WorldWideScience

Sample records for thermionic converter performance

  1. Thermionic photovoltaic energy converter

    Science.gov (United States)

    Chubb, D. L. (Inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  2. DEXTER: A one-dimensional code for calculating thermionic performance of long converters

    Science.gov (United States)

    Sawyer, C. D.

    1971-01-01

    A versatile code is described for computing the coupled thermionic electric-thermal performance of long thermionic converters in which the temperature and voltage variations cannot be neglected. The code is capable of accounting for a variety of external electrical connection schemes, coolant flow paths and converter failures by partial shorting. Example problem solutions are included along with a user's manual.

  3. Dexter - A one-dimensional code for calculating thermionic performance of long converters.

    Science.gov (United States)

    Sawyer, C. D.

    1971-01-01

    This paper describes a versatile code for computing the coupled thermionic electric-thermal performance of long thermionic converters in which the temperature and voltage variations cannot be neglected. The code is capable of accounting for a variety of external electrical connection schemes, coolant flow paths and converter failures by partial shorting. Example problem solutions are given.

  4. Hybrid thermionic-photovoltaic converter

    Energy Technology Data Exchange (ETDEWEB)

    Datas, A. [Instituto de Energía Solar, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-04-04

    A conceptual device for the direct conversion of heat into electricity is presented. This concept hybridizes thermionic (TI) and thermophotovoltaic (TPV) energy conversion in a single thermionic-photovoltaic (TIPV) solid-state device. This device transforms into electricity both the electron and photon fluxes emitted by an incandescent surface. This letter presents an idealized analysis of this device in order to determine its theoretical potential. According to this analysis, the key advantage of this converter, with respect to either TPV or TI, is the higher power density in an extended temperature range. For low temperatures, TIPV performs like TPV due to the negligible electron flux. On the contrary, for high temperatures, TIPV performs like TI due to the great enhancement of the electron flux, which overshadows the photon flux contribution. At the intermediate temperatures, ∼1650 K in the case of this particular study, I show that the power density potential of TIPV converter is twice as great as that of TPV and TI. The greatest impact concerns applications in which the temperature varies in a relatively wide range, for which averaged power density enhancement above 500% is attainable.

  5. Materials for thermionic energy converters

    NARCIS (Netherlands)

    Wolff, L.R.; Hermans, J.M.; Adriaansen, J.K.M.; Gubbels, G.H.M.; Vincenzini, P.

    1987-01-01

    This paper deals with the design and construction of a combustion heated Thermionic Energy Converter (TEC). Main components of this TEC are: 1. A ''Hot Shell'' protecting the TEC from the combustion environment 2. A ''Ceramic Seal'' electrically insulating the emitter from the collector 3. A

  6. A new concept of thermionic converter

    International Nuclear Information System (INIS)

    Musa, G.

    1978-10-01

    The parameters of a new type of thermionic converter which has a number of concentric electrodes, is computed. The obtained theoretical efficiency of this new type of converter is nearly the efficiency of the ideal thermionic converter. The obtained results are explained by the reduction of the radiation loss from the emitter due to the electrode configuration. Efficiencies as high as 20% are expected from this type of converter now in construction. (author)

  7. Radioisotope thermionic converters for space applications

    International Nuclear Information System (INIS)

    Miskolczy, G.; Lieb, D.P.

    1990-01-01

    The recent history of radioisotope thermionics is reviewed, with emphasis on the U.S. programs, and the prospects for the future are assessed. In radioisotope thermionic converters the emitter heat is generated by the decay of a radioactive isotope. The thermionic converter emitter is mounted directly on a capsule containing the isotope. The rest of the capsule is generally insulated to reduce thermal loss. The development of isotope-fueled thermionic power systems for space application has been pursued since the late 1950's. The U.S. effort was concentrated on modular systems with alpha emitters as the isotope heat source. In the SNAP-13 program, the heat sources were Cerium isotopes and each module produced about 100 watts. The converters were planar diodes and the capsule was insulated with multi-foil insulation

  8. Design and operation of a thermionic converter in air

    International Nuclear Information System (INIS)

    Horner, M.H.; Begg, L.L.; Smith, J.N. Jr.; Geller, C.B.; Kallnowski, J.E.

    1995-01-01

    An electrically heated thermionic converter has been designed, built and successfully tested in air. Several unique features were incorporated in this converter: an integral cesium reservoir, innovative ceramic-to-metal seals, a heat rejection system coupling the collector to a low temperature heat sink and an innovative cylindrical heater filament. The converter was operated for extended periods of time with the emitter at about 1900 K. the collector at about 700 K, and a power density of over 2 w(e)/sq. cm. Input power transients were run between 50% and 100% thermal power, at up to 1% per second, without instabilities in performance

  9. Comparison between arc drops in ignited thermionic converters with and without ion reflections at the emitter

    International Nuclear Information System (INIS)

    Lundgren, L.

    1985-01-01

    The output performance of two thermionic energy converters is compared. One converter has a normal emitter, working with zero field at the emitter which is close to the optimum working point, and the other has a low work function emitter and ion reflection at the emitter. A simple model of the plasma and the sheaths shows that a converter working with a low work function emitter and ion reflections gives a worse performance than a similar converter with a normal emitter

  10. Thermionic emission from monolayer graphene, sheath formation and its feasibility towards thermionic converters

    Science.gov (United States)

    Misra, Shikha; Upadhyay Kahaly, M.; Mishra, S. K.

    2017-02-01

    A formalism describing the thermionic emission from a single layer graphene sheet operating at a finite temperature and the consequent formation of the thermionic sheath in its proximity has been established. The formulation takes account of two dimensional densities of state configuration, Fermi-Dirac (f-d) statistics of the electron energy distribution, Fowler's treatment of electron emission, and Poisson's equation. The thermionic current estimates based on the present analysis is found to be in reasonably good agreement with experimental observations (Zhu et al., Nano Res. 07, 1 (2014)). The analysis has further been simplified for the case where f-d statistics of an electron energy distribution converges to Maxwellian distribution. By using this formulation, the steady state sheath features, viz., spatial dependence of the surface potential and electron density structure in the thermionic sheath are derived and illustrated graphically for graphene parameters; the electron density in the sheath is seen to diminish within ˜10 s of Debye lengths. By utilizing the graphene based cathode in configuring a thermionic converter (TC), an appropriate operating regime in achieving the efficient energy conversion has been identified. A TC configured with the graphene based cathode (operating at ˜1200 K/work function 4.74 V) along with the metallic anode (operating at ˜400 K/ work function 2.0 V) is predicted to display ˜56% of the input thermal flux into the electrical energy, which infers approximately ˜84% of the Carnot efficiency.

  11. A thermionic energy converter with A molybdenum alumina cermet emitter

    NARCIS (Netherlands)

    Gubbels, G.H.M.; Wolff, L.R.; Metselaar, R.; Yogi Goswami, D.

    1988-01-01

    The I-V characteristics of a thermionic converter equipped with a Mo-1w/o AI203 emitter and a Mo collector were measured. The conditions were varied over a limited range without, as well as with Cs. Work functions of Mo as well as Mo-1w/o AI203 were determined. Measurements were carried out in a

  12. High Efficiency Thermionics (HET-IV) and Converter Advancement (CAP) programs. Final reports

    Energy Technology Data Exchange (ETDEWEB)

    Geller, C.B.; Murray, C.S.; Riley, D.R. [Bettis Atomic Power Lab., West Mifflin, PA (United States); Desplat, J.L.; Hansen, L.K.; Hatch, G.L.; McVey, J.B.; Rasor, N.S. [Rasor Associates, Inc., Sunnyvale, CA (United States)

    1996-04-01

    This report contains the final report of the High Efficiency Thermionics (HET-IV) Program, Attachment A, performed at Rasor Associates, Inc. (RAI); and the final report of the Converter Advancement Program (CAP), performed at the Bettis Atomic Power Laboratory, Attachment B. The phenomenology of cesium-oxygen thermionic converters was elucidated in these programs, and the factors that had prevented the achievement of stable, enhanced cesium-oxygen converter performance for the previous thirty years were identified. Based on these discoveries, cesium-oxygen vapor sources were developed that achieved stable performance with factor-of-two improvements in power density and thermal efficiency, relative to conventional, cesium-only ignited mode thermionic converters. Key achievements of the HET-IV/CAP programs are as follows: a new technique for measuring minute traces of oxygen in cesium atmospheres; the determination of the proper range of oxygen partial pressures for optimum converter performance--10{sup {minus}7} to 10{sup {minus}9} torr; the discovery, and analysis of the cesium-oxygen liquid migration and compositional segregation phenomena; the successful use of capillary forces to contain the migration phenomenon; the use of differential heating to control compositional segregation, and induce vapor circulation; the development of mechanically and chemically stable, porous reservoir structures; the development of precise, in situ oxygen charging methods; stable improvements in emitter performance, up to effective emitter bare work functions of 5.4 eV; stable improvements in barrier index, to value below 1.8 Volts; the development of detailed microscopic models for cesium-oxygen reservoir dynamics and collector work function behavior; and the discovery of new relationships between electrode geometry and Schock Instability.

  13. Life Testing and Diagnostics of a Planar Out-of-Core Thermionic Converter

    Science.gov (United States)

    Thayer, Kevin L.; Ramalingam, Mysore L.; Young, Timothy J.; Lamp, Thomas R.

    1994-07-01

    This paper details the design and performance of an automated computer data acquisition system for a planar, out-of-core thermionic converter with CVD rhenium electrodes. The output characteristics of this converter have been mapped for emitter temperatures ranging from approximately 1700K to 2000K, and life testing of the converter is presently being performed at the design point of operation. An automated data acquisition system has been constructed to facilitate the collection of current density versus output voltage (J-V) and temperature data from the converter throughout the life test. This system minimizes the amount of human interaction necessary during the lifetest to measure and archive the data and present it in a usable form. The task was accomplished using a Macintosh Ilcx computer, two multiple-purpose interface boards, a digital oscilloscope, a sweep generator, and National Instrument's LabVIEW application software package.

  14. Test results on two thermionic converters with cermet emitters

    International Nuclear Information System (INIS)

    Saunders, M.; Danielson, L.; Huffman, F.

    1983-01-01

    An emitter made of a directionally solidified Mo-Al 2 O 3 , Cr 2 O 3 eutectic was provided by Eindhoven University of Technology in Eindhoven, The Netherlands. Although the high temperature braze cycle used in bonding this electrode to the emitter substrate destroyed its characteristic needle microstructure, the converter gave good performance. Apparently, chemical species evaporated from the emitter onto the collector provided a low collector work function. The resulting low barrier indices suggest that this surface is a promising emitter

  15. Cesium-plasma-conductivity enhancement in the advanced thermionic energy converter. Final report

    International Nuclear Information System (INIS)

    Manikopoulos, C.N.

    Two methods of plasma conductivity enhancement in a cesium vapor thermionic energy converter have been studied. The first involved resonance photoabsorption of several cesium lines and the second utilized cesium plasma sustenance by application of microwave power. An extensive study of ionization processes in a cesium discharge in the presence of resonance ionization was made. Calculations were made of expected percentage excitation levels for several cesium resonance transitions for different values of neutral density and temperature as well as incident radiation power levels. The results of some of these computations were tabulated. Several ionization schemes were considered. A number of cesium transitions were investigated in the range of 799 to 870 nanometers for four different cesium reservoir temperatures, 467, 511, 550 and 591 K. The related absorption coefficients of the radiation lines in the plasma were deduced and tabulated. The resulting plasma conductivity increase was recorded and the associated ionization enhancement was deduced. A microwave cavity was built where the emitter and collector of a simple thermionic converter made up two of the cavity walls and resonant microwave power was externally applied. The I-V characteristics of the thermionic converter were studied under several microwave power levels in the range of 0 to 2 watts. Significant shifts to higher currents were observed as the microwave power levels were raised. In conclusion, both methods show promise as auxiliary ionization mechanisms for the thermionic energy converter, especially at low emitter temperatures

  16. A thermionic energy converter with a molybdenum-alumina cermet emitter

    NARCIS (Netherlands)

    Gubbels, G.H.M.; Wolff, L.R.; Metselaar, R.

    1990-01-01

    A study is made of the properties of cermets as electrode materials for thermionic energy converters. For thermodynamic reasons it is expected that all cermets composed of pure Mo and refractory oxides have the same bare work function. From data on the work function of Mo in an oxygen atmosphere

  17. Negative space charge effects in photon-enhanced thermionic emission solar converters

    International Nuclear Information System (INIS)

    Segev, G.; Weisman, D.; Rosenwaks, Y.; Kribus, A.

    2015-01-01

    In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionic converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163

  18. Calculational models of close-spaced thermionic converters

    International Nuclear Information System (INIS)

    McVey, J.B.

    1983-01-01

    Two new calculational models have been developed in conjunction with the SAVTEC experimental program. These models have been used to analyze data from experimental close-spaced converters, providing values for spacing, electrode work functions, and converter efficiency. They have also been used to make performance predictions for such converters over a wide range of conditions. Both models are intended for use in the collisionless (Knudsen) regime. They differ from each other in that the simpler one uses a Langmuir-type formulation which only considers electrons emitted from the emitter. This approach is implemented in the LVD (Langmuir Vacuum Diode) computer program, which has the virtue of being both simple and fast. The more complex model also includes both Saha-Langmuir emission of positive cesium ions from the emitter and collector back emission. Computer implementation is by the KMD1 (Knudsen Mode Diode) program. The KMD1 model derives the particle distribution functions from the Vlasov equation. From these the particle densities are found for various interelectrode motive shapes. Substituting the particle densities into Poisson's equation gives a second order differential equation for potential. This equation can be integrated once analytically. The second integration, which gives the interelectrode motive, is performed numerically by the KMD1 program. This is complicated by the fact that the integrand is often singular at one end point of the integration interval. The program performs a transformation on the integrand to make it finite over the entire interval. Once the motive has been computed, the output voltage, current density, power density, and efficiency are found. The program is presently unable to operate when the ion richness ratio β is between about .8 and 1.0, due to the occurrence of oscillatory motives

  19. Energy balance measurements for the determination of physical and technical operation parameters of thermionic converters

    International Nuclear Information System (INIS)

    Ritz, K.

    1975-01-01

    An introduction into the fundamental theoretical principles of the thermionic Cs converter is followed by the set-up of a special measuring converter as proposed by J. Bohdansky which permits the defined setting of the electrode distance under service conditions. Measurements thus carried out present quantitative data on efficiency, on energy transfer between the electrodes by means of radiation and heat transfer, and on the actual collector potential, the latter which surprisingly shows a distance dependency. (orig./GG) [de

  20. In-pile experimental device for Sirene thermionic converters

    International Nuclear Information System (INIS)

    Bliaux, J.; Durand, J.; Lazare-Chopard, G.

    1969-01-01

    The irradiation device described here, was built for in pile life tests of 100 We SIRENE converters. The nuclear converter is located in a sealed vacuum chamber, which is plugged at the lower end of a coaxial tubing acting as electrical leads. The output power is available on a variable resistive load on the bank of the reactor pool. Thermal, electrical and neutronic parameters of the converter are recorded. Since 1967, two permanent devices allowed five experiments in the swimming pool TRITON (CEN-FAR) and the results, obtained till now, are presented. (authors) [fr

  1. Analysis of instability growth and collisionless relaxation in thermionic converters using 1-D PIC simulations

    International Nuclear Information System (INIS)

    Kreh, B.B.

    1994-12-01

    This work investigates the role that the beam-plasma instability may play in a thermionic converter. The traditional assumption of collisionally dominated relaxation is questioned, and the beam-plasma instability is proposed as a possible dominant relaxation mechanism. Theory is developed to describe the beam-plasma instability in the cold-plasma approximation, and the theory is tested with two common Particle-in-Cell (PIC) simulation codes. The theory is first confirmed using an unbounded plasma PIC simulation employing periodic boundary conditions, ES1. The theoretically predicted growth rates are on the order of the plasma frequencies, and ES1 simulations verify these predictions within the order of 1%. For typical conditions encountered in thermionic converters, the resulting growth period is on the order of 7 x 10 -11 seconds. The bounded plasma simulation PDP1 was used to evaluate the influence of finite geometry and the electrode boundaries. For this bounded plasma, a two-stream interaction was supported and resulting in nearly complete thermalization in approximately 5 x 10 -10 seconds. Since the electron-electron collision rate of 10 9 Hz and the electron atom collision rate of 10 7 Hz are significantly slower than the rate of development of these instabilities, the instabilities appear to be an important relaxation mechanism

  2. Electric strength of metal-ceramic brazed units of thermionic energy converters in cesium vapours

    International Nuclear Information System (INIS)

    Belousenko, A.P.; Vasilchenko, A.V.; Nikolaev, Y.V.

    1989-01-01

    The investigation of electric strength characteristics of the hollow metal-ceramic brazed units of thermionic energy converters with the insulator 1 = 10-50 mm from polycrystal aluminum oxide at the temperature T = 450-750 degrees and the cesium vapour pressure P Cs = 10 - 1 -10 3 Pa has been carried out. The experimental dependencies of the break-down voltage of the brazed units on the temperature, parameter P Cs · 1 and the value of surface electric resistance of the insulators are given as well as the empiric equations obtained with the help of experimental data for calculating the break-down voltage. A mechanism of ceramic insulator influence on electric strength characteristics of the cesium gap is investigated. A breakdown model explaining this influence is proposed

  3. Characterization of sputter deposited thin film scandate cathodes for miniaturized thermionic converter applications

    Science.gov (United States)

    Zavadil, Kevin R.; Ruffner, Judith H.; King, Donald B.

    1999-01-01

    We have successfully developed a method for fabricating scandate-based thermionic emitters in thin film form. The primary goal of our effort is to develop thin film emitters that exhibit low work function, high intrinsic electron emissivity, minimum thermal activation properties and that can be readily incorporated into a microgap converter. Our approach has been to incorporate BaSrO into a Sc2O3 matrix using rf sputtering to produce thin films. Diode testing has shown the resulting films to be electron emissive at temperatures as low as 900 K with current densities of 0.1 mA.cm-2 at 1100 K and saturation voltages. We calculate an approximate maximum work function of 1.8 eV and an apparent emission constant (Richardson's constant, A*) of 36 mA.cm-2.K-2. Film compositional and structural analysis shows that a significant surface and subsurface alkaline earth hydroxide phase can form and probably explains the limited utilization and stability of Ba and its surface complexes. The flexibility inherent in sputter deposition suggests alternate strategies for eliminating undesirable phases and optimizing thin film emitter properties.

  4. Some properties of low-vapor-pressure braze alloys for thermionic converters

    Science.gov (United States)

    Bair, V. L.

    1978-01-01

    Density, dc electrical resistivity, thermal conductivity, and linear thermal expansion are measured for arc-melted rod-shaped samples of binary eutectics of Zr, Hf, Ru, Nb, Ir, Mo, Ta, Os, Re, and W selected as very-low-pressure braze fillers for thermionic converters. The first two properties are measured at 296 K for Zr-21.7 at% Ru, Zr-13 wt% W, Zr-19 wt% W, Zr-22.3 at% Nb, Nb-66.9 at% Ru, Hf-25.3 wt% Re, Zr-25.7 at% Ta, Hf-22.5 at% W, and Nb-35 wt% Mo. The last property is measured from 293 K to 2/3 melting point for specified alloys of different compositions. Resistivities of 0.000055 to 0.000181 ohm-cm are observed with the alloys having resistivities about ten times that of the less resistive constituent metal and about three times that of the more resistive constituent metal, except for Zr-19 wt% W and Nb-35 wt% Mo (greater resistivities). Thermal expansion coefficients vary from 0.000006 to 0.0000105/K. All brazes exhibit linear thermal expansion near that of their constituent metals.

  5. Thermionic nuclear reactor systems

    International Nuclear Information System (INIS)

    Kennel, E.B.

    1986-01-01

    Thermionic nuclear reactors can be expected to be candidate space power supplies for power demands ranging from about ten kilowatts to several megawatts. The conventional ''ignited mode'' thermionic fuel element (TFE) is the basis for most reactor designs to date. Laboratory converters have been built and tested with efficiencies in the range of 7-12% for over 10,000 hours. Even longer lifetimes are projected. More advanced capabilities are potentially achievable in other modes of operation, such as the self-pulsed or unignited diode. Coupled with modest improvements in fuel and emitter material performance, the efficiency of an advanced thermionic conversion system can be extended to the 15-20% range. Advanced thermionic power systems are expected to be compatible with other advanced features such as: (1) Intrinsic subcritically under accident conditions, ensuring 100% safety upon launch abort; (2) Intrinsic low radiation levels during reactor shutdown, allowing manned servicing and/or rendezvous; (3) DC to DC power conditioning using lightweight power MOSFETS; and (4) AC output using pulsed converters

  6. Effect of the work function and emission of the collector on the parameters of thermionic converters (TC)

    International Nuclear Information System (INIS)

    Kaibyshev, V.Z.

    1986-01-01

    In the optimal, relative to the temperature of the collector, state of modern thermionic converters (TC) the emission of the electrons from it has a substantial effect on the voltage drop in the gap. This paper preents an analysis of the boundary conditions at the collector of the TC. Calculations are presented which show that with a constant current the plasma parameters at the boundary with the collector are virtually independent of the emission from the collector right up to vanishing of the potential jump. The optimal regime with respect to temperatuer and work function of the collector is examined. The collector with a nonuniform work function is discussed

  7. DOD's advanced thermionics program an overview

    International Nuclear Information System (INIS)

    Drake, T.R.

    1998-01-01

    The Defense Special Weapons Agency (DSWA) manages a congressionally mandated program in advanced thermionics research. Guided by congressional language to advance the state-of-the-art in the US and support the Integrated Solar Upper Stage (ISUS) program, DSWA efforts concentrate on four areas: an electrically testable design of a high-performance, in-core thermionic fuel element (TFE), the ISUS program, a microminiature thermionic converter and several modeling efforts. The DSWA domestic program is augmented by several small contracts with Russian institutes, awarded under the former TOPAZ International Program that the Ballistic Missile Defense Organization transferred to DSWA. The design effort at General Atomics will result in an electrically testable, multi-cell TFE for in-core conversion, involving system design and advanced collector and emitter technologies. For the ISUS program, DSWA funded a portion of the engine ground demonstration, including development of the power management system and the planar diodes. Current efforts supporting ISUS include continued diode testing and developing an advanced planar diode. The MTC program seeks to design a mass producable, close-spaced thermionic converter using integrated circuit technologies. Modeling and analysis at DSWA involves development of the Reactor System Mass with Thermionics estimation model (RSMASS-T), developing a new thermionic theory, and reviewing applications for the MTC technology. The Russian deliverables include several reports and associated hardware that describe many of its state-of-the-art thermionic technologies and processes

  8. Surface properties of ceramic/metal composite materials for thermionic converter applications

    International Nuclear Information System (INIS)

    Davis, P.R.; Bozack, M.J.; Swanson, L.W.

    1983-01-01

    Ceramic/metal composite electrode materials are of interest for thermionic energy conversion (TEC) applications for several reasons. These materials consist of submicron metal fibers or islands in an oxide matrix and therefore provide a basis for fabricating finely structured electrodes, with projecting or recessed metallic regions for more efficient electron emission or collection. Furthermore, evaporation and surface diffusion of matrix oxides may provide oxygen enhancement of cesium adsorption and work function lowering at both the collecting and emitting electrode surfaces of the TEC. Finally, the high work function oxide matrix or oxide-metal interfaces may provide efficient surface ionization of cesium for space-charge reduction in the device. The authors are investigating two types of ceramic/metal composite materials. One type is a directionally solidified eutectic consisting of a bulk oxide matrix such as UO 2 or stabilized ZrO 2 with parallel metal fibers (W) running through the oxide being exposed at the surface by cutting perpendicular to the fiber direction. The second type of material, called a surface eutectic, consists of a refractory substrate (Mo) with a thin layer of deposited and segregated material (Mo-Cr 2 O 3 -A1 2 O 3 ) on the surface. The final configuration of this layer is an oxide matrix with metallic islands scattered throughout

  9. Irradiation behaviour of UO2/Mo porous cermets for thermionic converters

    International Nuclear Information System (INIS)

    Stora, J.P.; Kauffmann, Y.

    1975-01-01

    Two types of UO 2 Mo porous cernets have been fabricated and irradiated in a Cythere irradiation device. The first cermet is constituted by little bits of dense fuel in which the two constituants are finely dispersed. The whole open porosity is located between the granules. This type of cermet is called breche (33.4vol%UO 2 , 51vol%Mo, 14.8vol%porosity). At the end of the irradiation the burn up was 19000MWd/t(U) and neither swelling of the cermet nor deformation of the can were noted. On the contrary, a shrinkage of the emitter was observed attributed to a fuel densification under irradiation. The second type of cermet is called macrogranule (36vol%UO 2 , 49vol%Mo 15vol%porosity). UO 2 granules of 0.07cm mean diameter are dispersed in the molybdenum matrix. The porosity is regularly distributed all around the UO 2 kernels. The post irradiation metrology shows that the emitter is fairly stable. Only a slight ovalisation of about 0.5% was noted, but the granules of UO 2 were redistributed inside the molybdenum matrix, overlapping the metallic cavity by a condensation-evaporation process. The matrix has crept into the central void and consequently the volume has grown and the whole porosity has increased from about 15% to about 23%. This creeping is due to the fission gas pressure in the molybdenum cavities after 3000 hours of irradiation. In conclusion two types of cermets have shown good behaviour under irradiation and should allow lifetimes of several thousand hours of operation for thermionic fuel elements [fr

  10. The advanced thermionics initiative...program update

    International Nuclear Information System (INIS)

    Lamp, T.R.; Donovan, B.D.

    1993-01-01

    The United States Air Force has had a long standing interest in thermionic space power dating back to the early 1960s when a heat pipe cooled thermionic converter was demonstrated through work at the predecessor to Wright Laboratory (WL). With the exception of the short hiatus in the mid-70s, Air Force thermionics work at Wright Laboratory has continued to the present time with thermionic technology programs including the burst power thermionic phase change concepts, heat pipe cooled planar diodes, and advanced in-core concept developments such as composite materials, insulators and oxygenation. The Advanced Thermionics Initiative (ATI) program was organized to integrate thermionic technology advances into a converter suitable for in-core reactor applications in the 10 to 40 kWe power range. As an advanced thermionics technology program, the charter and philosophy of the ATI program is to provide the needed advanced converter concepts in support of national thermionic space power programs

  11. Heat-pipe thermionic reactor concept

    DEFF Research Database (Denmark)

    Storm Pedersen, E.

    1967-01-01

    Main components are reactor core, heat pipe, thermionic converter, secondary cooling system, and waste heat radiator; thermal power generated in reactor core is transported by heat pipes to thermionic converters located outside reactor core behind radiation shield; thermionic emitters are in direct...

  12. Thermionics. A bibliography with abstracts. Search period covered: 1970--Apr 1975. [190 references

    Energy Technology Data Exchange (ETDEWEB)

    Grooms, D.W.

    1975-04-01

    Research on thermionic power generation, power plant design, converter design, and basic research on thermionic materials are cited in the bibliography. Spacecraft applications are included. (Contains 190 abstracts).

  13. High-Performance Data Converters

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    -resolution internal D/A converters are required. Unit-element mismatch-shaping D/A converters are analyzed, and the concept of mismatch-shaping is generalized to include scaled-element D/A converters. Several types of scaled-element mismatch-shaping D/A converters are proposed. Simulations show that, when implemented...... in a standard CMOS technology, they can be designed to yield 100 dB performance at 10 times oversampling. The proposed scaled-element mismatch-shaping D/A converters are well suited for use as the feedback stage in oversampled delta-sigma quantizers. It is, however, not easy to make full use of their potential......-order difference of the output signal from the loop filter's first integrator stage. This technique avoids the need for accurate matching of analog and digital filters that characterizes the MASH topology, and it preserves the signal-band suppression of quantization errors. Simulations show that quantizers...

  14. Performance review of thermionic electron gun developed for RF linear accelerators at RRCAT

    International Nuclear Information System (INIS)

    Wanmode, Yashwant; Mulchandani, J.; Reddy, T.S.; Bhisikar, A.; Singh, H.G.; Shrivastava, Purushottam

    2015-01-01

    RRCAT is engaged in development of RF electron linear accelerator for irradiation of industrial and agricultural products. Thermionic electron gun is primary source for this accelerator as beam current in the RF accelerator is modest and thermionic emission is most prevalent option for electron gun development. An electron gun has to meet high cathode emission capability, low filament power, good accessibility for cathode replacement and should provide short time for maintenance. Electron linear accelerator up to beam energy of 10 MeV require electron source of 45-50 keV beam energy and emission current of 1 A. Electron optics of gun and electron beam profile simulations were carried out using CST's particle tracking code and EGUN code. Triode type electron gun of cathode voltage 50 kV pulsed has been designed, developed and integrated with 10 MeV electron linear accelerators at RRCAT. Beam current of more than 600 mA has been measured with faraday cup in the test stand developed for characterizing the electron gun. Two accelerators one is imported and another one developed indigenously has been energized using this electron gun. Beam energy of 5-10 MeV has been achieved with beam current of 250-400 mA by integrating this electron gun with the linear accelerator. This paper reviews the performance of indigenously developed electron gun for both linear accelerators. (author)

  15. NUCLEAR THERMIONIC SPACE POWER SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Howard, R. C.; Rasor, N. S.

    1963-03-15

    The various concepts for utilizing thermionic conversion in space reactor power plants are described and evaluated. The problems (and progress toward their solution) of the in-core concept, particularly, are considered. Progress in thermionic conversion technology is then reviewed from both the hardware and research points of view. Anticipated progress in thermionic conversion and the possible consequences for the performance of electrical propulsion systems are summarized. 46 references. (D.C.W.)

  16. In-pile experimental device for Sirene thermionic converters; Dispositif d'experimentation en pile des convertisseurs thermoioniques sirene

    Energy Technology Data Exchange (ETDEWEB)

    Bliaux, J; Durand, J; Lazare-Chopard, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The irradiation device described here, was built for in pile life tests of 100 We SIRENE converters. The nuclear converter is located in a sealed vacuum chamber, which is plugged at the lower end of a coaxial tubing acting as electrical leads. The output power is available on a variable resistive load on the bank of the reactor pool. Thermal, electrical and neutronic parameters of the converter are recorded. Since 1967, two permanent devices allowed five experiments in the swimming pool TRITON (CEN-FAR) and the results, obtained till now, are presented. (authors) [French] Le dispositif d'irradiation SIRENE decrit ici a ete concu en vue d'une etude statistique de performances de convertisseurs thermoioniques nucleaires de puissance unitaire 100 We. Le dispositif doit assurer la bonne marche du convertisseur en pile, permettre le changement de la position verticale du convertisseur dans le coeur, sortir du coeur la puissance electrique convertie sans degradation notable et enregistrer les differents parametres thermiques, electriques et neutroniques du convertisseur. Depuis 1967, deux dispositifs fonctionnent en permanence et ont permis de faire cinq experiences dans le reacteur piscine TRITON du CEN-FAR. Les resultats obtenus jusqu'a present, sont presentes. (auteurs)

  17. High performance emitter for thermionic diode obtained by chemical vapor deposition

    International Nuclear Information System (INIS)

    Faron, R.; Bargues, M.; Durand, J.P.; Gillardeau, J.

    1973-01-01

    Vapor deposition process conditions presently known for tungsten and molybdenum (specifically the range of high temperatures and low pressures) permit the achievement of high performance thermionic emitters when used with an appropriate technology. One example of this uses the following series of successive vapor deposits, the five last vapor deposits constituting the fabrication of the emitting layer: Mo deposit for the formation of the nuclear fuel mechanical support; Mo deposit, which constitutes the sheath of the nuclear fuel; epitaxed Mo--W alloy deposit; epitaxed tungsten deposit; fine-grained tungsten deposit; and tungsten deposit with surface orientation according to plane (110)W. In accordance with vapor deposition techniques previously developed, such a sequence of deposits can easily be achieved with the same equipment, even without having to take out the part during the course of the process. (U.S.)

  18. Thermionic cogeneration burner design

    Science.gov (United States)

    Miskolczy, G.; Goodale, D.; Moffat, A. L.; Morgan, D. T.

    Since thermionic converters receive heat at very high temperatures (approximately 1800 K) and reject heat at moderately high temperatures (approximately 800 K), they are useful for cogeneration applications involving high temperature processes. The electric power from thermionic converters is produced as a high amperage, low-voltage direct current. An ideal cogeneration application would be to utilize the reject heat at the collector temperature and the electricity without power conditioning. A cogeneration application in the edible oil industry fulfills both of these requirements since both direct heat and hydrogen gas are required in the hydrogenation of the oils. In this application, the low-voltage direct current would be used in a hydrogen electrolyzer.

  19. Performance evaluation and parametric optimum design of a vacuum thermionic solar cell

    International Nuclear Information System (INIS)

    Liao, Tianjun; Chen, Xiaohang; Chen, Jincan; Lin, Bihong

    2016-01-01

    A model of the vacuum thermionic solar cell (VTSC) consisting of a solar concentrator, an emitter, and a collector is proposed, in which the various heat losses including the far- and near-field thermal radiation are taken into account. Formula for the overall efficiency of the system is analytically derived. For given values of the ratio of the front surface area of the absorber to that of the emitter and the vacuum gap between the emitter and the collector, the operating temperatures of the emitter and collector are determined by solving the energy balance equations. The maximum efficiency of the VTSC are calculated for given values of the work functions of the emitter and collector materials, and some key parameters such as the net current density of the VTSC, operating temperatures of the emitter and collector, vacuum gap between the emitter and the collector, and area ratio of the absorber to the emitter are optimally determined. Furthermore, the effects of the work functions and the concentration ratio of the solar irradiation on the performance of the VTSC are discussed and several parametric selection criteria are obtained

  20. NASA thermionic-conversion program

    International Nuclear Information System (INIS)

    Morris, J.F.

    1977-01-01

    NASA's program for applied research and technology (ART) in thermionic energy conversion (TEC) has made worthwhile contributions in a relatively short time: Many of these accomplishments are incremental, yet important. And their integration has yielded gains in performance as well as in the knowledge necessary to point productive directions for future work. Both promise and problems derive from the degrees of freedom allowed by the current programmatic emphasis on out-of-core thermionics. Materials and designs previously prohibited by in-core nucleonics and geometries now offer new potentialities. But as a result a major TEC-ART responsibility is the efficient reduction of the glitter of diverse possibilities to the hard glint of reality. As always high-temperature material effects are crucial to the level and duration of TEC performance: New electrodes must increase and maintain power output regardless of emitter-vapor deposition on collectors. They must also serve compatibly with hot-shell alloys. And while space TEC must face high-temperature vaporization problems externally as well as internally, terrestrial TEC must tolerate hot corrosive atmospheres outside and near-vacuum inside. Furthermore, some modes for decreasing interelectrode losses appear to require rather demanding converter geometries to produce practical power densities. In these areas and others significant progress is being made in the NASA TEC-ART Program

  1. Measured and projected performance of plasma direct converters

    International Nuclear Information System (INIS)

    Barr, W.L.; Moir, R.W.

    1981-01-01

    Test results from two plasma direct converters and their predicted cost and performance on tandem mirror fusion reactors are present. The tests were done at high power density (approx. 70 W/cm 2 ) in steady state to simulate the predicted conditions in a reactor. A single stage unit and a two-stage unit of the Venetian blind type were tested at up to 100 kV and 6 kW for a total time of about 80 hours. Measured efficiencies, when projected to a reactor, are typically about 50% for a single stage unit and 60 to 70% for a two-stage unit, depending on the energy distribution of the ions, the degree of subdivision of the collectors, and on the gas pressure. The high ambipolar potential in tandem mirror devices makes this good efficiency possible. When radiatively cooled grids are used, the incident power density is limited to about 100 W/cm 2 by the thermionic emission of electrons

  2. Thermionic conversion reactor technology assessment. Final report

    International Nuclear Information System (INIS)

    1984-02-01

    The in-core thermionic space nuclear power supply may be the only identified reactor-power concept that can meet the SP-100 size functional requirements with demonstrated state-of-the-art reactor system and space-qualified power system component temperatures. The SP-100 configuration limits provide a net 40 m 2 of primary non-deployed radiator area. If a reasonable 7-year degradation allowance of 15% to 20% is provided then the beginning of life (BOL) net power output requirement is about 120 kWe. Consequently, the SP-100 power system must produce a P/A of 2.7 kWe/m 2 . This non-deployed radiator area power density performance can only be reasonably achieved by the thermionic in-core convertr system, the potassium Rankine turbine system and the Stirling engine system. The purpose of this study is to examine past and current tests and data, and to assess the potential for successful development of suitable fueled-thermionic converters that will meet SP-100 and growth requirements. The basis for the assessment will be provided and the recommended key developments plan set forth

  3. A50-kW(el) solar energy thermionic power generator for spacecraft

    International Nuclear Information System (INIS)

    Sahin, S.

    1978-01-01

    The technical limits of thermionic reactors in space craft and the potentials of solar energy thermionic converters are discussed. The technical design of a solar energy thermionic generator for 50 kW(el) as a secondary energy source in unmanned space craft is presented. (GG) [de

  4. Oscillating thermionic conversion for high-density space power

    International Nuclear Information System (INIS)

    Jacobson, D.L.; Morris, J.F.

    1988-01-01

    The compactness, maneuverability, and productive weight utilization of space nuclear reactors benefit from the use of thermionic converters at high temperature. Nuclear-thermionic-conversion power requirements are discussed, and the role of oscillations in thermionic energy conversion (TEC) history is examined. Proposed TEC oscillations are addressed, and the results of recent studies of TEC oscillations are reviewed. The possible use of high-frequency TEC oscillations to amplify low-frequency ones is considered. The accomplishments of various programs studying the use of high-temperature thermionic oscillators are examined. 16 references

  5. High temperature cogeneration with thermionic burners

    International Nuclear Information System (INIS)

    Fitzpatrick, G.O.; Britt, E.J.; Dick, R.S.

    1981-01-01

    The thermionic cogeneration combustor was conceived to meet industrial requirements for high-temperature direct heat, typically in the form of gas at temperatures from 800 to 1900 K, while at the same time supplying electricity. The thermionic combustor is entirely self-contained, with heat from the combustion region absorbed by the emitters of thermionic converters to be converted to electric power and the high-temperature reject heat from the converters used to preheat the air used for combustion. Depending on the temperature of the process gas produced, energy savings of around 10% with respect to that used to produce the same amount of electricity and heat without cogeneration are possible with present technology, and savings of up to 20% may be possible with advanced converters. Possible thermionic combustor designs currently under investigation include a configuration in which heat is collected by heat pipes lining the periphery of the combustion region, and a fire-tube converter in which combustion occurs within the cylindrical emitter of each converter. Preliminary component tests of these designs have been encouraging

  6. High temperature cogeneration with thermionic burners

    Science.gov (United States)

    Fitzpatrick, G. O.; Britt, E. J.; Dick, R. S.

    The thermionic cogeneration combustor was conceived to meet industrial requirements for high-temperature direct heat, typically in the form of gas at temperatures from 800 to 1900 K, while at the same time supplying electricity. The thermionic combustor is entirely self-contained, with heat from the combustion region absorbed by the emitters of thermionic converters to be converted to electric power and the high-temperature reject heat from the converters used to preheat the air used for combustion. Depending on the temperature of the process gas produced, energy savings of around 10% with respect to that used to produce the same amount of electricity and heat without cogeneration are possible with present technology, and savings of up to 20% may be possible with advanced converters. Possible thermionic combustor designs currently under investigation include a configuration in which heat is collected by heat pipes lining the periphery of the combustion region, and a fire-tube converter in which combustion occurs within the cylindrical emitter of each converter. Preliminary component tests of these designs have been encouraging.

  7. High-efficiency AlxGa1-xAs/GaAs cathode for photon-enhanced thermionic emission solar energy converters

    Science.gov (United States)

    Feng, Cheng; Zhang, Yijun; Qian, Yunsheng; Wang, Ziheng; Liu, Jian; Chang, Benkang; Shi, Feng; Jiao, Gangcheng

    2018-04-01

    A theoretical emission model for AlxGa1-xAs/GaAs cathode with complex structure based on photon-enhanced thermionic emission is developed by utilizing one-dimensional steady-state continuity equations. The cathode structure comprises a graded-composition AlxGa1-xAs window layer and an exponential-doping GaAs absorber layer. In the deduced model, the physical properties changing with the Al composition are taken into consideration. Simulated current-voltage characteristics are presented and some important factors affecting the conversion efficiency are also illustrated. Compared with the graded-composition and uniform-doping cathode structure, and the uniform-composition and uniform-doping cathode structure, the graded-composition and exponential-doping cathode structure can effectively improve the conversion efficiency, which is ascribed to the twofold built-in electric fields. More strikingly, this graded bandgap structure is especially suitable for photon-enhanced thermionic emission devices since a higher conversion efficiency can be achieved at a lower temperature.

  8. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    . Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes...

  9. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into waveenergy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. Thisimplicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  10. Mechanism of explosive emission excitation in thermionic energy conversion processes

    Energy Technology Data Exchange (ETDEWEB)

    Bulyga, A.V.

    1983-01-01

    A study has been made of the mechanism of explosive electron emission in vacuum thermionic converters induced by thermionic currents in the case of the anomalous Richardson effect. The latter is associated with a spotted emitting surface and temperature fluctuations. In order to account for one of the components of the electrode potential difference, it is proposed that allowance be made for the difference between the polarization signal velocity in a dense metal electron gas and that in the electron-ion gas of the electrode gap. Ways to achieve explosive emission in real thermionic converters are discussed.

  11. Development of a thermionic-reactor space-power system. Final summary report

    International Nuclear Information System (INIS)

    1973-01-01

    Initial experimental work led to the award of the first AEC thermionic contract on May 1, 1962, for the development of fission heated thermionic cells with an operating life of 10,000 hours or more. Two types of converters were fabricated: (1) electrically heated, and (2) fission heated where the fuel was either uranium carbide or uranium oxide. Competition between GGA and GE was climaxed on July 1, 1970 by the award to GGA of a contract to develop an in-core thermionic reactor. This report is divided into the following: thermionic research, materials technology, thermionic fuel element development, reactor technology, and systems technology

  12. Thermionic reactors for space nuclear power

    Science.gov (United States)

    Homeyer, W. G.; Merrill, M. H.; Holland, J. W.; Fisher, C. R.; Allen, D. T.

