period. In addition to design specifications being given, some experimental results are presented utilizing: (1) an unprotected Faraday shield, (2) insulating guard limiters, (3) unshielded antenna experiments, (4) method for detecting small rf driven currents, (5) rf fast wave current drive experiments, (6) alfven wave interactions with electrons, and (7) machine conditioning, impurity generation and density control

  19. Plasmas for the low-temperature growth of high-quality GaN films by molecular beam epitaxy and remote plasma MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, M.; Capezzuto, P.; Bruno, G. [Plasmachemistry Research Center, CNR, Bari (Italy); Namkoong, G.; Doolittle, W.A.; Brown, A.S. [Georgia Inst. of Tech., Atlanta (United States). School of Electrical and Computer Engineering, Microelectronic Research Center

    2002-03-16

    GaN heteroepitaxial growth on sapphire (0001) substrates was carried out by both radio-frequency (rf) remote plasma metalorganic chemical vapor deposition (RP-MOCVD) and molecular beam epitaxy (MBE). A multistep growth process including substrate plasma cleaning and nitridation, buffer growth, its subsequent annealing and epilayer growth was used. In order to achieve a better understanding of the GaN growth, in-situ real time investigation of the surface chemistry is performed for all the steps using the conventional reflection high-energy electron spectroscopy (RHEED) during the MBE process, while laser reflectance interferometry (LRI) and spectroscopic ellipsometry (SE), which do not require UHV conditions, are used for the monitoring of the RP-MOCVD process. The chemistry of the rf N{sub 2} plasma sapphire nitridation and its effect on the epilayer growth and quality are discussed in both MBE and RP-MOCVD. (orig.)

  20. Reducing Energy Degradation Due to Back-bombardment Effect with Modulated RF Input in S-band Thermionic RF Gun

    Science.gov (United States)

    Kii, Toshiteru; Nakai, Yoko; Fukui, Toshio; Zen, Heishun; Kusukame, Kohichi; Okawachi, Norihito; Nakano, Masatsugu; Masuda, Kai; Ohgaki, Hideaki; Yoshikawa, Kiyoshi; Yamazaki, Tetsuo

    2007-01-01

    Energy degradation due to back-bombardment effect is quite serious to produce high-brightness electron beam with long macro-pulse with thermionic rf gun. To avoid the back-bombardment problem, a laser photo cathode is used at many FEL facilities, but usually it costs high and not easy to operate. Thus we have studied long pulse operation of the rf gun with thermionic cathode, which is inexpensive and easy to operate compared to the photocathode rf gun. In this work, to reduce the energy degradation, we controlled input rf power amplitude by controlling pulse forming network of the power modulator for klystron. We have successfully increased the pulse duration up to 4 μs by increasing the rf power from 7.8 MW to 8.5 MW during the macro pulse.