    1985-01-01

    Thermionic reactor designs for a variety of space power applications spanning the range from 5 kWe to 3 MWe are described. In all of these reactors, nuclear heat is converted directly to electrical energy in thermionic fuel elements (TFEs). A circulating reactor coolant carries heat from the core of TFEs directly to a heat rejection radiator system. The recent design of a thermionic reactor to meet the SP-100 requirements is emphasized. Design studies of reactors at other power levels show that the same TFE can be used over a broad range in power, and that design modifications can extend the range to many megawatts. The design of the SP-100 TFE is similar to that of TFEs operated successfully in test reactors, but with design improvements to extend the operating lifetime to seven years.

  13. System modeling for the advanced thermionic initiative single cell thermionic space nuclear reactor

    International Nuclear Information System (INIS)

    Lee, H.H.; Lewis, B.R.; Klein, A.C.; Pawlowski, R.A.

    1993-01-01

    Incore thermionic space reactor design concepts which operate in a nominal power output range of 20 to 40 kWe are described. Details of the neutronics, thermionic, shielding, and heat rejection performance are presented. Two different designs, ATI-Driven and ATI-Driverless, are considered. Comparison of the core overall performance of these two configurations are described. The comparison of these two cores includes the overall conversion efficiency, reactor mass, shield mass, and heat rejection mass. An overall system design has been developed to model the advanced incore thermionic energy conversion based nuclear reactor systems for space applications in this power range

  14. Metamaterial polarization converter analysis: limits of performance

    DEFF Research Database (Denmark)

    Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim

    2013-01-01

    and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design......In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter...

  15. Thermionic Power Cell To Harness Heat Energies for Geothermal Applications

    Science.gov (United States)

    Manohara, Harish; Mojarradi, Mohammad; Greer, Harold F.

    2011-01-01

    A unit thermionic power cell (TPC) concept has been developed that converts natural heat found in high-temperature environments (460 to 700 C) into electrical power for in situ instruments and electronics. Thermionic emission of electrons occurs when an emitter filament is heated to gwhite hot h temperatures (>1,000 C) allowing electrons to overcome the potential barrier and emit into the vacuum. These electrons are then collected by an anode, and transported to the external circuit for energy storage.

  16. Preliminary testing of a planar converter with uranium oxide pellets in the emitter

    International Nuclear Information System (INIS)

    Miskolczy, G.; Lieb, D.P.; Hatch, G.L.

    1992-01-01

    Nuclear reactor thermionic space power systems incorporating thermionic fuel element generally use refractory metal emitters, which contain the nuclear fuel. The purpose of the current work is to determine the effect, if any, of the diffusion of uranium oxide fuel through chemically vapor deposited (CVD) tungsten on converter performance. This paper describes the preliminary testing of the converter to assess the converter performance before any significant diffusion takes place. In testing, the emitter temperature was 1800 K and the collector temperature was varied from 1000 K to 1070 K. Experiments also examined pressure versus loading characteristics of the graphite

  17. SP-100 thermionic technology program annual integrated technical progress report for the period ending September 30, 1984

    International Nuclear Information System (INIS)

    Holland, J.W.

    1984-11-01

    The thermionic technology program addresses the feasibility issues of a seven-year-life thermionic fuel element (TFE) for the SP-100 Thermionic Reactor Space Power System. These issues relate to the extension of TFE lifetime from three to seven years, one of the SP-100 requirements. The technology to support three-year lifetimes was demonstrated in the earlier TFE development program conducted in the late-1960s and 1970s. Primary life-limiting factors were recognized to be thermionic emitter dimensional increases due to swelling of the nuclear fuel and electrical structural damage from fast neutrons. The 1984-85 technology program is investigating the fueled emitter and insulator lifetime issues, both experimentally and analytically. The goal is to analytically project the lifetime of the fueled emitter and insulator and to experimentally verify these projection methods. In 1984, the efforts were largely devoted to the design and building of fueled emitters for irradiation in 1985, validation of fuel-emitter models, development of irradiation-resistant metal-ceramic seal and sheath insulator, modeling of insulator lifetime, and development of wide-spread, high-performance thermionic converters

  18. Electrostatic direct energy converter performance and cost scaling laws

    International Nuclear Information System (INIS)

    Hoffman, M.A.

    1977-08-01

    This study is concerned with electrostatic type direct energy converters for direct recovery of a large fraction of the plasma ion energy from fusion reactors. Simplified equations are presented for each of the important loss mechanisms in both single-stage direct converters and multistage ''Venetian Blind'' type direct converters. These equations can be used to estimate the efficiency and electric power output of the direct converter subsystem. Scaling relations for the cost of each major component in the direct converter subsystem are also given; these include the vacuum tank, direct converter modules, the DC power conditioning equipment, cryogenic vacuum pumping system and the thermal bottoming plant. The performance and cost scaling laws have been developed primarily for use in overall fusion power plant systems codes. However, to illustrate their utility, cost-effectiveness studies of two specific reference direct converter designs are presented in terms of the specific capital costs (i.e., the capital cost per unit electric power produced) for the Direct Converter Subsystem alone. Some examples of design improvements which can significantly reduce the specific capital costs of the Direct Converter Subsystem are also given

  19. Effects of cavitation on performance of automotive torque converter

    Directory of Open Access Journals (Sweden)

    Jaewon Ju

    2016-06-01

    Full Text Available Cavitation is a phenomenon whereby vapor bubbles of a flowing liquid are formed in a local region where the pressure of the liquid is below its vapor pressure. It is well known that cavitation in torque converters occurs frequently when a car with an automatic transmission makes an abrupt start. Cavitation is closely related to a performance drop and noise generation at a specific operating condition in a car and a torque converter itself. This study addressed the relation between cavitation and performance in an automotive torque converter in a quantitative and qualitative manner using numerical simulations. The cavitation was calculated at various operating conditions using a commercial flow solver with the homogeneous cavitation model, and the torque converter performance was compared with the experimental data. Numerical results well match to the data and indicate that the cavitation causes significant performance drop, as the pump speed increases or both speed ratio and reference pressure decrease.

  20. Control for nuclear thermionic power source

    International Nuclear Information System (INIS)

    Fletcher, J.C.; Sawyer, C.D.

    1978-01-01

    A control for a power source is described which includes nuclear fuel interspersed with thermionic converters, including a power regulator that maintains a substantially constant output voltage to a variable load, and a control circuit that drives a neutron flux regulator in accordance with the current supplied to the power regulator and the neutron flux density in the region of the converters. The control circuit generates a control signal which is the difference between the neutron flux density and a linear fucntion of the current, and which drives the neutron regulator in a direction to decrease or increase the neutron flux according to the polarity of the control signal

  1. Distance relay performance in future converter dominated power systems

    DEFF Research Database (Denmark)

    Sarkar, Moumita; Jia, Jundi; Yang, Guangya

    2017-01-01

    Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up ...... of converter controls on fault current response of converter-based generations is also investigated. Index Terms—Converter control, distance relays, power system protection, system modelling....... to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of converter dominated systems on performance of distance relays. Backup functionality of the distance...... relay is major concern as miscoordination of backup relays in case of cascading faults can lead to severe stress in system, which can develop into blackout. In this paper, response of relays in traditional system is compared with response of relays in low short-circuit-current power systems. Impact...

  2. CID thermionic gun system

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1981-10-01

    A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

  3. CID thermionic gun system

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1982-01-01

    A new high-current thermionic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nanosecond pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 10 11 electrons in a single S-band accelerated bunch. Preliminary operation of the gun is described, and details of the avalanche cathode drive pulser are presented

  4. The mechanism of explosive emission excitation in thermionic energy conversion processes

    Science.gov (United States)

    Bulyga, A. V.

    A study has been made of the mechanism of explosive electron emission in vacuum thermionic converters induced by thermionic currents in the case of the anomalous Richardson effect. The latter is associated with a spotted emitting surface and temperature fluctuations. In order to account for one of the components of the electrode potential difference, it is proposed that allowance be made for the difference between the polarization signal velocity in a dense metal electron gas and that in the electron-ion gas of the electrode gap. Ways to achieve explosive emission in real thermionic converters are discussed.

  5. Thermionics basic principles of electronics

    CERN Document Server

    Jenkins, J; Ashhurst, W

    2013-01-01

    Basic Principles of Electronics, Volume I : Thermionics serves as a textbook for students in physics. It focuses on thermionic devices. The book covers topics on electron dynamics, electron emission, and the themionic vacuum diode and triode. Power amplifiers, oscillators, and electronic measuring equipment are studied as well. The text will be of great use to physics and electronics students, and inventors.

  6. Optimizing the design of very high power, high performance converters

    International Nuclear Information System (INIS)

    Edwards, R.J.; Tiagha, E.A.; Ganetis, G.; Nawrocky, R.J.

    1980-01-01

    This paper describes how various technologies are used to achieve the desired performance in a high current magnet power converter system. It is hoped that the discussions of the design approaches taken will be applicable to other power supply systems where stringent requirements in stability, accuracy and reliability must be met

  7. Practical performances of MPC for wave energy converters

    DEFF Research Database (Denmark)

    Ferri, Francesco; Tetu, Amelie; Hals, J.

    2016-01-01

    Maximising the efficiency of Wave Energy Converter (WEC) is one of the important tasks toward the exploitation of the wave energy resource. Along with a proper design of the device, an important way to achieve better energy performances is to improve the wave-body interaction by applying an appro...

  8. Performance characteristics of proximity focused ultraviolet image converters

    Science.gov (United States)

    Williams, J. T.; Feibelman, W. A.

    1973-01-01

    Performance characteristics of Bendix type BX 8025-4522 proximity focused image tubes for UV to visible light conversion are presented. Quantum efficiency, resolution, background, geometric distortion, and environmental test results are discussed. The converters use magnesium fluoride input windows with Cs-Te photocathodes and P-11 phosphors on fiber optic output windows.

  9. High-precision performance testing of the LHC power converters

    CERN Document Server

    Bastos, M; Dreesen, P; Fernqvist, G; Fournier, O; Hudson, G

    2007-01-01

    The magnet power converters for LHC were procured in three parts, power part, current transducers and control electronics, to enable a maximum of industrial participation in the manufacturing and still guarantee the very high precision (a few parts in 10-6) required by LHC. One consequence of this approach was several stages of system tests: factory reception tests, CERN reception tests, integration tests , short-circuit tests and commissioning on the final load in the LHC tunnel. The majority of the power converters for LHC have now been delivered, integrated into complete converter and high-precision performance testing is well advanced. This paper presents the techniques used for high-precision testing and the results obtained.

  10. Isotopic Thermionic Generator

    International Nuclear Information System (INIS)

    Clemot, M.; Devin, B.; Durand, J.P.

    1967-01-01

    This report describes the general design of a thermionic direct conversion space generator. The power source used is a radioisotope. Two radioisotopes are considered: Pu 238 and Cm 244. The system is made up of a heat pipe concentrating the thermal flux from the isotope to the emitter, and of a second heat pipe evacuating the waste heat from the collector to the outer wall used as radiating panel. Calculations are given in the particular case of a 100 electrical watts output power. (authors) [fr

  11. Photophysics of fullerenes: Thermionic emission

    International Nuclear Information System (INIS)

    Compton, R.N.; Tuinman, A.A.; Huang, J.

    1996-01-01

    Multiphoton ionization of fullerenes using long-pulse length lasers occurs mainly through vibrational autoionization. In many cases the laser ionization can be described as thermionic in analogy to the boiling off of electrons from a filament. Thermionic emission manifests itself as a delayed emission of electrons following pulsed laser excitation. Klots has employed quasiequilibrium theory to calculate rate constants for thermionic emission from fullerenes which seem to quantitatively account for the observed delayed emission times and the measured electron energy distributions. The theory of Klots also accounts for the thermionic emission of C 60 excited by a low power CW Argon Ion laser. Recently Klots and Compton have reviewed the evidence for thermionic emission from small aggregates where mention was also made of experiments designed to determine the effects of externally applied electric fields on thermionic emission rates. The authors have measured the fullerene ion intensity as a function of the applied electric field and normalized this signal to that produced by single photon ionization of an atom in order to correct for all collection efficiency artifacts. The increase in fullerene ion signal relative to that of Cs + is attributed to field enhanced thermionic emission. From the slope of the Schottky plot they obtain a temperature of approximately 1,000 K. This temperature is comparable to but smaller than that estimated from measurements of the electron kinetic energies. This result for field enhanced thermionic emission is discussed further by Klots and Compton. Thermionic emission from neutral clusters has long been known for autodetachment from highly excited negative ions. Similarly, electron attachment to C 60 in the energy range from 8 to 12 eV results in C 60 anions with lifetimes in the range of microseconds. Quasiequilibrium theory (QET) calculations are in reasonable accord with these measurements

  12. Photophysics of fullerenes: Thermionic emission

    Energy Technology Data Exchange (ETDEWEB)

    Compton, R.N. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Tuinman, A.A. [Univ. of Tennessee, Knoxville, TN (United States); Huang, J. [Ames Lab., IA (United States)

    1996-09-01

    Multiphoton ionization of fullerenes using long-pulse length lasers occurs mainly through vibrational autoionization. In many cases the laser ionization can be described as thermionic in analogy to the boiling off of electrons from a filament. Thermionic emission manifests itself as a delayed emission of electrons following pulsed laser excitation. Klots has employed quasiequilibrium theory to calculate rate constants for thermionic emission from fullerenes which seem to quantitatively account for the observed delayed emission times and the measured electron energy distributions. The theory of Klots also accounts for the thermionic emission of C{sub 60} excited by a low power CW Argon Ion laser. Recently Klots and Compton have reviewed the evidence for thermionic emission from small aggregates where mention was also made of experiments designed to determine the effects of externally applied electric fields on thermionic emission rates. The authors have measured the fullerene ion intensity as a function of the applied electric field and normalized this signal to that produced by single photon ionization of an atom in order to correct for all collection efficiency artifacts. The increase in fullerene ion signal relative to that of Cs{sup +} is attributed to field enhanced thermionic emission. From the slope of the Schottky plot they obtain a temperature of approximately 1,000 K. This temperature is comparable to but smaller than that estimated from measurements of the electron kinetic energies. This result for field enhanced thermionic emission is discussed further by Klots and Compton. Thermionic emission from neutral clusters has long been known for autodetachment from highly excited negative ions. Similarly, electron attachment to C{sub 60} in the energy range from 8 to 12 eV results in C{sub 60} anions with lifetimes in the range of microseconds. Quasiequilibrium theory (QET) calculations are in reasonable accord with these measurements.

  13. Advanced thermionic reactor systems design code

    International Nuclear Information System (INIS)

    Lewis, B.R.; Pawlowski, R.A.; Greek, K.J.; Klein, A.C.

    1991-01-01

    An overall systems design code is under development to model an advanced in-core thermionic nuclear reactor system for space applications at power levels of 10 to 50 kWe. The design code is written in an object-oriented programming environment that allows the use of a series of design modules, each of which is responsible for the determination of specific system parameters. The code modules include a neutronics and core criticality module, a core thermal hydraulics module, a thermionic fuel element performance module, a radiation shielding module, a module for waste heat transfer and rejection, and modules for power conditioning and control. The neutronics and core criticality module determines critical core size, core lifetime, and shutdown margins using the criticality calculation capability of the Monte Carlo Neutron and Photon Transport Code System (MCNP). The remaining modules utilize results of the MCNP analysis along with FORTRAN programming to predict the overall system performance

  14. Low-temperature thermionics in space nuclear power systems with the safe-type fast reactor

    International Nuclear Information System (INIS)

    Zrodnikov, A.V.; Yarygin, V.I.; Lazarenko, G.E.; Zabudko, A.N.; Ovcharenko, M.K.; Pyshko, A.P.; Mironov, V.S.; Kuznetsov, R.V.

    2007-01-01

    The potentialities of the use of the low-temperature thermionic converters (TIC) with the emitter temperature ≤ 1500 K in the space nuclear power system (SNPS) with the SAFE-type (Safe Affordable Fission Engine) fast reactor proposed and developed by common efforts of American experts have been considered. The main directions of the 'SAFE-300-TEG' SNPS (300 kW(thermal)) design update by replacing the thermoelectric converters with the low-temperature high-performance thermionic converters (with the barrier index V B ≤ 1.9 eV and efficiency ≥ 10%) meant for a long-term operation (5 years at least) as the components of the SAFE-300-TIC SNPS for a Lunar base have been discussed. The concept of the SNPS with the SAFE-type fast reactor and low-temperature TICs with specific electric power of about 1.45 W/cm 2 as the components of the SAFE-300-TIC system meeting the Nasa's initial requirements to a Lunar base with the electric power demand of about 30 kW(electrical) for robotic mission has been considered. The results, involving optimization and mass-and-size estimation, show that the SAFE-300-TIC system meets the initial requirements by Nasa to the lunar base power supply. The main directions of the system update aimed at the output electric power increase up to 100 kW(electrical) have also been presented. (authors)

  15. Photon enhanced thermionic emission

    Science.gov (United States)

    Schwede, Jared; Melosh, Nicholas; Shen, Zhixun

    2014-10-07

    Photon Enhanced Thermionic Emission (PETE) is exploited to provide improved efficiency for radiant energy conversion. A hot (greater than 200.degree. C.) semiconductor cathode is illuminated such that it emits electrons. Because the cathode is hot, significantly more electrons are emitted than would be emitted from a room temperature (or colder) cathode under the same illumination conditions. As a result of this increased electron emission, the energy conversion efficiency can be significantly increased relative to a conventional photovoltaic device. In PETE, the cathode electrons can be (and typically are) thermalized with respect to the cathode. As a result, PETE does not rely on emission of non-thermalized electrons, and is significantly easier to implement than hot-carrier emission approaches.

  16. Cesium iodide photon converter performance in a gaseous RICH detector

    CERN Document Server

    Gernhäuser, R; Homolka, J; Kastenmüller, A; Kienle, P; Körner, H J; Maier-Komor, P; Peter, M; Zeitelhack, K

    1999-01-01

    The performance of a 48x48 cm sup 2 multi-wire proportional chamber for VUV photon detection in a RICH setup is reported. The MWPC pad cathode was covered with a solid CsI photo converter layer of 230 mu g/cm sup 2 thickness deposited on a resin-stabilized graphite (RSG) coating. Cherenkov light radiated from cosmic muons was detected in the wavelength region 160 nm95% and a constant long-term stability of the photo cathode were observed.

  17. Impact of Converter Interfaced Generation and Load on Grid Performance

    Science.gov (United States)

    Ramasubramanian, Deepak

    Alternate sources of energy such as wind, solar photovoltaic and fuel cells are coupled to the power grid with the help of solid state converters. Continued deregulation of the power sector coupled with favorable government incentives has resulted in the rapid growth of renewable energy sources connected to the distribution system at a voltage level of 34.5kV or below. Of late, many utilities are also investing in these alternate sources of energy with the point of interconnection with the power grid being at the transmission level. These converter interfaced generation along with their associated control have the ability to provide the advantage of fast control of frequency, voltage, active, and reactive power. However, their ability to provide stability in a large system is yet to be investigated in detail. This is the primary objective of this research. In the future, along with an increase in the percentage of converter interfaced renewable energy sources connected to the transmission network, there exists a possibility of even connecting synchronous machines to the grid through converters. Thus, all sources of energy can be expected to be coupled to the grid through converters. The control and operation of such a grid will be unlike anything that has been encountered till now. In this dissertation, the operation and behavior of such a grid will be investigated. The first step in such an analysis will be to build an accurate and simple mathematical model to represent the corresponding components in commercial software. Once this bridge has been crossed, conventional machines will be replaced with their solid state interfaced counterparts in a phased manner. At each stage, attention will be devoted to the control of these sources and also on the stability performance of the large power system. This dissertation addresses various concerns regarding the control and operation of a futuristic power grid. In addition, this dissertation also aims to address the issue

  18. The SSG Wave Energy Converter: Performance, Status and Recent Developments

    Directory of Open Access Journals (Sweden)

    Mariano Buccino

    2012-01-01

    Full Text Available The Sea-wave Slot-cone Generator (SSG is a Wave Energy Converter based on the wave overtopping principle; it employs several reservoirs placed on top of each other, in which the energy of incoming waves is stored as potential energy. Then, the captured water runs through turbines for electricity production. The system works under a wide spectrum of different wave conditions, giving a high overall efficiency. It can be suitable for shoreline and breakwater applications and presents particular advantages, such as sharing structure costs, availability of grid connection and recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installations are in progress at the Svaaheia site (Norway, the port of Hanstholm (Denmark and the port of Garibaldi (Oregon, USA. In the last-mentioned two projects, the Sea-wave Slot-cone Generator technology is integrated into the outer harbor breakwater and jetty reconstruction projects. In the last years extensive studies have been performed on the hydraulic and the structural response of this converter, with the aim of optimizing the design process. The investigations have been conducted by physical model tests and numerical simulations and many results have been published on both conference proceedings and journals. The main scope of this paper is reviewing the most significant findings, to provide the reader with an organic overview on the present status of knowledge.

  19. Distance relay performance in future converter dominated power systems

    OpenAIRE

    Sarkar, Moumita; Jia, Jundi; Yang, Guangya

    2017-01-01

    Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of...

  20. Performance evaluation of converted and upgraded PARR-1

    International Nuclear Information System (INIS)

    Pervez, Showket; Iqbal, Masood

    1998-01-01

    Pakistan Research Reactor-1 (PARR-1), a swimming pool MTR type research reactor which attained full power of 5 MW in June, 1996, with 93% high enriched uranium (HEU) fuel was converted to ,20% Low Enriched Uranium (LEU) fuel in october, 1991. The reactor power was also upgraded from 5 MW to 9 MW and then to 10 MW. Different critical and full power operational core configurations were assembled with the new fuel. The final equilibrium core was assembled with 27 standard fuel elements and five control fuel elements having a central flux trap facility for high neutron flux. detailed neutronics and thermal-hydraulic design calculations were made for the core conversion programme. After achieving the initial criticality several critical and power experiments were performed on the new core for the verification of design data and to determine the nuclear performance of the reactor. a comparison of the measured and the calculated results was also made. the results of the characteristics tests indicate that the performance of the new reactor is within the design limits. In flux trap thermal neutron flux is about 2x10 14 n.cm - 2. s - 1 which is five times higher than the average neutron flux of the core, seven standard and two control fuel elements have achieved designed burnup of 35%. Their physical inspection predicts excellent condition. (author)

  1. Very High-Performance Advanced Filter Bank Analog-to-Digital Converter (AFB ADC) Project

    National Research Council Canada - National Science Library

    Velazquez, Scott

    1999-01-01

    ... of the art by using a parallel array of individual commercial off the shelf converters. The significant performance improvements afforded by the Advanced Filter Bank Analog to Digital Converter (AFB ADC...

  2. Thermionic reactor power conditioner design for nuclear electric propulsion.

    Science.gov (United States)

    Jacobsen, A. S.; Tasca, D. M.

    1971-01-01

    Consideration of the effects of various thermionic reactor parameters and requirements upon spacecraft power conditioning design. A basic spacecraft is defined using nuclear electric propulsion, requiring approximately 120 kWe. The interrelationships of reactor operating characteristics and power conditioning requirements are discussed and evaluated, and the effects on power conditioner design and performance are presented.

  3. Capacitor performance limitations in high power converter applications

    DEFF Research Database (Denmark)

    El-Khatib, Walid Ziad; Holbøll, Joachim; Rasmussen, Tonny Wederberg

    2013-01-01

    High voltage low inductance capacitors are used in converters as HVDC-links, snubber circuits and sub model (MMC) capacitances. They facilitate the possibility of large peak currents under high frequent or transient voltage applications. On the other hand, using capacitors with larger equivalent...... series inductances include the risk of transient overvoltages, with a negative effect on life time and reliability of the capacitors. These allowable limits of such current and voltage peaks are decided by the ability of the converter components, including the capacitors, to withstand them over...... the expected life time. In this paper results are described from investigations on the electrical environment of these capacitors, including all the conditions they would be exposed to, thereby trying to find the tradeoffs needed to find a suitable capacitor. Different types of capacitors with the same voltage...

  4. Performance simulations of catalytic converters during the Federal Test Procedure

    Energy Technology Data Exchange (ETDEWEB)

    Shen, H.; Shamim, T.; Sengupta, S.; Son, S.; Adamczyk, A.A.

    1999-07-01

    A numerical study is carried out to predict the tailpipe emissions and emission conversion efficiencies of unburned hydrocarbon, nitrogen oxide and carbon monoxide flowing through a catalytic converter during the Federal Test Procedure (FTP). The model considers the effect of heat transfer in the catalytic converter, coupled with catalyst chemical kinetics, including an oxygen storage mechanism. The resulting governing equations based on the conservation of mass and energy are solved by a tridiagonal matrix algorithm (TDMA) with a successive line under relaxation method. The numerical scheme for this non-linear problem is found to have good convergence efficiency. The simulation for the complete FTP cycle is accomplished in less than fifteen minutes on a desktop personal computer. A 13-step reaction mechanism plus a nine-step O{sub 2} storage mechanism is used to simulate the chemical kinetics. The energy equations include the heat loss due to conduction and convection plus the energy liberated by chemical reactions. The effect of radiation is assumed to be negligible and is not considered. The results of the numerical model for both the instantaneous and accumulated emissions are found to be in good agreement with experimental measurements. The conversion efficiencies of HC, CO and NO as predicted by the model are found to be within 5% of those dynamic measurements, and calculated results of accumulated HC, CO and NO{sub x} are in fair agreement with experimental measurements. The transient measurements are also used to check the robustness of the numerical model. The model is found to be robust and hence can simulate various operating conditions of engine output to the converter.

  5. Power converter topologies for wind energy conversion systems: Integrated modeling, control strategy and performance simulation

    Energy Technology Data Exchange (ETDEWEB)

    Melicio, R.; Catalao, J.P.S. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Mendes, V.M.F. [Department of Electrical Engineering and Automation, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emidio Navarro, 1950-062 Lisbon (Portugal)

    2010-10-15

    This paper presents new integrated model for variable-speed wind energy conversion systems, considering a more accurate dynamic of the wind turbine, rotor, generator, power converter and filter. Pulse width modulation by space vector modulation associated with sliding mode is used for controlling the power converters. Also, power factor control is introduced at the output of the power converters. Comprehensive performance simulation studies are carried out with matrix, two-level and multilevel power converter topologies in order to adequately assert the system performance. Conclusions are duly drawn. (author)

  6. MATERIALS REQUIREMENTS FOR THERMIONIC ENERGY CONVERSION

    Energy Technology Data Exchange (ETDEWEB)

    Allen, R. C.; Skeen, C. H.

    1963-03-15

    The fundamentals of the thermionic energy conversion and its potential applications are reviewed. Materials problems associated with thermionic emitters are considered in relation to the following: work function; emissivity; vaporization; thermal, mechanical, and electrical properties; chemical stability; permeation; and stability under nuclear radiation. Cesium purity and materials suitable for collectors, electrical leads, support structures, insulators, and seals are also discussed. Experimental work on problems involved is reviewed. It is concluded that significant developments have occurred recently in all areas of thermionic energy conversion. (40 references) (A.G.W.)

  7. Development of integrated thermionic circuits for high-temperature applications

    International Nuclear Information System (INIS)

    McCormick, J.B.; Wilde, D.; Depp, S.; Hamilton, D.J.; Kerwin, W.; Derouin, C.; Roybal, L.; Dooley, R.

    1981-01-01

    A class of devices known as integrated thermionic circuits (ITC) capable of extended operation in ambient temperatures up to 500 0 C is described. The evolution of the ITC concept is discussed. A set of practical design and performance equations is demonstrated. Recent experimental results are discussed in which both devices and simple circuits have successfully operated in 500 0 C environments for extended periods of time

  8. How the Brain Converts Negative Evaluation into Performance Facilitation.

    Science.gov (United States)

    Prévost, Charlotte; Lau, Hakwan; Mobbs, Dean

    2018-02-01

    Surpassing negative evaluation is a recurrent theme of success stories. Yet, there is little evidence supporting the counterintuitive idea that negative evaluation might not only motivate people, but also enhance performance. To address this question, we designed a task that required participants to decide whether taking up a risky challenge after receiving positive or negative evaluations from independent judges. Participants believed that these evaluations were based on their prior performance on a related task. Results showed that negative evaluation caused a facilitation in performance. Concurrent functional magnetic resonance imaging revealed that the motivating effect of negative evaluation was represented in the insula and striatum, while the performance boost was associated with functional positive connectivity between the insula and a set of brain regions involved in goal-directed behavior and the orienting of attention. These findings provide new insight into the neural representation of negative evaluation-induced facilitation. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Control of Series Resonant Converter with Robust Performance Against Load and Power Circuit Components Uncertainties

    Directory of Open Access Journals (Sweden)

    A. Mohammadpour

    2009-12-01

    Full Text Available Robust performance controller design for duty-cycle controlled series resonant converter (SRC is proposed in this paper. The uncertainties of the converter are analyzed with load variation and power circuit components tolerances are taken into consideration. Additionally, a nominal performance (NP controller is designed. Closed-loop system is simulated with Orcad and simulation results of robust controller are compared with nominal performance controller. Although nominal performance controller has better performance for nominal plant, the robust performance controller is advantageous in dealing with uncertainties.

  10. Thermionic integrated circuits: electronics for hostile environments

    International Nuclear Information System (INIS)

    Lynn, D.K.; McCormick, J.B.; MacRoberts, M.D.J.; Wilde, D.K.; Dooley, G.R.; Brown, D.R.

    1985-01-01

    Thermionic integrated circuits combine vacuum tube technology with integrated circuit techniques to form integrated vacuum triode circuits. These circuits are capable of extended operation in both high-temperature and high-radiation environments

  11. The SSG Wave Energy Converter: Performance, Status and Recent Developments

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... applications, presenting particular advantages such as: sharing structure costs, availability of grid connection and infrastructures, recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installation were in progress...... on wave loadings and on hydraulic performances (overtopping and reflection) in order to optimize the structure design. This paper addresses the influence of various parameters (geometry, wave characteristics) on overtopping, reflection and wave loading and it draws conclusions on performances...

  12. HEAT Sensor: Harsh Environment Adaptable Thermionic Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Limb, Scott J. [Palo Alto Research Center, Palo Alto, CA (United States)

    2016-05-31

    This document is the final report for the “HARSH ENVIRONMENT ADAPTABLE THERMIONIC SENSOR” project under NETL’s Crosscutting contract DE-FE0013062. This report addresses sensors that can be made with thermionic thin films along with the required high temperature hermetic packaging process. These sensors can be placed in harsh high temperature environments and potentially be wireless and self-powered.

  13. Thermionic detector with multiple layered ionization source

    International Nuclear Information System (INIS)

    Patterson, P. L.

    1985-01-01

    Method and apparatus for analyzing specific chemical substances in a gaseous environment comprises a thermionic source formed of multiple layers of ceramic material composition, an electrical current instrumentality for heating the thermionic source to operating temperatures in the range of 100 0 C. to 1000 0 C., an instrumentality for exposing the surface of the thermionic source to contact with the specific chemical substances for the purpose of forming gas phase ionization of the substances by a process of electrical charge emission from the surface, a collector electrode disposed adjacent to the thermiomic source, an instrumentality for biasing the thermionic source at an electrical potential which causes the gas phase ions to move toward the collector, and an instrumentality for measuring the ion current arriving at the collector. The thermionic source is constructed of a metallic heater element molded inside a sub-layer of hardened ceramic cement material impregnated with a metallic compound additive which is non-corrosive to the heater element during operation. The sub-layer is further covered by a surface-layer formed of hardened ceramic cement material impregnated with an alkali metal compound in a manner that eliminates corrosive contact of the alkali compounds with the heater element. The sub-layer further protects the heater element from contact with gas environments which may be corrosive. The specific ionization of different chemical substances is varied over a wide range by changing the composition and temperature of the thermionic source, and by changing the composition of the gas environment

  14. Two Level Versus Matrix Converters Performance in Wind Energy Conversion Systems Employing DFIG

    Science.gov (United States)

    Reddy, Gongati Pandu Ranga; Kumar, M. Vijaya

    2017-10-01

    Wind power capacity has received enormous growth during past decades. With substantial development of wind power, it is expected to provide a fifth of world's electricity by the end of 2030. In wind energy conversion system, the power electronic converters play an important role. This paper presents the two level and matrix converters performance in wind energy conversion system employing Doubly Fed Induction Generator (DFIG). The DFIG is a wound rotor induction generator. Because of the advantages of the DFIG over other generators it is being used for most of the wind applications. This paper also discusses control of converters using the space vector pulse width modulation technique. The MATLAB/SIMULINK ® software is used to study the performance of the converters.

  15. Performance of Series Connected GaAs Photovoltaic Converters under Multimode Optical Fiber Illumination

    Directory of Open Access Journals (Sweden)

    Tiqiang Shan

    2014-01-01

    Full Text Available In many military and industrial applications, GaAs photovoltaic (PV converters are connected in series in order to generate the required voltage compatible with most common electronics. Multimode optical fibers are usually used to carry high-intensity laser and illuminate the series connected GaAs PV converters in real time. However, multimode optical fiber illumination has a speckled intensity pattern. The series connected PV array is extremely sensitive to nonuniform illumination; its performance is limited severely by the converter that is illuminated the least. This paper quantifies the effects of multimode optical fiber illumination on the performance of series connected GaAs PV converters, analyzes the loss mechanisms due to speckles, and discusses the maximum illumination efficiency. In order to describe the illumination dependent behavior detailedly, modeling of the series connected PV array is accomplished based on the equivalent circuit for PV cells. Finally, a series of experiments are carried out to demonstrate the theory analysis.

  16. Thermionic energy conversion heat - electric power; Termojonisk energiomvandling vaerme-elektrisk energi

    Energy Technology Data Exchange (ETDEWEB)

    Holmlid, L; Svensson, R [Gothenburg Univ. and Chalmers Univ. of Technology (Sweden)

    1993-09-15

    Research and development related to Thermionic Energy Converters (TEC) in Holland and Sweden is directed towards terrestrial applications, while the development work in Russia and the US primarily is directed towards thermionic nuclear reactor for use in space. We have during the project continued our work on the utilization of the so called Rydberg matter in converters. Our patented construction has very good (low) values of the barrier index (figure of merit for the converter), probably the lowest ones ever measured. International patents have been applied for as well. We can summarize the achievements of the project such that solutions to practically all the problems related to the inner function of thermionic converters have been found. During this year a large number of studies have been carried out concerning the properties of the Rydberg matter in the TEC, and related to the highly excited states of Cs which exist in the TEC, partially in cooperation with an American research company. An international conference within the TEC field has been arranged in Gothenburg. Two Ph.D. theses are also under completion within the project

  17. Performance testing of self-powered detector signal converters at Dukovany nuclear power plant - stage 1

    International Nuclear Information System (INIS)

    Erben, O.; Hajek, P.; Zerola, L.; Karsulin, M.

    1990-11-01

    The converters were manufactured at the Institute of Nuclear Research, Rez. Dynamic functions of the converters were tested during the start-up of reactor unit 4, Dukovany nuclear power plant, and their stability during its normal operation. The results and evaluation of the measurements show a good performance of converters. They have a low offset, good stability and the values of current are in a good agreement with the values obtained using other methods. The values of insulation resistance are in a good agreement with the values obtained manually using the method of additional resistance. These converters are planned to be used in the upgraded in-service inspection system in WWER-440 nuclear power plants. (Z.S.) 9 tabs., 22 figs., 1 ref

  18. Investigation of Grid-connected Voltage Source Converter Performance under Unbalanced Faults

    DEFF Research Database (Denmark)

    Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde

    2016-01-01

    Renewable energy sources (RES) and HVDC links are typically interfaced with the grid by power converters, whose performance during grid faults is significantly different from that of traditional synchronous generators. This paper investigates the performance of grid-connected voltage source...... that the performance of VSCs varies with their control strategies. Negative-sequence current control is necessary to restrict converter current in each phase under unbalanced faults. Among presented control strategies, the balanced current control strategy complies with the present voltage support requirement best...

  19. Performance Improvement of Sensorless Vector Control for Matrix Converter Drives Using PQR Transformation

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Blaabjerg, Frede

    2005-01-01

    This paper presents a new method to improve sensorless performance of matrix converter drives using PQR power transformation. The non-linearity of matrix converter drives such as commutation delay, turn-on and turn-off time of switching device, and on-state switching device voltage drop is modelled...... using PQR transformation and compensated using a reference current control scheme. To eliminate the input current distortion due to the input voltage unbalance, a simple method using PQR transformation is also proposed. The proposed compensation method is applied for high performance induction motor...

  20. Performance improvement of sensorless vector control for matrix converter drives using PQR power theory

    DEFF Research Database (Denmark)

    Lee, Kyo Beum; Blaabjerg, Frede

    2007-01-01

    This paper presents a new method to improve sensorless performance of matrix converter drives using PQR power transformation. The non-linearity of matrix converter drives such as commutation delay, turn-on and turn-off time of switching device, and on-state switching device voltage drop is modelled...... using PQR transformation and compensated using a reference current control scheme. To eliminate the input current distortion due to the input voltage unbalance, a simple method using PQR transformation is also proposed. The proposed compensation method is applied for high performance induction motor...

  1. Progress in radiation immune thermionic integrated circuits

    International Nuclear Information System (INIS)

    Lynn, D.K.; McCormick, J.B.

    1985-08-01

    This report describes the results of a program directed at evaluating the thermionic integrated circuit (TIC) technology for applicability to military systems. Previous programs under the sponsorship of the Department of Energy, Office of Basic Energy Sciences, have developed an initial TIC technology base and demonstrated operation in high-temperature and high-radiation environments. The program described in this report has two parts: (1) a technical portion in which experiments and analyses were conducted to refine perceptions of near-term as well as ultimate performance levels of the TIC technology and (2) an applications portion in which the technical conclusions were to be evaluated against potential military applications. This report draws several conclusions that strongly suggest that (1) useful radiation-hard/high-temperature operable integrated circuits can be developed using the TIC technology; (2) because of their ability to survive and operate in hostile environments, a variety of potential military applications have been projected for this technology; and (3) based on the above two conclusions, an aggressive TIC development program should be initiated to provide the designers of future systems with integrated circuits and devices with the unique features of the TICs

  2. Progress in radiation immune thermionic integrated circuits

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, D.K.; McCormick, J.B. (comps.)

    1985-08-01

    This report describes the results of a program directed at evaluating the thermionic integrated circuit (TIC) technology for applicability to military systems. Previous programs under the sponsorship of the Department of Energy, Office of Basic Energy Sciences, have developed an initial TIC technology base and demonstrated operation in high-temperature and high-radiation environments. The program described in this report has two parts: (1) a technical portion in which experiments and analyses were conducted to refine perceptions of near-term as well as ultimate performance levels of the TIC technology and (2) an applications portion in which the technical conclusions were to be evaluated against potential military applications. This report draws several conclusions that strongly suggest that (1) useful radiation-hard/high-temperature operable integrated circuits can be developed using the TIC technology; (2) because of their ability to survive and operate in hostile environments, a variety of potential military applications have been projected for this technology; and (3) based on the above two conclusions, an aggressive TIC development program should be initiated to provide the designers of future systems with integrated circuits and devices with the unique features of the TICs.

  3. Loss Performance Analysis of an Isolated Power Supply for Ultrafast Tracking Converters

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents the loss performance analysis of an isolated power supply that is designed for ultra-fast tracking converters. The results of the analysis provide insights into the operation of the proposed power supply, how each physical component contributes to the total loss, and how its...

  4. Performance analysis of commercial MOSFET packages in Class E converter operating at 2.56 MHz

    DEFF Research Database (Denmark)

    Nair, Unnikrishnan Raveendran; Munk-Nielsen, Stig; Jørgensen, Asger Bjørn

    2017-01-01

    resistance and high temperature operation over Si devices have aided in the paradigm shift towards wide bandgap devices. The low gate charge requirements of SiC MOSFETs enables use of these devices in radio frequency (RF) converters using resonant topologies operating at MHz frequency range. The RF...... are not commercially available and power modules have to be custom designed for these applications. This work demonstrates performance of various commercial MOSFET packages at frequency of 2.56 MHz. Commercial SiC MOSFETs in TO-247 and D2Pak packs are tested in Class E resonant converter operating at 2.56 MHz...

  5. Effect of heat and mass transfer coefficients on the performance of automotive catalytic converters

    Energy Technology Data Exchange (ETDEWEB)

    Shamim, T. [Michigan Univ., Dept. of Mechanical Engineering, Dearborn, MI (United States)

    2003-06-01

    This paper numerically investigates the role of heat and mass transfer coefficients on the performance of automotive catalytic converters, which are employed to reduce engine exhaust emissions. The pollutant conversion performance of a converter is influenced by a number of physical and chemical processes that take place in gaseous and solid phases as the exhaust gases flow through the catalyst. A quantitative predictive understanding of these complex catalyst processes involving flow dynamics, heterogeneous surface reactions and heat and mass transport mechanisms is important in improving the converter design. The role of convective transport phenomena becomes important at high temperature when the mass transfer becomes rate-limiting to an increasing extent. The objective of the present study is to elucidate the influence of convective heat and mass transfer coefficients (mechanisms). The mathematical model considers the conservation of mass, momentum and energy in both gaseous and solid phases. In addition to the heterogeneous surface reactions, the model also takes into account the adsorption/desorption of oxygen in the catalyst during non-stoichiometric composition of air/fuel mixtures. The governing equations are solved by an implicit scheme using a successive line under a relaxation method. The converter performance under the transient conditions as simulated by the US Federal Test Procedure (US-FTP) is analysed. (Author)

  6. Solar electron source and thermionic solar cell

    Directory of Open Access Journals (Sweden)

    Parham Yaghoobi

    2012-12-01

    Full Text Available Common solar technologies are either photovoltaic/thermophotovoltaic, or use indirect methods of electricity generation such as boiling water for a steam turbine. Thermionic energy conversion based on the emission of electrons from a hot cathode into vacuum and their collection by an anode is also a promising route. However, thermionic solar conversion is extremely challenging as the sunlight intensity is too low for heating a conventional cathode to thermionic emission temperatures in a practical manner. Therefore, compared to other technologies, little has been done in this area, and the devices have been mainly limited to large experimental apparatus investigated for space power applications. Based on a recently observed “Heat Trap” effect in carbon nanotube arrays, allowing their efficient heating with low-power light, we report the first compact thermionic solar cell. Even using a simple off-the-shelf focusing lens, the device delivered over 1 V across a load. The device also shows intrinsic storage capacity.

  7. Thermionic cogeneration burner assessment study. Third quarterly technical progress report, April-June, 1983

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    The specific tasks of this study are to mathematically model the thermionic cogeneration burner, experimentally confirm the projected energy flows in a thermal mock-up, make a cost estimate of the burner, including manufacturing, installation and maintenance, review industries in general and determine what groups of industries would be able to use the electrical power generated in the process, select one or more industries out of those for an in-depth study, including determination of the performance required for a thermionic cogeneration system to be competitive in that industry. Progress is reported. (WHK)

  8. Design and performance study of a DC-DC flyback converter based on wide bandgap power devices for photovoltaic applications

    Science.gov (United States)

    Alharbi, Salah S.; Alharbi, Saleh S.; Al-bayati, Ali M. S.; Matin, Mohammad

    2017-08-01

    This paper presents a high-performance dc-dc flyback converter design based on wide bandgap (WBG) semiconductor devices for photovoltaic (PV) applications. Two different power devices, a gallium nitride (GaN)-transistor and a silicon (Si)-MOSFET, are implemented individually in the flyback converter to examine their impact on converter performance. The total power loss of the converter with different power devices is analyzed for various switching frequencies. Converter efficiency is evaluated at different switching frequencies, input voltages, and output power levels. The results reveal that the converter with the GaN-transistor has lower total power loss and better efficiency compared to the converter with the conventional Si-MOSFET.

  9. Step-Up Partial Power DC-DC Converters for Two-Stage PV Systems with Interleaved Current Performance

    Directory of Open Access Journals (Sweden)

    Jaime Wladimir Zapata

    2018-02-01

    Full Text Available This work presents a partial power converter allowing us to obtain, with a single DC-DC converter, the same feature as the classical interleaved operation of two converters. More precisely, the proposed topology performs similarly as the input-parallel output-series (IPOS configuration reducing the current ripple at the input of the system and dividing the individual converters power rating, compared to a single converter. The proposed topology consists of a partial DC-DC converter processing only a fraction of the total power, thus allowing high efficiency. Experimental results are provided to validate the proposed converter topology with a Flyback-based 100 W test bench with a transformer turns ratio n 1 = n 2 . Experimental results show high performances reducing the input current ripple around 30 % , further increasing the conversion efficiency.

  10. Thermionic combustor application to combined gas and steam turbine power plants

    International Nuclear Information System (INIS)

    Miskolczy, G.; Wang, C.C.; Lieb, D.P.

    1981-01-01

    A design for the insertion of thermionic converters into the wall of a conventional combustor to produce electricity in a topping cycle is described, and a study for applications in gas and steam generators of 70 and 30 MW is evaluated for engineering and economic feasibility. Waste heat from the thermionic elements is used to preheat the combustor air, the heat absorbed by the elements plus further quenching of the exhaust gases with ammonia is projected to reduce NO(x) emissions to acceptable levels. Schematics, flow diagrams, and components of a computer model for cost projections are provided. It was found that temperatures around the emitters must be maintained above 1,600 K, with maximum efficiency and allowable temperature at 1,800 K, while collectors generate maximally at 950 K, with a corresponding work function of 1.5 eV. Cost sensitive studies indicate an installed price of $475/kW for the topping cycle, with improvements in thermionic converter characteristics bringing the cost to $375/kW at a busbar figure of 500 mills/kWh

  11. Thermionic combustor application to combined gas and steam turbine power plants

    Science.gov (United States)

    Miskolczy, G.; Wang, C. C.; Lieb, D. P.; Margulies, A. E.; Fusegni, L. J.; Lovell, B. J.

    A design for the insertion of thermionic converters into the wall of a conventional combustor to produce electricity in a topping cycle is described, and a study for applications in gas and steam generators of 70 and 30 MW is evaluated for engineering and economic feasibility. Waste heat from the thermionic elements is used to preheat the combustor air; the heat absorbed by the elements plus further quenching of the exhaust gases with ammonia is projected to reduce NO(x) emissions to acceptable levels. Schematics, flow diagrams, and components of a computer model for cost projections are provided. It was found that temperatures around the emitters must be maintained above 1,600 K, with maximum efficiency and allowable temperature at 1,800 K, while collectors generate maximally at 950 K, with a corresponding work function of 1.5 eV. Cost sensitive studies indicate an installed price of $475/kW for the topping cycle, with improvements in thermionic converter characteristics bringing the cost to $375/kW at a busbar figure of 500 mills/kWh.

  12. Performance of a Single-Phase UPS with Passive Boost Converter

    Directory of Open Access Journals (Sweden)

    PONNURAJ Radika

    2010-05-01

    Full Text Available The purpose of an Uninterruptible PowerSupply (UPS system is to ensure continuous powerflow to critical loads like computers,telecommunication systems, medical equipments andon-line management systems etc.,Boost converters areespecially useful in stepping-up the low voltage froma battery or fuel cells/solar cells to match the loadrequirements. This paper presents a performance of apassive lossless snubber for soft-switching the boostconverter of a on-line UPS system. This snubberprovides zero-voltage switching for the convertermain switch and snubber stored energy is recoveredeffectively into the output capacitor,therebyimproving the converter performance. A briefdescription of the conventional, proposed UPSsystems and snubber circuits are explained.Experimental results and MATLAB/Simulink resultsobtained are discussed.

  13. Performance Analysis of a Voltage Source Converter (VSC based HVDC Transmission System under Faulted Conditions

    Directory of Open Access Journals (Sweden)

    Amiri RABIE

    2009-12-01

    Full Text Available Voltage Source Converter (VSC based HVDC transmission technology hasbeen selected as the basis for several recent projects due to its controllability,compact modular design, ease of system interface, and low environmentalimpact. This paper investigates the dynamic performance of a 200MW,±100kV VSC-HVDC transmission system under some faulted conditionsusing MATLAB/Simulink. Simulation results confirm the satisfactoryperformance of the proposed system under active and reactive powervariations and fault conditions.

  14. Comparison of two different high performance mixed signal controllers for DC/DC converters

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.

    2006-01-01

    This paper describes how mixed signal controllers combining a cheap microcontroller with a simple analogue circuit can offer high performance digital control for DC/DC converters. Mixed signal controllers have the same versatility and performance as DSP based controllers. It is important to have...... an engineer experienced in microcontroller programming write the software algorithms to achieve optimal performance. Two mixed signal controller designs based on the same 8-bit microcontroller are compared both theoretically and experimentally. A 16-bit PID compensator with a sampling frequency of 200 k......Hz implemented in the 16 MIPS, 8-bit ATTiny26 microcontroller is demonstrated....

  15. Structured Innovation of High-Performance Wave Energy Converter Technology: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jochem W. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Laird, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-01-25

    Wave energy converter (WEC) technology development has not yet delivered the desired commercial maturity nor, and more importantly, the techno-economic performance. The reasons for this have been recognized and fundamental requirements for successful WEC technology development have been identified. This paper describes a multi-year project pursued in collaboration by the National Renewable Energy Laboratory and Sandia National Laboratories to innovate and develop new WEC technology. It specifies the project strategy, shows how this differs from the state-of-the-art approach and presents some early project results. Based on the specification of fundamental functional requirements of WEC technology, structured innovation and systemic problem solving methodologies are applied to invent and identify new WEC technology concepts. Using Technology Performance Levels (TPL) as an assessment metric of the techno-economic performance potential, high performance technology concepts are identified and selected for further development. System performance is numerically modelled and optimized and key performance aspects are empirically validated. The project deliverables are WEC technology specifications of high techno-economic performance technologies of TPL 7 or higher at TRL 3 with some key technology challenges investigated at higher TRL. These wave energy converter technology specifications will be made available to industry for further, full development and commercialisation (TRL 4 - TRL 9).

  16. Boost Converter Fed High Performance BLDC Drive for Solar PV Array Powered Air Cooling System

    Directory of Open Access Journals (Sweden)

    Shobha Rani Depuru

    2017-01-01

    Full Text Available This paper proposes the utilization of a DC-DC boost converter as a mediator between a Solar Photovoltaic (SPV array and the Voltage Source Inverters (VSI in an SPV array powered air cooling system to attain maximum efficiency. The boost converter, over the various common DC-DC converters, offers many advantages in SPV based applications. Further, two Brushless DC (BLDC motors are employed in the proposed air cooling system: one to run the centrifugal water pump and the other to run a fan-blower. Employing a BLDC motor is found to be the best option because of its top efficiency, supreme reliability and better performance over a wide range of speeds. The air cooling system is developed and simulated using the MATLAB/Simulink environment considering the steady state variation in the solar irradiance. Further, the efficiency of BLDC drive system is compared with a conventional Permanent Magnet DC (PMDC motor drive system and from the simulated results it is found that the proposed system performs better.

  17. Design and testing of a combustion-heated nineteen-converter SAVTEC array

    International Nuclear Information System (INIS)

    Nyren, T.; Fitzpatrick, G.O.; Korringa, M.; McVey, J.; Sahines, T.

    1984-01-01

    The SAVTEC (Self-Adjusting Versatile Thermionic Energy Converter) is a new design approach for achieving very close (<12μ) interelectrode spacing in a thermionic converter. Techniques were developed for fabricating an array of nineteen SAVTEC converters. The array was incorporated in an SiC protective ''hot shell'' which also served as a radiant heat source for the emitter of each converter. The completed assembly was tested with a specially constructed combustion heat source. Electric output was generated by sixteen of the nineteen converters, despite poor thermal contact in a cooling block, which resulted in high collector temperatures. Details of the array design and test results are described

  18. POPS: the 60MW power converter for the PS accelerator: Control strategy and performances

    CERN Document Server

    Boattini, Fulvio; Skawinski, Gregory

    2015-01-01

    The main power supply of Proton-Synchrotron (PS) accelerator is one of the biggest at CERN. The old rotating machine system has been replaced with a new NPC based DC/DC power supply named POPS (Power system for PS main magnets) with capacitor banks as energy storage mean. POPS is in operation since February 2011. The operation of the PS accelerator requires a specific design of the control system with very high performance requirements in term of accuracy and precision. This paper describes the main lines of the control strategies analyzing the problems encountered and the solutions adopted. The performances of the converter are presented throughout the paper.

  19. Development and Performance Analysis of a Photonics-Assisted RF Converter for 5G Applications

    Science.gov (United States)

    Borges, Ramon Maia; Muniz, André Luiz Marques; Sodré Junior, Arismar Cerqueira

    2017-03-01

    This article presents a simple, ultra-wideband and tunable radiofrequency (RF) converter for 5G cellular networks. The proposed optoelectronic device performs broadband photonics-assisted upconversion and downconversion using a single optical modulator. Experimental results demonstrate RF conversion from DC to millimeter waves, including 28 and 38 GHz that are potential frequency bands for 5G applications. Narrow linewidth and low phase noise characteristics are observed in all generated RF carriers. An experimental digital performance analysis using different modulation schemes illustrates the applicability of the proposed photonics-based device in reconfigurable optical wireless communications.

  20. Analytical Performance Verification of FCS-MPC Applied to Power Electronic Converters

    DEFF Research Database (Denmark)

    Novak, Mateja; Dragicevic, Tomislav; Blaabjerg, Frede

    2017-01-01

    Since the introduction of finite control set model predictive control (FCS-MPC) in power electronics the algorithm has been missing an important aspect that would speed up its implementation in industry: a simple method to verify the algorithm performance. This paper proposes to use a statistical...... model checking (SMC) method for performance evaluation of the algorithm applied to power electronics converters. SMC is simple to implement, intuitive and it requires only an operational model of the system that can be simulated and checked against properties. Device under test for control algorithm...

  1. Thermionic refrigeration at CNT-CNT junctions

    Science.gov (United States)

    Li, C.; Pipe, K. P.

    2016-10-01

    Monte Carlo (MC) simulation is used to study carrier energy relaxation following thermionic emission at the junction of two van der Waals bonded single-walled carbon nanotubes (SWCNTs). An energy-dependent transmission probability gives rise to energy filtering at the junction, which is predicted to increase the average electron transport energy by as much as 0.115 eV, leading to an effective Seebeck coefficient of 386 μV/K. MC results predict a long energy relaxation length (˜8 μm) for hot electrons crossing the junction into the barrier SWCNT. For SWCNTs of optimal length, an analytical transport model is used to show that thermionic cooling can outweigh parasitic heat conduction due to high SWCNT thermal conductivity, leading to a significant cooling capacity (2.4 × 106 W/cm2).

  2. Photocathode operation of a thermionic RF gun

    International Nuclear Information System (INIS)

    Thorin, S.; Cutic, N.; Lindau, F.; Werin, S.; Curbis, F.

    2009-01-01

    The thermionic RF gun using a BaO cathode at the MAX-lab linac injector has been successfully commissioned for additional operation as a photocathode gun. By retaining the BaO cathode, lowering the temperature below thermal emission and illuminating it with a UV (263 nm) 9 ps laser pulse a reduced emittance and enhanced emission control has been achieved. Measurements show a normalised emittance of 5.5 mm mrad at 200 pC charge and a maximum quantum efficiency of 1.1x10 -4 . The gun is now routinely switched between storage ring injections in thermionic mode and providing a beam for the MAX-lab test FEL in photocathode mode.

  3. Performance of arrays of direct-driven wave energy converters under optimal power take-off damping

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-08-01

    Full Text Available It is well known that the total power converted by a wave energy farm is influenced by the hydrodynamic interactions between wave energy converters, especially when they are close to each other. Therefore, to improve the performance of a wave energy farm, the hydrodynamic interaction between converters must be considered, which can be influenced by the power take-off damping of individual converters. In this paper, the performance of arrays of wave energy converters under optimal hydrodynamic interaction and power take-off damping is investigated. This is achieved by coordinating the power take-off damping of individual converters, resulting in optimal hydrodynamic interaction as well as higher production of time-averaged power converted by the farm. Physical constraints on motion amplitudes are considered in the solution, which is required for the practical implementation of wave energy converters. Results indicate that the natural frequency of a wave energy converter under optimal damping will not vary with sea states, but the production performance of a wave energy farm can be improved significantly while satisfying the motion constraints.

  4. Performance of arrays of direct-driven wave energy converters under optimal power take-off damping

    Science.gov (United States)

    Wang, Liguo; Engström, Jens; Leijon, Mats; Isberg, Jan

    2016-08-01

    It is well known that the total power converted by a wave energy farm is influenced by the hydrodynamic interactions between wave energy converters, especially when they are close to each other. Therefore, to improve the performance of a wave energy farm, the hydrodynamic interaction between converters must be considered, which can be influenced by the power take-off damping of individual converters. In this paper, the performance of arrays of wave energy converters under optimal hydrodynamic interaction and power take-off damping is investigated. This is achieved by coordinating the power take-off damping of individual converters, resulting in optimal hydrodynamic interaction as well as higher production of time-averaged power converted by the farm. Physical constraints on motion amplitudes are considered in the solution, which is required for the practical implementation of wave energy converters. Results indicate that the natural frequency of a wave energy converter under optimal damping will not vary with sea states, but the production performance of a wave energy farm can be improved significantly while satisfying the motion constraints.

  5. Performance and scalability of isolated DC-DC converter topologies in low voltage, high current applications

    Energy Technology Data Exchange (ETDEWEB)

    Vaisanen, V.

    2012-07-01

    Fuel cells are a promising alternative for clean and efficient energy production. A fuel cell is probably the most demanding of all distributed generation power sources. It resembles a solar cell in many ways, but sets strict limits to current ripple, common mode voltages and load variations. The typically low output voltage from the fuel cell stack needs to be boosted to a higher voltage level for grid interfacing. Due to the high electrical efficiency of the fuel cell, there is a need for high efficiency power converters, and in the case of low voltage, high current and galvanic isolation, the implementation of such converters is not a trivial task. This thesis presents galvanically isolated DC-DC converter topologies that have favorable characteristics for fuel cell usage and reviews the topologies from the viewpoint of electrical efficiency and cost efficiency. The focus is on evaluating the design issues when considering a single converter module having large current stresses. The dominating loss mechanism in low voltage, high current applications is conduction losses. In the case of MOSFETs, the conduction losses can be efficiently reduced by paralleling, but in the case of diodes, the effectiveness of paralleling depends strongly on the semiconductor material, diode parameters and output configuration. The transformer winding losses can be a major source of losses if the windings are not optimized according to the topology and the operating conditions. Transformer prototyping can be expensive and time consuming, and thus it is preferable to utilize various calculation methods during the design process in order to evaluate the performance of the transformer. This thesis reviews calculation methods for solid wire, litz wire and copper foil winding losses, and in order to evaluate the applicability of the methods, the calculations are compared against measurements and FEM simulations. By selecting a proper calculation method for each winding type, the winding

  6. Thermionic field emission in gold nitride Schottky nanodiodes

    Science.gov (United States)

    Spyropoulos-Antonakakis, N.; Sarantopoulou, E.; Kollia, Z.; Samardžija, Z.; Kobe, S.; Cefalas, A. C.

    2012-11-01

    We report on the thermionic field emission and charge transport properties of gold nitride nanodomains grown by pulsed laser deposition with a molecular fluorine laser at 157 nm. The nanodomains are sandwiched between the metallic tip of a conductive atomic force microscope and a thin gold layer forming thus a metal-semiconductor-metal junction. Although the limited existing data in the literature indicate that gold nitride was synthesized previously with low efficiency, poor stability, and metallic character; in this work, it is shown that gold nitride nanodomains exhibit semiconducting behavior and the metal-semiconductor-metal contact can be modeled with the back-to-back Schottky barrier model. From the experimental I-V curves, the main charge carrier transport process is found to be thermionic field emission via electron tunneling. The rectifying, near symmetric and asymmetric current response of nanocontacts is related to the effective contact area of the gold nitride nanodomains with the metals. A lower limit for the majority charge carriers concentration at the boundaries of nanodomains is also established using the full depletion approximation, as nanodomains with thickness as low as 6 nm were found to be conductive. Current rectification and charge memory effects are also observed in "quite small" conductive nanodomains (6-10 nm) due to stored charges. Indeed, charges near the surface are identified as inversion domains in the phase shift mapping performed with electrostatic force microscopy and are attributed to charge trapping at the boundaries of the nanodomains.

  7. Thermionic system evaluated test (TSET) facility description

    Science.gov (United States)

    Fairchild, Jerry F.; Koonmen, James P.; Thome, Frank V.

    1992-01-01

    A consortium of US agencies are involved in the Thermionic System Evaluation Test (TSET) which is being supported by the Strategic Defense Initiative Organization (SDIO). The project is a ground test of an unfueled Soviet TOPAZ-II in-core thermionic space reactor powered by electrical heat. It is part of the United States' national thermionic space nuclear power program. It will be tested in Albuquerque, New Mexico at the New Mexico Engineering Research Institute complex by the Phillips Laboratoty, Sandia National Laboratories, Los Alamos National Laboratory, and the University of New Mexico. One of TSET's many objectives is to demonstrate that the US can operate and test a complete space nuclear power system, in the electrical heater configuration, at a low cost. Great efforts have been made to help reduce facility costs during the first phase of this project. These costs include structural, mechanical, and electrical modifications to the existing facility as well as the installation of additional emergency systems to mitigate the effects of utility power losses and alkali metal fires.

  8. High Performance Multi Barrier Thermionic Devices

    National Research Council Canada - National Science Library

    Vashaee, Daryoosh; Shakouri, Ali

    2003-01-01

    Thermoelectric transport perpendicular to layers in multiple barrier superlattice structures is investigated theoretically in two limiting cases of no lateral momentum scattering and strong scattering...

  9. Advances in Thermionic Energy Conversion through Single-Crystal n-Type Diamond

    Directory of Open Access Journals (Sweden)

    Franz A. M. Koeck

    2017-12-01

    Full Text Available Thermionic energy conversion, a process that allows direct transformation of thermal to electrical energy, presents a means of efficient electrical power generation as the hot and cold side of the corresponding heat engine are separated by a vacuum gap. Conversion efficiencies approaching those of the Carnot cycle are possible if material parameters of the active elements at the converter, i.e., electron emitter or cathode and collector or anode, are optimized for operation in the desired temperature range. These parameters can be defined through the law of Richardson–Dushman that quantifies the ability of a material to release an electron current at a certain temperature as a function of the emission barrier or work function and the emission or Richardson constant. Engineering materials to defined parameter values presents the key challenge in constructing practical thermionic converters. The elevated temperature regime of operation presents a constraint that eliminates most semiconductors and identifies diamond, a wide band-gap semiconductor, as a suitable thermionic material through its unique material properties. For its surface, a configuration can be established, the negative electron affinity, that shifts the vacuum level below the conduction band minimum eliminating the surface barrier for electron emission. In addition, its ability to accept impurities as donor states allows materials engineering to control the work function and the emission constant. Single-crystal diamond electrodes with nitrogen levels at 1.7 eV and phosphorus levels at 0.6 eV were prepared by plasma-enhanced chemical vapor deposition where the work function was controlled from 2.88 to 0.67 eV, one of the lowest thermionic work functions reported. This work function range was achieved through control of the doping concentration where a relation to the amount of band bending emerged. Upward band bending that contributed to the work function was attributed to

  10. A Methodology for Equitable Performance Assessment and Presentation of Wave Energy Converters Based on Sea Trials

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Pecher, Arthur; Margheritini, Lucia

    2013-01-01

    This paper provides a methodology for the analysis and presentation of data obtained from sea trials of wave energy converters (WEC). The equitable aspect of this methodology lies in its wide application, as any WEC at any scale or stage of development can be considered as long as the tests are p...... parameters influence the performance of the WEC can also be investigated using this methodology.......This paper provides a methodology for the analysis and presentation of data obtained from sea trials of wave energy converters (WEC). The equitable aspect of this methodology lies in its wide application, as any WEC at any scale or stage of development can be considered as long as the tests...... leads to testing campaigns that are not as extensive as desired. Therefore, the performance analysis should be robust enough to allow for not fully complete sea trials and sub optimal performance data. In other words, this methodology is focused at retrieving the maximum amount of useful information out...

  11. Drag Reduction and Performance Improvement of Hydraulic Torque Converters with Multiple Biological Characteristics

    Directory of Open Access Journals (Sweden)

    Liu Chunbao

    2016-01-01

    Full Text Available Fish-like, dolphin-like, and bionic nonsmooth surfaces were employed in a hydraulic torque converter to achieve drag reduction and performance improvement, which were aimed at reducing profile loss, impacting loss and friction loss, respectively. YJSW335, a twin turbine torque converter, was bionically designed delicately. The biological characteristics consisted of fish-like blades in all four wheels, dolphin-like structure in the first turbine and the stator, and nonsmooth surfaces in the pump. The prediction performance of bionic YJSW335, obtained by computational fluid dynamics simulation, was improved compared with that of the original model, and then it could be proved that drag reduction had been achieved. The mechanism accounting for drag reduction of three factors was also investigated. After bionic design, the torque ratio and the highest efficiencies of YJSW335 were both advanced, which were very difficult to achieve through traditional design method. Moreover, the highest efficiency of the low speed area and high speed area is 85.65% and 86.32%, respectively. By economic matching analysis of the original and bionic powertrains, the latter can significantly reduce the fuel consumption and improve the operating economy of the loader.

  12. Joining and Performance of Alkali Metal Thermal-to-electric Converter (AMTEC)

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Min-Soo; Lee, Wook-Hyun; Woo, Sang-Kuk [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2017-07-15

    The alkali-Metal Thermal-to-electric Converter (AMTEC) is one of the promising static energy conversion technologies for the direct conversion of thermal energy to electrical energy. The advantages over a conventional energy converter are its high theoretical conversion efficiency of 40% and power density of 500 W/kg. The working principle of an AMTEC battery is the electrochemical reaction of the sodium through an ion conducting electrolyte. Sodium ion pass through the hot side of the beta”-alumina solid electrolyte (BASE) primarily as a result of the pressure difference. This pressure difference across the BASE has a significant effect on the overall performance of the AMTEC system. In order to build the high pressure difference across the BASE, hermeticity is required for each joined components for high temperature range of 900°C. The AMTEC battery was manufactured by utilizing robust joining technology of BASE/insulator/metal flange interfaces of the system for both structural and electrical stability. The electrical potential difference between the anode and cathode sides, where the electrons emitted from sodium ionization and recombined into sodium, was characterized as the open-circuit voltage. The efforts of technological improvement were concentrated on a high-power output and conversion efficiency. This paper discusses about the joining and performance of the AMTEC systems.

  13. Performance predictions for solar-chemical converters based on photoelectrochemical I-V curves

    Energy Technology Data Exchange (ETDEWEB)

    Luttmer, J.D.; Trachtenberg, I.

    1985-06-01

    Texas Instruments' solar energy system contains a solar-chemical converter (SCC) which converts solar energy into chemical energy via the electrolysis of hydrobromic acid (HBr) into hydrogen (H/sub 2/) and bromine (Br/sub 2/). Previous predictions of SCC performance have employed electrical dry-probe data and a computer simulation model to predict the H/sub 2/ generation rates. The method of prediction described here makes use of the photoelectrochemical Icurves to determine the ''wet'' probe parameters of V /SUB oc/ J /SUB sc/ FF, and efficiency for anodes and cathodes. The advantages of this technique over the dry-probe/computer simulation method are discussed. A comparison of predicted and measured H/sub 2/ generation rates is presented. Solar to chemical efficiencies of 8.6% have been both predicted and measured for the electrolysis of 48% HBr to hydrogen and bromine by a full anode/cathode array. Individual cathode solar to hydrogen efficiencies of 9.5% have been obtained.

  14. Performance Analysis of Trench Power MOSFETs in High-Frequency Synchronous Buck Converter Applications

    Directory of Open Access Journals (Sweden)

    Yali Xiong

    2008-01-01

    Full Text Available This paper investigates the performance perspectives and theoretical limitations of trench power MOSFETs in synchronous rectifier buck converters operating in the MHz frequency range. Several trench MOSFET technologies are studied using a mixed-mode device/circuit modeling approach. Individual power loss contributions from the control and synchronous MOSFETs, and their dependence on switching frequency between 500 kHz and 5 MHz are discussed in detail. It is observed that the conduction loss contribution decreases from 40% to 4% while the switching loss contribution increases from 60% to 96% as the switching frequency increases from 500 KHz to 5 MHz. Beyond 1 MHz frequency there is no obvious benefit to increase the die size of either SyncFET or CtrlFET. The RDS(ON×QG figure of merit (FOM still correlates well to the overall converter efficiency in the MHz frequency range. The efficiency of the hard switching buck topology is limited to 80% at 2 MHz and 65% at 5 MHz even with the most advanced trench MOSFET technologies.

  15. Electrical performance of GaN diode as betavoltaic isotope battery energy converter

    International Nuclear Information System (INIS)

    Wang Guanquan; Yang Yuqing; Liu Yebing; Hu Rui; Li Hao; Zhong Zhengkun; Luo Shunzhong

    2013-01-01

    Two kinds of GaN PiN diodes were prepared to be the energy converters of betavoltaic batteries, and irradiated by 63 Ni and 3 H radioactive sources. The I sc was 5.4 nA and V oc was 771 mV for 63 Ni source; the I sc was 10.8 nA and V oc was 839 mV for 3 H source. These results show that their V oc are far better than silicon diodes', but their I sc are poor. And there are some differences between the theory values and experiment results. There would be greatly improving space in electrical performance of beta voltaic isotope batteries with GaN diodes as the energy converters, if the dislocation could be reduced in GaN material producing process, the Ohmic contact could be prepared very well and the diodes configuration could be designed more optimizedly in the future. (authors)

  16. Beam emittance measurement from CERN thermionic guns

    International Nuclear Information System (INIS)

    Kester, O.; Rao, R.; Rinolfi, L.

    1992-01-01

    In the LEP Injector Linacs (LIL) a thermionic gun provides electron beams with different peak intensities at an energy of 80 keV. The beam emittances were estimated from the EGUN programme. Since the gun is of triode type, the main contribution to the emittance comes from the grid. The simulation programme does not model the real geometry by assuming a cylindrical symmetry, while the grid does not have such symmetry. A Gun Test Facility (GTF), allowing emittance measurements, based on the 3-gradients-method was installed. The experimental results are presented. (author) 6 refs.; 6 figs

  17. A high-brightness thermionic microwave electron gun

    International Nuclear Information System (INIS)

    Borland, M.

    1991-02-01

    In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun's performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ''State-of-the-art'' microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of e c · μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 10 9 e - per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically e · μm

  18. A high-brightness thermionic microwave electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Borland, Michael [Stanford Univ., CA (United States)

    1991-02-01

    In a collaborative effort by SSRL, AET Associates, and Varian Associates, a high-brightness microwave electron gun using a thermionic cathode has been designed, built, tested, and installed for use with the SSRL 150 MeV linear accelerator. This thesis discusses the physics behind the design and operation of the gun and associated systems, presenting predictions and experimental tests of the gun`s performance. The microwave gun concept is of increasing interest due to its promise of providing higher-current, lower-emittance electron beams than possible from conventional, DC gun technology. In a DC guns, accelerating gradients are less than 8 MV/m, while those in a microwave gun can exceed 100 MV/m, providing much more rapid initial acceleration, thereby reducing the deleterious effects of space-charge. Microwave guns produce higher momentum beams than DC guns, thus lessening space-charge effects during subsequent beam transport. Typical DC guns produce kinetic energies of 80--400 KeV, compared to 2--3 MeV for the SSRL microwave gun. ``State-of-the-art`` microwave gun designs employ laser-driven photocathodes, providing excellent performance but with greater complexity and monetary costs. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of magnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exist of < 10 π • mec • μm for a beam consisting of approximately 50% of the particles emitted from the gun, and having a momentum spread ±10%. These emittances are for up to 5 x 109e- per bunch. Chromatic aberrations in the transport line between the gun and linear accelerator increase this to typically < 30 π • me • μm.

  19. On the Effects of Geometry Control on the Performance of Overtopping Wave Energy Converters

    DEFF Research Database (Denmark)

    Victor, Lander; Troch, Peter; Kofoed, Jens Peter

    2011-01-01

    Overtopping wave energy converters (OWECs) are designed to extract energy from ocean waves based on wave overtopping into a reservoir, which is emptied into the ocean through a set of low-head turbines, and typically feature a low crest freeboard and a smooth impermeable steep slope. In the process...... of optimizing the performance of OWECs, the question arises whether adapting the slope geometry to the variable wave characteristics at the deployment site (i.e., geometry control) can increase the overall hydraulic efficiency and overall hydraulic power compared to a fixed slope geometry. The effect of five...... different geometry control scenarios on the overall hydraulic efficiency and overall hydraulic power of OWECs has been simulated for three possible deployment sites using empirical prediction formulae. The results show that the effect of an adaptive slope angle is relatively small. On the other hand...

  20. Experimental investigation on the hydrodynamic performance of a wave energy converter

    Science.gov (United States)

    Zheng, Xiong-bo; Ma, Yong; Zhang, Liang; Jiang, Jin; Liu, Heng-xu

    2017-06-01

    Wave energy is an important type of marine renewable energy. A wave energy converter (WEC) moored with two floating bodies was developed in the present study. To analyze the dynamic performance of the WEC, an experimental device was designed and tested in a tank. The experiment focused on the factors which impact the motion and energy conversion performance of the WEC. Dynamic performance was evaluated by the relative displacements and velocities of the oscillator and carrier which served as the floating bodies of WEC. Four factors were tested, i.e. wave height, wave period, power take-off (PTO) damping, and mass ratio ( R M) of the oscillator and carrier. Experimental results show that these factors greatly affect the energy conversion performance, especially when the wave period matches R M and PTO damping. According to the results, we conclude that: (a) the maximization of the relative displacements and velocities leads to the maximization of the energy conversion efficiency; (b) the larger the wave height, the higher the energy conversion efficiency will be; (c) the relationships of energy conversion efficiency with wave period, PTO damping, and R M are nonlinear, but the maximum efficiency is obtained when these three factors are optimally matched. Experimental results demonstrated that the energy conversion efficiency reached the peak at 28.62% when the wave height was 120 mm, wave period was 1.0 s, R M was 0.21, and the PTO damping was corresponding to the resistance of 100 Ω.

  1. Active energy recovery clamping circuit to improve the performance of power converters

    Science.gov (United States)

    Whitaker, Bret; Barkley, Adam

    2017-05-09

    A regenerative clamping circuit for a power converter using clamping diodes to transfer charge to a clamping capacitor and a regenerative converter to transfer charge out of the clamping capacitor back to the power supply input connection. The regenerative converter uses a switch connected to the midpoint of a series connected inductor and capacitor. The ends of the inductor and capacitor series are connected across the terminals of the power supply to be in parallel with the power supply.

  2. Capabilities, performance, and future possibilities of high frequency polyphase resonant converters

    International Nuclear Information System (INIS)

    Reass, W.A.; Baca, D.M.; Bradley, J.T. III; Hardek, T.W.; Kwon, S.I.; Lynch, M.T.; Rees, D.E.

    2004-01-01

    High Frequency Polyphase Resonant Power Conditioning (PRPC) techniques developed at Los Alamos National Laboratory (LANL) are now being utilized for the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS) accelerator klystron RF amplifier power systems. Three different styles of polyphase resonant converter modulators were developed for the SNS application. The various systems operate up to 140 kV, or 11 MW pulses, or up to 1.1 MW average power, all from a DC input of +/- 1.2 kV. Component improvements realized with the SNS effort coupled with new applied engineering techniques have resulted in dramatic changes in RF power conditioning topology. As an example, the high-voltage transformers are over 100 times smaller and lighter than equivalent 60 Hz versions. With resonant conversion techniques, load protective networks are not required. A shorted load de-tunes the resonance and little power transfer can occur. This provides for power conditioning systems that are inherently self-protective, with automatic fault 'ride-through' capabilities. By altering the Los Alamos design, higher power and CW power conditioning systems can be realized without further demands of the individual component voltage or current capabilities. This has led to designs that can accommodate 30 MW long pulse applications and megawatt class CW systems with high efficiencies. The same PRPC techniques can also be utilized for lower average power systems (∼250 kW). This permits the use of significantly higher frequency conversion techniques that result in extremely compact systems with short pulse (10 to 100 us) capabilities. These lower power PRPC systems may be suitable for medical Linacs and mobile RF systems. This paper will briefly review the performance achieved for the SNS accelerator and examine designs for high efficiency megawatt class CW systems and 30 MW peak power applications. The devices and designs for compact higher frequency converters utilized for short pulse

  3. Optimizing the Performance of Solo Duck Wave Energy Converter in Tide

    Directory of Open Access Journals (Sweden)

    Jinming Wu

    2017-02-01

    Full Text Available The high efficiency performance of the Edinburgh Duck wave energy converter (WEC in 2D regular wave tests makes it a promising wave energy conversion scheme. A solo Duck WEC will be able to apply the point absorber effect to further enhance its performance. Since released degree of freedom will decrease the efficiency, a Duck WEC with fixed pitching axis will be a better option. However, for fixed supported WECs, tide is a non-ignorable consideration. In this paper, a movable mass method is utilized in the whole tidal range to not only balance the Duck to appropriate beak angles, but also follow the variation of hydrodynamic coefficients to keep cancelling the reactance of the system impedance so that complex conjugate control can be realized to optimize the power capture performance of the Duck WEC in tide. Results show that the beak angle should be adjusted to as large a value as possible so that the response amplitude of the Duck at maximum relative capture width will be reasonable small, and the lowest weight of the movable mass is found when its designed position locates at the center of the Duck profile.

  4. Recent advances in Alkali Metal Thermoelectric Converter (AMTEC) electrode performance and modeling. [for space power systems

    Science.gov (United States)

    Bankston, C. P.; Williams, R. M.; Jeffries-Nakamura, B.; Loveland, M. E.; Underwood, M. L.

    1988-01-01

    The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion device, utilizing a high sodium vapor pressure or activity ratio across a beta-double prime-alumina solid electrolyte (BASE). This paper describes progress on the remaining scientific issue which must be resolved to demonstrate AMTEC feasibility for space power systems: a stable, high power density electrode. Two electrode systems have recently been discovered at JPL that now have the potential to meet space power requirements. One of these is a very thin sputtered molybdenum film, less than 0.5 micron thick, with overlying current collection grids. This electrode has experimentally demonstrated stable performance at 0.4-0.5 W/sq cm for hundreds of hours. Recent modeling results show that at least 0.7 W/sq cm can be achieved. The model of electrode performance now includes all loss mechanisms, including charge transfer resistances at the electrode/electrolyte interface. A second electrode composition, cosputtered platinum/tungsten, has demonstrated 0.8 W/sq cm for 160 hours. Systems studies show that a stable electrode performance of 0.6 W/sq cm will enable high efficiency space power systems.

  5. Thermionic phenomena the collected works of Irving Langmuir

    CERN Document Server

    Suits, C Guy

    1961-01-01

    Thermionic Phenomena is the third volume of the series entitled The Collected Works of Irving Langmuir. This volume compiles articles written during the 1920's and early 1930's, the period when the science of thermionics is beginning to be of importance. This text is divided into two parts. The first part discusses vacuum pumps, specifically examining the effect of space charge and residual gases on thermionic currents in high vacuum. This part also explains fundamental phenomena in electron tubes having tungsten cathodes and the use of high-power vacuum tubes. The second part of this text loo

  6. Thermal Performance and Efficiency Investigation of Conventional Boost, Z-source and Y-source Converters

    DEFF Research Database (Denmark)

    Gadalla, Brwene Salah Abdelkarim; Schaltz, Erik; Siwakoti, Yam Prasad

    2016-01-01

    Boost converters are needed in many applications that require the output voltage to be higher than the input voltage. Recently, boost type converters have been attracted by the industrial applications, and hence it has become an extremely hot topic of research. Recently, many researchers proposed...... the impedance source converters with their unique advantages as having a high voltage gain in a small range of duty cycle ratio. However, the thermal behaviour of the semiconductor devices and passive elements in the impedance source converter is an important issue from a reliability point of view and has...... not been investigated yet. Therefore this paper presents a comparison between the conventional boost, the Z-source, and the Y-source converters based on the thermal evaluation of semiconductors. In addition, the three topologies are also compared with respect to their efficiency. The operational principle...

  7. Performance Analysis of Multiple Wave Energy Converters Placed on a Floating Platform in the Frequency Domain

    Directory of Open Access Journals (Sweden)

    Hyebin Lee

    2018-02-01

    Full Text Available Wind-wave hybrid power generation systems have the potential to become a significant source of affordable renewable energy. However, their strong interactions with both wind- and wave-induced forces raise a number of technical challenges for modelling. The present study undertakes a numerical investigation on multi-body hydrodynamic interaction between a wind-wave hybrid floating platform and multiple wave energy converters (WECs in a frequency domain. In addition to the exact responses of the platform and the WECs, the power take-off (PTO mechanism was taken into account for analysis. The coupled hydrodynamic coefficients and wave exciting forces were obtained from WAMIT, the 3D diffraction/radiation solver based on the boundary element method. The overall performance of the multiple WECs is presented and compared with the performance of a single isolated WEC. The analysis showed significant differences in the dynamic responses of the WECs when the multi-body interaction was considered. In addition, the PTO damping effect made a considerable difference to the responses of the WECs. However, the platform response was only minimally affected by PTO damping. With regard to energy capture, the interaction effect of the designed multiple WEC array layout is evaluated. The WEC array configuration showed both constructive and destructive effects in accordance with the incident wave frequency and direction.

  8. Modelling performance of a small array of Wave Energy Converters: Comparison of Spectral and Boussinesq models

    International Nuclear Information System (INIS)

    Greenwood, Charles; Christie, David; Venugopal, Vengatesan; Morrison, James; Vogler, Arne

    2016-01-01

    This paper presents results from numerical simulations of three Oscillating Wave Surge Converters (OWSC) using two different computational models, Boussinesq wave (BW) and Spectral wave (SW) of the commercial software suite MIKE. The simulation of a shallow water wave farm applies alternative methods for implementing a frequency dependent absorption in both the BW and SW models, where energy extraction is based on experimental data from a scaled Oyster device. The effects of including wave diffraction within the SW model is tested by using diffraction smoothing steps and various directional wave conditions. The results of this study reveal important information on the models realms of validity that is heavily dependent on the incident sea state and the removal of diffraction for the SW model. This yields an increase in simulation accuracy for far-field disturbances when diffraction is entirely removed. This highlights specific conditions where the BW and SW model may thrive but also regions where reduced performance is observed. The results presented in this paper have not been validated with real sea site wave device array performance, however, the methodology described would be useful to device developers to arrive at preliminary decisions on array configurations and to minimise negative environmental impacts.

  9. Simulation of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

    International Nuclear Information System (INIS)

    Meng, X.T.; Levin, D.S.; Chapman, J.W.; Zhou, B.

    2016-01-01

    The ATLAS Muon Spectrometer endcap thin-Resistive Plate Chamber trigger project compliments the New Small Wheel endcap Phase-1 upgrade for higher luminosity LHC operation. These new trigger chambers, located in a high rate region of ATLAS, will improve overall trigger acceptance and reduce the fake muon trigger incidence. These chambers must generate a low level muon trigger to be delivered to a remote high level processor within a stringent latency requirement of 43 bunch crossings (1075 ns). To help meet this requirement the High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by CERN Microelectronics group, has been proposed for the digitization of the fast front end detector signals. This paper investigates the HPTDC performance in the context of the overall muon trigger latency, employing detailed behavioral Verilog simulations in which the latency in triggerless mode is measured for a range of configurations and under realistic hit rate conditions. The simulation results show that various HPTDC operational configurations, including leading edge and pair measurement modes can provide high efficiency (>98%) to capture and digitize hits within a time interval satisfying the Phase-1 latency tolerance.

  10. Comparison of catalytic converter performance in internal combustion engine fueled with Ron 95 and Ron 97 gasoline

    Science.gov (United States)

    Leman, A. M.; Rahman, Fakhrurrazi; Jajuli, Afiqah; Feriyanto, Dafit; Zakaria, Supaat

    2017-09-01

    Generating ideal stability between engine performance, fuel consumption and emission is one of the main challenges in the automotive industry. The characteristics of engine combustion and creation of emission might simply change with different types of operating parameters. This study aims in investigating the relationship between two types of fuels on the performance and exhaust emission of internal combustion engine using ceramic and metallic catalytic converters. Experimental tests were performed on Mitsubishi 4G93 engine by applying several ranges of engine speeds to determine the conversion of pollutant gases released by the engine. The obtained results specify that the usage of RON 97 equipped with metallic converters might increase the conversion percentage of 1.31% for CO and 126 ppm of HC gases. The metallic converters can perform higher conversion compared to ceramic because in the high space velocities, metallic has higher surface geometry area and higher amount of transverse Peclet number (Pi). Ceramic converters achieved conversion at 2496 ppm of NOx gas, which is higher than the metallic converter.

  11. Nuclear thermionic power plant integration problems

    International Nuclear Information System (INIS)

    Fraas, A.P.

    1967-02-01

    The numerous boundary conditions to be met in preparing a well proportioned, properly integrated design for a thermionic cell reactor are discussed with the emphasis on materials and fabrication problems. Pertinent experience with fuel elements, tube header sheets, electric heaters, and pressure vessels is cited to highlight key limitations that have been encountered in structurally similar equipment. A reference design is presented to indicate how one might attempt to satisfy all of the many boundary conditions. The study indicates that it will be difficult to get a reactor core power density greater than about 35 w/cm 3 and that, while it is possible to minimize the ill effects of failures within individual cells by employing series-parallel connections, the study further indicates that there is inherently a high probability of leaks and electrical shorts and arcs within the reactor so that it is doubtful that good reliability can be obtained

  12. Thermionic system evaluation test (TSET) facility construction: A United States and Russian effort

    International Nuclear Information System (INIS)

    Wold, S.K.

    1993-01-01

    The Thermionic System Evaluation Test (TSET) is a ground test of an unfueled Russian TOPAZ-II in-core thermionic space reactor powered by electric heaters. The facility that will be used for testing of the TOPAZ-II systems is located at the New Mexico Engineering Research Institute (NMERI) complex in Albuquerque, NM. The reassembly of the Russian test equipment is the responsibility of International Scientific Products (ISP), a San Jose, CA, company and Inertek, a Russian corporation, with support provided by engineers and technicians from Phillips Laboratory (PL), Sandia National Laboratories (SNL), Los Alamos National Laboratory (LANL), and the University of New Mexico (UNM). This test is the first test to be performed under the New Mexico Strategic Alliance agreement. This alliance consists of the PL, SNL, LANL, and UNM. The testing is being funded by the Strategic Defense Initiative Organization (SDIO) with the PL responsible for project execution

  13. 3-D simulation study for a thermionic RF gun using an FDTD method

    Energy Technology Data Exchange (ETDEWEB)

    Hama, H. E-mail: hama@lns.tohoku.ac.jp; Hinode, F.; Shinto, K.; Miyamoto, A.; Tanaka, T

    2004-08-01

    Beam dynamics in a thermionic RF gun for a new pre-injector in a future synchrotron radiation facility at Tohoku university has been studied by developing a 3-D Maxwell's equation solver. Backbombardment (BB) effect on a cathode, which is a crucial problem for performance of the thermionic RF gun, has been investigated. It is found that an external dipole magnetic field applying around the cathode is effective to reduce high-energy backstreaming electrons from the accelerating cell. However, the low-energy electrons coming back from the first cell inevitably hit the cathode, so that characteristics of the cathode material seems to be crucial for reduction of the BB effect.

  14. The performance of the DC motor by the PID controlling PWM DC-DC boost converter

    OpenAIRE

    Can, Erol; Sayan, Hasan Hüseyin

    2017-01-01

    This paper presents the PID controlling direct current (DC) to the direct current boost converter feds DC motor which has a 3.68 kW and 240 V of DC voltage input on its characteristics. What is first formed is the boost converter mathematical model at the design stage. Secondly, a mathematical model of the DC motor is created so that the boost converter with the machine can be established and modeled at the Matlab Simulink. The PID controller is considered for arranging a pulse width modulati...

  15. Thermionic integrated circuit technology for high power space applications

    International Nuclear Information System (INIS)

    Yadavalli, S.R.

    1984-01-01

    Thermionic triode and integrated circuit technology is in its infancy and it is emerging. The Thermionic triode can operate at relatively high voltages (up to 2000V) and at least tens of amperes. These devices, including their use in integrated circuitry, operate at high temperatures (800 0 C) and are very tolerant to nuclear and other radiations. These properties can be very useful in large space power applications such as that represented by the SP-100 system which uses a nuclear reactor. This paper presents an assessment of the application of thermionic integrated circuitry with space nuclear power system technology. A comparison is made with conventional semiconductor circuitry considering a dissipative shunt regulator for SP-100 type nuclear power system rated at 100 kW. The particular advantages of thermionic circuitry are significant reductions in size and mass of heat dissipation and radiation shield subsystems

  16. A methodology to determine the power performance of wave energy converters at a particular coastal location

    International Nuclear Information System (INIS)

    Carballo, R.; Iglesias, G.

    2012-01-01

    Highlights: ► We develop a method to accurately compute the power output of a WEC at a site. ► The analysis of the wave resource is integrated seamlessly with the WEC efficiency. ► The intra-annual variability of the resource is considered. ► The method is illustrated with a case study: a WEC projected to be built in Spain. - Abstract: The assessment of the power performance of a wave energy converter (WEC) at a given site involves two tasks: (i) the characterisation of the wave resource at the site in question, and (ii) the computation of its power performance. These tasks are generally seen as disconnected, and tackled as such; they are, however, deeply interrelated – so much so that they should be treated as two phases of the same procedure. Indeed, beyond the characterisation of the wave resource of a certain area lies a crucial question: how much power would a WEC installed in that area output to the network? This work has two main objectives. First, to develop a methodology that integrates both tasks seamlessly and guarantees the accurate computation of the power performance of a WEC installed at a site of interest; it involves a large dataset of deepwater records and the implementation of a high-resolution, nested spectral model, which is used to propagate 95% of the total offshore wave energy to the WEC site. The second objective is to illustrate this methodology with a case study: an Oscillating Water Column (OWC) projected to be constructed at the breakwater of A Guarda (NW Spain). It is found that the approach presented allows to accurately determine the power that the WEC will output to the network, and that this power exhibits a significant monthly variability, so an estimate of the energy production based on mean annual values may be misleading.

  17. Reforming performance of a plasma-catalyst hybrid converter using low carbon fuels

    International Nuclear Information System (INIS)

    Horng, R.-F.; Lai, M.-P.; Huang, H.-H.; Chang, Y.-P.

    2009-01-01

    The reforming performance of a plasma-catalyst hybrid converter using different low carbon fuels was investigated. The methodology was to use arc from spark discharge combined with an appropriate oxygen/carbon molar ratio (O 2 /C) and feeding rate of the supplied mixture. To enhance the mixing and reforming reaction, a gas intake swirl was generated by inducing the mixture tangentially into the reaction chamber. The required energy for fuel processing was provided by heat released through the oxidation of the air-fuel mixture. The reforming temperature as well as the effect of steam addition on the hydrogen production was studied. The results showed that reformate gas temperature had a profound effect on the overall reaction. The H 2 /(CO + CO 2 ) ratio reformed by both methane and propane was shown to increase with temperature and that the optimum ratio was obtained when reforming methane under 650 deg. C. The conversion efficiency of the fuel was also shown to increase with increasing temperature. The best thermal efficiency of 72.01% was obtained near 750 deg. C. The theoretical equilibrium calculations and the experimental results were compared.

  18. System modeling and reactor design studies of the Advanced Thermionic Initiative space nuclear reactor

    International Nuclear Information System (INIS)

    Lee, H.H.; Abdul-Hamid, S.; Klein, A.C.

    1996-01-01

    In-core thermionic space reactor design concepts that operate at a nominal power output range of 20 to 50 kW(electric) are described. Details of the neutronic, thermionic, thermal hydraulics, and shielding performance are presented. Because of the strong absorption of thermal neutrons by natural tungsten and the large amount of natural tungsten within the reactor core, two designs are considered. An overall system design code has been developed at Oregon State University to model advanced in-core thermionic energy conversion-based nuclear reactor systems for space applications. The results show that the driverless single-cell Advanced Thermionic Initiative (ATI) configuration, which does not have driver fuel rods, proved to be more efficient than the driven core, which has driver rods. The results also show that the inclusion of the true axial and radial power distribution decrease the overall conversion efficiency. The flattening of the radial power distribution by three different methods would lead to a higher efficiency. The results show that only one TFE works at the optimum emitter temperature; all other TFEs are off the optimum performance and result in a 40% decrease of the efficiency of the overall system. The true axial profile is significantly different as there is a considerable amount of neutron leakage out of the top and bottom of the reactor. The analysis reveals that the axial power profile actually has a chopped cosine shape. For this axial profile, the reactor core overall efficiency for the driverless ATI reactor version is found to be 5.84% with a total electrical power of 21.92 kW(electric). By considering the true axial power profile instead of the uniform power profile, each TFE loses ∼80 W(electric)

  19. A high performance DC-DC converter with intelligent control for photovoltaic applications

    OpenAIRE

    M. Niroomand; M. Sherkat; M. Soheili

    2013-01-01

    In this paper, a SEPIC (Single-Ended Primary Inductance Converter) with high efficiency has been proposed for photovoltaic applications. In the proposed converter, an auxiliary circuit without any additional switches has been used. The switch works under ZCS and ZVS conditions. No auxiliary switch was added to the circuit, thus any additional drive circuit is not needed. The proposed control system based on fuzzy logic method, has shown the smart accurate and faster tracking of the maximum po...

  20. Performance evaluation of a three-phase dual active bridge DC-DC converter with different transformer winding configurations

    NARCIS (Netherlands)

    Baars, N.; Everts, J.; Wijnands, K.; Lomonova, E.

    2016-01-01

    This paper investigates the impact of three transformer winding configurations, i.e. the Y-Y, the Y-Delta, and the Delta-Delta configuration, on the performance of a three-phase dual active bridge (DAB) dc–dc converter. For each configuration, equations for the phase currents, power flow, and zero

  1. Performance Improvement of Sensorless Vector Control for Induction Motor Drives Fed by Matrix Converter Using Nonlinear Model and Disturbance Observer

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Blaabjerg, Frede

    2004-01-01

    This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with a non-linearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by communication delay and on-state voltage drop in switching...

  2. Performance analysis of pulse analog control schemes for LLC resonant DC/DC converters suitable in portable applications

    Directory of Open Access Journals (Sweden)

    P. Kowstubha

    2016-12-01

    Full Text Available Performance Analysis of Pulse Analog Control Schemes, predominantly Pulse-Width Modulation (PWM and Pulse-Position Modulation (PPM for LLC resonant DC/DC converter suitable in portable applications is addressed in this paper. The analysis is done for closed loop performance, frequency domain performance, primary and secondary side conduction losses and soft commutation using PSIM 6.0 software and observed that PPM scheme provides better performance at high input voltage with a good selectivity of frequency over a wide range of line and load variations. The performance of LLC resonant DC/DC converter is demonstrated using PPM scheme for a design specifications of 12 V, 5 A output.

  3. Performance characteristics of a combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  4. Performance tests of a power-electronics converter for multi-megawatt wind turbines using a grid emulator

    International Nuclear Information System (INIS)

    Averous, Nurhan Rizqy; Berthold, Anica; Monti, Antonello; De Doncker, Rik W.; Schneider, Alexander; Schwimmbeck, Franz

    2016-01-01

    A vast increase of wind turbines (WT) contribution in the modern electrical grids have led to the development of grid connection requirements. In contrast to the conventional test method, testing power-electronics converters for WT using a grid emulator at Center for Wind Power Drives (CWD) RWTH Aachen University offers more flexibility for conducting test scenarios. Further analysis on the performance of the device under test (DUT) is however required when testing with grid emulator since the characteristic of the grid emulator might influence the performance of the DUT. This paper focuses on the performance analysis of the DUT when tested using grid emulator. Beside the issue regarding the current harmonics, the performance during Fault Ride-Through (FRT) is discussed in detail. A power hardware in the loop setup is an attractive solution to conduct a comprehensive study on the interaction between the power-electronics converters and the electrical grids. (paper)

  5. Performance tests of a power-electronics converter for multi-megawatt wind turbines using a grid emulator

    Science.gov (United States)

    Rizqy Averous, Nurhan; Berthold, Anica; Schneider, Alexander; Schwimmbeck, Franz; Monti, Antonello; De Doncker, Rik W.

    2016-09-01

    A vast increase of wind turbines (WT) contribution in the modern electrical grids have led to the development of grid connection requirements. In contrast to the conventional test method, testing power-electronics converters for WT using a grid emulator at Center for Wind Power Drives (CWD) RWTH Aachen University offers more flexibility for conducting test scenarios. Further analysis on the performance of the device under test (DUT) is however required when testing with grid emulator since the characteristic of the grid emulator might influence the performance of the DUT. This paper focuses on the performance analysis of the DUT when tested using grid emulator. Beside the issue regarding the current harmonics, the performance during Fault Ride-Through (FRT) is discussed in detail. A power hardware in the loop setup is an attractive solution to conduct a comprehensive study on the interaction between the power-electronics converters and the electrical grids.

  6. Optimized Reactive Power Flow of DFIG Power Converters for Better Reliability Performance Considering Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2015-01-01

    . In order to fulfill the modern grid codes, over-excited reactive power injection will further reduce the lifetime of the rotor-side converter. In this paper, the additional stress of the power semiconductor due to the reactive power injection is firstly evaluated in terms of modulation index...

  7. Performance Improvement of DTC-SVM for Matrix Converter Drives Using an Overmodulation Strategy

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Blaabjerg, Frede

    2005-01-01

    In this paper, an improved direct torque control (DTC) method for matrix converter drives is proposed which enables to minimize torque ripple and to obtain unity input power factor, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages o...

  8. The Electrostatic Wind Energy Converter : Electrical performance of a high voltage prototype

    NARCIS (Netherlands)

    Djairam, D.

    2008-01-01

    Wind energy is converted to electrical energy by letting the wind move charged particles against the direction of an electric field. The advantage of this type of conversion is that no rotational movement, which occurs in conventional wind turbines, is required. An electrostatic wind energy

  9. Transient Performance Improvement Circuit (TPIC)s for DC-DC converter applications

    Science.gov (United States)

    Lim, Sungkeun

    of the slow inductor current slew rate which is determined by the input voltage, output voltage, and the inductance. The remaining inductor current in the power delivery path will charge the output capacitors and develop a voltage across the ESR. As a result, large output voltage spikes occur during load current transients. Due to their limited control bandwidth, traditional VRs can not sufficiently respond rapidly to certain load transients. As a result, a large output voltage spike can occur during load transients, hence requiring a large amount of bulk capacitance to decouple the VR from the load [2]. If the remaining inductor current is removed from the power stage or the inductor current slew rate is changed, the output voltage spikes can be clamped, allowing the output capacitance to be reduced. A new design methodology for a Transient Performance Improvement Circuit(TPIC) based on controlling the output impedance of a regulator is presented. The TPIC works in parallel with a voltage regulator (VR)'s ceramic capacitors to achieve faster voltage regulation without the need for a large bulk capacitance, and can serve as a replacement for bulk capacitors. The specific function of the TPIC is to mimic the behavior of the bulk capacitance in a traditional VRM by sinking and sourcing large currents during transients, allowing the VR to respond quickly to current transients without the need for a large bulk capacitance. This will allow fast transient response without the need for a large bulk capacitor. The main challenge in applying the TPIC is creating a design which will not interfere with VR operation. A TPIC for a 4 Switch Buck-Boost (4SBB) converter is presented which functions by con- trolling the inductor current slew rate during load current transients. By increasing the inductor current slew rate, the remaining inductor current can be removed from the 4SBB power delivery path and the output voltage spike can be clamped. A second TPIC is presented which is

  10. Isotopic Thermionic Generator; Generateur thermoionique isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Clemot, M; Devin, B; Durand, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    This report describes the general design of a thermionic direct conversion space generator. The power source used is a radioisotope. Two radioisotopes are considered: Pu 238 and Cm 244. The system is made up of a heat pipe concentrating the thermal flux from the isotope to the emitter, and of a second heat pipe evacuating the waste heat from the collector to the outer wall used as radiating panel. Calculations are given in the particular case of a 100 electrical watts output power. (authors) [French] Ce rapport decrit la structure d'un generateur spatial d'electricite a conversion directe du type thermoionique. La source d'energie est un radioisotope. Deux isotopes sont envisages: le Pu 238 et le Cm 244. Le systeme comporte pour l'emetteur un caloduc concentreur de flux thermique et pour le collecteur, un caloduc evacuateur vers l'enveloppe du generateur utilise, en panneau rayonnant. Les calculs ont ete conduits dans le cas particulier d'une puissance convertie de 100 watts electriques. (auteurs)

  11. Theoretical studies of thermionic conversion of solar energy with graphene as emitter and collector

    Science.gov (United States)

    Olawole, Olukunle C.; De, Dilip Kumar

    2018-01-01

    Thermionic energy conversion (TEC) using nanomaterials is an emerging field of research. It is known that graphene can withstand temperatures as high as 4600 K in vacuum, and it has been shown that its work function can be engineered from a high value (for monolayer/bilayer) of 4.6 eV to as low as 0.7 eV. Such attractive electronic properties (e.g., good electrical conductivity and high dielectric constant) make engineered graphene a good candidate as an emitter and collector in a thermionic energy converter for harnessing solar energy efficiently. We have used a modified Richardson-Dushman equation and have adopted a model where the collector temperature could be controlled through heat extraction in a calculated amount and a magnet can be attached on the back surface of the collector for future control of the space-charge effect. Our work shows that the efficiency of solar energy conversion also depends on power density falling on the emitter surface, and that a power conversion efficiency of graphene-based solar TEC as high as 55% can be easily achieved (in the absence of the space-charge effect) through proper choice of work functions, collector temperature, and emissivity of emitter surfaces. Such solar energy conversion would reduce our dependence on silicon solar panels and offers great potential for future renewable energy utilization.

  12. Thermionic nuclear reactor with internal heat distribution and multiple duct cooling

    Science.gov (United States)

    Fisher, C.R.; Perry, L.W. Jr.

    1975-11-01

    A Thermionic Nuclear Reactor is described having multiple ribbon-like coolant ducts passing through the core, intertwined among the thermionic fuel elements to provide independent cooling paths. Heat pipes are disposed in the core between and adjacent to the thermionic fuel elements and the ribbon ducting, for the purpose of more uniformly distributing the heat of fission among the thermionic fuel elements and the ducts.

  13. Current measurement in high-performance frequency converters; Strommessung in Hochleistungsumrichtern

    Energy Technology Data Exchange (ETDEWEB)

    Marien, Jan; Hetzler, Ullrich [Isabellenhuette Heusler GmbH und Co. KG, Dillenburg (Germany); Hornung, Hans-Georg; Zwinger, Stefan [Sensor-Technik Wiedemann GmbH, Kaufbeuren (Germany)

    2011-04-15

    The load cycles (raising, lowering, accelerating, braking) of cranes, lift trucks and other off-road vehicles are ideally suited for the efficient deployment of hybrid or full electrical drive technology. Current measurement is a key technology for advancing electrification. Sensor Technik Wiedemann places by her frequency converters on a shunt-based current measurement module from Isabellenhuette Heusler which permits highly accurate measurements. (orig.)

  14. SSG wave energy converter. Design, reliability and hydraulic performance of an innovative overtopping device

    Energy Technology Data Exchange (ETDEWEB)

    Margheritini, L.; Frigaard, P. [Department of Civil Engineering, Aalborg University. Sohngaardsholmsvej 57, DK-9000 Aalborg (Denmark); Vicinanza, D. [Department of Civil Engineering - CIRIAM, Seconda Universita di Napoli. Via Roma 29, 81031 Aversa (Caserta) (Italy)

    2009-05-15

    The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each other above the mean water level in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low head hydro-turbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter and the studies behind the process that leads to its construction. The pilot plant is an on-shore full-scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests' results will be used here to describe the pilot plant and its characteristics. (author)

  15. Measurement of vehicle emissions and power performance of an engine dedicated to gasoline converted to natural gas vehicular

    Directory of Open Access Journals (Sweden)

    Flores-Meneses Oscar Febo

    2017-05-01

    Full Text Available The present research work reports the factorial experiment carried out in the Institute of Mechanical and Electromechanical Research (IIME of the Major Saint Andrew University (UMSA, the purpose was to evaluate vehicle power and emission of greenhouse gas carbon dioxide, as well as other gases with harmful effects on human health, carbon monoxide, nitrogen oxides and total hydrocarbons generated by an internal combustion engine dedicated to gasoline and converted to bi-fuel CNG. For experimentation, a test stand was assembled with a motor commonly used in light transport vehicles in the city of La Paz, and converted to CNG in two types of transformation technology, third and fifth generation, the first being subsidized by the Bolivian State. The results allowed to determine that emissions depend on the operating regime and that the vehicles converted to CNG do not significantly reduce the emission of GHG issued per unit time in relation to original operation with gasoline, this is because they generate higher emission gas flows in the same operating regimes. Emission of other gases harmful to health are significantly superior when converting to the engine with technology of 3rd generation without use of mixer. Being also its performance of lower power, it falls between 87 and 75% of the original value. It is evident that the type of technology and mode of conversion applied influences the emissions and vehicular power.

  16. Investigation of Efficiency and Thermal Performance of The Y-source Converters for a Wide Voltage Range

    Directory of Open Access Journals (Sweden)

    Brwene Salah Gadalla

    2015-12-01

    Full Text Available The Y-source topology has a unique advantage of having high voltages gain with small shoot through duty cycles. Furthermore, having the advantage of high modulation index which increase the power density and improve the performance of the converter. In this paper, a collective thermal and efficiency investigation has been performed in order to improve the reliability of the converter. Evaluation of relevant losses as ( switching, conduction, capacitor ESR, core and winding losses , and evaluation of the junction temperature of the devices under 25C ambient temperature. The analysis is done for different voltage gain factors (2, 3, and 4, and different winding factor (4, and 5 using PLECS toolbox. The results shows that the higher the voltage gain and winding factor, the higher power losses and rising in the junction temperature of the device.

  17. A NEW THERMIONIC RF ELECTRON GUN FOR SYNCHROTRON LIGHT SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Kutsaev, Sergey; Agustsson, R.; Hartzell, J; Murokh, A.; Nassiri, A.; Savin, E.; Smirnov, A.V.; Smirnov, A. Yu; Sun, Y.; Verma, A; Waldschmidt, Geoff; Zholents, A.

    2017-06-02

    A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source at Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity and report the progress towards high power tests of the cathode assembly of the new gun.

  18. The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter

    Directory of Open Access Journals (Sweden)

    Ke Ma

    2012-07-01

    Full Text Available Power semiconductor switching devices play an important role in the performance of high power wind energy generation systems. The state-of-the-art device choices in the wind power application as reported in the industry include IGBT modules, IGBT press-pack and IGCT press-pack. Because of significant deviation in the packaging structure, electrical characteristics, as well as thermal impedance, these available power switching devices may have various thermal cycling behaviors, which will lead to converter solutions with very different cost, size and reliability performance. As a result, this paper aimed to investigate the thermal related characteristics of some important power switching devices. Their impact on the thermal cycling of a 10 MW three-level Neutral-Point-Clamped wind power converter is then evaluated under various operating conditions; the main focus will be on the grid connected inverter. It is concluded that the thermal performances of the 3L-NPC wind power converter can be significantly changed by the power device technology as well as their parallel configurations.

  19. Analysis of thermionic DC electron gun for 125 MeV linac

    International Nuclear Information System (INIS)

    Kanno, K.; Sato, Isamu; Sato, K.

    2000-01-01

    The beam trace calculation for the 100 kV thermionic DC electron gun with EIMAC 646E cathode, which is currently used for the 125 MeV linac at Nihon University, has been performed using EGUN code. The result showed a strong focus of the beam at the exit of the anode. A better geometry of the gun has been investigated by varying the shape of the wehnelt electrode. Also the trace calculation has been performed for the case of EIMAC 646B, which showed a considerably small emittance compared with that estimated for the present gun. (author)

  20. Analysis of thermionic DC electron gun for 125 MeV linac

    Energy Technology Data Exchange (ETDEWEB)

    Kanno, K. [Graduate School of Science and Technology, Nihon Univ., Funabashi, Chiba (Japan); Sato, Isamu; Sato, K. [Nihon Univ., Funabashi, Chiba (Japan). Atomic Energy Research Inst] [and others

    2000-07-01

    The beam trace calculation for the 100 kV thermionic DC electron gun with EIMAC 646E cathode, which is currently used for the 125 MeV linac at Nihon University, has been performed using EGUN code. The result showed a strong focus of the beam at the exit of the anode. A better geometry of the gun has been investigated by varying the shape of the wehnelt electrode. Also the trace calculation has been performed for the case of EIMAC 646B, which showed a considerably small emittance compared with that estimated for the present gun. (author)

  1. Transient and steady-state analyses of an electrically heated Topaz-II Thermionic Fuel Element

    International Nuclear Information System (INIS)

    El-Genk, M.S.; Xue, H.

    1992-01-01

    Transient and steady-state analyses of electrically heated, Thermionic Fuel Elements (TFEs) for Topaz-II space power system are performed. The calculated emitter and collector temperatures, load electric power and conversion efficiency are in good agreement with reported data. In this paper the effects or Cs pressure, thermal power input, and load resistance on the steady-state performance of the TFE are also investigated. In addition, the thermal response of the ZrH moderator during a startup transient and following a change in the thermal power input is examined

  2. Thermodynamics of photon-enhanced thermionic emission solar cells

    International Nuclear Information System (INIS)

    Reck, Kasper; Hansen, Ole

    2014-01-01

    Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE solar cells including an analysis of the entropy production due to thermionic emission of general validity. The model is applied to find the maximum efficiency of a PETE cell for given cathode and anode work functions and temperatures

  3. Small Delay and High Performance AD/DA Converters of Lease Circuit System for AM&FM Broadcast

    Science.gov (United States)

    Takato, Kenji; Suzuki, Dai; Ishii, Takashi; Kobayashi, Masato; Yamada, Hirokazu; Amano, Shigeru

    Many AM&FM broadcasting stations in Japan are connected by the leased circuit system of NTT. Small delay and high performance AD/DA converter was developed for the system. The system was designed based on ITU-T J.41 Recommendation (384kbps), the transmission signal is 11bit-32 kHz where the Gain-frequency characteristics between 40Hz to 15kHz have to be quite flat. The ΔΣAD/DA converter LSIs for audio application in the market today realize very high performance. However the performance is not enough for the leased circuit system. We found that it is not possible to meet the delay and Gain-frequency requirements only by using ΔΣAD/DA converter LSI in normal operation, because 15kHz the highest frequency and 16kHz Nyquist frequency are too close, therefore there are aliasing around Nyquist frequency. In this paper, we designed AD/DA architecture having small delay (1msec) and sharp cut off LPF (100dB attenuation at 16kHz, and 1500dB/Oct from 15kHz to 16kHz) by operating ΔΣAD/DA converter LSIs over-sampling rate such as 128kHz and by adding custom LPF designed Infinite Impulse Response (IIR) filter. The IIR filter is a 16th order elliptic type and it is consist of eight biquad filters in series. We described how to evaluate the stability of IIR filter theoretically by calculating frequency response, Pole and Zero Layout and impulse response of each biquad filter, and experimentally by adding overflow detection circuit on each filters and input overlord signal.

  4. Conceptual engineering design study of thermionic topping of fossil power plants

    Energy Technology Data Exchange (ETDEWEB)

    1978-02-15

    Primary objectives of this study are to investigate alternative design concepts of thermal coupling of thermionic energy converters (TECs) to the steam cycle and the mechanical and electrical aspects of integrating TEC design into the steam power station. The specific tasks include: (1) evaluate design concepts of TEC topping of solvent refined liquified coal-fired steam power plants, with main emphasis devoted to thermal, mechanical, and electrical design aspects. (2) Develop preliminary conceptual design of a modular TEC assembly. (3) Develop preliminary cost estimates of the design modification to a liquified coal-fired steam power plant with TEC topping. (4) Provide support to Thermo Electron Corporation in planning TEC hardware testing. Results are presented in detail.

  5. Comparative assessment of out-of-core nuclear thermionic power systems

    International Nuclear Information System (INIS)

    Estabrook, W.C.; Koenig, D.R.; Prickett, W.Z.

    1975-01-01

    The hardware selections available for fabrication of a nuclear electric propulsion stage for planetary exploration were explored. The investigation was centered around a heat-pipe-cooled, fast-spectrum nuclear reactor for an out-of-core power conversion system with sufficient detail for comparison with the in-core system studies completed previously. A survey of competing power conversion systems still indicated that the modular reliability of thermionic converters makes them the desirable choice to provide the 240-kWe end-of-life power for at least 20,000 full power hours. The electrical energy will be used to operate a number of mercury ion bombardment thrusters with a specific impulse in the range of about 4,000-5,000 seconds. (Author)

  6. Performance of an optical equalizer in a 10 G wavelength converting optical access network.

    Science.gov (United States)

    Mendinueta, José Manuel D; Cao, Bowen; Thomsen, Benn C; Mitchell, John E

    2011-12-12

    A centralized optical processing unit (COPU) that functions both as a wavelength converter (WC) and optical burst equaliser in a 10 Gb/s wavelength-converting optical access network is proposed and experimentally characterized. This COPU is designed to consolidate drifting wavelengths generated with an uncooled laser in the upstream direction into a stable wavelength channel for WDM backhaul transmission and to equalize the optical loud/soft burst power in order to relax the burst-mode receiver dynamic range requirement. The COPU consists of an optical power equaliser composed of two cascaded SOAs followed by a WC. Using an optical packet generator and a DC-coupled PIN-based digital burst-mode receiver, the COPU is characterized in terms of payload-BER for back-to-back and backhaul transmission distances of 22, 40, and 62 km. We show that there is a compromise between the receiver sensitivity and overload points that can be optimized tuning the WC operating point for a particular backhaul fiber transmission distance. Using the optimized settings, sensitivities of -30.94, -30.17, and -27.26 dBm with overloads of -9.3, -5, and >-5 dBm were demonstrated for backhaul transmission distances of 22, 40 and 62 km, respectively. © 2011 Optical Society of America

  7. High-performance feedback-type active damping of LCL-filtered voltage source converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    a generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller design method based on the z-domain root contours and frequency-domain passivity theorem is proposed. It not only allows a co-design of the grid current controller and damping controller......Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing......, but ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate...

  8. Beta Radiation Enhanced Thermionic Emission from Diamond Thin Films

    Directory of Open Access Journals (Sweden)

    Alex Croot

    2017-11-01

    Full Text Available Diamond-based thermionic emission devices could provide a means to produce clean and renewable energy through direct heat-to-electrical energy conversion. Hindering progress of the technology are the thermionic output current and threshold temperature of the emitter cathode. In this report, we study the effects on thermionic emission caused by in situ exposure of the diamond cathode to beta radiation. Nitrogen-doped diamond thin films were grown by microwave plasma chemical vapor deposition on molybdenum substrates. The hydrogen-terminated nanocrystalline diamond was studied using a vacuum diode setup with a 63Ni beta radiation source-embedded anode, which produced a 2.7-fold increase in emission current compared to a 59Ni-embedded control. The emission threshold temperature was also examined to further assess the enhancement of thermionic emission, with 63Ni lowering the threshold temperature by an average of 58 ± 11 °C compared to the 59Ni control. Various mechanisms for the enhancement are discussed, with a satisfactory explanation remaining elusive. Nevertheless, one possibility is discussed involving excitation of preexisting conduction band electrons that may skew their energy distribution toward higher energies.

  9. Thermodynamics of photon-enhanced thermionic emission solar cells

    DEFF Research Database (Denmark)

    Reck, Kasper; Hansen, Ole

    2014-01-01

    Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE...

  10. Processes of preparation, deposition and analysis of thermionic emissive substances

    International Nuclear Information System (INIS)

    Romao, B.M. Verdelli; Muraro Junior, A.; Tessaroto, L.A.B.; Takahashi, J.

    1992-09-01

    This paper shows the results of the optimization of the process of preparation and deposition of thermionic emissive substances that are used in the oxide-cathodes which are utilized in the gun of the IEAv linear electron accelerator. (author). 5 refs., 5 figs

  11. Using Multispectral Imaging to Measure Temperature Profiles and Emissivity of Large Thermionic Dispenser, Cathodes

    International Nuclear Information System (INIS)

    Simmons, D.F.; Fortgang, C.M.; Holtkamp, D.B.

    2001-01-01

    Thermionic dispenser cathodes are widely used in modern high-power microwave tubes. Use of these cathodes has led to significant improvement in performance. In recent years these cathodes have been used in electron linear accelerators (LINACs), particularly in induction LINACs, such as the Experimental Test Accelerator at Lawrence Livermore National Laboratory and the Relativistic Test Accelerator at Lawrence Berkeley National Laboratory. For induction LINACs, the thermionic dispenser cathode provides greater reproducibility, longer pulse lengths, and lower emittance beams than does a field emission cathode. Los Alamos National Laboratory is fabricating a dual-axis X-ray radiography machine called dual-axis radiograph hydrodynamic test (DARHT). The second axis of DARHT consists of a 2-kA, 20-MeV induction LINAC that uses a 3.2-MeV electron gun with a tungsten thermionic-dispenser cathode. Typically the DARHT cathode current density is 10 A/cm 2 at 1050 C. Under these conditions current density is space-charge limited, which is desirable since current density is independent of temperature. At lower temperature (the temperature-limited regime) there are variations in the local current density due to a nonuniform temperature profile. To obtain the desired uniform current density associated with space-charge limited operation, the coolest area on the cathode must be at a sufficiently high temperature so that the emission is space-charge limited. Consequently, the rest of the cathode is emitting at the same space-charge-limited current density but is at a higher temperature than necessary. Because cathode lifetime is such a strong function of cathode temperature, there is a severe penalty for nonuniformity in the cathode temperature. For example, a temperature increase of 50 C means cathode lifetime will decrease by a factor of at least four. Therefore, we are motivated to measure the temperature profiles of our large-area cathodes

  12. Effect of updated data base and improved analysis on performance of radioisotope thermophotovoltaic converter

    International Nuclear Information System (INIS)

    Schock, A.; Or, C.T.

    1996-01-01

    Previous analyses of RTPV space power systems published by the authors were based on a number of approximations employed to permit early dissemination of preliminary results pending availability of fuller experimental data need3d to conduct more rigorous analyses. Among those approximations were: (1) the use of limited test data and optimistic projections of the spectral transmissivity of the RTPV's selective IR filters and of the spectral quantum efficiency of the GaSb PV cells; (2) the use of theoretical formulas instead of experimental measurements of the PV cell's open-circuit voltage, fill factor, and optimum voltage instead of its measured current-voltage characteristics; (3) rough estimates of the TPV converter's active-area fraction instead of computed values based on detailed designs; (4) inadequate accounting for the effect of radiation reflected by the IR filter and absorbed by the emitter in reducing the generator's required heat input; and (5) omission of the shadowing effect and ohmic losses caused by the PV cell's grid lines. The above-listed shortcomings of the previously published analyses are addressed in the present paper, which describes revised analyses based on recently obtained experimental data of IR filter reflectivities and PV cell quantum efficiencies and current-voltage characteristic, measured by EDTEK under an OSC-initiated subcontract to its ongoing DOE contract. Their test results show that EDTEK has been eminently successful in improving the reflectivities of the IR filters and in reproducing the quantum efficiencies of Boeing's best PV cells, but their initial (Dec-95) PV cell fell far short of matching the open-circuit voltages and fill factors predicted by theory

  13. Performance evaluation of a high power DC-DC boost converter for PV applications using SiC power devices

    Science.gov (United States)

    Almasoudi, Fahad M.; Alatawi, Khaled S.; Matin, Mohammad

    2016-09-01

    The development of Wide band gap (WBG) power devices has been attracted by many commercial companies to be available in the market because of their enormous advantages over the traditional Si power devices. An example of WBG material is SiC, which offers a number of advantages over Si material. For example, SiC has the ability of blocking higher voltages, reducing switching and conduction losses and supports high switching frequency. Consequently, SiC power devices have become the affordable choice for high frequency and power application. The goal of this paper is to study the performance of 4.5 kW, 200 kHz, 600V DC-DC boost converter operating in continuous conduction mode (CCM) for PV applications. The switching behavior and turn on and turn off losses of different switching power devices such as SiC MOSFET, SiC normally ON JFET and Si MOSFET are investigated and analyzed. Moreover, a detailed comparison is provided to show the overall efficiency of the DC-DC boost converter with different switching power devices. It is found that the efficiency of SiC power switching devices are higher than the efficiency of Si-based switching devices due to low switching and conduction losses when operating at high frequencies. According to the result, the performance of SiC switching power devices dominate the conventional Si power devices in terms of low losses, high efficiency and high power density. Accordingly, SiC power switching devices are more appropriate for PV applications where a converter of smaller size with high efficiency, and cost effective is required.

  14. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    Science.gov (United States)

    Kang, Tae-Woon; Noh, Yong-Jin; Yun, Jin-Mun; Yang, Si-Young; Yang, Yong-Eon; Lee, Hae-Seong; Na, Seok-In

    2015-06-01

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs.

  15. Electro-Mechanical Modeling and Performance Analysis of Floating Wave Energy Converters Utilizing Yo-Yo Vibrating System

    International Nuclear Information System (INIS)

    Sim, Kyuho; Park, Jisu; Jang, Seon-Jun

    2015-01-01

    This paper proposes a floating-type wave energy conversion system that consists of a mechanical part (yo-yo vibrating system, motion rectifying system, and power transmission system) and electrical part (power generation system). The yo-yo vibrating system, which converts translational input to rotational motion, is modeled as a single degree-of-freedom system. It can amplify the wave input via the resonance phenomenon and enhance the energy conversion efficiency. The electromechanical model is established from impedance matching of the mechanical part to the electrical system. The performance was analyzed at various wave frequencies and damping ratios for a wave input acceleration of 0.14 g. The maximum output occurred at the resonance frequency and optimal load resistance, where the power conversion efficiency and electrical output power reached 48% and 290 W, respectively. Utilizing the resonance phenomenon was found to greatly enhance the performance of the wave energy converter, and there exists a maximum power point at the optimum load resistance

  16. Electro-Mechanical Modeling and Performance Analysis of Floating Wave Energy Converters Utilizing Yo-Yo Vibrating System

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Kyuho; Park, Jisu [Seoul National University, Seoul (Korea, Republic of); Jang, Seon-Jun [Innovation KR, Seoul (Korea, Republic of)

    2015-01-15

    This paper proposes a floating-type wave energy conversion system that consists of a mechanical part (yo-yo vibrating system, motion rectifying system, and power transmission system) and electrical part (power generation system). The yo-yo vibrating system, which converts translational input to rotational motion, is modeled as a single degree-of-freedom system. It can amplify the wave input via the resonance phenomenon and enhance the energy conversion efficiency. The electromechanical model is established from impedance matching of the mechanical part to the electrical system. The performance was analyzed at various wave frequencies and damping ratios for a wave input acceleration of 0.14 g. The maximum output occurred at the resonance frequency and optimal load resistance, where the power conversion efficiency and electrical output power reached 48% and 290 W, respectively. Utilizing the resonance phenomenon was found to greatly enhance the performance of the wave energy converter, and there exists a maximum power point at the optimum load resistance.

  17. Performance Assessment of the Wave Dragon Wave Energy Converter Based on the EquiMar Methodology

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Chozas, Julia Fernandez; Pecher, Arthur

    2011-01-01

    At the present pre-commercial phase of the wave energy sector, device developers are called to provide reliable estimates on power performance and production at possible deployment locations. The EU EquiMar project has proposed a novel approach, where the performance assessment is based mainly...... on experimental data deriving from sea trials rather than solely on numerical predictions. The study applies this methodology to evaluate the performance of Wave Dragon at two locations in the North Sea, based on the data acquired during the sea trials of a 1:4.5 scale prototype. Indications about power...

  18. Angiotensin I - Converting Enzyme (ACE) gene polymorphism in relation to physical performance, cognition and survival

    DEFF Research Database (Denmark)

    Frederiksen, Henrik; Gaist, David; Bathum, Lise

    2003-01-01

    Studies of younger individuals have suggested an association between ACE genotype and physical and cognitive performance. Using a longitudinal study of elderly twins we studied the association between ACE genotype and physical and cognitive functioning and survival in old age.......Studies of younger individuals have suggested an association between ACE genotype and physical and cognitive performance. Using a longitudinal study of elderly twins we studied the association between ACE genotype and physical and cognitive functioning and survival in old age....

  19. New features of the MAX IV thermionic pre-injector

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, J., E-mail: joel.andersson@maxiv.lu.se; Olsson, D., E-mail: david.olsson@maxiv.lu.se; Curbis, F.; Malmgren, L.; Werin, S.

    2017-05-21

    The MAX IV facility in Lund, Sweden consists of two storage rings for production of synchrotron radiation. The smaller 1.5 GeV ring is presently under construction, while the larger 3 GeV ring is being commissioned. Both rings will be operating with top-up injections from a full-energy injector. During injection, the electron beam is first delivered to the main injector from a thermionic pre-injector which consists of a thermionic RF gun, a chopper system, and an energy filter. In order to reduce losses of high-energy electrons along the injector and in the rings, the electron beam provided by the thermionic pre-injector should have the correct time structure and energy distribution. In this paper, the design of the MAX IV thermionic pre-injector with all its sub components is presented. The electron beam delivered by the pre-injector and its dependence on parameters such as optics, cathode temperature, and RF power are studied. Measurements are here compared with simulation results obtained by particle tracking and electromagnetic codes. The chopper system is described in detail, and different driving schemes that optimize the injection efficiency for the two storage rings are investigated. During operation, it was discovered that the structure of the beam delivered by the gun is affected by mode beating between the accelerating and a low-order mode. This mode beating is also studied in detail. Finally, initial measurements of the electron beam delivered to the 3 GeV ring during commissioning are presented.

  20. Small ex-core heat pipe thermionic reactor concept (SEHPTR)

    International Nuclear Information System (INIS)

    Jacox, M.G.; Bennett, R.G.; Lundberg, L.B.; Miller, B.G.; Drexler, R.L.

    1991-01-01

    The Idaho National Engineering Laboratory (INEL) has developed an innovative space nuclear power concept with unique features and significant advantages for both Defense and Civilian space missions. The Small Ex-core Heat Pipe Thermionic Reactor (SEHPTR) concept was developed in response to Air Force needs for space nuclear power in the range of 10 to 40 kilowatts. This paper describes the SEHPTR concept and discusses the key technical issues and advantages of such a system

  1. THERMIONIC EMISSION ENHANCEMENT FROM CESIUM COATED RHENIUM IN ELECTRIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    de Steese, J. G.; Zollweg, R. J.

    1963-04-15

    The plasma-anode technique was used to observe anomalously high thermionic emission from a rhenium surface with small cesium coverage, where the work function of the composite surface is greater than the ionization potential of cesium. Data suggest that emission enhancement is caused by increased cesium coverage because of cesiumion trapping near the emitter surface under the influence of an ion-rich sheath. (auth)

  2. ITER convertible blanket evaluation

    International Nuclear Information System (INIS)

    Wong, C.P.C.; Cheng, E.

    1995-01-01

    Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate

  3. A performance study on a direct drive hydro turbine for wave energy converter

    International Nuclear Information System (INIS)

    Choi, Young Do; Kim, Chang Goo; Kim, You Taek; Lee, Young Ho; Song, Jung Il

    2010-01-01

    Clean and renewable energy technologies using ocean energy give us non-polluting alternatives to fossil-fueled power plants as a countermeasure against global warming and growing demand for electrical energy. Among the ocean energy resources, wave power takes a growing interest because of its enormous amount of potential energy in the world. Therefore, various types of wave power systems to capture the energy of ocean waves have been developed. However, a suitable turbine type is not yet normalized because of relatively low efficiency of the turbine systems. The purpose of this study is to investigate the performance of a newly developed direct drive hydro turbine (DDT), which will be built in a caisson for a wave power plant. Experiment and CFD analysis are conducted to clarify the turbine performance and internal flow characteristics. The results show that the DDT obtains fairly good turbine efficiency in cases with and without wave conditions. Most of the output power is generated at the runner passage of Stage 2. Relatively larger amount of the decreased tangential velocity at Stage 2 produces more angular momentum than that at Stage 1 and thus, the larger angular momentum at the Stage 2 makes a greater contribution to the generation of total output power in comparison with that at Stage 1. Large vortex existing in the upper-left region of the runner passage forms a large recirculation region in the runner passage, and the recirculating flow consumes the output power at Region 2

  4. A performance study on a direct drive hydro turbine for wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Do [Mokpo National University, Muan (Korea, Republic of); Kim, Chang Goo; Kim, You Taek; Lee, Young Ho [Korea Maritime University, Busan (Korea, Republic of); Song, Jung Il [Changwon National University, Changwon (Korea, Republic of)

    2010-11-15

    Clean and renewable energy technologies using ocean energy give us non-polluting alternatives to fossil-fueled power plants as a countermeasure against global warming and growing demand for electrical energy. Among the ocean energy resources, wave power takes a growing interest because of its enormous amount of potential energy in the world. Therefore, various types of wave power systems to capture the energy of ocean waves have been developed. However, a suitable turbine type is not yet normalized because of relatively low efficiency of the turbine systems. The purpose of this study is to investigate the performance of a newly developed direct drive hydro turbine (DDT), which will be built in a caisson for a wave power plant. Experiment and CFD analysis are conducted to clarify the turbine performance and internal flow characteristics. The results show that the DDT obtains fairly good turbine efficiency in cases with and without wave conditions. Most of the output power is generated at the runner passage of Stage 2. Relatively larger amount of the decreased tangential velocity at Stage 2 produces more angular momentum than that at Stage 1 and thus, the larger angular momentum at the Stage 2 makes a greater contribution to the generation of total output power in comparison with that at Stage 1. Large vortex existing in the upper-left region of the runner passage forms a large recirculation region in the runner passage, and the recirculating flow consumes the output power at Region 2

  5. Study on the Performance of the “Pendulor” Wave Energy Converter in an Array Configuration

    Directory of Open Access Journals (Sweden)

    Sudath Prasanna Gunawardane

    2016-04-01

    Full Text Available For over three decades the “Pendulor” wave energy device has had a significant influence in this field, triggering several research endeavours. It includes a top-hinged flap propelled by the standing waves produced in a caisson with a back wall on the leeward side. However, one of the main disadvantages which impedes its progress is the enormous expense involved in the construction of the custom made typical caisson structure, about a little more than one-quarter of the wave length. In this study, the influence of such design parameters on the performance of the device is investigated, via numerical modelling for a device arranged in an array configuration, for irregular waves. The potential wave theory is applied to derive the frequency-dependent hydrodynamic parameters by making a distinction in the fluid domain into a separate sea side and lee side. The Cummins equation was utilised for the development of the time domain equation of motion while the transfer function estimation methods were used to solve the convolution integrals. Finally, the device was tested numerically for irregular wave conditions for a 50 kW class unit. It was observed that in irregular wave operating conditions, the caisson chamber length could be reduced by 40% of the value estimated for the regular waves. Besides, the device demonstrated around 80% capture efficiency for irregular waves thus allowing provision for avoiding the employment of any active control.

  6. Comparison of performance of analog-to-digital converters (ADC) for pulse height analyzers

    International Nuclear Information System (INIS)

    Suzuki, Shogo; Hirai, Shoji

    1981-01-01

    In the recent ADCs for pulse height analyzers (PHA), Wilkinson type is a leading one, and those with 50 to 200 MHz clock frequency and 8K channel are mostly on the market. The comparison of the performance of ADCs was conducted under the condition of using these multi-channel PHAs as γ-ray spectrometers. The following three ADCs were compared: ADC incorporated in CANBERRA 8100 MCA, and CANBERRA 8060 ADCs used as the ADCs for 1st and 2nd GAMA systems. In this case, the conversion gains of these ADCs were set at 4K because the memory of 8100 MCA was 4K, and the GAMA systems were also mostly operated at 4K. In this paper, report is made on the measurements of dead time, the change of γ peaks immediately after the power was turned on, the temperature dependence of ADCs the long term stability of ADCs, derivative non-linearity, and integration non-linearity. The dead time of the ADC of 8100 CMA was shorter in the range up to 1000 channels. The temperature dependence was -0.017%/deg C in 8100 MCA, and -0.061 and -0.072%/deg C in GAMA. The long term stability was -0.02%/14 hr in 8100 MCA, and -0.027%/14 hr in 8060 of 1st GAMA. The derivative non-linearity was 0.45% in 8100 MCA, 0.67% in 8060 of 1st GAMA, and the integration non-linearity was 0.075% for 8100 MCA, and 0.085 - 0.1% in 8060 ADCs. Also, the change of γ peaks immediately after the power was turned on for 8100 ADC was better than that of 8060 ADC. (Wakatsuki, Y.)

  7. Comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element

    International Nuclear Information System (INIS)

    Wernsman, Bernard

    1997-01-01

    A comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element (TFE) is made. The single-cell TFE used in this study is the prototype for the 40 kW e space nuclear power system that is similar to the 6 kW e TOPAZ-II. The steady-state I-V measurements influence the emitter temperature due to electron cooling. Therefore, to eliminate the steady-state I-V measurement influence on the TFE and provide a better understanding of the behavior of the thermionic energy converter and TFE characteristics, dynamic I-V measurements are made. The dynamic I-V measurements are made at various input power levels, cesium pressures, collector temperatures, and steady-state current levels. From these measurements, it is shown that the dynamic I-V's do not change the TFE characteristics at a given operating point. Also, the evaluation of the collector work function from the dynamic I-V measurements shows that the collector optimization is not due to a minimum in the collector work function but due to an emission optimization. Since the dynamic I-V measurements do not influence the TFE characteristics, it is believed that these measurements can be done at a system level to understand the influence of TFE placement in the reactor as a function of the core thermal distribution

  8. An Improved Current Controller to ensure the robust performance of grid-connected converters under weak grid conditions

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2016-01-01

    Voltage Source Converters (VSCs) operating in very weak grids with low Short Circuit Ratio (SCR) are known to meet stability challenges. This article investigates instability of a grid connected current-controlled converter under weak grid conditions, which is often attributed to the dynamic...

  9. Electrical performance characteristics of high power converters for space power applications. Final report, 1 January 1988-30 September 1989

    International Nuclear Information System (INIS)

    Stuart, T.A.; King, R.J.

    1989-09-01

    The first goal of this project was to investigate various converters that would be suitable for processing electric power derived from a nuclear reactor. The implementation is indicated of a 20 kHz system that includes a source converter, a ballast converter, and a fixed frequency converter for generating the 20 kHz output. This system can be converted to dc simply by removing the fixed frequency converter. This present study emphasized the design and testing of the source and ballast converters. A push-pull current-fed (PPCF) design was selected for the source converter, and a 2.7 kW version of this was implemented using three 900 watt modules in parallel. The characteristic equation for two converters in parallel was derived, but this analysis did not yield any experimental methods for measuring relative stability. The three source modules were first tested individually and then in parallel as a 2.7 kW system. All tests proved to be satisfactory; the system was stable; efficiency and regulation were acceptable; and the system was fault tolerant. The design of a ballast-load converter, which was operated as a shunt regulator, was investigated. The proposed power circuit is suitable for use with BJTs because proportional base drive is easily implemented. A control circuit which minimizes switching frequency ripple and automatically bypasses a faulty shunt section was developed. A nonlinear state-space-averaged model of the shunt regulator was developed and shown to produce an accurate incremental (small-signal) dynamic model, even though the usual state-space-averaging assumptions were not met. The nonlinear model was also shown to be useful for large-signal dynamic simulation using PSpice

  10. Evidence for cluster shape effects on the kinetic energy spectrum in thermionic emission.

    Science.gov (United States)

    Calvo, F; Lépine, F; Baguenard, B; Pagliarulo, F; Concina, B; Bordas, C; Parneix, P

    2007-11-28

    Experimental kinetic energy release distributions obtained for the thermionic emission from C(n) (-) clusters, 10theory, these different features are analyzed and interpreted as the consequence of contrasting shapes in the daughter clusters; linear and nonlinear isomers have clearly distinct signatures. These results provide a novel indirect structural probe for atomic clusters associated with their thermionic emission spectra.

  11. Determining the thermionic converter interval parameters according to volt-ampere characteristics

    International Nuclear Information System (INIS)

    Kajbyshev, V.Z.

    1986-01-01

    On the basis of the condition for independence of plasma parameters on the collector emission and the expression for the ratio of the current from collector into plasma to the passing current at a great collector emission, the technique for determining the electron temperature near the collector, voltage drop in collector, and collector work function according to experimental characteristics is developed

  12. Gridded thermionic gun and integral superconducting ballistic bunch compression cavity

    Energy Technology Data Exchange (ETDEWEB)

    Schultheiss, Thomas [Advanced Energy Systems, Inc., Medford, NY (United States)

    2015-11-16

    Electron-Ion colliders such as the Medium energy Electron Ion Collider (MEIC) being developed by JLAB require high current electrons with low energy spread for electron cooling of the collider ring. Accelerator techniques for improving bunch charge, average current, emittance, and energy spread are required for Energy Recovery Linacs (ERLs) and Circulator Rings (CR) for next generation colliders for nuclear physics experiments. Example candidates include thermionic-cathode electron guns with RF accelerating structures. Thermionic cathodes are known to produce high currents and have excellent lifetime. The success of the IR and THz Free-Electron Laser (FEL) designed and installed by Advanced Energy Systems at the Fritz Haber Institute (FHI) of the Max Planck Society in Berlin [1,2] demonstrates that gridded thermionic cathodes and rf systems be considered for next generation collider technology. In Phase 1 Advanced Energy Systems (AES) developed and analyzed a design concept using a superconducting cavity pair and gridded thermionic cathode. Analysis included Beam Dynamics and thermal analysis to show that a design of this type is feasible. The latest design goals for the MEIC electron cooler were for electron bunches of 420 pC at a frequency of 952.6 MHz with a magnetic field on the cathode of 2kG. This field magnetizes the beam imparting angular momentum that provides for helical motion of the electrons in the cooling solenoid. The helical motion increases the interaction time and improves the cooling efficiency. A coil positioned around the cathode providing 2kG field was developed. Beam dynamics simulations were run to develop the particle dynamics near the cathode and grid. Lloyd Young added capability to Tstep to include space charge effects between two plates and include image charge effects from the grid. He also added new pepper-pot geometry capability to account for honeycomb grids. These additions were used to develop the beam dynamics for this gun. The

  13. Near-field enhanced thermionic energy conversion for renewable energy recycling

    Science.gov (United States)

    Ghashami, Mohammad; Cho, Sung Kwon; Park, Keunhan

    2017-09-01

    This article proposes a new energy harvesting concept that greatly enhances thermionic power generation with high efficiency by exploiting the near-field enhancement of thermal radiation. The proposed near-field enhanced thermionic energy conversion (NETEC) system is uniquely configured with a low-bandgap semiconductor cathode separated from a thermal emitter with a subwavelength gap distance, such that a significant amount of electrons can be photoexcited by near-field thermal radiation to contribute to the enhancement of thermionic current density. We theoretically demonstrate that the NETEC system can generate electric power at a significantly lower temperature than the standard thermionic generator, and the energy conversion efficiency can exceed 40%. The obtained results reveal that near-field photoexcitation can enhance the thermionic power output by more than 10 times, making this hybrid system attractive for renewable energy recycling.

  14. Nano-textured W shows improvement of thermionic emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Barmina, E.V.; Serkov, A.A.; Shafeev, G.A. [General Physics Institute of the Russian Academy of Sciences, Wave Research Center of A.M. Prokhorov, Moscow (Russian Federation); Stratakis, E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, (IESL-FORTH), Heraklion (Greece); University of Crete, Materials Science and Technology Department, Heraklion (Greece); Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, (IESL-FORTH), Heraklion (Greece); University of Crete, Physics Department, Heraklion (Greece); Stolyarov, V.N.; Stolyarov, I.N. [Roentgenprom, Protvino, Moscow (Russian Federation)

    2012-01-15

    Laser-assisted nano-texturing of W substrates cathodes via ablation in liquid environment is experimentally realized. Two laser sources are used, either a Ti:sapphire femtosecond laser or a Nd:YAG laser with pulse duration of 350 ps. Laser exposure of W results in the formation of hemi-spherical nanostructures situated on top of periodic ripples. Nano-textured thermionic W cathode demonstrates the decrease of the efficient work function by 0.3 eV compared to pristine surface. (orig.)

  15. Multi-channel pulser for the SLC thermionic electron source

    International Nuclear Information System (INIS)

    Browne, M.J.; Clendenin, J.E.; Corredoura, P.L.; Jobe, R.K.; Koontz, R.F.; Sodja, J.

    1985-01-01

    A new pulser developed for the SLC thermionic gun has been operational since September 1984. It consists of two planar triode amplifiers with a common output triode driving the gun cathode to produce two independent pulses of up to 9A with a 3 nsec FWHM pulse width. Three long-pulse amplifiers are also connected to the cathode to produce pulses with widths controllable between 100 nsec and 1.6 μsec. Each amplifier has independent timing and amplitude control through a fiber optic link to the high voltage plane of the gun cathode-grid structure. The pulser and its operating characteristics are described. 15 refs., 3 figs

  16. Practical implementation of the concept of converted electric vehicle with advanced traction and dynamic performance and environmental safety indicators

    Science.gov (United States)

    Sidorov, K. M.; Yutt, V. E.; Grishchenko, A. G.; Golubchik, T. V.

    2018-02-01

    The objective of the work presented in this paper is to describe the implementation of the technical solutions have been developed, with regard to structure, composition, and characteristics, for an experimental prototype of an electric vehicle which has been converted from a conventional vehicle. The methodology of the study results is based on the practical implementation of the developed concept of the conversion of conventional vehicles into electric vehicles. The main components of electric propulsion system of the experimental prototype of electric vehicle are developed and manufactured on the basis of computational researches, taking into account the criteria and principles of conversion within the framework of presented work. The article describes a schematic and a design of power conversion and commutation electrical equipment, traction battery, electromechanical transmission. These results can serve as guidance material in the design and implementation of electric propulsion system (EPS) components of electric vehicles, facilitate the development of optimal technical solutions in the development and manufacture of vehicles, including those aimed at autonomy of operation and the use of perspective driver assistance systems. As part of this work, was suggested a rational structure for an electric vehicle experimental prototype, including technical performance characteristics of the components of EPS.

  17. Performance and impedance studies of thin, porous molybdenum and tungsten electrodes for the alkali metal thermoelectric converter

    Science.gov (United States)

    Wheeler, B. L.; Williams, R. M.; Jeffries-Nakamura, B.; Lamb, J. L.; Loveland, M. E.; Bankston, C. P.; Cole, T.

    1988-01-01

    Columnar, porous, magnetron-sputtered molybdenum and tungsten films show optimum performance as alkali metal thermoelectric converter electrodes at thicknesses less than 1.0 micron when used with molybdenum or nickel current collector grids. Power densities of 0.40 W/sq cm for 0.5-micron molybdenum films at 1200 K and 0.35 W/sq cm for 0.5-micron tungsten films at 1180 K were obtained at electrode maturity after 40-90 h. Sheet resistances of magnetron sputter deposited films on sodium beta-double-prime-alumina solid electrolyte (BASE) substrates were found to increase very steeply as thickness is decreased below about 0.3-double-prime 0.4-micron. The ac impedance data for these electrodes have been interpreted in terms of contributions from the bulk BASE and the porous electrode/BASE interface. Voltage profiles of operating electrodes show that the total electrode area, of electrodes with thickness less than 2.0 microns, is not utilized efficiently unless a fairly fine (about 1 x 1 mm) current collector grid is employed.

  18. Mission operations for unmanned nuclear electric propulsion outer planet exploration with a thermionic reactor spacecraft.

    Science.gov (United States)

    Spera, R. J.; Prickett, W. Z.; Garate, J. A.; Firth, W. L.

    1971-01-01

    Mission operations are presented for comet rendezvous and outer planet exploration NEP spacecraft employing in-core thermionic reactors for electric power generation. The selected reference missions are the Comet Halley rendezvous and a Jupiter orbiter at 5.9 planet radii, the orbit of the moon Io. The characteristics of the baseline multi-mission NEP spacecraft are presented and its performance in other outer planet missions, such as Saturn and Uranus orbiters and a Neptune flyby, are discussed. Candidate mission operations are defined from spacecraft assembly to mission completion. Pre-launch operations are identified. Shuttle launch and subsequent injection to earth escape by the Centaur D-1T are discussed, as well as power plant startup and the heliocentric mission phases. The sequence and type of operations are basically identical for all missions investigated.

  19. Thermionic RF Gun and Linac Pre-Injector for SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.

    2003-08-11

    Preparations are underway to upgrade the Spear2 to the third generation light source. Installation of all the subsystems will start in April 2003. Although the Spear3 RF system is entirely different from the present form, the pre-injector gun/linac and booster synchrotron will remain the same even after the upgrade. The thermionic rf gun reliability and stability are to be improved to inject 500 mA of stored current in shortest possible time. When a top-up mode is enforced, where the stored beam decay is replenished to maintain the constant current and thus constant light intensity, the Spear3 will take injection every few minutes. In that case the gun, linac, and booster must stay on at all times. In this report we will describe some improvements made on the gun and linac in the recent past, as well as their present performance and future upgrade to be made.

  20. Thermionic cooling devices based on resonant-tunneling AlGaAs/GaAs heterostructure

    Science.gov (United States)

    Bescond, M.; Logoteta, D.; Michelini, F.; Cavassilas, N.; Yan, T.; Yangui, A.; Lannoo, M.; Hirakawa, K.

    2018-02-01

    We study by means of full quantum simulations the operating principle and performance of a semiconductor heterostructure refrigerator combining resonant tunneling filtering and thermionic emission. Our model takes into account the coupling between the electric and thermal currents by self-consistently solving the transport equations within the non-equilibrium Green’s function framework and the heat equation. We show that the device can achieve relatively high cooling power values, while in the considered implementation, the maximum lattice temperature drop is severely limited by the thermal conductivity of the constituting materials. In such an out-of-equilibrium structure, we then emphasize the significant deviation of the phonon temperature from its electronic counterpart which can vary over several hundred Kelvin. The interplay between those two temperatures and the impact on the electrochemical potential is also discussed. Finally, viable options toward an optimization of the device are proposed.

  1. X-Band Thermionic Cathode RF Gun at UTNL

    CERN Document Server

    Fukasawa, Atsushi; Dobashi, Katsuhiro; Ebina, Futaro; Hayano, Hitoshi; Higo, Toshiyasu; Kaneyasu, Tatsuo; Matsuo, Kennichi; Ogino, Haruyuki; Sakae, Hisaharu; Sakamoto, Fumito; Uesaka, Mitsuru; Urakawa, Junji

    2005-01-01

    The X-band (11.424 GHz) linac for compact Compton scattering hard X-ray source are under construction at Nuclear Engineering Research Laboratory, University of Tokyo. This linac designed to accelerate up to 35 MeV, and this electron beam will be used to produce hard X-ray by colliding with laser. It consists of a thermionic cathode RF gun, an alpha magnet, and a traveling wave tube. The gun has 3.5 cells (unloaded Q is 8250) and will be operated at pi-mode. A dispenser cathode is introduced. Since the energy spread of the beam from the gun is predicted to be broad due to the continuous emission from the thermionic cathode, a slit is placed in the alpha magnet to eliminate low energy electrons. The simulation on the injector shows the beam energy 2.9 MeV, the charge 23 pC/bunch, and the emittance less than 10 mm.mrad. The experiment on the gun is planed in the beginning of 2005, and the details will be discussed on the spot.

  2. Thermionic vacuum arc (TVA) technique for magnesium thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Balbag, M.Z., E-mail: zbalbag@ogu.edu.t [Eskisehir Osmangazi University, Education Faculty, Primary Education, Meselik Campus, Eskisehir 26480 (Turkey); Pat, S.; Ozkan, M.; Ekem, N. [Eskisehir Osmangazi University, Art and Science Faculty, Physics Department, Eskisehir 26480 (Turkey); Musa, G. [Ovidius University, Physics Department, Constanta (Romania)

    2010-08-15

    In this study, magnesium thin films were deposited on glass substrate by the Thermionic Vacuum Arc (TVA) technique for the first time. We present a different technique for deposition of high-quality magnesium thin films. By means of this technique, the production of films is achieved by condensing the plasma of anode material generated using Thermionic Vacuum Arc (TVA) under high vacuum conditions onto the surface to be coated. The crystal orientation and morphology of the deposited films were investigated by using XRD, EDX, SEM and AFM. The aim of this study is to search the use of TVA technique to coat magnesium thin films and to determine some of the physical properties of the films generated. Furthermore, this study will contribute to the scientific studies which search the thin films of magnesium or the compounds containing magnesium. In future, this study will be preliminary work to entirely produce magnesium diboride (MgB{sub 2}) superconductor thin film with the TVA technique.

  3. Thermionic emission of cermets made of refractory carbides

    International Nuclear Information System (INIS)

    Samsonow, G.W.; Bogomol, I.W.; Ochremtschuk, L.N.; Podtschernjajewa, I.A.; Fomenko, W.S.

    1975-01-01

    In order to improve the resistance to thermal variations of refractory carbides having good behavior for thermionic emission, they have been combined with transition metals d. Thermionic emission was studied with cermets in compact samples. Following systems were examined: TiC-Nb, TiC-Mo, TiC-W, ZrC-Nb, ZrC-Mo, ZrC-W, WC-Mo with compositions of: 75% M 1 C-25% M 2 , 50%M 1 C-50%M 2 , 25%M 1 C-75%M 2 . When following the variation of electron emission energy phi versus the composition, it appears that in the range of mixed crystals (M 1 M 2 )C, phi decreases and the resistance to thermal variations of these phases is higher than that of individual carbides. The study of obtained cermets shows that their resistance to thermal variations is largely superior to the one of starting carbides; TiC and ZrC carbides, combined with molybdenum and tungsten support the highest number of thermic cycles

  4. Thermionic and Photo-excited Electron Emission for Energy Conversion Processes

    Directory of Open Access Journals (Sweden)

    Patrick T. McCarthy

    2014-12-01

    Full Text Available This article describes advances in thermionic and photoemission materials and applications dating back to the work on thermionic emission by Guthrie in 1873 and the photoelectric effect by Hertz in 1887. Thermionic emission has been employed for electron beam generation from Edison’s work with the light bulb to modern day technologies such as scanning and transmission electron microscopy. The photoelectric effect has been utilized in common devices such as cameras and photocopiers while photovoltaic cells continue to be widely successful and further researched. Limitations in device efficiency and materials have thus far restricted large-scale energy generation sources based on thermionic and photoemission. However, recent advances in the fabrication of nanoscale emitters suggest promising routes for improving both thermionic and photo-enhanced electron emission along with newly developed research concepts, e.g., photonically enhanced thermionic emission. However, the abundance of new emitter materials and reduced dimensions of some nanoscale emitters increases the complexity of electron emission theory and engender new questions related to the dimensionality of the emitter. This work presents derivations of basic two and three-dimensional thermionic and photoemission theory along with comparisons to experimentally acquired data. The resulting theory can be applied to many different material types regardless of composition, bulk and surface structure.

  5. Thermionic and Photo-Excited Electron Emission for Energy-Conversion Processes

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, Patrick T. [Birck Nanotechnology Center, School of Mechanical Engineering, Purdue University, West Lafayette, IN (United States); Reifenberger, Ronald G. [Birck Nanotechnology Center, School of Physics, Purdue University, West Lafayette, IN (United States); Fisher, Timothy S., E-mail: tsfisher@purdue.edu [Birck Nanotechnology Center, School of Mechanical Engineering, Purdue University, West Lafayette, IN (United States)

    2014-12-09

    This article describes advances in thermionic and photo-emission materials and applications dating back to the work on thermionic emission by Guthrie (1873) and the photoelectric effect by Hertz (1893). Thermionic emission has been employed for electron beam generation from Edison’s work with the light bulb to modern day technologies such as scanning and transmission electron microscopy. The photoelectric effect has been utilized in common devices such as cameras and photocopiers while photovoltaic cells continue to be widely successful and further researched. Limitations in device efficiency and materials have thus far restricted large-scale energy generation sources based on thermionic and photoemission. However, recent advances in the fabrication of nanoscale emitters suggest promising routes for improving both thermionic and photo-enhanced electron emission along with newly developed research concepts, e.g., photonically enhanced thermionic emission. However, the abundance of new emitter materials and reduced dimensions of some nanoscale emitters increases the complexity of electron-emission theory and engender new questions related to the dimensionality of the emitter. This work presents derivations of basic two and three-dimensional thermionic and photo-emission theory along with comparisons to experimentally acquired data. The resulting theory can be applied to many different material types regardless of composition, bulk, and surface structure.

  6. Nano-scale investigations of electric-dipole-layer enhanced field and thermionic emission from high current density cathodes

    Science.gov (United States)

    Vlahos, Vasilios

    Cesium iodide coated graphitic fibers and scandate cathodes are two important electron emission technologies. The coated fibers are utilized as field emitters for high power microwave sources. The scandate cathodes are promising thermionic cathode materials for pulsed power vacuum electron devices. This work attempts to understand the fundamental physical and chemical relationships between the atomic structure of the emitting cathode surfaces and the superior emission characteristics of these cathodes. Ab initio computational modeling in conjunction with experimental investigations was performed on coated fiber cathodes to understand the origin of their very low turn on electric field, which can be reduced by as much as ten-fold compared to uncoated fibers. Copious amounts of cesium and oxygen were found co-localized on the fiber, but no iodine was detected on the surface. Additional ab initio studies confirmed that cesium oxide dimers could lower the work function significantly. Surface cesium oxide dipoles are therefore proposed as the source of the observed reduction in the turn on electric field. It is also proposed that emission may be further enhanced by secondary electrons from cesium oxide during operation. Thermal conditioning of the coated cathode may be a mechanism by which surface cesium iodide is converted into cesium oxide, promoting the depletion of iodine by formation of volatile gas. Ab initio modeling was also utilized to investigate the stability and work functions of scandate structures. The work demonstrated that monolayer barium-scandium-oxygen surface structures on tungsten can dramatically lower the work function of the underlying tungsten substrate from 4.6 eV down to 1.16 eV, by the formation of multiple surface dipoles. On the basis of this work, we conclude that high temperature kinetics force conventional dispenser cathodes (barium-oxygen monolayers on tungsten) to operate in a non-equilibrium compositional steady state with higher than

  7. Hydrogen converters

    International Nuclear Information System (INIS)

    Mondino, Angel V.

    2003-01-01

    The National Atomic Energy Commission of Argentina developed a process of 99 Mo production from fission, based on irradiation of uranium aluminide targets with thermal neutrons in the RA-3 reactor of the Ezeiza Atomic Centre. These targets are afterwards dissolved in an alkaline solution, with the consequent liberation of hydrogen as the main gaseous residue. This work deals with the use of a first model of metallic converter and a later prototype of glass converter at laboratory scale, adjusted to the requirements and conditions of the specific redox process. Oxidized copper wires were used, which were reduced to elementary copper at 400 C degrees and then regenerated by oxidation with hot air. Details of the bed structure and the operation conditions are also provided. The equipment required for the assembling in cells is minimal and, taking into account the operation final temperature and the purge with nitrogen, the procedure is totally safe. Finally, the results are extrapolated for the design of a converter to be used in a hot cell. (author)

  8. Single conversion audio amplifier and DC-AC converters with high performance and low complexity control scheme

    DEFF Research Database (Denmark)

    Poulsen, Søren; Andersen, Michael Andreas E.

    2004-01-01

    This paper proposes a novel control topology for a mains isolated single conversion audio amplifier and DC-AC converters. The topology is made for use in audio applications, and differs from prior art in terms of significantly reduced distortion as well as lower system complexity. The topology can...

  9. High performance control strategy for single-phase three-level neutral-point-clamped traction four-quadrant converters

    DEFF Research Database (Denmark)

    Kejian, Song; Konstantinou, Georgios; Jing, Li

    2017-01-01

    Operational data from Chinese railways indicate a number of challenges for traction four-quadrant converter (4QC) control including low-order voltage and current harmonics and reference tracking. A control strategy for a single-phase three-level neutral-point-clamped 4QC employed in the electric...

  10. The effect of samarium doping on structure and enhanced thermionic emission properties of lanthanum hexaboride fabricated by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shenlin; Hu, Qianglin [College of Mathematics and Physics, Jinggangshan University, Jian (China); Zhang, Jiuxing; Liu, Danmin [Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing (China); Huang, Qingzhen [NIST Center for Neutron Research, National Institute of Standards and Technology, MD (United States)

    2014-03-15

    Single-phase polycrystalline solid solutions (La{sub 1-x}Sm{sub x})B{sub 6} (x = 0, 0.2, 0.4, 0.8, 1) are fabricated by spark plasma sintering (SPS). This study demonstrates a systematic investigation of structure-property relationships in Sm-doped LaB{sub 6} ternary rare-earth hexaborides. The microstructure, crystallographic orientation, electrical resistivity, and thermionic emission performance of these compounds are investigated. Analysis of the results indicates that samarium (Sm) doping has a noticeable effect on the structure and performance of lanthanum hexaboride (LaB{sub 6}). The analytical investigation of the electron backscatter diffraction confirms that (La{sub 0.6}Sm{sub 0.4})B{sub 6} exhibits a clear (001) texture that results in a low work function. Work functions are determined by pulsed thermionic diode measurements at 1500-1873 K. The (La{sub 0.6}Sm{sub 0.4})B{sub 6} possesses improved thermionic emission properties compared to LaB{sub 6}. The current density of (La{sub 0.6}Sm{sub 0.4})B{sub 6} is 42.4 A cm{sup -2} at 1873 K, which is 17.5% larger than that of LaB{sub 6}. The values of Φ{sub R} for (La{sub 0.6}Sm{sub 0.4})B{sub 6} and LaB{sub 6} are 1.98 ± 0.03 and 1.67 ± 0.03 eV, respectively. Furthermore, the Sm substitution of lanthanum (La) effectively increases the electrical resistivity. These results reveal that Sm doping lead to significantly enhanced thermionic emission properties of LaB{sub 6}. The compound (La{sub 0.6}Sm{sub 0.4})B{sub 6} appears most promising as a future emitter material. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Improving Power Converter Reliability

    DEFF Research Database (Denmark)

    Ghimire, Pramod; de Vega, Angel Ruiz; Beczkowski, Szymon

    2014-01-01

    of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental......The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector?emitter voltage...... is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation...

  12. Simulations of thermionic suppression during tungsten transient melting experiments.

    Czech Academy of Sciences Publication Activity Database

    Komm, Michael; Tolias, P.; Ratynskaia, S.; Dejarnac, Renaud; Gunn, J. P.; Krieger, K.; Podolník, Aleš; Pitts, R.A.; Pánek, Radomír

    T170, December (2017), č. článku 014069. ISSN 0031-8949. [PFMC 2017: 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications. Düsseldorf, 16.05.2017-19.05.2017] R&D Projects: GA ČR(CZ) GA16-14228S; GA MŠk(CZ) 8D15001 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : tokamak * thermionic emission * tungsten * melt * plasma-facing component Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: 1.3 Physical sciences Impact factor: 1.280, year: 2016 http://iopscience.iop.org/article/10.1088/1402-4896/aa9209

  13. Solid-State Thermionic Nuclear Power for Megawatt Propulsion, Planetary Surface and Commercial Power Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermionic (TI) power conversion is a promising technology first investigated for power conversion in the 1960’s, and of renewed interest due to modern...

  14. Determination of rare earth elements in high purity rare earth oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry

    International Nuclear Information System (INIS)

    Stijfhoorn, D.E.; Stray, H.; Hjelmseth, H.

    1993-01-01

    A high-performance liquid chromatographic (HPLC) method for the determination of rare earth elements in rocks has been modified and used for the determination of rare earth elements (REE) in high purity rare earth oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare earth oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix element was not collected, interference from this element during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those elements that were not affected by the matrix. Commercial samples of high purity Nd 2 O 3 , Gd 2 O 3 and Dy 2 O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS is presented. (Author)

  15. Ray converter

    International Nuclear Information System (INIS)

    Reiss, K.H.

    1976-01-01

    In a radiographic system a converter is used for changing image forming intensity distribution in a bundle of penetrating rays into a flow of electrically charged particles by electrodes located in a gas space and partly latticed (grids) which lie at potentials stepped from cathode to anode. The invention is particularly characterized by the provision of at least two grids extending between and parallel to the cathode and the anode. The electrical field which lies between two electrodes lies at least between the grids located closest to the cathode being to the extent of between 1 and 10 percent, in the average preferably 3 percent below the electrical break down field in the gas in a homogeneous electrical field

  16. Development of a novel thermionic RF electron gun applied on a compact THz-FEL facility

    Science.gov (United States)

    Hu, T. N.; Pei, Y. J.; Qin, B.; Liu, K. F.; Feng, G. Y.

    2018-04-01

    The current requirements from civil and commercial applications lead to the development of compact free-electron laser (FEL)-based terahertz (THz) radiation sources. A picosecond electron gun plays an important role in an FEL-THz facility and attracts significant attention, as machine performance is very sensitive to initial conditions. A novel thermionic gun with an external cathode (EC) and two independently tunable cavities (ITCs) has been found to be a promising alternative to conventional electron sources due to its remarkable characteristics, and correspondingly an FEL injector can achieve a balance between a compact layout and high brightness benefitting from the velocity bunching properties and RF focusing effects in the EC-ITC gun. Nevertheless, the EC-ITC gun has not been extensively examined as part of the FEL injector in the past years. In this regard, to fill this gap, a development focusing on the experimental setup of an FEL injector based on an EC-ITC gun is described in detail. Before assembly, dynamic beam simulations were performed to investigate the optimal mounting position for the Linac associated with the focusing coils, and a suitable radio-frequency (RF) system was established based on a power coupling design and allocation. The testing bench proved to be fully functional through basic experiments using typical diagnostic approaches for estimating primary parameters. Associated with dynamic beam calculations, a performance evaluation for an EC-ITC gun was established while providing indirect testing results for an FEL injector.

  17. Impedance interactions in bidirectional cascaded converter

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Chen, Zhe

    2016-01-01

    A cascaded converter is built by connecting one elementary converter to another. Output impedance of one converter will therefore interact with input impedance of the other converter. This interaction will change when power flow reverses. To compare this difference, an investigation is performed...

  18. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    International Nuclear Information System (INIS)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-01-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012 © . RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance

  19. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    Energy Technology Data Exchange (ETDEWEB)

    Rimjaem, S., E-mail: sakhorn.rimjaem@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand); Kusoljariyakul, K.; Thongbai, C. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400 (Thailand)

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012{sup ©}. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  20. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    Science.gov (United States)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012©. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  1. Measuring current emission and work functions of large thermionic cathodes

    International Nuclear Information System (INIS)

    Fortgang, C.M.

    2001-01-01

    As one component of the nations Stockpile Stewardship program, Los Alamos National Laboratory is constructing a 20 MeV, 2 kA (with a 4 kA upgrade capability), 3ps induction linac for doing x-ray radiography of explosive devices. The linac is one leg of a facility called the Dual-Axis Radiography Hydrodynamic Test Facility (DARHT). The electron gun is designed to operate at 3.2 MV. The gun is a Pierce type design and uses a 6.5' cathode for 2 kA operation and an 8' cathode for 4 kA operation. We have constructed a small facility called the Cathode Test Stand (CTS) to investigate engineering and physics issues regarding large thermionic dispenser-cathodes. In particular, we have looked at the issues of temperature uniformity on the cathode surface and cathode quality as measured by its work function. We have done thermal imaging of both 8' and 6.5' cathodes. Here we report on measurements of the cathode work function, both the average value and how it vanes across the face of the cathode.

  2. Development and fabrication of insulator seals for thermionic diodes

    Science.gov (United States)

    Poirier, V. L.

    1972-01-01

    Eight different types of cermet seals for thermionic diodes were investigated: (1) 1 micron Al2O3 with Nb spheres; (2) 200 A Al2O3 with Nb spheres; (3) 1 micron Al2O3 with Nb 1% Zr spheres; (4) 200 A Al2O3 with Nb 1% Zr spheres; (5) Pure Y2O3 with Nb 1% Zr spheres; (6) Y2O3 3% ZrO2 with Nb 1% Zr spheres; (7) Y2O3 10% ZrO2 with Nb 1% Zr spheres; and (8) ZrO2 12% Y2O3 with Nb 1% Zr spheres. Investigations were made to determine the most favorable fabrication techniques and the effect of the bonding cycle, (length of bonding time and shutdown sequences). The analysis of the seals included tensile test, vacuum test, electrical test and metallurgical examination. At the conclusion of the development phase, 36 seals were fabricated for delivery for evaluation.

  3. The influence of internal current loop on transient response performance of I-V droop controlled paralleled DC-DC converters

    DEFF Research Database (Denmark)

    Wang, Haojie; Han, Minxiao; Guerrero, Josep M.

    2017-01-01

    The external droop control loop of I-V droop control is designed as a voltage loop with embedded virtual impedance, so the internal current loop plays a major role in the system bandwidth. Thus, in this paper, the influence of internal current loop on transient response performance of I-V droop...... controlled paralleled dc-dc converters is analyzed, which is guided and significant for its industry application. The model which is used for dynamic analysis is built, and the root locus method is used based on the model to analyze the dynamic response of the system by shifting different control parameters...

  4. On thermionic emission from plasma-facing components in tokamak-relevant conditions.

    Czech Academy of Sciences Publication Activity Database

    Komm, Michael; Ratynskaia, S.; Tolias, P.; Cavalier, Jordan; Dejarnac, Renaud; Gunn, J. P.; Podolník, Aleš

    2017-01-01

    Roč. 59, č. 9 (2017), č. článku 094002. ISSN 0741-3335 R&D Projects: GA ČR(CZ) GA16-14228S; GA MŠk(CZ) 8D15001 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : thermionic * PIC * tungsten * tokamak * thermionic emission * plasma facing components * particle-in-cell Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.392, year: 2016 http://iopscience.iop.org/article/10.1088/1361-6587/aa78c4/pdf

  5. Simulation Results of Double Forward Converter

    Directory of Open Access Journals (Sweden)

    P. Vijaya KUMAR

    2009-12-01

    Full Text Available This work aims to find a better forward converter for DC to DC conversion.Simulation of double forward converter in SMPS system is discussed in this paper. Aforward converter with RCD snubber to synchronous rectifier and/or to current doubleris also discussed. The evolution of the forward converter is first reviewed in a tutorialfashion. Performance parameters are discussed including operating principle, voltageconversion ratio, efficiency, device stress, small-signal dynamics, noise and EMI. Itscircuit operation and its performance characteristics of the forward converter with RCDsnubber and double forward converter are described and the simulation results arepresented.

  6. High-performance control of a three-phase voltage-source converter including feedforward compensation of the estimated load current

    International Nuclear Information System (INIS)

    Leon, Andres E.; Solsona, Jorge A.; Busada, Claudio; Chiacchiarini, Hector; Valla, Maria Ines

    2009-01-01

    In this paper a new control strategy for voltage-source converters (VSC) is introduced. The proposed strategy consists of a nonlinear feedback controller based on feedback linearization plus a feedforward compensation of the estimated load current. In our proposal an energy function and the direct-axis current are considered as outputs, in order to avoid the internal dynamics. In this way, a full linearization is obtained via nonlinear transformation and feedback. An estimate of the load current is feedforwarded to improve the performance of the whole system and to diminish the capacitor size. This estimation allows to obtain a more rugged and cheaper implementation. The estimate is calculated by using a nonlinear reduced-order observer. The proposal is validated through different tests. These tests include performance in presence of switching frequency, measurement filters delays, parameters uncertainties and disturbances in the input voltage.

  7. The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2012-01-01

    Power semiconductor switching devices play an important role in the performance of high power wind energy generation systems. The state-of-the-art device choices in the wind power application as reported in the industry include IGBT modules, IGBT press-pack and IGCT press-pack. Because...

  8. Energy Storage System by Means of Improved Thermal Performance of a 3 MW Grid Side Wind Power Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    method of the energy storage system. Then the conventional thermal evaluation approach is simplified for evaluation with long term wind profile. The case studies are done to address the optimal power size and capacity of the energy storage system by comparing the improvement of the thermal performance....... Also, the two promising candidates, ultracapacitors and batteries, are compared....

  9. 3D nanoporous graphene films converted from liquid-crystalline holey graphene oxide for thin and high-performance supercapacitors

    Science.gov (United States)

    Wang, Bin; Liu, Jinzhang; Zhao, Yi; Zheng, Dezhi; Li, Yan; Sha, Jiangbo

    2018-01-01

    Holey graphene oxide (HGO) is prepared and its liquid crystal (LC) formation in water is investigated. The blade-coated LC-HGO hydrogel is hydrothermally reduced to form 3D nanoporous films used as supercapacitor electrodes. Holey graphene sheets are rumpled and interconnected to form a cellular structure with pore size around 100 nm during the reduction process. Reduced HGO films with different thicknesses are integrated into solid-state symmetric supercapacitors and their electrochemical performances are studied. High specific capacitance up to 304 F g-1 and high volumetric capacitance around 400 F cm-3 are achieved from our thin and flexible devices.

  10. High Performance Reduced Order Models for Wind Turbines with Full-Scale Converters Applied on Grid Interconnection Studies

    DEFF Research Database (Denmark)

    Pereira, Heverton A.; F. Cupertino, Allan; Teodorescu, Remus

    2014-01-01

    Wind power has achieved technological evolution, and Grid Code (GC) requirements forced wind industry consolidation in the last three decades. However, more studies are necessary to understand how the dynamics inherent in this energy source interact with the power system. Traditional energy...... of Absolute Error (NIAE). Models are analyzed during wind speed variations and balanced voltage dip. During faults, WPPs must be able to supply reactive power to the grid, and this characteristic is analyzed. Using the proposed performance index, it is possible to conclude if a reduced order model is suitable...

  11. Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Haertelt, M.; Meijer, G.; Fielicke, A.; Bakker, J. M.

    2013-01-01

    The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb-n (n = 5-20) over the 200-350 cm(-1)

  12. Numerical simulations of the thermionic electron gun for electron-beam welding and micromachining

    Czech Academy of Sciences Publication Activity Database

    Jánský, Pavel; Zlámal, J.; Lencová, Bohumila; Zobač, Martin; Vlček, Ivan; Radlička, Tomáš

    2009-01-01

    Roč. 84, č. 2 (2009), s. 357-362 ISSN 0042-207X R&D Projects: GA AV ČR IAA100650805 Institutional research plan: CEZ:AV0Z20650511 Keywords : Numerical simulation * Thermionic emission * Electron gun Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.975, year: 2009

  13. Simple model for the description of a thermionic Cs diode in operation

    International Nuclear Information System (INIS)

    Tschersich, K.G.

    1975-01-01

    Because of the small voltage loss in the space between the electrodes, Cs is the most common work medium in thermionic diodes. With the model calculations of the processes in the space between the electrodes, the author aims to explain the formation of Cs ions and the current transport through the electrode gap at these low voltages. (RW/AK) [de

  14. Measures to alleviate the back bombardment effect of thermionic rf electron gun

    International Nuclear Information System (INIS)

    Huang, Y.; Xie, J.

    1991-01-01

    Thermionic rf electron gun finds application as a high brightness electron source for rf linacs. However, cathode heating from back-bombardment effect causes a ramp in the macro-pulse beam current and limit the usable pulse width. Three methods: ring cathode, magnetic deflection and laser assisted heating are studied in theory and in experiment. The results of these studies are reported

  15. Simulation and performance enhancement of the air cooling system in a DC/AC power converter station

    Energy Technology Data Exchange (ETDEWEB)

    Lozowy, R.; El-Shaboury, A.; Soliman, H.; Ormiston, S. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical and Manufacturing Engineering

    2010-07-01

    This study analyzed the flow structure and heat transfer in a large 3-dimensional domain with turbulence, mixed convection, an impinging jet, and flow over heated blocks. The objective was to better understand turbulent mixed-convection cooling of heat-generating bodies in 3-dimensional enclosures, which is important to industry. The cooling of 2 thyristor valve halls was simulated. Each valve hall housed 3 towers that contained electronics used in DC/AC power conversion. The simulation results included the magnitudes of the net air flows for all the inter-block gaps and the maximum temperature in each gap. A parametric study was also performed to investigate the effects of the air inlet location, size and aspect ratio. The effects of the air injection angle on cooling effectiveness was also examined. The study showed that for fixed inlet mass flow rate, significant improvement in the cooling effectiveness can be obtained by changing the injection angle of the inlet air jet, the location of the inlet grill, or the size of the inlet grill. It was concluded that these study results may be relevant to other applications, such as the design of power transformers, the design of cooling systems for spent nuclear fuel and computer server cooling racks. 13 refs., 12 figs.

  16. Transformerless dc-Isolated Converter

    Science.gov (United States)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  17. The Use of Angiotensin-I Converting Enzyme I/D Genetic Polymorphism as a Biomarker of Athletic Performance in Humans

    Directory of Open Access Journals (Sweden)

    Maria Fernanda De Mello Costa

    2012-10-01

    Full Text Available Angiotensin II is a key regulator of blood pressure and cardiovascular function in mammals. The conversion of angiotensin into its active form is carried out by Angiotensin I-Converting Enzyme (ACE. The measurement of ACE concentration in plasma or serum, its enzymatic activity, and the correlation between an insertion/deletion (I/D genetic polymorphism of the ACE gene have been investigated as possible indicators of superior athletic performance in humans. In this context, other indicators of superior adaptation to exercise resulting in better athletic performance (such as ventricular hypertrophy, VO2 max, and competition results were mostly used to study the association between ACE I/D polymorphism and improved performance. Despite the fact that the existing literature presents little consensus, there is sufficient scientific evidence to warrant further investigation on the usage of ACE activity and the I/D ACE gene polymorphism as biomarkers of superior athletic performance in humans of specific ethnicities or in athletes involved in certain sports. In this sense, a biomarker would be a substance or genetic component that could be measured to provide a degree of certainty, or an indication, of the presence of a certain trait or characteristic that would be beneficial to the athlete’s performance. Difficulties in interpreting and comparing the results of scientific research on the topic arise from dissimilar protocols and variation in study design. This review aims to investigate the current literature on the use of ACE I/D polymorphism as a biomarker of performance in humans through the comparison of scientific publications.

  18. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  19. Performance modeling of an integral, self-regulating cesium reservoir for the ATI-TFE

    International Nuclear Information System (INIS)

    Thayer, K.L.; Ramalingam, M.L.; Young, T.J.

    1993-01-01

    This work covers the performance modeling of an integral metal-matrix cesium-graphite reservoir for operation in the Advanced Thermionic Initiative-Thermionic Fuel Element (ATI-TFE) converter configuration. The objectives of this task were to incorporate an intercalated cesium-graphite reservoir for the 3C 24 Cs→2C 36 Cs+Cs (g) two phase equilibrium reaction into the emitter lead region of the ATI-TFE. A semi two-dimensional, cylindrical TFE computer model was used to obtain thermal and electrical converter output characteristics for various reservoir locations. The results of this study are distributions for the interelectrode voltage, output current density, and output power density as a function of axial position along the TFE emitter. This analysis was accomplished by identifying an optimum cesium pressure for three representative pins in the ATI ''driverless'' reactor core and determining the corresponding position of the graphite reservoir in the ATI-TFE lead region. The position for placement of the graphite reservoir was determined by performing a first-order heat transfer analysis of the TFE lead region to determine its temperature distribution. The results of this analysis indicate that for the graphite reservoirs investigated the 3C 24 Cs→2C 36 Cs+Cs (g) equilibrium reaction reservoir is ideal for placement in the TFE emitter lead region. This reservoir can be directly coupled to the emitter, through conduction, to provide the desired cesium pressure for optimum performance. The cesium pressure corresponding to the optimum converter output performance was found to be 2.18 torr for the ATI core least power TFE, 2.92 torr for the average power TFE, and 4.93 torr for the maximum power TFE

  20. Research and Development of a New Field Enhanced Low Temperature Thermionic Cathode that Enables Fluorescent Dimming and Loan Shedding without Auxiliary Cathode Heating

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jin

    2009-01-07

    This is the final report for project entitled 'Research and development of a new field enhanced low temperature thermionic cathode that enables fluorescent dimming and load shedding without auxiliary cathode heating', under Agreement Number: DE-FC26-04NT-42329. Under this project, a highly efficient CNT based thermionic cathode was demonstrated. This cathode is capable of emitting electron at a current density two order of magnitude stronger then a typical fluorescent cathode at same temperatures, or capable of emitting at same current density but at temperature about 300 C lower than that of a fluorescent cathode. Detailed fabrication techniques were developed including CVD growth of CNTs and sputter deposition of oxide thin films on CNTs. These are mature technologies that have been widely used in industry for large scale materials processing and device fabrications, thus, with further development work, the techniques developed in this project can be scaled-up in manufacturing environment. The prototype cathodes developed in this project were tested in lighting plasma discharge environment. In many cases, they not only lit and sustain the plasma, but also out perform the fluorescent cathodes in key parameters such like cathode fall voltages. More work will be needed to further evaluate more detailed and longer term performance of the prototype cathode in lighting plasma.

  1. High-Performance, 0.6-eV, GA0.32In0.68As/In0.32P0.68 Thermophotovoltaic Converters and Monolithically Interconnected Modules

    International Nuclear Information System (INIS)

    Duda, A.; Murray, C.S.

    1998-01-01

    Recent progress in the development of high-performance, 0.6-eV Ga0.32In0.68As/InAs0.32P0.68 thermophotovoltaic (TPV) converters and monolithically interconnected modules (MIMs) is described. The converter structure design is based on using a lattice-matched InAs0.32P0.68/Ga0.32In0.68As/InAs0.32P0.68 double-heterostructure (DH) device, which is grown lattice-mismatched on an InP substrate, with an intervening compositionally step-graded region of InAsyP1-y. The Ga0.32In0.68As alloy has a room-temperature band gap of 0.6 eV and contains a p/n junction. The InAs0.32P0.68 layers have a room-temperature band gap of 0.96 eV and serve as passivation/confinement layers for the Ga0.32In0.68As p/n junction. InAsyP1-y step grades have yielded DH converters with superior electronic quality and performance characteristics. Details of the microstructure of the converters are presented. Converters prepared for this work were grown by atmospheric-pressure metalorganic vapor-phase epitaxy (APMOVPE) and were processed using a combination of photolithography, wet-chemical etching, and conventional metal and insulator deposition techniques. Excellent performance characteristics have been demonstrated for the 0.6-eV TPV converters. Additionally, the implementation of MIM technology in these converters has been highly successful

  2. Technologies for converter topologies

    Science.gov (United States)

    Zhou, Yan; Zhang, Haiyu

    2017-02-28

    In some embodiments of the disclosed inverter topologies, an inverter may include a full bridge LLC resonant converter, a first boost converter, and a second boost converter. In such embodiments, the first and second boost converters operate in an interleaved manner. In other disclosed embodiments, the inverter may include a half-bridge inverter circuit, a resonant circuit, a capacitor divider circuit, and a transformer.

  3. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  4. Non-equilibrium thermionic electron emission for metals at high temperatures

    Science.gov (United States)

    Domenech-Garret, J. L.; Tierno, S. P.; Conde, L.

    2015-08-01

    Stationary thermionic electron emission currents from heated metals are compared against an analytical expression derived using a non-equilibrium quantum kappa energy distribution for the electrons. The latter depends on the temperature decreasing parameter κ ( T ) , which decreases with increasing temperature and can be estimated from raw experimental data and characterizes the departure of the electron energy spectrum from equilibrium Fermi-Dirac statistics. The calculations accurately predict the measured thermionic emission currents for both high and moderate temperature ranges. The Richardson-Dushman law governs electron emission for large values of kappa or equivalently, moderate metal temperatures. The high energy tail in the electron energy distribution function that develops at higher temperatures or lower kappa values increases the emission currents well over the predictions of the classical expression. This also permits the quantitative estimation of the departure of the metal electrons from the equilibrium Fermi-Dirac statistics.

  5. Performance Improvement for Two-Stage Single-Phase Grid-Connected Converters Using a Fast DC Bus Control Scheme and a Novel Synchronous Frame Current Controller

    Directory of Open Access Journals (Sweden)

    Bingzhang Li

    2017-03-01

    Full Text Available Two-stage single-phase grid-connected converters are widely used in renewable energy applications. Due to the presence of a second harmonic ripple across the DC bus voltage, it is very challenging to design the DC bus voltage control scheme in single-phase grid-connected inverters. The DC bus voltage controller must filter the ripple and balance a tradeoff between low harmonic distortion and high bandwidth. This paper presents a fast DC bus voltage controller, which uses a second order digital finite impulse response (FIR notch filter in conjunction with input power feedforward scheme to ensure the steady-state and dynamic performance. To gain the input power without extra hardware, a Kalman filter is incorporated to estimate the DC bus input current. At the same time, a modulation compensation strategy is implemented to eliminate the nonlinearity of the grid current control loop, which is caused by the DC bus voltage ripple. Moreover, a novel synchronous frame current controller for single-phase systems is also introduced, and its equivalent model in stationary frame has been derived. Simulation and experimental results are provided to verify the effective of the proposed control scheme.

  6. Potential Therapeutic Applications of Mucuna pruriens Peptide Fractions Purified by High-Performance Liquid Chromatography as Angiotensin-Converting Enzyme Inhibitors, Antioxidants, Antithrombotic and Hypocholesterolemic Agents.

    Science.gov (United States)

    Herrera-Chalé, Francisco; Ruiz-Ruiz, Jorge Carlos; Betancur-Ancona, David; Segura-Campos, Maira Rubi

    2016-02-01

    A Mucuna pruriens protein concentrate was hydrolyzed with a digestive (pepsin-pancreatin) enzymatic system. The soluble portion of the hydrolysate was fractionated by ultrafiltration and the ultrafiltered peptide fraction (PF) with lower molecular weight was purified by reversed-phase high-performance liquid chromatography. The PF obtained were evaluated by testing the biological activity in vitro. Fractions showed that the ability to inhibit the angiotensin-converting enzyme had IC50 values that ranged from 2.7 to 6.2 μg/mL. Trolox equivalent antioxidant capacity values ranged from 132.20 to 507.43 mM/mg. The inhibition of human platelet aggregation ranged from 1.59% to 11.11%, and the inhibition of cholesterol micellar solubility ranged from 0.24% to 0.47%. Hydrophobicity, size, and amino acid sequence could be factors in determining the biological activity of peptides contained in fractions. This is the first report that M. pruriens peptides act as antihypertensives, antioxidants, and inhibitors for human platelet aggregation and cholesterol micellar solubility in vitro.

  7. Thermionic detection of the ionic fragments of continiuum-state pair absorption systems

    International Nuclear Information System (INIS)

    Hotop, R.; Niemax, K.; Richter, J.; Weber, K.H.

    1981-01-01

    Using a thermionic diode we have detected the ionic fragments formed by associative ionization and dissociation after continuum-state pair absorption processes in Cs-Cs and Cs-K systems. Assuming an ionization probability of unity of the excited species and calibrating the pair absorption bands by taking into account the known photoionization cross section of the atoms we found excellent agreement with data from classical absorption measurements. (orig.)

  8. Evaluation of precision in measurements of uranium isotope ratio by thermionic mass spectrometry

    International Nuclear Information System (INIS)

    Moraes, N.M.P. de; Rodrigues, C.

    1977-01-01

    The parameters which affect the precision and accuracy of uranium isotopic ratios measurements by thermionic mass spectrometry are discussed. A statistical designed program for the analysis of the internal and external variances are presented. It was done an application of this statistical methods, in order to get mass discrimination factor, and its standard mean deviation, by using some results already published for 235 U/ 238 U ratio in NBS uranium samples, and natural uranium [pt

  9. Performance Comparison between ĆUK and SEPIC Converters for Maximum Power Point Tracking Using Incremental Conductance Technique in Solar Power Applications

    OpenAIRE

    James Dunia; Bakari M. M. Mwinyiwiwa

    2013-01-01

    Photovoltaic (PV) energy is one of the most important energy resources since it is clean, pollution free, and endless. Maximum Power Point Tracking (MPPT) is used in photovoltaic (PV) systems to maximize the photovoltaic output power, irrespective the variations of temperature and radiation conditions. This paper presents a comparison between Ćuk and SEPIC converter in maximum power point tracking (MPPT) of photovoltaic (PV) system. In the paper, advantages and disadvantages of both converter...

  10. Work function and surface stability of tungsten-based thermionic electron emission cathodes

    Science.gov (United States)

    Jacobs, Ryan; Morgan, Dane; Booske, John

    2017-11-01

    Materials that exhibit a low work function and therefore easily emit electrons into vacuum form the basis of electronic devices used in applications ranging from satellite communications to thermionic energy conversion. W-Ba-O is the canonical materials system that functions as the thermionic electron emitter commercially used in a range of high-power electron devices. However, the work functions, surface stability, and kinetic characteristics of a polycrystalline W emitter surface are still not well understood or characterized. In this study, we examined the work function and surface stability of the eight lowest index surfaces of the W-Ba-O system using density functional theory methods. We found that under the typical thermionic cathode operating conditions of high temperature and low oxygen partial pressure, the most stable surface adsorbates are Ba-O species with compositions in the range of Ba0.125O-Ba0.25O per surface W atom, with O passivating all dangling W bonds and Ba creating work function-lowering surface dipoles. Wulff construction analysis reveals that the presence of O and Ba significantly alters the surface energetics and changes the proportions of surface facets present under equilibrium conditions. Analysis of previously published data on W sintering kinetics suggests that fine W particles in the size range of 100-500 nm may be at or near equilibrium during cathode synthesis and thus may exhibit surface orientation fractions well described by the calculated Wulff construction.

  11. The Performance of Chrome-Coated Copper as Metallic Catalytic Converter to Reduce Exhaust Gas Emissions from Spark-Ignition Engine

    Science.gov (United States)

    Warju; Harto, S. P.; Soenarto

    2018-01-01

    One of the automotive technologies to reduce exhaust gas emissions from the spark-ignition engine (SIE) is by using a catalytic converter. The aims of this research are firstly to conduct a metallic catalytic converter, secondly to find out to what extend chrome-coated copper plate (Cu+Cr) as a catalyst is efficient. To measure the concentration of carbon monoxide (CO) and hydrocarbon (HC) on the frame there are two conditions required. First is when the standard condition, and second is when Cu+Cr metallic catalytic converter is applied using exhaust gas analyzer. Exhaust gas emissions from SIE are measured by using SNI 19-7118.1-2005. The testing of CO and HC emissions were conducted with variable speed to find the trend of exhaust gas emissions from idle speed to high speed. This experiment results in the fact that the use of Cu+Cr metallic catalytic converter can reduce the production of CO and HC of a four-stroke gasoline engine. The reduction of CO and HC emission are 95,35% and 79,28%. Using active metal catalyst in form of metallic catalytic converter, it is gained an optimum effective surface of a catalyst which finally is able to decrease the amount of CO and HC emission significantly in every spinning happened in the engine. Finally, this technology can be applied to the spark ignition engine both car and motorcycle to support blue sky program in Indonesia.

  12. Study of beam transverse properties of a thermionic electron gun for application to a compact THz free electron laser

    International Nuclear Information System (INIS)

    Hu, Tongning; Qin, Bin; Tan, Ping; Chen, Qushan; Yang, Lei; Pei, Yuanji; Li, Ji

    2014-01-01

    A novel thermionic electron gun adopted for use in a high power THz free electron laser (FEL) is proposed in this paper. By optimization of the structural and radiofrequency (RF) parameters, the physical design of the gun is performed using dynamic calculations. Velocity bunching is used to minimize the bunch's energy spread, and the dynamic calculation results indicate that high quality beams can be provided. The transverse properties of the beams generated by the gun are also analyzed. The novel RF focusing effects of the resonance cavity are investigated precisely and are used to establish emittance compensation, which enables the injector length to be reduced. In addition, the causes of the extrema of the beam radius and the normalized transverse emittance are analyzed and interpreted, respectively, and slice simulations are performed to illustrate how the RF focusing varies along the bunch length and to determine the effects of that variation on the emittance compensation. Finally, by observation of the variations of the beam properties in the drift tube behind the electron gun, prospective assembly scenarios for the complete THz-FEL injector are discussed, and a joint-debugging process for the injector is implemented

  13. Smart AD and DA Converters

    NARCIS (Netherlands)

    Roermund, van A.H.M.; Hegt, J.A.; Harpe, P.J.A.; Radulov, G.I.; Zanikopoulos, A.; Doris, K.; Quinn, P.J.

    2005-01-01

    In this paper, a concept is proposed to solve the problems related to the embedding of AD and DA converters in system-on-chips, FPGAs or other VLSI solutions. Problems like embedded testing, yield, reliability and reduced design space become crucial bottlenecks in the integration of high-performance

  14. Power converters definitions, classification and converter topologies

    CERN Document Server

    Bordry, Frederick

    2006-01-01

    This paper introduces power conversion principles and defines the terminology. The concepts of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the notions of commutation cell and soft commutation are introduced and discussed.

  15. Optimal thermionic energy conversion with established electrodes for high-temperature topping and process heating. [coal combustion product environments

    Science.gov (United States)

    Morris, J. F.

    1980-01-01

    Applied research-and-technology (ART) work reveals that optimal thermionic energy conversion (TEC) with approximately 1000 K to approximately 1100 K collectors is possible using well established tungsten electrodes. Such TEC with 1800 K emitters could approach 26.6% efficiency at 27.4 W/sq cm with approximately 1000 K collectors and 21.7% at 22.6 W/sq cm with approximately 1100 K collectors. These performances require 1.5 and 1.7 eV collector work functions (not the 1 eV ultimate) with nearly negligible interelectrode losses. Such collectors correspond to tungsten electrode systems in approximately 0.9 to approximately 6 torr cesium pressures with 1600 K to 1900 K emitters. Because higher heat-rejection temperatures for TEC allow greater collector work functions, interelectrode loss reduction becomes an increasingly important target for applications aimed at elevated temperatures. Studies of intragap modifications and new electrodes that will allow better electron emission and collection with lower cesium pressures are among the TEC-ART approaches to reduced interelectrode losses. These solutions will provide very effective TEC to serve directly in coal-combustion products for high-temperature topping and process heating. In turn this will help to use coal and to use it well.

  16. The Thermionic System Evaluation Test (TSET): Descriptions, limitations, and the involvement of the space nuclear power community

    International Nuclear Information System (INIS)

    Morris, D.B.

    1993-01-01

    Project and test planning for the Thermionic System Evaluation Test (TSET) Project began in August 1990. Since the formalization of the contract agreement two years ago, the TOPAZ-II testing hardware was delivered in May 1992. In the months since the delivery of the test hardware, Russians and Americans working side-by-side installed the equipment and are preparing to begin testing in early 1993. The procurement of the Russian TOPAZ-II unfueled thermionic space nuclear power system (SNP) provides a unique opportunity to understand a complete thermionic system and enhances the possibility for further study of this type of power conversion for space applications. This paper will describe the program and test article, facility and test article limitations, and how the government and industry are encouraged to be involved in the program

  17. Multilevel converters for 10 MW Wind Turbines

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2011-01-01

    Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters...... that the three-level and five-level H-bridge converter topologies both have potential to achieve improved thermal performances compared to the three-level Neutral-Point-Clamped converter topology in the wind power application....

  18. Cascaded resonant bridge converters

    Science.gov (United States)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  19. The influences of noble gas on the volt-ampere characteristics of a thermionic Cs diode

    International Nuclear Information System (INIS)

    Tschersich, K.G.

    1975-10-01

    The influence of the distance between electrodes and of the partial pressure of added xenon on the voltage drop in the electrode gap is investigated by measuring current density-voltage curves on plane parallel thermionic test diodes. With unchanged diode parameters, an addition of xenon reduces the voltage drop when the product of Cs vapour pressure and electrode gap is smaller than an optimum value of about 5 x 10 -2 cm.Torr. The xenon influences the mobility and thus the duration of the Cs ions. These procedures are explained and discussed using a relatively simple mathematical model. (GG/LH) [de

  20. Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P.; Sun, Y.; Harris, J.R.; Lewellen, J.W.

    2017-06-02

    Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current.

  1. The outlook for application of powerful nuclear thermionic reactor -powered space electric jet propulsion engines

    International Nuclear Information System (INIS)

    Semyonov, Y.P.; Bakanov, Y.A.; Synyavsky, V.V.; Yuditsky, V.D.

    1997-01-01

    This paper summarizes main study results for application of powerful space electric jet propulsion unit (EJPUs) which is powered by Nuclear Thermionic Power Unit (NTPU). They are combined in Nuclear Power/Propulsion Unit (NPPU) which serves as means of spacecraft equipment power supply and spacecraft movement. Problems the paper deals with are the following: information satellites delivery and their on-orbit power supply during 10-15 years, removal of especially hazardous nuclear wastes, mining of asteroid resources and others. Evaluations on power/time/mass relationship for this type of mission are given. EJPU parameters are compatible with Russian existent or being under development launch vehicle. (author)

  2. Theory of thermionic emission from a two-dimensional conductor and its application to a graphene-semiconductor Schottky junction

    Science.gov (United States)

    Trushin, Maxim

    2018-04-01

    The standard theory of thermionic emission developed for three-dimensional semiconductors does not apply to two-dimensional materials even for making qualitative predictions because of the vanishing out-of-plane quasiparticle velocity. This study reveals the fundamental origin of the out-of-plane charge carrier motion in a two-dimensional conductor due to the finite quasiparticle lifetime and huge uncertainty of the out-of-plane momentum. The theory is applied to a Schottky junction between graphene and a bulk semiconductor to derive a thermionic constant, which, in contrast to the conventional Richardson constant, is determined by the Schottky barrier height and Fermi level in graphene.

  3. Surface phenomena in thermionic research. Oberflaechenphysikalische Probleme der Thermionik. Vortrage aus der Round-table- Konferenz im Institut fuer Energiewandlung und Elektrische Antriebe der DFVLR in Stuttgart 1972 [Nine papers, 4 summaries

    Energy Technology Data Exchange (ETDEWEB)

    Henne, R. (ed.)

    1973-07-15

    This report compiles papers concerning especially recent developments in work function theory and work function measurements, which were given at a round table conference about surface phenomena in thermionic research, arranged by the 'Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt' in Stuttgart on Nov. 20 and Dec. 1, 1972. 9 papers are printed completely, 4 others in form of a summary. Two of them concern the work function of uncovered surfaces, 2 others show the influence of adsorbed electropositive elements (Cs, Sr) on work function. In 4 papers the coadsorption of electropositive (Cs, Sr, resp. Ba) and electronegative (O {sub 2}) elements and their influence on work function of different surfaces are discussed. Finally a paper is added, describing the development of Sr-Cs-alloys, which are of interest for the generation of the atmosphere of a Sr-Cs-converter by means of one single reservoir. (auth)

  4. Surface phenomena in thermionic research. Oberflaechenphysikalische Probleme der Thermionik. Vortrage aus der Round-table- Konferenz im Institut fuer Energiewandlung und Elektrische Antriebe der DFVLR in Stuttgart 1972 [Nine papers, 4 summaries

    Energy Technology Data Exchange (ETDEWEB)

    Henne, R [ed.

    1973-07-15

    This report compiles papers concerning especially recent developments in work function theory and work function measurements, which were given at a round table conference about surface phenomena in thermionic research, arranged by the 'Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt' in Stuttgart on Nov. 20 and Dec. 1, 1972. 9 papers are printed completely, 4 others in form of a summary. Two of them concern the work function of uncovered surfaces, 2 others show the influence of adsorbed electropositive elements (Cs, Sr) on work function. In 4 papers the coadsorption of electropositive (Cs, Sr, resp. Ba) and electronegative (O {sub 2}) elements and their influence on work function of different surfaces are discussed. Finally a paper is added, describing the development of Sr-Cs-alloys, which are of interest for the generation of the atmosphere of a Sr-Cs-converter by means of one single reservoir. (auth)

  5. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...... head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...

  6. Electric current - frequency converter

    International Nuclear Information System (INIS)

    Kumahara, Tadashi; Kinbana, Setsuro.

    1967-01-01

    Herein disclosed is an improved simple electric current-frequency converter, the input current and output frequency linearity of which is widened to a range of four to five figures while compensating, for temperature. The converter may be used for computor processing and for telemetering the output signals from a nuclear reactor. The converter is an astable multivibrator which includes charging circuits comprising emitter-voltage compensated NPN transistors, a charged voltage detecting circuit of temperature compensated field effect transistors, and a transistor switching circuit for generating switching pulses independent of temperature. The converter exhibited a 0.7% frequency change within a range of 5 - 45 0 C and less than a 0.1% frequency drift after six hours of operation when the input current was maintained constant. (Yamaguchi, T.)

  7. The measure system of thermion energy switch over in reactor

    International Nuclear Information System (INIS)

    Li Xing

    1999-01-01

    The system is the application of VI in the field of reactor, to use LabWINDOW/CVI and currency PC collection card, the system can measure and analyse the speciality of V-I and temperature. It is perfectly and high rate performance system, it can be expand to 128 channels for get dissimilitude signal. It can be used in M and C of all kinds field

  8. Development of Kabila rocket: A radioisotope heated thermionic plasma rocket engine

    Directory of Open Access Journals (Sweden)

    Kalomba Mboyi

    2015-04-01

    Full Text Available A new type of plasma rocket engine, the Kabila rocket, using a radioisotope heated thermionic heating chamber instead of a conventional combustion chamber or catalyst bed is introduced and it achieves specific impulses similar to the ones of conventional solid and bipropellant rockets. Curium-244 is chosen as a radioisotope heat source and a thermal reductive layer is also used to obtain precise thermionic emissions. The self-sufficiency principle is applied by simultaneously heating up the emitting material with the radioisotope decay heat and by powering the different valves of the plasma rocket engine with the same radioisotope decay heat using a radioisotope thermoelectric generator. This rocket engine is then benchmarked against a 1 N hydrazine thruster configuration operated on one of the Pleiades-HR-1 constellation spacecraft. A maximal specific impulse and power saving of respectively 529 s and 32% are achieved with helium as propellant. Its advantages are its power saving capability, high specific impulses and simultaneous ease of storage and restart. It can however be extremely voluminous and potentially hazardous. The Kabila rocket is found to bring great benefits to the existing spacecraft and further research should optimize its geometric characteristics and investigate the physical principals of its operation.

  9. Design study on an independently-tunable-cells thermionic RF gun

    International Nuclear Information System (INIS)

    Hama, H.; Tanaka, T.; Hinode, F.; Kawai, M.

    2006-01-01

    Characteristics of a thermionic RF gun have been studied by a 3-D simulation code developed using an FDTD (Finite Difference Time Domain) method as a Maxwell's equations solver. The gun is consists of two independent power feeding cavities, so that we call it independently-tunable-cells (ITC)'-RF gun. The first cell is the cathode cell and the second one is an accelerating cell. The ITC gun can be operated at various modes of different RF-power ratio and phase between two cavities. Simulation study shows a velocity-bunching like effect may be occurred in the gun, so that the short pulse beam from the thermionic RF gun is a better candidate to produce the coherent THz synchrotron radiation. Expected bunch length with a total charge of ∼20 pC (1% energy width from the top energy) is around 200 fs (fwhm). Even the beam energy extracted from the gun is varied by which the input powers are changed, almost same shape of the longitudinal phase space can be produced by tuning the phase. (author)

  10. Advantages and implications of U233 fueled thermionic space power energy conversion

    International Nuclear Information System (INIS)

    Terrell, C.W.

    1992-01-01

    In this paper two recent analyses are reported which demonstrate advantages of a U233 fueled thermionic fuel element (TFE) compared to 93 w/o U235, and that application (mission) has broad latitude in how space power reactor systems could or should be optimized. A reference thermionic reactor system was selected to provide the basis for the fuel comparisons. Both oxide and metal fuel forms were compared. Of special interest was to estimate the efficiencies of the four fuel forms to produce electrical power. A figure of merit (FOM) was defined which is directly proportional to the electrical average electrical power produced is proportional to the electrical power produced per unit uranium mass. In a TFE the average electrical power produced is proportional to the emitter surface area (Esa), hence the ratio Esa/Mu was selected as the FOM. Results indicate that the choice of fuel type and form leads to wide variations in critical and system masses FOM values, and system total power

  11. Design and implementation of a fs-resolved transmission electron microscope based on thermionic gun technology

    Energy Technology Data Exchange (ETDEWEB)

    Piazza, L., E-mail: luca.piazza@epfl.ch [Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), ICMP, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Masiel, D.J. [Integrated Dynamic Electron Solutions, Inc., 455 Bolero Drive, Danville, CA 94526 (United States); LaGrange, T.; Reed, B.W. [Condensed Matter and Materials Division Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Barwick, B. [Department of Physics, Trinity College, 300 Summit St., Hartford, CT 06106 (United States); Carbone, Fabrizio [Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), ICMP, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)

    2013-09-23

    Highlights: • We present the implementation of a femtosecond-resolved ultrafast TEM. • This is the first ultrafast TEM based on a thermionic gun geometry. • An additional condenser lens has been used to maximize the electron count. • We achieved a time resolution of about 300 fs and an energy resolution of 1 eV. - Abstract: In this paper, the design and implementation of a femtosecond-resolved ultrafast transmission electron microscope is presented, based on a thermionic gun geometry. Utilizing an additional magnetic lens between the electron acceleration and the nominal condenser lens system, a larger percentage of the electrons created at the cathode are delivered to the specimen without degrading temporal, spatial and energy resolution significantly, while at the same time maintaining the femtosecond temporal resolution. Using the photon-induced near field electron microscopy effect (PINEM) on silver nanowires the cross-correlation between the light and electron pulses was measured, showing the impact of the gun settings and initiating laser pulse duration on the electron bunch properties. Tuneable electron pulses between 300 fs and several ps can be obtained, and an overall energy resolution around 1 eV was achieved.

  12. Thermionic Properties of Carbon Based Nanomaterials Produced by Microhollow Cathode PECVD

    Science.gov (United States)

    Haase, John R.; Wolinksy, Jason J.; Bailey, Paul S.; George, Jeffrey A.; Go, David B.

    2015-01-01

    Thermionic emission is the process in which materials at sufficiently high temperature spontaneously emit electrons. This process occurs when electrons in a material gain sufficient thermal energy from heating to overcome the material's potential barrier, referred to as the work function. For most bulk materials very high temperatures (greater than 1500 K) are needed to produce appreciable emission. Carbon-based nanomaterials have shown significant promise as emission materials because of their low work functions, nanoscale geometry, and negative electron affinity. One method of producing these materials is through the process known as microhollow cathode PECVD. In a microhollow cathode plasma, high energy electrons oscillate at very high energies through the Pendel effect. These high energy electrons create numerous radical species and the technique has been shown to be an effective method of growing carbon based nanomaterials. In this work, we explore the thermionic emission properties of carbon based nanomaterials produced by microhollow cathode PECVD under a variety of synthesis conditions. Initial studies demonstrate measureable current at low temperatures (approximately 800 K) and work functions (approximately 3.3 eV) for these materials.

  13. Synthesis, thermionic emission and magnetic properties of (NdxGd1–x)B6

    International Nuclear Information System (INIS)

    Bao Li-Hong; Zhang Jiu-Xing; Zhou Shen-Lin; Tegus

    2011-01-01

    Polycrystalline rare-earth hexaborides (Nd x Gd 1–x )B 6 (x = 0, 0.2, 0.6, 0.8, 1) were prepared by the reactive spark plasma sintering (SPS) method using mixed powder of GdH 2 , NdH 2 and B. The effects of Nd doping on the crystal structure, the grain orientation, the thermionic emission and the magnetic properties of the hexaboride were investigated by X-ray diffraction, electron backscattered diffraction and magnetic measurements. It is found that all the samples sintered by the SPS method exhibit high densities (> 95%) and high values of Vickers hardness (2319 kg/mm 2 ). The values are much higher than those obtained in the traditional method. With the increase of Nd content, the thermionic emission current density increases from 11 to 16.30 A/cm 2 and the magnetic phase transition temperature increases from 5.85 to 7.95 K. Thus, the SPS technique is a suitable method to synthesize the dense rare-earth hexaborides with excellent properties. (interdisciplinary physics and related areas of science and technology)

  14. A THREE-PHASE BOOST DC-AC CONVERTER

    African Journals Online (AJOL)

    dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.

  15. Enhancing the performance of photovoltaic cells by using down-converting KCaGd(PO4)2∶Eu3+ phosphors

    Institute of Scientific and Technical Information of China (English)

    Yen-Chi Chen; Woan-Yu Huang; Teng-Ming Chen

    2011-01-01

    The goal of this work is aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic (PV) cells by using the solar spectral conversion principle,which employed a down-converting phosphor to convert a high-energy ultraviolet photon to the less energetic red-emitting photons to improve the spectral response of Si solar cells.In this study,the surface of silicon solar cells was coated with a red-emitting KCaGd(PO4)2∶Eu3+ phosphor by using the screen-printing technique.In addition to the investigation on the microstructure using scanning electron microscopy (SEM),we measured the short circuit current (Isc),open circuit voltage (Voc),and power conversion efficiency (η) of spectral-conversion cells and compared with those of bare solar cells as a reference.Preliminary experimental results revealed that in an optimized PV cell,an enhancement of (0.64+0.01)% (from 16.03% to 16.67%) in △η ofa Si-based PV cell was achieved.

  16. Novel screening techniques for wind turbine power converters

    DEFF Research Database (Denmark)

    Jørgensen, Asger Bjørn; Sønderskov, Simon Dyhr; Christensen, Nicklas

    2016-01-01

    Power converters represent one of the highest failure rates in the wind turbine. Therefore converter manufacturers perform burn-in tests to prevent shipping of faulty converters. Recent developments in junction temperature estimation, based on accurate online IGBT collector-emitter voltage...... measurements, allow for thermal stress estimation of the IGBT modules. This is utilized to detect infant mortalities in power converters, by comparing thermal responses of IGBTs for faulty and non-faulty converters. The method proves to be a time and cost efficient candidate to replace burn-in tests of power...... converters for wind turbines applications....

  17. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  18. Converting the reset

    NARCIS (Netherlands)

    J.K. Hoogland (Jiri); C.D.D. Neumann; D. Bloch

    2001-01-01

    textabstractWe give a simple algorithm to incorporate the effects of resets in convertible bond prices, without having to add an extra factor to take into account the value of the reset. Furthermore we show that the effect of a notice period, and additional make-whole features, can be treated in a

  19. Definition of Power Converters

    CERN Document Server

    Bordry, F

    2015-01-01

    The paper is intended to introduce power conversion principles and to define common terms in the domain. The concept s of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the commutation cell and soft commuta tion are introduced and discussedd.

  20. Thermoelectrode for thermoelectric converter

    International Nuclear Information System (INIS)

    Bodiul, Pavel; Bondarciuc, Nicolae; Ghitu, Dumitru; Nikolaeva, Albina; Konopko, Leonid; Turcan, Ana

    2008-01-01

    The invention relates to the electronic engneering and can be used for manufacturing of thermoelectrodes for thermoelectric converters. The thermoelectrode is made of semiconductor anisotropic material in the form of thread in glass insulation. At the same timer, the thread is made of stannum-doped tellurium in the ratio of 0.1...3 at.%.

  1. The Convertible Arbitrage Strategy Analyzed

    NARCIS (Netherlands)

    Loncarski, I.; Ter Horst, J.R.; Veld, C.H.

    2006-01-01

    This paper analyzes convertible bond arbitrage on the Canadian market for the period 1998 to 2004.Convertible bond arbitrage is the combination of a long position in convertible bonds and a short position in the underlying stocks. Convertible arbitrage has been one of the most successful strategies

  2. Generation of multi-branch beam with thermionic gun for the Japan linear collider

    International Nuclear Information System (INIS)

    Naito, T.; Akemoto, M.; Matsumonto, H.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

    1992-01-01

    We report on the development of a thermionic gun that is capable of producing multi-bunch beam to be used at the KEK Accelerator Test Facility for the Japan Linear Collider project. Two types of grid pulse generators have been developed. One is an avalanche pulse generator. A Y-646E cathode was successfully operated to generate double-bunch beam with a pulse width shorter than 700 ps, bunch spacing 1.4 ns, and a peak current 4.3 A. The other grid pulse generator is a fast ECL circuit with an RF power amplifier. Generation of 20-pulse trains with 2.1 ns time spacing has been demonstrated. (Author) 4 refs., 6 figs

  3. Current transmission and nonlinear effects in un-gated thermionic cathode RF guns

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Harris, J. R. [Air Force Weapons Lab

    2017-05-03

    Un-gated thermionic cathode RF guns are well known as a robust source of electrons for many accelerator applications. These sources are in principle scalable to high currents without degradation of the transverse emittance due to control grids but they are also known for being limited by back-bombardment. While back-bombardment presents a significant limitation, there is still a lack of general understanding on how emission over the whole RF period will affect the nature of the beams produced from these guns. In order to improve our understanding of how these guns can be used in general we develop analytical models that predict the transmission efficiency as a function of the design parameters, study how bunch compression and emission enhancement caused by Schottky barrier lowering affect the output current profile in the gun, and study the onset of space-charge limited effects and the resultant virtual cathode formation leading to a modulation in the output current distribution.

  4. Communication: Effects of thermionic-gun parameters on operating modes in ultrafast electron microscopy

    Directory of Open Access Journals (Sweden)

    Erik Kieft

    2015-09-01

    Full Text Available Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes. This has been demonstrated with conventional Wehnelt electrodes and absent any applied bias. Here, by conducting simulations using the General Particle Tracer code, we define the electron-gun parameter space within which various modes may be optimized. The properties of interest include electron collection efficiency, temporal and energy spreads, and effects of laser-pulse duration incident on the LaB6 source. We find that collection efficiencies can reach 100% for all modes, despite there being no bias applied to the electrode.

  5. Photon-Enhanced Thermionic Emission in Cesiated p-Type and n-Type Silicon

    DEFF Research Database (Denmark)

    Reck, Kasper; Dionigi, Fabio; Hansen, Ole

    2014-01-01

    electrons. Efficiencies above 60% have been predicted theoretically for high solar concentration systems. Silicon is an interesting absorber material for high efficiency PETE solar cells, partly due to its mechanical and thermal properties and partly due to its electrical properties, including a close......Photon-enhanced thermionic emission (PETE) is a relatively new concept for high efficiency solar cells that utilize not only the energy of electrons excited across the band gap by photons, as in conventional photovoltaic solar cells, but also the energy usual lost to thermalization of the excited...... to ideal band gap. The work function of silicon is, however, too high for practical PETE implementations. A well-known method for lowering the work function of silicon (and other materials) is to apply approximately a monolayer of cesium to the silicon surface. We present the first measurements of PETE...

  6. 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.

  7. Experimental investigation of high temperature high voltage thermionic diode for the space power nuclear reactor

    International Nuclear Information System (INIS)

    Onufriyev, Valery V.

    2001-01-01

    It is well known that the rise of arc from the dense glow discharge is connected with the thermion and secondary processes on the cathode surface (Granovsky, 1971; Leob, 1953; Engel, 1935). First model of breakdown of the cathode layer is connected with the increase of the cathode temperature in consequence of the ion bombardment that leads to the grows its thermo-emissive current. Other model shows the main role of the secondary effects on the cathode surface-the increase of the secondary ion emission coefficient--γ i with the grows of glow discharge voltage. But the author of this investigation work of breakdown in Cs vapor (a transmission the glow discharge into self-maintaining arc discharge) discovered the next peculiarity: the value of breakdown voltage is constant when the values of vapor temperature (its pressure p cs ) and cathode temperature T k is constant too (U b =constant with T k =constant and p cs =constant) and it is not a statistical value (Onufryev, Grishin, 1996) (that was observed in gas glow discharges other authors (Granovsky, 1971; Leob, 1953; Engel, 1935)). The investigations of thermion high voltage high temperature diode (its breakdown characteristics in closed state and voltage-current characteristics in disclosed state) showed that the value of the breakdown voltage is depended on the vapor pressure in inter-electrode gap (IEG)-p cs and cathode temperature-T k and is independent on IEG length--Δ ieg . On this base it was settled that the main role in transition of glow discharge to self-maintaining arc discharge plays an ion cathode layer but more exactly--the region of excited atoms--''Aston glow.''

  8. Experimental investigation of high temperature high voltage thermionic diode for the space power nuclear reactor

    Science.gov (United States)

    Onufriyev, Valery. V.

    2001-02-01

    It is well known that the rise of arc from the dense glow discharge is connected with the thermion and secondary processes on the cathode surface (Granovsky, 1971; Leob, 1953; Engel, 1935). First model of breakdown of the cathode layer is connected with the increase of the cathode temperature in consequence of the ion bombardment that leads to the grows its thermo-emissive current. Other model shows the main role of the secondary effects on the cathode surface-the increase of the secondary ion emission coefficient-γi with the grows of glow discharge voltage. But the author of this investigation work of breakdown in Cs vapor (a transmission the glow discharge into self-maintaining arc discharge) discovered the next peculiarity: the value of breakdown voltage is constant when the values of vapor temperature (its pressure pcs) and cathode temperature Tk is constant too (Ub=constant with Tk=constant and pcs=constant) and it is not a statistical value (Onufryev, Grishin, 1996) (that was observed in gas glow discharges other authors (Granovsky, 1971; Leob, 1953; Engel, 1935)). The investigations of thermion high voltage high temperature diode (its breakdown characteristics in closed state and voltage-current characteristics in disclosed state) showed that the value of the breakdown voltage is depended on the vapor pressure in inter-electrode gap (IEG)-pcs and cathode temperature-Tk and is independent on IEG length-Δieg. On this base it was settled that the main role in transition of glow discharge to self-maintaining arc discharge plays an ion cathode layer but more exactly-the region of excited atoms-``Aston glow.'' .

  9. Efficient Wide Range Converters (EWiRaC): A new family of high efficient AC-DC Converters

    DEFF Research Database (Denmark)

    Petersen, Lars; Andersen, Michael Andreas E.

    2006-01-01

    The performance in terms of efficiency of the existing power supplies used for PFC is very dependent on the input voltage range. The boost converter is the most commonly used PFC converter because of its simplicity and high efficiency. But, the boost converter as well as other known converters...... suffers a major penalty in efficiency when used at the low end of the voltage range (90VAC) in a universal voltage range application (90-270VAC). This paper addresses this problem by suggesting a new family of converters that effectively reduces the apparent voltage range with a factor of 2 by changing...... the converter topology according to the input voltage. This new converter type has been named: efficient wide range converter (EWiRaC). The performance of the EWiRaC is experimental verified in a universal input range (90-270VAC) application with an output voltage of 185VDC capable of 500W output power. The EWi...

  10. Converter topologies and control

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Fernando; Qin, Hengsi; Chapman, Patrick

    2018-05-01

    An inverter includes a transformer that includes a first winding, a second winding, and a third winding, a DC-AC inverter electrically coupled to the first winding of the transformer, a cycloconverter electrically coupled to the second winding of the transformer, an active filter electrically coupled to the third winding of the transformer. The DC-AC inverter is adapted to convert the input DC waveform to an AC waveform delivered to the transformer at the first winding. The cycloconverter is adapted to convert an AC waveform received at the second winding of the transformer to the output AC waveform having a grid frequency of the AC grid. The active filter is adapted to sink and source power with one or more energy storage devices based on a mismatch in power between the DC source and the AC grid.

  11. Converting high boiling hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Terrisse, H; DuFour, L

    1929-02-12

    A process is given for converting high boiling hydrocarbons into low boiling hydrocarbons, characterized in that the high boiling hydrocarbons are heated to 200 to 500/sup 0/C in the presence of ferrous chloride and of such gases as hydrogen, water gas, and the like gases under a pressure of from 5 to 40 kilograms per square centimeter. The desulfurization of the hydrocarbons occurs simultaneously.

  12. Advanced converters and reactors

    International Nuclear Information System (INIS)

    Haefele, W.; Kessler, G.

    1984-01-01

    As Western Europe and most countries of the Asia-Pacific region (except Australia) have only small natural uranium resources, they must import nuclear fuel from the major uranium supplier countries. The introduction of advanced converter and breeder reactor technology allows a fuel utilization of a factor of 4 to 100 higher than with present low converters (LWRs) and will make uranium-importing countries less vulnerable to price jumps and supply stops in the uranium market. In addition, breeder-reactor technology will open up a potential that can cover world energy requirements for several thousand years. The enormous development costs of advanced converter and breeder technologies can probably be raised only by highly industrialized countries. Those highly industrialized countries that have little or no uranium resources (Western Europe, Japan) will probably be the first to introduce this advanced reactor technology on a commercial scale. A number of small countries and islands will need only small power reactors with inherent safety capabilities, especially in the beginning of their nuclear energy programs. For economic reasons, the fuel cycle services should come from large reprocessing centers of countries having sufficiently large nuclear power programs or from international fuel cycle centers. (author)

  13. Effect of inlet cone pipe angle in catalytic converter

    Science.gov (United States)

    Amira Zainal, Nurul; Farhain Azmi, Ezzatul; Arifin Samad, Mohd

    2018-03-01

    The catalytic converter shows significant consequence to improve the performance of the vehicle start from it launched into production. Nowadays, the geometric design of the catalytic converter has become critical to avoid the behavior of backpressure in the exhaust system. The backpressure essentially reduced the performance of vehicles and increased the fuel consumption gradually. Consequently, this study aims to design various models of catalytic converter and optimize the volume of fluid flow inside the catalytic converter by changing the inlet cone pipe angles. Three different geometry angles of the inlet cone pipe of the catalytic converter were assessed. The model is simulated in Solidworks software to determine the optimum geometric design of the catalytic converter. The result showed that by decreasing the divergence angle of inlet cone pipe will upsurge the performance of the catalytic converter.

  14. 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.

  15. Fracture-resistant ultralloys for space-power systems: nuclear-thermionic-conversion implications of W,27Re

    International Nuclear Information System (INIS)

    Moraga, N.O.; Jacobsen, D.L.; Morris, J.F.

    1989-01-01

    Rhenium (Re) added to tungsten (W) improves the creep strength, recrystallization resistance and ductility. W,27Re is a good workable ultra alloy for use in space nuclear reactor (SNR) systems and perhaps its most practical processing procedure is sintering. A promising SNR application for such ultralloys is very-high-temperature thermionic energy conversion. Therefore determinations of thermionic and thermal emissive characteristics for sintered W,27Re at temperatures near and above 2000 K in hard vacuum enable both scientific and pragmatic progress. Such research results comprise the data and interpretive presentations in this paper. These findings emphasize the fallacy of characterizing ultralloys similar to W,27Re with single-valued thermophysicochemical properties - such as the work function. They further stress the necessity for investigations of this type to determine and demonstrate effective prototypic ultralloy compositions and processing methods. (author)

  16. A three-port direct current converter

    DEFF Research Database (Denmark)

    2016-01-01

    circuit comprises a connection between the at least one input direct current source and the at least one storage battery, the primary side circuit configured for operating as a buck converter; a second magnetic component serially coupled to the first single magnetic component, wherein the first and second...... magnetic components are configured to perform a voltage step-up, wherein the secondary side circuit comprises a connection between the at least one storage battery and at least one load, the secondary side configured for operating as a tapped boost converter; wherein the three-port direct current converter......The three-port direct current converter comprising: at least one input direct current source; at least one storage battery; a primary side circuit; a secondary side circuit; a first single magnetic component shared by the primary side circuit and the secondary side circuit, wherein the primary side...

  17. Convertible bond valuation focusing on Chinese convertible bond market

    OpenAIRE

    Yang, Ke

    2010-01-01

    This paper mainly discusses the methods of valuation of convertible bonds in Chinese market. Different from common convertible bonds in European market, considering the complicate features of Chinese convertible bond, this paper represents specific pricing approaches for pricing convertible bonds with different provisions along with the increment of complexity of these provisions. More specifically, this paper represents the decomposing method and binomial tree method for pricing both of Non-...

  18. Modulation and control of matrix converter for aerospace application

    Science.gov (United States)

    Kobravi, Keyhan

    In the context of modern aircraft systems, a major challenge is power conversion to supply the aircraft's electrical instruments. These instruments are energized through a fixed-frequency internal power grid. In an aircraft, the available sources of energy are a set of variable-speed generators which provide variable-frequency ac voltages. Therefore, to energize the internal power grid of an aircraft, the variable-frequency ac voltages should be converted to a fixed-frequency ac voltage. As a result, an ac to ac power conversion is required within an aircraft's power system. This thesis develops a Matrix Converter to energize the aircraft's internal power grid. The Matrix Converter provides a direct ac to ac power conversion. A major challenge of designing Matrix Converters for aerospace applications is to minimize the volume and weight of the converter. These parameters are minimized by increasing the switching frequency of the converter. To design a Matrix Converter operating at a high switching frequency, this thesis (i) develops a scheme to integrate fast semiconductor switches within the current available Matrix Converter topologies, i.e., MOSFET-based Matrix Converter, and (ii) develops a new modulation strategy for the Matrix Converter. This Matrix Converter and the new modulation strategy enables the operation of the converter at a switching-frequency of 40kHz. To provide a reliable source of energy, this thesis also develops a new methodology for robust control of Matrix Converter. To verify the performance of the proposed MOSFET-based Matrix Converter, modulation strategy, and control design methodology, various simulation and experimental results are presented. The experimental results are obtained under operating condition present in an aircraft. The experimental results verify the proposed Matrix Converter provides a reliable power conversion in an aircraft under extreme operating conditions. The results prove the superiority of the proposed Matrix

  19. The design of a 3 GHz thermionic RF-gun and energy filter for MAX-lab

    CERN Document Server

    Anderberg, B; Demirkan, M; Eriksson, M; Malmgren, L; Werin, S

    2002-01-01

    A new pre-injector has been designed for the MAX-laboratory. It consists of an RF-gun and a magnetic energy filter. The newly designed RF-gun geometry will be operated at 3 GHz in the thermionic mode using a BaO cathode. The pre-injector will provide a 2.3 MeV electron beam in 3 ps micro pulses to a new injector system currently under construction.

  20. Prospects for the use of thermionic nuclear power plants for interorbital transfers of space vehicles in near space

    International Nuclear Information System (INIS)

    Andreev, P.V.; Zhabotinskii, E.E.; Nikonov, A.M.

    1993-01-01

    In a previous study the authors considered the use of thermionic nuclear power plants with a thermal reactor for interorbital transfers of space vehicles by electrojet propulsion systems (EJPSs), opening up broad prospects for putting payloads into a high orbit with relatively inexpensive means for a launch into a reference orbit, e.g., the Proton launch vehicle. This is of major importance for the commercial use of space technology, in particular, for erecting technological platforms for the production of various materials. In the work reported here the authors continue the study of interorbital transfers and explore the potentialities of thermionic NPPs with a thermal reactor and with a fast reactor. In boosted operation the electrical power of the latter may reach several hundred kilowatts. What type of NPP is desirable for testing an electrojet propulsion system in interorbital transfers from a reference orbit to a high orbit, providing that the time is limited, depends on the class of the launch vehicle characterized by the mass M o that the vehicle can carry into the reference orbit, where radiation safety conditions allow the NPP to be started up. Results of studies are presented that give an idea of the rational choice of type of thermionic NPP for the organization in interorbital transfers

  1. X-Y Converter Family

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Sanjeevikumar, Padmanaban; Wheeler, Patrick

    2016-01-01

    A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter...... system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct...... features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed...

  2. Resonant power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2012-01-01

    This book is devoted to resonant energy conversion in power electronics. It is a practical, systematic guide to the analysis and design of various dc-dc resonant inverters, high-frequency rectifiers, and dc-dc resonant converters that are building blocks of many of today's high-frequency energy processors. Designed to function as both a superior senior-to-graduate level textbook for electrical engineering courses and a valuable professional reference for practicing engineers, it provides students and engineers with a solid grasp of existing high-frequency technology, while acquainting them wit

  3. Simulated potential for enhanced performance of mechanically stacked hybrid III-V/Si tandem photovoltaic modules using DC-DC converters

    Science.gov (United States)

    MacAlpine, Sara; Bobela, David C.; Kurtz, Sarah; Lumb, Matthew P.; Schmieder, Kenneth J.; Moore, James E.; Walters, Robert J.; Alberi, Kirstin

    2017-10-01

    This work examines a tandem module design with GaInP2 mechanically stacked on top of crystalline Si, using a detailed photovoltaic (PV) system model to simulate four-terminal (4T) unconstrained and two-terminal voltage-matched (2T VM) parallel architectures. Module-level power electronics is proposed for the 2T VM module design to enhance its performance over the breadth of temperatures experienced by a typical PV installation. Annual, hourly simulations of various scenarios indicate that this design can reduce annual energy losses to ˜0.5% relative to the 4T module configuration. Consideration is given to both performance and practical design for building or ground mount installations, emphasizing compatibility with existing standard Si modules.

  4. High Efficiency Reversible Fuel Cell Power Converter

    DEFF Research Database (Denmark)

    Pittini, Riccardo

    as well as different dc-ac and dc-dc converter topologies are presented and analyzed. A new ac-dc topology for high efficiency data center applications is proposed and an efficiency characterization based on the fuel cell stack I-V characteristic curve is presented. The second part discusses the main...... converter components. Wide bandgap power semiconductors are introduced due to their superior performance in comparison to traditional silicon power devices. The analysis presents a study based on switching loss measurements performed on Si IGBTs, SiC JFETs, SiC MOSFETs and their respective gate drivers...

  5. Alternative model of space-charge-limited thermionic current flow through a plasma

    Science.gov (United States)

    Campanell, M. D.

    2018-04-01

    It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge-limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate a fundamentally different current-limited mode. In the "inverse" mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting the circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. The inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.

  6. The Properties of Binary and Ternary Ti Based Coatings Produced by Thermionic Vacuum Arc (TVA Technology

    Directory of Open Access Journals (Sweden)

    Aurelia Mandes

    2018-03-01

    Full Text Available A series of the multicomponent thin films (binary: Ti-C; Ti-Ag and ternary: Ti-C-Ag; Ti-C-Al were fabricated by Thermionic Vacuum Arc (TVA technology in order to study the wear resistance and the anticorrosion properties. The effects of Ti amount on the microstructure, tribological and morphological properties were subsequently investigated. TVA is an original deposition method using a combination of anodic arc and electron gun systems for the growth of films. The samples were characterized using scanning electron microscope (SEM and a transmission electron microscope (TEM accompanied by selected area electron diffraction (SAED. Tribological properties were studied by a ball-on-disc tribometer in the dry regime and the wettability was assessed by measuring the contact angle with the See System apparatus. Wear Rate results indicate an improved sliding wear behavior for Ti-C-Ag: 1.31 × 10−7 mm3/N m (F = 2 N compared to Ti-C-Al coating wear rate: 4.24 × 10−7 mm3/N m. On the other hand, by increasing the normal load to 3 N an increase to the wear rate was observed for Ti-C-Ag: 2.58 × 10−5 mm3 compared to 2.33 × 10−6 mm3 for Ti-C-Al coating.

  7. Development of a thermionic magnicon amplifier at 11.4 GHz

    International Nuclear Information System (INIS)

    Gold, S.H.; Hafizi, B.; Fliflet, A.W.; Kinkead, A.K.; True, R.

    1997-01-01

    The magnicon is a scanning-beam microwave amplifier tube that is being developed as an rf source for the proposed TeV Next Linear Collider. In it, a solid electron beam is spun up to high transverse momentum in a series of deflection cavities containing synchronously rotating TM modes, and then spun down again in an output cavity whose mode is synchronous with that of the deflection cavities. A recent magnicon experiment at NRL, using a ∼ 650 kV, 225 A, 5.5-mm-diam. electron beam produced from a cold cathode driven by a single-shot Marx generator, demonstrated 14 MW (±3 dB) at 11.12 GHz with 105 efficiency in the synchronous magnicon mode, but was limited by plasma loading in the deflection cavities to a regime in which the last cavity of the deflection system (the penultimate cavity) was unstable. A new 11.4 GHz rep-rated thermionic magnicon experiment is being assembled, using an advanced ultra-high-convergence electron gun driven by a 10 Hz, 1.5 microsecond modulator top produce a 500 kV, 210 A, 2-mm diameter electron beam. The magnicon circuit has been optimized for minimum surface rf fields and maximum efficiency, and will be engineered for high temperature bakeout and high vacuum operation. This experiment should begin operation in the Summer of 1997. The predicted power is 60 MW at ∼ 60% efficiency

  8. Adherence of diamond films on refractory metal substrates for thermionic applications

    International Nuclear Information System (INIS)

    Tsao, B.H.; Ramalingam, M.L.; Adams, S.F.; Cloyd, J.S.

    1991-01-01

    Diamond films are currently being considered as electrical insulation material for application in the thermionic fuel element of a power producing nuclear reactor system. The function of the diamond insulator in this application is to electrically isolate the collector of each cell in the TFE from the coolant and outer sheath. Deposition of diamond films on plane surfaces of Si/SiO 2 have already been demonstrated to be quite effective. However, the diamond films on refractory metal surfaces tend to spall off in the process of deposition revealing an inefficient adherence characteristic between the film and the substrate. This paper is geared towards explaining this deficiency by way of selected experimentation and the use of analytical tools to predict uncertainties such as the mismatch in coefficient of expansion, micrographic study of the interface between the film and the substrate and X-ray diffraction spectra. The investigation of the adherence characteristics of several diamond films on Mo and Nb substrates revealed that there was an allowable stress that resulted in the formation of the critical thickness for the diamond film

  9. Modeling transient thermal hydraulic behavior of a thermionic fuel element for nuclear space reactors

    International Nuclear Information System (INIS)

    Al-Kheliewi, A.S.; Klein, A.C.

    1994-01-01

    A transient code (TFETC) for determining the temperature distribution throughout the radial and axial positions of a thermionic fuel element (TFE) during changes in operating conditions has been successfully developed and tested. A fully implicit method is used to solve the system of equations for temperatures at each time step. Presently, TFETC has the ability to handle the following transients: startup, loss of flow accidents, and shutdown. The code has been applied to the startup of the ATI single cell configuration which appears to start up and shut down in an orderly and reasonable fashion. No unexpected transient features were observed. The TFE also appears to function robustly under loss of flow accident conditions. It appears hat sufficient time is available to shut the reactor down safely without melting point the fuel. The model shows that during a complete loss of flow accident (without shutdown) the coolant reaches its boiling point in approximately 35 seconds. The fuel may exceed its melting point after this time as the NaK coolant will boil if the reactor is not shut down. For 1/2, 1/3, and 1/4 pump failures, the fuel temperatures never exceed the fuel melting point even if the reactor is not shut down

  10. Performance of 22.4-kW nonlaminated-frame dc series motor with chopper controller. [a dc to dc voltage converter

    Science.gov (United States)

    Schwab, J. R.

    1979-01-01

    Performance data obtained through experimental testing of a 22.4 kW traction motor using two types of excitation are presented. Ripple free dc from a motor-generator set for baseline data and pulse width modulated dc as supplied by a battery pack and chopper controller were used for excitation. For the same average values of input voltage and current, the motor power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points lower on chopped dc than on ripple free dc. The chopped dc locked-rotor torque was approximately 1 to 3 percent greater than the ripple free dc torque for the same average current.

  11. Gas converter. Gaswandler

    Energy Technology Data Exchange (ETDEWEB)

    Eisenmann, A

    1984-09-27

    A gas converter is proposed for carbonisation gas containing hydrocarbons, consisting of a bricked shaft, which has a free combustion chamber and a solid bed of bulk grainy material with partly burnt hot carbonisation gases flowing through it as the lower boundary of this combustion chamber, in the upper part of which a hot reaction zone at about 1000 to 1200/sup 0/C is formed and which has a cracked gas extraction below the solid bed and an ash outlet. The solid bed is arranged at an angle to the vertical. The shaft has a solid material outlet for the bed material no longer capable of taking part in the reaction on the wall going obliquely downwards and a solid material inlet for new bulk bed material on the opposite wall going obliquely upwards.

  12. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  13. Power converters for ITER

    CERN Document Server

    Benfatto, I

    2006-01-01

    The International Thermonuclear Experimental Reactor (ITER) is a thermonuclear fusion experiment designed to provide long deuterium– tritium burning plasma operation. After a short description of ITER objectives, the main design parameters and the construction schedule, the paper describes the electrical characteristics of the French 400 kV grid at Cadarache: the European site proposed for ITER. Moreover, the paper describes the main requirements and features of the power converters designed for the ITER coil and additional heating power supplies, characterized by a total installed power of about 1.8 GVA, modular design with basic units up to 90 MVA continuous duty, dc currents up to 68 kA, and voltages from 1 kV to 1 MV dc.

  14. A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heeje; Kim, Jongrak; Shin, Dongsul [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); Kim, Hosung; Lee, Kyungjun [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea); Kim, Jonghyun; Yoo, Dongwook [New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea)

    2010-08-15

    A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter. (author)

  15. Power performance measurements on Wave Star in Nissum Bredning. Final report; Wave energy converter; Effektmaalinger paa Wave Star i Nissum Bredning. Afsluttende rapport

    Energy Technology Data Exchange (ETDEWEB)

    Frigaard, P.; Lykke Andersen, T.

    2009-04-15

    The Wave Star test machine in Nissum Bredning was put in continuous operation on 24 July 2006. Over the past 2 1/2 years the produced power was measured continuously and with only minor interruptions. The measurements cover operation for all seasons in a very changeable climate. There is thus gaining operational experience under different wave conditions. In the period the machine has been running with a simple form of control and Power Take Off system (PTO), which form the background for effect measurements with the existing control strategy. Calculations have shown that the use of more advanced forms of control can increase the efficiency of Wave Star significantly. New control systems are therefore still under development with the primary objective to increase performance from the wave energy plant. To test and develop the methods, a new mini-hydraulic station with associated second generation PTO was developed and constructed for testing in Nissum Bredning. The mini-hydraulic station is coupled to a single float, while the other machine's 39 floats are still connected to the existing PTO system. As the existing PTO system can be applied to the 39 floats simultaneously with the new PTO used on 1 float, effect can be measured on the two systems simultaneously. The first tentative experiments with the new second generation PTO seem very promising. During the first measurements made in March 2009 the new system achieved an average yield of 3.1 times the average output from a float on the existing machine. In the coming period more experiments will be performed with the mini-hydraulic station to test the new PTO in various sea conditions. Since the mini-hydraulic station can simulate various forms of control, they also will be tested under real wave conditions in Nissum Bredning. The effect optimization should continue to be subject to a greater targeted effort, as improvements in this area can increase energy production and thus reduce the kWh cost of energy

  16. Integrated power electronic converters and digital control

    CERN Document Server

    Emadi, Ali; Nie, Zhong

    2009-01-01

    Non-isolated DC-DC ConvertersBuck ConverterBoost ConverterBuck-Boost ConverterIsolated DC-DC ConvertersFlyback ConverterForward ConverterPush-Pull ConverterFull-Bridge ConverterHalf-Bridge ConverterPower Factor CorrectionConcept of PFCGeneral Classification of PFC CircuitsHigh Switching Frequency Topologies for PFCApplication of PFC in Advanced Motor DrivesIntegrated Switched-Mode Power ConvertersSwitched-Mode Power SuppliesThe Concept of Integrated ConverterDefinition of Integrated Switched-Mode Power Supplies (ISMPS)Boost-Type Integrated TopologiesGeneral Structure of Boost-Type Integrated T

  17. Artificial neural network control of sab dc/dc converter

    International Nuclear Information System (INIS)

    Mahar, M.A.; Abro, M.R.; Larik, A.S.

    2009-01-01

    The latest development of power semiconductor devices enable the modern power electronic converters to withstand high voltage and high power applications. Power electronic converters are mostly periodic variable structure systems due to their switched operations. The main drawback of these converters is the generation of oscillations which are developed during the operation of the converters under nonlinear situations. To handle these nonlinearities, various researchers have proposed different control techniques. Power electronic designers are devoting in the further development of converter topologies and their control techniques. SAB (Single Active Bridge) DC/DC converter is a new topology recently introduced by Demetriades. This topology is used in high voltage and high power applications. Because of its smart features, SAB converter has recently drawn attention of many researchers. However, during the operation of SAB converter severe oscillations are generated. In this research work, a novel NNC (Neural Network Controller) model is developed for SAB converter to minimize oscillations generated during its operation. NNC is believed to be an advanced nonlinear and robust controller which has the ability to map the nonlinear behaviour in a negligible response time. The performance of SAB converter with NNC is tested under dynamic region by considering the reference voltage variation and duty ratio variation. The SAB converter is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)

  18. Online Scheduling in Distributed Message Converter Systems

    NARCIS (Netherlands)

    Risse, Thomas; Wombacher, Andreas; Surridge, Mike; Taylor, Steve; Aberer, Karl

    The optimal distribution of jobs among hosts in distributed environments is an important factor to achieve high performance. The optimal strategy depends on the application. In this paper we present a new online scheduling strategy for distributed EDI converter system. The strategy is based on the

  19. multilevel buck converter for automotive electrical load

    African Journals Online (AJOL)

    ... from internal combustion engine (ICE). The mass production of the hybrid electric (HE) and the electric vehicle (EV) is still awaited due to subsystem inefficiencies. Increasing the efficiencies of the power converters within subsystems of these HEVs and EVs will increase the performance of the new transportation vehicles.

  20. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding...

  1. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  2. Performance Analysis of a Four-Switch Three-Phase Grid-Side Converter with Modulation Simplification in a Doubly-Fed Induction Generator-Based Wind Turbine (DFIG-WT with Different External Disturbances

    Directory of Open Access Journals (Sweden)

    Kai Ni

    2017-05-01

    Full Text Available This paper investigates the performance of a fault-tolerant four-switch three-phase (FSTP grid-side converter (GSC in a doubly-fed induction generator-based wind turbine (DFIG-WT. The space vector pulse width modulation (SVPWM technique is simplified and unified duty ratios are used for controlling the FSTP GSC. Steady DC-bus voltage, sinusoidal three-phase grid currents and unity power factor are obtained. In addition, the balance of capacitor voltages is accomplished based on the analysis of current flows at the midpoint of DC bus in different operational modes. Besides, external disturbances such as fluctuating wind speed and grid voltage sag are considered to test its fault-tolerant ability. Furthermore, the effects of fluctuating wind speed on the performance of DFIG-WT system are explained according to an approximate expression of the turbine torque. The performance of the proposed FSTP GSC is simulated in Matlab/Simulink 2016a based on a detailed 1.5 MW DFIG-WT Simulink model. Experiments are carried out on a 2 kW platform by using a discrete signal processor (DSP TMS320F28335 controller to validate the reliability of DFIG-WT for the cases with step change of the stator active power and grid voltage sag, respectively.

  3. Convertible shielding to ceramic breeding blanket

    International Nuclear Information System (INIS)

    Furuya, Kazuyuki; Kurasawa, Toshimasa; Sato, Satoshi; Nakahira, Masataka; Togami, Ikuhide; Hashimoto, Toshiyuki; Takatsu, Hideyuki; Kuroda, Toshimasa.

    1995-05-01

    Four concepts have been studied for the ITER convertible blanket: 1)Layered concept 2)BIT(Breeder-Inside-Tube)concept 3)BOT(Breeder-Out of-Tube)concept 4)BOT/mixed concept. All concepts use ceramic breeder and beryllium neutron multiplier, both in the shape of small spherical pebbles, 316SS structure, and H 2 O coolant (inlet/outlet temperatures : 100/150degC, pressure : 2 MPa). During the BPP, only beryllium pebbles (the primary pebble in case of BOT/mixed concept) are filled in the blanket for shielding purpose. Then, before the EPP operation, breeder pebbles will be additionally inserted into the blanket. Among possible conversion methods, wet method by liquid flow seems expecting for high and homogeneous pebble packing. Preliminary 1-D neutronics calculation shows that the BOT/mixed concept has the highest breeding and shielding performance. However, final selection should be done by R and D's and more detail investigation on blanket characteristics and fabricability. Required R and D's are also listed. With these efforts, the convertible blanket can be developed. However, the following should be noted. Though many of above R and D's are also necessary even for non-convertible blanket, R and D's on convertibility will be one of the most difficult parts and need significant efforts. Besides the installation of convertible blanket with required structures and lines for conversion will make the ITER basic machine more complicated. (author)

  4. Parametric pendulum based wave energy converter

    Science.gov (United States)

    Yurchenko, Daniil; Alevras, Panagiotis

    2018-01-01

    The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

  5. SIG Galileo final converter technical summary report

    International Nuclear Information System (INIS)

    Hinderman, J.D.

    1979-05-01

    The report is primarily concerned with the work performed for DOE on converter development and fabrication for the NASA Galileo Jupiter mission as a DOE prime contractor with interface primarily with Teledyne Energy Systems. The activities reported on were directed toward design, analysis and testing of modules and converters SN-1 thru SN-7 and attendant Quality Control and Reliability effort. Although assembly and testing of SN-1 was not accomplished due to the stop work order, the design was virtually completed and a significant amount of subcontracting and manufacturing of both module and converter components was underway. These subcontracting and manufacturing activities were selectively closed down depending upon degree of completion and material or hardware potential usage in the Technology Program

  6. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    -link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...... electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC...

  7. Data Converter for Multistandard Mobile Phones

    DEFF Research Database (Denmark)

    Yurttas, Aziz; Bruun, Erik; Jensen, Rasmus Glarborg

    2004-01-01

    This paper describes an analog to digital converter (ADC) for mobile communication systems using a direct down conversion architecture. The ADC can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication) and WCDMA (Wideband...... Code Division Multiple Access). The ADC is realized with a pipeline ADC architecture for WCDMA and a Sigma-Delta architecture for GSM. In order to have an optimized area and power consumption, the basic building blocks (opamps) of the converters are shared between the two converter architectures....... The entire ADC consumes about 5.5 mW and occupies an active area of about 0.36 mm(2). A test circuit has been developed and fabricated and measurements show that both the required programmability and the required performance can be obtained using the proposed configurations....

  8. Contingent Conversion Convertible Bond: New avenue to raise bank capital

    OpenAIRE

    DI GIROLAMO FRANCESCA; CAMPOLONGO FRANCESCA; DE SPIEGELEER JAN; SCHOUTENS WIM

    2016-01-01

    This paper provides an in-depth analysis of the structuring and the pricing of an innovative financial market product. This instrument is called a contingent conversion convertible bond or "CoCoCo". This hybrid bond is itself a combination of two other hybrid instruments: a contingent convertible ("CoCo") and a convertible bond. This combination introduces more complexity in the structure but it also allows investors to profit from strong share price performances. This upside potential is add...

  9. Large-signal stability analysis of PWM converters

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering

    1995-12-31

    Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.

  10. Enhanced Thermionic Emission and Low 1/f Noise in Exfoliated Graphene/GaN Schottky Barrier Diode.

    Science.gov (United States)

    Kumar, Ashutosh; Kashid, Ranjit; Ghosh, Arindam; Kumar, Vikram; Singh, Rajendra

    2016-03-01

    Temperature-dependent electrical transport characteristics of exfoliated graphene/GaN Schottky diodes are investigated and compared with conventional Ni/GaN Schottky diodes. The ideality factor of graphene/GaN and Ni/GaN diodes are measured to be 1.33 and 1.51, respectively, which is suggestive of comparatively higher thermionic emission current in graphene/GaN diode. The barrier height values for graphene/GaN diode obtained using thermionic emission model and Richardson plots are found to be 0.60 and 0.72 eV, respectively, which are higher than predicted barrier height ∼0.40 eV as per the Schottky-Mott model. The higher barrier height is attributed to hole doping of graphene due to graphene-Au interaction which shifts the Fermi level in graphene by ∼0.3 eV. The magnitude of flicker noise of graphene/GaN Schottky diode increases up to 175 K followed by its decrease at higher temperatures. This indicates that diffusion currents and barrier inhomogeneities dominate the electronic transport at lower and higher temperatures, respectively. The exfoliated graphene/GaN diode is found to have lower level of barrier inhomogeneities than conventional Ni/GaN diode, as well as earlier reported graphene/GaN diode fabricated using chemical vapor deposited graphene. The lesser barrier inhomogeneities in graphene/GaN diode results in lower flicker noise by 2 orders of magnitude as compared to Ni/GaN diode. Enhanced thermionic emission current, lower level of inhomogeneities, and reduced flicker noise suggests that graphene-GaN Schottky diodes may have the underlying trend for replacing metal-GaN Schottky diodes.

  11. Hydraulic Response of the Wave Energy Converter Wave Dragon in Nissum Bredning

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype.......This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype....

  12. Transition to chaos in periodically driven thermionic diodes at low pressure

    International Nuclear Information System (INIS)

    Klinger, T.; Timm, R.; Piel, A.

    1992-01-01

    The static I(U) characteristic of thermionic diodes at mbar pressures shows a large hysteresis, which describes the transition from the 'anode-glow-mode' (AGM), with essentially negative plasma potential, to the 'temperature-limited-mode' (TLM), with positive plasma potential. Many features of these modes are also found in magnetic-box discharges with filament cathodes at pressures of 10 -2 -10 -1 Pa. Although these two pressure regimes are basically different concerning the transport properties (diffusion vs. free streaming), the elementary processes that establish the AGM in the low pressure regime are very similar to the high pressure regime. Ions are produced in that part of the anode sheath where the potential exceeds the ionization energy. The production rate is enhanced by multiple reflections of electrons between the magnetic fields of the permanent magnet array at the anode and the repulsive potential of the cathode plasma. Although the mean free path for charge exchange or elastic collisions substantially exceeds the anode-cathode distance, some few ions are stopped and trapped within the potential well of the virtual cathode. This accumulation of ions forms a cathodic plasma, which is essentially at cathode potential. Plasma formation in the anode sheath is suppressed as long as the ion production time is larger than the ion transit time through the sheath. These model ideas are supported by 1d-Particle-in-cell simulations using a modified PDP1-code. The AGM is attractive for studies of nonlinear dynamics because of its feedback processes and oscillations, which occur close to the hysteresis point. (author) 7 refs., 3 figs

  13. A program-management plan with critical-path definition for Combustion Augmentation with Thermionic Energy Conversion (CATEC)

    Science.gov (United States)

    Morris, J. F.; Merrill, O. S.; Reddy, H. K.

    1981-01-01

    Thermionic energy conversion (TEC) is discussed. In recent TEC-topping analyses, overall plant efficiency (OPE) and cost of electricity (COE) improved slightly with current capabilities and substantially with fully matured technologies. Enhanced credibility derives from proven hot-corrosion protection for TEC by silicon-carbide clads in fossil fuel combustion products. Combustion augmentation with TEC (CATEC) affords minimal cost and plant perturbation, but with smaller OPE and COE improvements than more conventional topping applications. Risk minimization as well as comparative simplicity and convenience, favor CATEC for early market penetration. A program-management plan is proposed. Inputs, characteristics, outputs and capabilities are discussed.

  14. ANALYTICAL MODELING OF ELECTRON BACK-BOMBARDMENT INDUCED CURRENT INCREASE IN UN-GATED THERMIONIC CATHODE RF GUNS

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Sun, Y. [Argonne; Harris, J. R. [AFRL, NM; Lewellen, J. W. [Los Alamos Natl. Lab.

    2016-09-28

    In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, fieldenhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

  15. High power densities from high-temperature material interactions. [in thermionic energy conversion and metallic fluid heat pipes

    Science.gov (United States)

    Morris, J. F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs), offering unique advantages in terrestrial and space energy processing by virtue of operating on working-fluid vaporization/condensation cycles that accept great thermal power densities at high temperatures, share complex materials problems. Simplified equations are presented that verify and solve such problems, suggesting the possibility of cost-effective applications in the near term for TEC and MFHP devices. Among the problems discussed are: the limitation of alkali-metal corrosion, protection against hot external gases, external and internal vaporization, interfacial reactions and diffusion, expansion coefficient matching, and creep deformation.

  16. A program-management plan with critical-path definition for Combustion Augmentation with Thermionic Energy Conversion (CATEC)

    Science.gov (United States)

    Morris, J. F.; Merrill, O. S.; Reddy, H. K.

    Thermionic energy conversion (TEC) is discussed. In recent TEC-topping analyses, overall plant efficiency (OPE) and cost of electricity (COE) improved slightly with current capabilities and substantially with fully matured technologies. Enhanced credibility derives from proven hot-corrosion protection for TEC by silicon-carbide clads in fossil fuel combustion products. Combustion augmentation with TEC (CATEC) affords minimal cost and plant perturbation, but with smaller OPE and COE improvements than more conventional topping applications. Risk minimization as well as comparative simplicity and convenience, favor CATEC for early market penetration. A program-management plan is proposed. Inputs, characteristics, outputs and capabilities are discussed.

  17. Wavelength converter placement in optical networks with dynamic traffic

    DEFF Research Database (Denmark)

    Buron, Jakob Due; Ruepp, Sarah Renée; Wessing, Henrik

    2008-01-01

    We evaluate the connection provisioning performance of GMPLS-controlled wavelength routed networks under dynamic traffic load and using three different wavelength converter placement heuristics. Results show that a simple uniform placement heuristic matches the performance of complex heuristics...

  18. Design, construction and measurements of an alpha magnet as a solution for compact bunch compressor for the electron beam from Thermionic RF Gun

    Science.gov (United States)

    Rajabi, A.; Jazini, J.; Fathi, M.; Sharifian, M.; Shokri, B.

    2018-03-01

    The beam produced by a thermionic RF gun has wide energy spread that makes it unsuitable for direct usage in photon sources. Here in the present work, we optimize the extracted beam from a thermionic RF gun by a compact economical bunch compressor. A compact magnetic bunch compressor (Alpha magnet) is designed and constructed. A comparison between simulation results and experimental measurements shows acceptable conformity. The beam dynamics simulation results show a reduction of the energy spread as well as a compression of length less than 1 ps with 2.3 mm-mrad emittance.

  19. Proposed electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  20. Catalytic converters in the fireplace

    International Nuclear Information System (INIS)

    Kouki, J.

    1995-01-01

    In addition to selecting the appropriate means of heating and using dry fuel, the amount of harmful emissions contained by flue gases produced by fireplaces can be reduced by technical means. One such option is to use an oxidising catalytic converter. Tests at TTS Institute's Heating Studies Experimental Station have focused on two such converters (dense and coarse) mounted in light-weight iron heating stoves. The ability of the dense catalytic converter to oxidise carbon monoxide gases proved to be good. The concentration of carbon monoxide in the flue gases was reduced by as much as 90 %. Measurements conducted by VTT (Technical Research Centre of Finland) showed that the conversion of other gases, e.g. of methane, was good. The exhaust resistance caused by the dense converter was so great as to necessitate the mounting of a fluegas evacuation fan in the chimney for the purpose of creating sufficient draught. When relying on natural draught, the dense converter requires a chimney of at least 7 metres and a by-pass connection while the fire is being lit. In addition, the converter will have to be constructed to be less dense and this will mean that it's capability to oxidise non-combusted gases will be reduced. The coarse converter did not impair the draught but it's oxidising property was insufficient. With the tests over, the converter was not observed to have become blocked up by impurities

  1. Multilevel push pull power converter

    DEFF Research Database (Denmark)

    2007-01-01

    A power converter for converting an input voltage (Vin) into an output voltage (Vout), comprising a first supply potential and a second supply potential established by the input voltage, and at least one primary winding having two terminals, a center tap arranged between the two terminals and con...

  2. PV source based high voltage gain current fed converter

    Science.gov (United States)

    Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

    2017-11-01

    This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

  3. Analysis and Design of CLL Resonant Converter for Solar Panel-battery Systems

    OpenAIRE

    D.Ramasubramanian; C.Nagarajan; M.Muruganandam

    2012-01-01

    This paper presents a CLL resonant converter with DSP based Fuzzy Logic Controller (FLC) for solar panel to battery charging system. The mathematical model of the converters has been developed and simulated using MATLAB. The state space model of the converter is developed; it is used to analysis the steady state stability of the system. The aim of the proposed converter is to regulate and control of the output voltage from the solar panel voltage. The performance of the proposed converter is ...

  4. A CMOS rail-to-rail linear VI-converter

    NARCIS (Netherlands)

    Vervoort, P.P.; Vervoort, P.P.; Wassenaar, R.F.

    1995-01-01

    A linear CMOS VI-converter operating in strong inversion with a common-mode input range from the negative to the positive supply rail is presented. The circuit consists of three linear VI-converters based on the difference of squares principle. Two of these perform the actual V to I conversion,

  5. Development of a test platform for controlling parallel converters

    DEFF Research Database (Denmark)

    Bede, Lorand; Kopacz, Csaba; Kerekes, Tamas

    2014-01-01

    a proper interleaving angle between the converters the current ripple can be reduced considerably. In order to be able to investigate the performance of these converters a safe and cheap platform is essential. The development of a test platform for such an application is challenging, since a proper...

  6. X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes

    Science.gov (United States)

    Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

    1998-01-01

    NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

  7. Low work-function thermionic emission and orbital-motion-limited ion collection at bare-tether cathodic contact

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xin, E-mail: xin.chen@upm.es; Sanmartín, J. R., E-mail: juanr.sanmartin@upm.es [Departamento de Física Aplicada, Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio, Universidad Politécnica de Madrid, Plaza Cardenal Cisneros, 3, 28040 Madrid (Spain)

    2015-05-15

    With a thin coating of low-work-function material, thermionic emission in the cathodic segment of bare tethers might be much greater than orbital-motion-limited (OML) ion collection current. The space charge of the emitted electrons decreases the electric field that accelerates them outwards, and could even reverse it for high enough emission, producing a potential hollow. In this work, at the conditions of high bias and relatively low emission that make the potential monotonic, an asymptotic analysis is carried out, extending the OML ion-collection analysis to investigate the probe response due to electrons emitted by the negatively biased cylindrical probe. At given emission, the space charge effect from emitted electrons increases with decreasing magnitude of negative probe bias. Although emitted electrons present negligible space charge far away from the probe, their effect cannot be neglected in the global analysis for the sheath structure and two thin layers in between sheath and the quasineutral region. The space-charge-limited condition is located. It is found that thermionic emission increases the range of probe radius for OML validity and is greatly more effective than ion collection for cathodic contact of tethers.

  8. Particle Simulations of a Thermionic RF Gun with Gridded Triode Structure for Reduction of Back-Bombardment

    CERN Document Server

    Kusukame, K; Kii, T; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    Thermionic RF guns show advantageous features compared with photocathode ones such as easy operation and much higher repetition rate of micropulses, both of which are suitable for their application to high average power FELs. They however suffer from the back-bombardment effect [1], i.e., in conventional RF guns, electrons are extracted from cathode also in the latter half of accelerating phase and tend to back-stream to hit the cathode, and as a result the macropulse duration is limited down to severalμsec Against this adverse effect in thermionic RF guns, introduction of the triode structure has been proposed [2], where the accelerating phase and amplitude nearby the cathode can be controlled regardless of the phase of the first accelerating cell in the conventional RF gun. Our one-dimensional particle simulation results predict that the back-bombardment power can be reduced by 99 % only with 30-40 kW RF power fed to the grid in the present triode structure with an optimal phase difference from th...

  9. Radiation tolerant power converter controls

    CERN Document Server

    Todd, B; King, Q; Uznanski, S

    2012-01-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to signifi...

  10. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, B.; Tamborini, D.; Villa, F.; Tisa, S.; Tosi, A.; Zappa, F. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2012-07-15

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB{sub rms}. The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps{sub rms} (i.e., 36 ps{sub FWHM}) and in photon timing mode it is still better than 70 ps{sub FWHM}. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

  11. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    DC/DC conversion techniques have undergone rapid development in recent decades. With the pioneering work of these authors, DC/DC converters have now moved into their sixth generation. This book offers a concise, practical presentation of DC/DC converters, summarizing the spectrum of conversion tecnologies and presentingmany new ideas and more than 100 new topologies. Nowhere else in the literature are DC/DC converters so logically sorted and systematically introduced, and nowhere else can readers find detailed information on prototype topologies that represent a major contribution to modern power engineering. More than 320 figures, 60 tables, and 500 formulae facilitate understand and provide precise data.

  12. Estimation of reliability of a interleaving PFC boost converter

    Directory of Open Access Journals (Sweden)

    Gulam Amer Sandepudi

    2010-01-01

    Full Text Available Reliability plays an important role in power supplies. For other electronic equipment, a certain failure mode, at least for a part of the total system, can often be employed without serious (critical effects. However, for power supply no such condition can be accepted, since very high demands on its reliability must be achieved. At higher power levels, the continuous conduction mode (CCM boost converter is preferred topology for implementation a front end with PFC. As a result, significant efforts have been made to improve the performance of high boost converter. This paper is one of the efforts for improving the performance of the converter from the reliability point of view. In this paper, interleaving boost power factor correction converter is simulated with single switch in continuous conduction mode (CCM, discontinuous conduction mode (DCM and critical conduction mode (CRM under different output power ratings. Results of the converter are explored from reliability point of view.

  13. Time-to-digital converters

    CERN Document Server

    Henzler, Stephan

    2010-01-01

    This text covers the fundamentals of time-to-digital converters on analog and digital conversion principles. It includes a theoretical investigation into quantization, linearity, noise and variability, and it details a range of advanced TDC architectures.

  14. Picosecond image-converter diagnostics

    International Nuclear Information System (INIS)

    Schelev, M.Ya.

    1975-01-01

    A brief review is presented of the improvements in picosecond image-converter diagnostics carried out since the previous Congress in 1972. The account is given under the following headings: picosecond image converter cameras for visible and x-ray radiation diagnostics; Nd:glass and ruby mode-locked laser measurements; x-ray plasma emission diagnostics; computer treatment of pictures produced by picosecond cameras. (U.K.)

  15. Analysis of serum angiotensin-converting enzyme.

    Science.gov (United States)

    Muller, B R

    2002-09-01

    Serum angiotensin-converting enzyme (SACE) levels are influenced by genetic polymorphism. Interpretation of serum levels with the appropriate genotypic reference range improves the diagnostic sensitivity of the assay for sarcoidosis. SACE assays are performed by a large number of routine clinical laboratories. However, there is no external quality assessment (EQA) for SACE other than an informal regional scheme. This showed analytical performance of SACE assays to be poor, with a diversity of reference ranges, leading to widely disparate clinical classification of EQA samples. Genetic polymorphism combined with poor analytical performance suggest that perhaps SACE assays should revert to being the province of specialized laboratories.

  16. Cost Effectiveness Analysis of Converting a Classroom Course to a Network Based Instruction Module

    National Research Council Canada - National Science Library

    green, Samantha

    1997-01-01

    ...) classes into NBL modules. This thesis performs a cost effectiveness analysis on converting the two modules and discusses the intangible costs and benefits associated with converting traditional classroom courses...

  17. Liquid Nitrogen Temperature Operation of a Switching Power Converter

    Science.gov (United States)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

  18. Two-inductor boost and buck converters

    Science.gov (United States)

    White, J. L.; Muldoon, W. J.

    The derivation, analysis and design of a coupled inductor boost converter is presented. Aspects of the qualitative ac behavior of coupled inductor converters are discussed. Considerations for the design of the magnetics for such converters are addressed.

  19. Radiated electromagnetic emissions of DC-DC converters

    International Nuclear Information System (INIS)

    Feld, L; Jussen, R; Karpinski, W; Klein, K; Sammet, J; Wlochal, M

    2010-01-01

    For the CMS tracker at SLHC a new powering scheme is considered to be mandatory to allow the detector to provide at least the same performance as today at the LHC. The baseline solution of CMS foresees the use of DC-DC converters to provide larger currents with smaller losses. An important component of most converters are inductors which, however, tend to radiate the switching noise generated by the converter. The emissions of different inductors have been measured and simulated, the coil design has been optimized and noise susceptibility measurements, with present CMS hardware, have been performed. This article summarizes the results.

  20. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  1. Influence of intake manifold design on in-cylinder flow and engine performances in a bus diesel engine converted to LPG gas fuelled, using CFD analyses and experimental investigations

    International Nuclear Information System (INIS)

    Jemni, Mohamed Ali; Kantchev, Gueorgui; Abid, Mohamed Salah

    2011-01-01

    . -- Highlights: → The influence of the intake manifold geometry is studied on a converted gas engine. → In-cylinder flow modeling is made using CFD through two manifold designs. → An experimental comparison is made between manifolds by testing engine performances

  2. Modeling of asymmetrical boost converters

    Directory of Open Access Journals (Sweden)

    Eliana Isabel Arango Zuluaga

    2014-01-01

    Full Text Available The asymmetrical interleaved dual boost (AIDB is a fifth-order DC/DC converter designed to interface photovoltaic (PV panels. The AIDB produces small current harmonics to the PV panels, reducing the power losses caused by the converter operation. Moreover, the AIDB provides a large voltage conversion ratio, which is required to step-up the PV voltage to the large dc-link voltage used in grid-connected inverters. To reject irradiance and load disturbances, the AIDB must be operated in a closed-loop and a dynamic model is required. Given that the AIDB converter operates in Discontinuous Conduction Mode (DCM, classical modeling approaches based on Continuous Conduction Mode (CCM are not valid. Moreover, classical DCM modeling techniques are not suitable for the AIDB converter. Therefore, this paper develops a novel mathematical model for the AIDB converter, which is suitable for control-pur-poses. The proposed model is based on the calculation of a diode current that is typically disregarded. Moreover, because the traditional correction to the second duty cycle reported in literature is not effective, a new equation is designed. The model accuracy is contrasted with circuital simulations in time and frequency domains, obtaining satisfactory results. Finally, the usefulness of the model in control applications is illustrated with an application example.

  3. Grid converter for LED based intelligent light sources

    DEFF Research Database (Denmark)

    Török, Lajos

    The purpose of this thesis was to investigate the applicability and effects of digital control to line connected switched mode power supplies with power factor correction. The main approach was cost effectiveness with high efficiency. This involved hardware design for increased switching frequency...... and their implemented control algorithms. As digital control has to be competitive with the existing solutions it was investigated what digital signal processing solutions exist. A performance and cost comparison was also presented. The chosen converter topologies were thoroughly analyzed. Different converters were...... chosen for different power levels. At low power simple boost converter as power factor corrector (PFC) and a RCD-clamped forward converter was chosen as DC-DC converter. This with has double output and coupled lter inductor. To design a digital controller with the tools of the classical control theory...

  4. CAS CERN Accelerator School: Power converters for particle accelerators

    International Nuclear Information System (INIS)

    Turner, S.

    1990-01-01

    This volume presents the proceedings of the fifth specialized course organized by the CERN Accelerator School, the subject on this occasion being power converters for particle accelerators. The course started with lectures on the classification and topologies of converters and on the guidelines for achieving high performance. It then went on to cover the more detailed aspects of feedback theory, simulation, measurements, components, remote control, fault diagnosis and equipment protection as well as systems and grid-related problems. The important topics of converter specification, procurement contract management and the likely future developments in semiconductor components were also covered. Although the course was principally directed towards DC and slow-pulsed supplies, lectures were added on fast converters and resonant excitation. Finally the programme was rounded off with three seminars on the related fields of Tokamak converters, battery energy storage for electric vehicles, and the control of shaft generators in ships. (orig.)

  5. Temperature dependence of photon-enhanced thermionic emission from GaAs surface with nonequilibrium Cs overlayers

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravlev, A.G. [Rzhanov Institute of Semiconductor Physics, Pr. Lavrentieva, 13, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova, 2, 630090 Novosibirsk (Russian Federation); Alperovich, V.L., E-mail: alper@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Pr. Lavrentieva, 13, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova, 2, 630090 Novosibirsk (Russian Federation)

    2017-02-15

    Highlights: • Electronic properties of Cs/GaAs surface are studied at elevated temperatures. • Heating to ∼100 °C strongly affects photoemission current and surface band bending. • For θ < 0.4 ML photoemission current relaxation is due to band bending. • A spectral proof of the PETE process is obtained at Cs/GaAs thermal cycling. - Abstract: The temperature influence on the Cs/GaAs surface electronic properties, which determine the photon-enhanced thermionic emission (PETE), is studied. It was found that heating to moderate temperatures of about 100 °C leads to substantial changes in the magnitude and shape of Cs coverage dependences of photoemission current and surface band bending, along with the changes of relaxation kinetics after Cs deposition. A spectral proof of the PETE process is obtained under thermal cycling of the Cs/GaAs surface with 0.45 monolayer (ML) of Cs.

  6. Entanglement in a parametric converter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Su-Yong; Qamar, Shahid; Lee, Hai-Woong; Zubairy, M Suhail [Center for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)], E-mail: shahid_qamar@pieas.edu.pk, E-mail: zubairy@physics.tamu.edu

    2008-07-28

    In this paper, we consider a parametric converter as a source of entangled radiation. We examine recently derived conditions (Hillery and Zubairy 2006 Phys. Rev. Lett. 96 050503, Duan et al 2000 Phys. Rev. Lett. 84 2722) for determining when the two output modes in a parametric converter are entangled. We show that for different initial field states, the two criteria give different conditions that ensure that the output states are entangled. We also present an input-output calculation for the entanglement of the output field.

  7. AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Moh. Zaenal Efendi

    2014-06-01

    Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

  8. Current-to-frequency converter

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, S W [Institute of Nuclear Research, Warsaw (Poland)

    1981-07-15

    A current-to-frequency converter covering the range from 3 x 10/sup -10/ A up to 3 x 10/sup -5/ A of the input current is described. The circuit operates with nuclear detectors featuring a high internal resistance.

  9. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  10. A high speed digital-to-analogue converter

    International Nuclear Information System (INIS)

    Hallgren, B.I.

    1974-02-01

    An 8-bit Digital-to-Analogue converter of the current-weighting type has been constructed using 8 monolithic integrated circuit transistor arrays -one for each bit. The D/A-converter has a voltage output within the range 0 to -2V. The settling time to within half of the least significant bit is about 50 nsec. The temperature dependence and transient response of the converter has been analysed using computer aided design techniques. A comparison is made between the experimental and simulated transient performance. (Auth.)

  11. A DSP controlled one-to-three phase matrix converter

    Energy Technology Data Exchange (ETDEWEB)

    Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)

    1997-12-31

    This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.

  12. Torque converter transient characteristics prediction using computational fluid dynamics

    International Nuclear Information System (INIS)

    Yamaguchi, T; Tanaka, K

    2012-01-01

    The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.

  13. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based......, and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often...

  14. High Efficiency Boost Converter with Three State Switching Cell

    DEFF Research Database (Denmark)

    Klimczak, Pawel; Munk-Nielsen, Stig

    2009-01-01

    is on performance improvement of this type of the converter. Use of foil windings helps to reduce conduction losses in magnetic components and to reduce size of these components. Also it has been demonstrated that the regulation range of this type of converter can be increased by operation with duty cycle lower......The boost converter with the three-state switching cell seems to be a good candidate for a dc-dc stage for non-isolated generators based on alternative energy sources. It provides a high voltage gain, a reduced voltage stress on transistors and limited input current ripples. In this paper the focus...

  15. Analysis and Design of High-Order Parallel Resonant Converters

    Science.gov (United States)

    Batarseh, Issa Eid

    1990-01-01

    In this thesis, a special state variable transformation technique has been derived for the analysis of high order dc-to-dc resonant converters. Converters comprised of high order resonant tanks have the advantage of utilizing the parasitic elements by making them part of the resonant tank. A new set of state variables is defined in order to make use of two-dimensional state-plane diagrams in the analysis of high order converters. Such a method has been successfully used for the analysis of the conventional Parallel Resonant Converters (PRC). Consequently, two -dimensional state-plane diagrams are used to analyze the steady state response for third and fourth order PRC's when these converters are operated in the continuous conduction mode. Based on this analysis, a set of control characteristic curves for the LCC-, LLC- and LLCC-type PRC are presented from which various converter design parameters are obtained. Various design curves for component value selections and device ratings are given. This analysis of high order resonant converters shows that the addition of the reactive components to the resonant tank results in converters with better performance characteristics when compared with the conventional second order PRC. Complete design procedure along with design examples for 2nd, 3rd and 4th order converters are presented. Practical power supply units, normally used for computer applications, were built and tested by using the LCC-, LLC- and LLCC-type commutation schemes. In addition, computer simulation results are presented for these converters in order to verify the theoretical results.

  16. Converter Monitoring Unit for Retrofit of Wind Power Converters

    DEFF Research Database (Denmark)

    Rannestad, Bjorn; Maarbjerg, Anders Eggert; Frederiksen, Kristian

    2018-01-01

    A Converter Monitoring Unit (CMU), which will enable condition monitoring of wind turbine converters is presented in this paper. Reducing the cost of corrective maintenance by means of condition monitoring is a way of lowering Operation & Maintenance (O&M) costs for wind turbine systems....... The CMU must be able to detect a broad range of failure modes related to Insulated Gate Bipolar Transistor (IGBT) power modules and associated gate drives. IGBT collector-emitter on-state voltage (vceon) and current (ic) is sampled in the CMU and used for detection of emerging failures. A new method...... for compensation of unwanted inductive voltage drop in the vceon measurement path is presented, enabling retrofitting of CMUs in existing wind turbines. Finally, experimental results obtained on a prototype CMU are presented. Experimentally the vceon dependency to IGBT junction temperature and deterioration...

  17. Parametric study of laser photovoltaic energy converters

    Science.gov (United States)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  18. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  19. A Cost-Effective Design and Analysis of Full Bridge LLC Resonant Converter

    OpenAIRE

    Kaibalya Prasad Panda; Sreyasee Rout

    2016-01-01

    LLC (Inductor-inductor-capacitor) resonant converter has lots of advantages over other type of resonant converters which include high efficiency, more reliable and have high power density. This paper presents the design and analysis of a full bridge LLC resonant converter. In addition to the operational principle, the ZVS and ZCS conditions are also explained with the DC characteristics. Simulation of the LLC resonant converter is performed in MATLAB/ Simulink and the practical prototype setu...

  20. Multilevel Modular Converter for VSC-HVDC Transmission Applications: Control and Operational Aspects

    DEFF Research Database (Denmark)

    Gnanarathna, Udana N.; Gole, Aniruddha M.; Chaudhary, Sanjay Kumar

    2010-01-01

    Control methods for a new class of converter, the multilevel modular converter (MMC), recently introduced for HVDC transmission are discussed. The paper discusses converter-level controls including firing pulse generation and capacitor voltage balancing. It also covers higher level controls...... for incorporating the converter into a larger power network, with a weak ac receiving end. The performance behavior is studied using electromagnetic transients simulation....

  1. Design and Analysis of Two-Phase Boost DC-DC Converter

    OpenAIRE

    Taufik Taufik; Tadeus Gunawan; Dale Dolan; Makbul Anwari

    2010-01-01

    Multiphasing of dc-dc converters has been known to give technical and economical benefits to low voltage high power buck regulator modules. A major advantage of multiphasing dc-dc converters is the improvement of input and output performances in the buck converter. From this aspect, a potential use would be in renewable energy where power quality plays an important factor. This paper presents the design of a 2-phase 200W boost converter for battery charging application. Analysis of results fr...

  2. A nonlinearity compensation method for a matrix converter drive

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Blaabjerg, Frede

    2005-01-01

    converter model using the direction of current. The proposed method does not need any additional hardware or complicated software and it is easy to realize by applying the algorithm to the conventional vector control. The proposed compensation method is applied for high-performance induction motor drives...... using a 3-kW matrix converter system without a speed sensor. Experimental results show the proposed method provides good compensating characteristics....

  3. Injection of holes at indium tin oxide/dendrimer interface: An explanation with new theory of thermionic emission at metal/organic interfaces

    International Nuclear Information System (INIS)

    Peng Yingquan; Lu Feiping

    2006-01-01

    The traditional theory of thermionic emission at metal/inorganic crystalline semiconductor interfaces is no longer applicable for the interface between a metal and an organic semiconductor. Under the assumption of thermalization of hot carriers in the organic semiconductor near the interface, a theory for thermionic emission of charge carriers at metal/organic semiconductor interfaces is developed. This theory is used to explain the experimental result from Samuel group [J.P.J. Markham, D.W. Samuel, S.-C. Lo, P.L. Burn, M. Weiter, H. Baessler, J. Appl. Phys. 95 (2004) 438] for the injection of holes from indium tin oxide into the dendrimer based on fac-tris(2-phenylpyridyl) iridium(III)

  4. Development of a thermionic magnicon amplifier at 11.4 GHz. Technical progress report, 16 May 1994--31 December 1995

    International Nuclear Information System (INIS)

    Gold, S.H.; Fliflet, A.W.; Manheimer, W.M.

    1995-01-01

    This is a progress report on a four-year research program entitled 'Development of a Thermionic Magnicon Amplifier at 11.4 GHz', which is under way in the Plasma Physics Division of the Naval Research Laboratory (NRL) under Interagency Agreement DE-AI02-94ER40681. This report covers the period 16 May 1994 through 31 December 1995. The magnicon is an advanced microwave tube with potential application to future high gradient linear accelerators such as TeV colliders. Under this program, NRL plans to build and test a thermionic magnicon amplifier tube powered by a 500 kV, 200 A, 10 Hz modulator with a 1 μsec pulse. However, the experiments that were carried out during the period covered by this report were driven by a single-shot Marx generator, and the electron beam was produced from a graphite plasma cathode

  5. Multilevel Converter by Cascading Two-Level Three-Phase Voltage Source Converter

    Directory of Open Access Journals (Sweden)

    Abdullrahman A. Al-Shamma’a

    2018-04-01

    Full Text Available This paper proposes a topology using isolated, cascaded multilevel voltage source converters (VSCs and employing two-winding magnetic elements for high-power applications. The proposed topology synthesizes 6 two-level, three-phase VSCs, so the power capability of the presented converter is six times the capability of each VSC module. The characteristics of the proposed topology are demonstrated through analyzing its current relationships, voltage relationships and power capability in detail. The power rating is equally shared among the VSC modules without the need for a sharing algorithm; thus, the converter operates as a single three-phase VSC. The comparative analysis with classical neutral-point clamped, flying capacitor and cascaded H-bridge exhibits the superior features of fewer insulated gate bipolar transistors (IGBTs, capacitor requirement and fewer diodes. To validate the theoretical performance of the proposed converter, it is simulated in a MATLAB/Simulink environment and the results are experimentally demonstrated using a laboratory prototype.

  6. Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Nava, Vincenzo; Topper, Mathew B. R.

    2017-01-01

    This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC) arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation......, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA), a genetic algorithm (GA) and the glowworm swarm optimisation (GSO) algorithm...

  7. Aquabuoy Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Frigaard, Peter

    The work reported here is part of the contract agreement between the Finavera Renewables Ocean Energy Ltd. and the Department of Civil Engineering Hydraulics and Coastal Engineering Laboratory to instrument a model in scale 1:10 to prototype of the AquaBuOY (AB) wave energy converter and to analyse...... its performances in real sea testing in Nissum Bredning, Denmark. This report is part of Fineveras contribution to ForskEl project no 6435 “AquaBuOY skala 1:10 forsøg I Nissum Bredning”....

  8. Design, modeling and testing of data converters

    CERN Document Server

    Kiaei, Sayfe; Xu, Fang

    2014-01-01

    This book presents the a scientific discussion of the state-of-the-art techniques and designs for modeling, testing and for the performance analysis of data converters. The focus is put on sustainable data conversion. Sustainability has become a public issue that industries and users can not ignore. Devising environmentally friendly solutions for data conversion designing, modeling and testing is nowadays a requirement that researchers and practitioners must consider in their activities. This book presents the outcome of the IWADC workshop 2011, held in Orvieto, Italy.

  9. PEMODELAN DAN SIMULASI TOPOLOGI SINGLE ENDED PRIMARY INDUCTOR CONVERTER (SEPIC) UNTUK MINI 3 PLUS WIND TURBINE

    OpenAIRE

    Prasetiyo, Ryan; Maulana, Dwindra Wilham; Panatarani, Camellia; Joni, I Made

    2016-01-01

    In order to have a DC-DC buck boost converter with performances as desired specifications, the design process was performed by developing a model and simulation. The purpose of this research was to design a converter applied for a MINI 3 plus Wind Turbine. The converter topology was designed with Single Ended Primary Inductor Converter (SEPIC) using  a Continuous Conduction Mode (CCM). The output specifications of converter are input voltage 60 V, input current 7,5 A, output voltage 25 V...

  10. EMC Investigation of a Very High Frequency Self-oscillating Resonant Power Converter

    DEFF Research Database (Denmark)

    Pedersen, Jeppe Arnsdorf; Knott, Arnold; Andersen, Michael A. E.

    2016-01-01

    This paper focuses on the electromagnetic compatibility (EMC) performance of a Very High Frequency (VHF) converter and how to lower the emissions. To test the EMC performance a VHF converter is implemented with a Class-E inverter and a Class-DE rectifier. The converter is designed to deliver 3 W...... the regulations. This converter shows to be well below the levels for conducted emission even without filtering. For the radiated emissions the converter is above the limits without input and output filters. Several designs with different ways to lower the emissions are implemented and the different layouts...

  11. Decimal multiplication using compressor based-BCD to binary converter

    Directory of Open Access Journals (Sweden)

    Sasidhar Mukkamala

    2018-02-01

    Full Text Available The objective of this work is to implement a scalable decimal to binary converter from 8 to 64 bits (i.e 2-digit to 16-digit using parallel architecture. The proposed converters, along with binary coded decimal (BCD adder and binary to BCD converters, are used in parallel implementation of Urdhva Triyakbhyam (UT-based 32-bit BCD multiplier. To increase the performance, compressor circuits were used in converters and multiplier. The designed hardware circuits were verified by behavioural and post layout simulations. The implementation was carried out using Virtex-6 Field Programmable Gate Array (FPGA and Application Specific Integrated Circuit (ASIC with 90-nm technology library platforms. The results on FPGA shows that compressor based converters and multipliers produced less amount of propagation delay with a slight increase of hardware resources. In case of ASIC implementation, a compressor based converter delay is equivalent to conventional converter with a slight increase of gate count. However, the reduction of delay is evident in case of compressor based multiplier.

  12. Analysis of series resonant converter with series-parallel connection

    Science.gov (United States)

    Lin, Bor-Ren; Huang, Chien-Lan

    2011-02-01

    In this study, a parallel inductor-inductor-capacitor (LLC) resonant converter series-connected on the primary side and parallel-connected on the secondary side is presented for server power supply systems. Based on series resonant behaviour, the power metal-oxide-semiconductor field-effect transistors are turned on at zero voltage switching and the rectifier diodes are turned off at zero current switching. Thus, the switching losses on the power semiconductors are reduced. In the proposed converter, the primary windings of the two LLC converters are connected in series. Thus, the two converters have the same primary currents to ensure that they can supply the balance load current. On the output side, two LLC converters are connected in parallel to share the load current and to reduce the current stress on the secondary windings and the rectifier diodes. In this article, the principle of operation, steady-state analysis and design considerations of the proposed converter are provided and discussed. Experiments with a laboratory prototype with a 24 V/21 A output for server power supply were performed to verify the effectiveness of the proposed converter.

  13. Radiated EMI from power converters

    Directory of Open Access Journals (Sweden)

    Arnautovski-Toševa Vesna

    2005-01-01

    Full Text Available With the continuous increase of switching frequency together with the ongoing trend to higher complexity and functionality, power converters as a part of electronic systems have raised more and more electromagnetic energy pollution to the local system environment. In the same time, stringent demands are imposed on the designers of new circuits that electromagnetic interference (EMI has to be suppressed at its source before it is allowed to propagate into other circuits and systems. In this paper, the authors present a full-wave numerical method for calculation and simulation of electromagnetic field radiated by power converter circuitry. The main objective is to analyze the layout geometry in order to obtain competitive PCB layout that will enable suitably attenuated level of the radiated electric field to safe level. By this it would be possible to ensure reliable operation of the sensitive electronic components in the proximity.

  14. Vibration converter with magnetic levitation

    Science.gov (United States)

    Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

    2015-05-01

    The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

  15. Development of high torque belt CVT with torque converter; Torque converter tsuki daiyoryogata belt CVT no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, M; Fujikawa, T; Yoshida, K; Kobayahi, M [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    Nissan has successfully developed a new belt CVT (Continuously Variable Transmission) with torque converter and has installed it 2L-class vehicle for the first time in the world. This paper describes about the technology of high torque transmission, the need of torque converter, the importance of electronic control and the introduce of driving mode. As the result the CVT has improved driving performance and fuel economy for current CVT and 4 speed automatic transmission. 13 figs., 2 tabs.

  16. Status of advanced bremsstrahlung converters

    International Nuclear Information System (INIS)

    Halbleib, J.A.

    1980-01-01

    This paper is an attempt to review the somewhat ill-defined area of advanced converter research in a more or less chronological fashion. Section 2 reviews the early B/sub z/ work that was motivated by the CASINO project. More recent work makes liberal use of technology from ICF research using REBs is discussed in Sec. 3. Section 4 discusses possible directions for future research, some of which are being actively pursued at Sandia National Laboratories (SNL) and elsewhere

  17. Responses and mechanisms of positive electron affinity molecules in the N2 mode of the thermionic ionization detector and the electron-capture detector

    International Nuclear Information System (INIS)

    Jones, C.S.

    1989-01-01

    Very little knowledge has been acquired in the past on the mechanistic pathway by which molecules respond in the N 2 mode of the thermionic ionization detector. An attempt is made here to elucidate the response mechanism of the detector. The basic response mechanisms are known for the electron capture detector, and an attempt is made to identify the certain mechanism by which selected molecules respond. The resonance electron capture rate constant has been believed to be temperature independent, and investigations of the temperature dependence of electron capture responses are presented. Mechanisms for the N 2 mode of the thermionic ionization detector have been proposed by examining the detector response to positive electron affinity molecules and by measurement of the ions produced by the detector. Electron capture mechanisms for selected molecules have been proposed by examining their temperature dependent responses in the electron capture detector and negative ion mass spectra of the samples. In studies of the resonance electron capture rate constant, the relative responses of selected positive electron affinity molecules and their temperature dependent responses were investigated. Positive electron affinity did not guarantee large responses in the N 2 mode thermionic ionization detector. High mass ions were measured following ionization of samples in the detector. Responses in the electron capture detector varied with temperature and electron affinity

  18. Fermi level splitting and thermionic current improvement in low-dimensional multi-quantum-well (MQW) p-i-n structures

    International Nuclear Information System (INIS)

    Varonides, Argyrios C.

    2006-01-01

    Photo-excitation and subsequent thermionic currents are essential components of photo-excited carrier transport in multi-quantum-well photovoltaic (hetero-PV) structures. p-i-n multi-quantum structures are useful probes for a better understanding of PV device properties. Illumination of the intrinsic region of p-i-n multi-structures causes carrier trapping in any of the quantum wells, and subsequent carrier recombination or thermal escape is possible. At the vicinity of a quantum well, we find that the (quasi) Fermi levels undergo an upward split by a small, but non-negligible, energy amount ΔE F in the order of 12 meV. We conclude this fact by comparing the photo-excited carriers trapped in a quantum well, under illumination, to the carrier concentrations under dark. Based on such a prediction, we subsequently relate thermionic current density dependence on Fermi level splitting, concluding that excess thermal currents may increase by a factor of the order of 2. We conclude that illumination causes (a) Fermi level separation and (b) an apparent increase in thermionic currents

  19. Development of a high temperature solar receiver for high-efficient thermionic conversion systems; Fukugo netsuden henkan system yo chokoon taiyo junetsuki no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Umeoka, T; Naito, H; Yugami, H; Arashi, H [Tohoku University, Sendai (Japan). Faculty of Engineering

    1996-10-27

    For thermionic conversion systems (TIC) using concentrated sunlight as heat source, the newly developed solar receiver was tested. Concentrated sunlight aims at the inner surface of the cavity type solar receiver. The emitter of TIC installed in the rear of the solar receiver is uniformly heated over 1700K by thermal radiation from the rear of the solar receiver, emitting thermion. Electric power is generated by collecting the thermion by collector. Mo is used as emitter material, however, because of poor heat absorption of Mo, high-absorptive TiC is used for heat absorption surface to heat Mo by thermal conduction from high-temperature TiC. Functionally gradient material (FGM) with an intermediate layer of gradient TiC/Mo ratios between TiC and Mo is used as emitter material. The emitter is thus uniformly heated at high temperatures of 1723{plus_minus}12K. As a result, the developed solar receiver is applicable to heat the emitter of TIC. Heat flux measurement at the graphite cavity clarified that cavity temperature of as high as 1780K and heat flow of 50W/cm{sup 2} are obtained at 4.7kW in input. 6 figs.

  20. Computerized simulation of converter process

    Energy Technology Data Exchange (ETDEWEB)

    Jalkanen, H; Suomi, M L; Wallgren, M [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy

    1997-12-31

    Converter process is essentially an oxidising refining process aiming in addition to (1) the primary refining action, decarburisation of high carbon iron melt, also to (2) maximal elimination of impurity elements, especially silicon, phosphorus and sulphur, (3) melting of substantial amounts of scrap using the extra heat released in oxidation reactions and (4) to exact final steel temperature control, optimal for further treatments. `Quantitative modelling of such a complex non-stationary chemical process as oxygen converting necessitates extensive formulation of chemical and thermal evolution of the process in connection with the technological properties of the reactor and the process control measures. A comprehensive converter simulation program like CONSIM-3. 1 and its preceding versions that is based on the theoretical and practical knowledge on the process can be used for (1) educating specialists and smelter personnel, (2) planning of the blowing programs, (3) developing and testing of process control systems and after some elaboration and restructuring (4) it can be integrated to static or dynamic process control systems. (orig.) SULA 2 Research Programme; 10 refs.

  1. Computerized simulation of converter process

    Energy Technology Data Exchange (ETDEWEB)

    Jalkanen, H.; Suomi, M.L.; Wallgren, M. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy

    1996-12-31

    Converter process is essentially an oxidising refining process aiming in addition to (1) the primary refining action, decarburisation of high carbon iron melt, also to (2) maximal elimination of impurity elements, especially silicon, phosphorus and sulphur, (3) melting of substantial amounts of scrap using the extra heat released in oxidation reactions and (4) to exact final steel temperature control, optimal for further treatments. `Quantitative modelling of such a complex non-stationary chemical process as oxygen converting necessitates extensive formulation of chemical and thermal evolution of the process in connection with the technological properties of the reactor and the process control measures. A comprehensive converter simulation program like CONSIM-3. 1 and its preceding versions that is based on the theoretical and practical knowledge on the process can be used for (1) educating specialists and smelter personnel, (2) planning of the blowing programs, (3) developing and testing of process control systems and after some elaboration and restructuring (4) it can be integrated to static or dynamic process control systems. (orig.) SULA 2 Research Programme; 10 refs.

  2. Development of a Compact Matrix Converter

    Directory of Open Access Journals (Sweden)

    J. Bauer

    2009-01-01

    Full Text Available This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. This is enabled by 9 bidirectional switches, which are provided by anti-serial connection of 18 IGBT transistors. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods. 

  3. Effect of pole zero location on system dynamics of boost converter for micro grid

    Science.gov (United States)

    Lavanya, A.; Vijayakumar, K.; Navamani, J. D.; Jayaseelan, N.

    2018-04-01

    Green clean energy like photo voltaic, wind energy, fuel cell can be brought together by microgrid.For low voltage sources like photovoltaic cell boost converter is very much essential. This paper explores the dynamic analysis of boost converter in a continuous conduction mode (CCM). The transient performance and stability analysis is carried out in this paper using time domain analysis and frequency domain analysis techniques. Boost converter is simulated using both PSIM and MATLAB software. Furthermore, state space model obtained and the transfer function is derived. The converter behaviour when a step input is applied is analyzed and stability of the converter is analyzed from bode plot frequency for open loop. Effect of the locations of poles and zeros in the transfer function of boost converter and how the performance parameters are affected is discussed in this paper. Closed loop performance with PI controller is also analyzed for boost converter.

  4. A PIPO Boost Converter with Low Ripple and Medium Current Application

    Science.gov (United States)

    Bandri, S.; Sofian, A.; Ismail, F.

    2018-04-01

    This paper presents a Parallel Input Parallel Output (PIPO) boost converter is proposed to gain power ability of converter, and reduce current inductors. The proposed technique will distribute current for n-parallel inductor and switching component. Four parallel boost converters implement on input voltage 20.5Vdc to generate output voltage 28.8Vdc. The PIPO boost converter applied phase shift pulse width modulation which will compare with conventional PIPO boost converters by using a similar pulse for every switching component. The current ripple reduction shows an advantage PIPO boost converter then conventional boost converter. Varies loads and duty cycle will be simulated and analyzed to verify the performance of PIPO boost converter. Finally, the unbalance of current inductor is able to be verified on four area of duty cycle in less than 0.6.

  5. Control of improved full-bridge three-level DC/DC converter for wind turbines in a DC grid

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter......This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency...

  6. PENGGUNAAN FUZZY LOGIC UNTUK KONTROL PARALLEL CONVERTER DC-DC

    Directory of Open Access Journals (Sweden)

    Bambang Prio Hartono

    2012-09-01

    Full Text Available Abstract: Using system fuzzy logic as control  technology have been used on low load dc-dc converter with combined parallel compiled  dc-dc converter can  obtain big load.   With existence of differrence of component parameter and each parallel compiled converter can obtained different current  and voltage output.  Function of controller  for to do adjustment, so that current which is applied  to  load by each converter  can be obtained  difference error as small as possible or same. The object of research is developing design of large signal dc-dc converter which is  combined with using  FLC so that  obtain  better performance.  To get better performance have been made plant model and simulation with CDE method.  The more systematic  system and design is needed to overcome bigger load  on dc-dc converter, so that parallel  compiled current master slave control system on dc-dc converter with using fuzzy logic  controller is used. Result of  research showed that error or difference of  current  which is applied to load can handled by fuzzy logic  controller.  Technic of current and voltage controller co to do adjustment current and voltage distribution  equally to load.  Distribution of iL1,iL2 and  output voltage Vo on dc-dc  converter with load 2,25 until  7,875 and voltage  100  until 120 volt,  load current beetwen  12 until 48, % relatif  error  Vo  0,4% until  0,9%.

  7. Resonant Tunneling Analog-To-Digital Converter

    Science.gov (United States)

    Broekaert, T. P. E.; Seabaugh, A. C.; Hellums, J.; Taddiken, A.; Tang, H.; Teng, J.; vanderWagt, J. P. A.

    1995-01-01

    As sampling rates continue to increase, current analog-to-digital converter (ADC) device technologies will soon reach a practical resolution limit. This limit will most profoundly effect satellite and military systems used, for example, for electronic countermeasures, electronic and signal intelligence, and phased array radar. New device and circuit concepts will be essential for continued progress. We describe a novel, folded architecture ADC which could enable a technological discontinuity in ADC performance. The converter technology is based on the integration of multiple resonant tunneling diodes (RTD) and hetero-junction transistors on an indium phosphide substrate. The RTD consists of a layered semiconductor hetero-structure AlAs/InGaAs/AlAs(2/4/2 nm) clad on either side by heavily doped InGaAs contact layers. Compact quantizers based around the RTD offer a reduction in the number of components and a reduction in the input capacitance Because the component count and capacitance scale with the number of bits N, rather than by 2 (exp n) as in the flash ADC, speed can be significantly increased, A 4-bit 2-GSps quantizer circuit is under development to evaluate the performance potential. Circuit designs for ADC conversion with a resolution of 6-bits at 25GSps may be enabled by the resonant tunneling approach.

  8. Auxiliary resonant DC tank converter

    Science.gov (United States)

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  9. Comparison of multi-MW converters considering the determining factors in wind power application

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    converters are normally targeted to the industrial drive applications, and they did not take into account the special requirements in the case of wind power. This paper tries to unify and compare several promising wind power converters by a series new model and perspective. The evaluation criteria...... will mainly focus on the costeffectiveness of power semiconductors and the converter performances when complying with grid codes - which are more crucial for the wind power converters. It is concluded that the power converters with various voltage levels, topologies, and paralleling structures are possible...... to be unified for comparison. And the two-level low-voltage converter solution still shows cost advantage regarding power semiconductors, while some multi-level medium-voltage converter solutions can show better performance when complying with the grid codes....

  10. Electromechanical converters for electric vehicles

    Science.gov (United States)

    Ambros, T.; Burduniuc, M.; Deaconu, S. I.; Rujanschi, N.

    2018-01-01

    The paper presents the analysis of various constructive schemes of synchronous electromechanical converters with permanent magnets fixed on the rotor and asynchronous with the short-circuit rotor. Various electrical stator winding schemes have also been compared, demonstrating the efficiency of copper utilization in toroidal windings. The electromagnetic calculus of the axial machine has particularities compared to the cylindrical machine, in the paper is presented the method of correlating the geometry of the cylindrical and axial machines. In this case the method and recommendations used in the design of such machines may be used.

  11. Power electronics converters and regulators

    CERN Document Server

    Dokić, Branko L

    2015-01-01

    This book is the result of the extensive experience the authors gained through their year-long occupation at the Faculty of Electrical Engineering at the University of Banja Luka. Starting at the fundamental basics of electrical engineering, the book guides the reader into this field and covers all the relevant types of converters and regulators. Understanding is enhanced by the given examples, exercises and solutions. Thus this book can be used as a textbook for students, for self-study or as a reference book for professionals.

  12. OAM mode converter in twisted fibers

    DEFF Research Database (Denmark)

    Usuga Castaneda, Mario A.; Beltran-Mejia, Felipe; Cordeiro, Cristiano

    2014-01-01

    We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA.......We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA....

  13. Investigation of barium-calcium aluminate process to manufacture and characterize impregnated thermionic cathode for power microwave devices

    International Nuclear Information System (INIS)

    Higashi, Cristiane

    2006-01-01

    In the present work it is described the barium calcium aluminate manufacture processes employed to produce impregnated cathodes to be used in a traveling-wave tube (TWT). The cathodes were developed using a tungsten body impregnated with barium and calcium aluminate with a 5:3:2 proportion (molar). Three different processes were investigated to obtain this material: solid-state reaction, precipitation and crystallization. Thermal analysis, thermogravimetry specifically, supported to determine an adequate preparation procedure (taking into account temperature, time and pyrolysis atmosphere). It was verified that the crystallization showed a better result when compared to those investigated (solid-state reaction and precipitation techniques - formation temperature is about 1000 deg C in hydrogen atmosphere), whereas it presented the lower formation temperature (800 deg C) in oxidizing atmosphere (O 2 ). It was used the practical work function distribution theory (PWFD) of Miram to characterize thermionic impregnated cathode. The PWFD curves were used to characterize the barium-calcium aluminate cathode. PWFD curves shown that the aluminate cathode work function is about 2,00 eV. (author)

  14. A PVTC system integrating photon-enhanced thermionic emission and methane reforming for efficient solar power generation

    Institute of Scientific and Technical Information of China (English)

    Wenjia Li; Hongsheng Wang; Yong Hao

    2017-01-01

    A new photovoltaic-thermochemical (PVTC) conceptual system integrating photon-enhanced thermionic emission (PETE) and methane steam reforming is proposed.Major novelty of the system lies in its potential adaptivity to primary fuels (e.g.methane) and high efficiencies of photovoltaic and thermochemical power generation,both of which result from its operation at much elevated temperatures (700-1000 ℃)compared with conventional photovoltaic-thermal (PVT) systems.Analysis shows that an overall power generation efficiency of 45.3% and a net solar-to-electric efficiency of 39.1% could be reached at an operating temperature of 750 ℃,after considering major losses during solar energy capture and conversion processes.The system is also featured by high solar share (37%) in the total power output,as well as high energy storage capability and very low CO2 emissions,both enabled by the integration of methane reforming with photovoltaic generation at high temperatures.

  15. Development of high-current-density LAB6 thermionic emitters for a space-charge-limited electron gun

    International Nuclear Information System (INIS)

    Herniter, M.E.; Getty, W.D.

    1987-01-01

    An electron gun has been developed for investigation of high current density, space charge limited operation of a lenthanum hexaboride (LaB 6 ) thermionic cathode. The 2.8 cm 2 cathode disk is heated by electron bombardment from a tungsten filament. For LaB 6 cathode temperatures greater than 1600 0 C it has been found that evaporation from the LaB 6 causes an increase in the tungsten filament emission, leading to an instability in the bombardment heating system. This instability has been investigated and eliminated by using a graphite disk in place of the LaB 6 cathode or by shielding the filament from the LaB 6 cathode by placing the LaB 6 in a graphite cup and bombarding the cup. The graphite disk has been heated to 1755 0 C with 755 W of heating power, and the shielded LaB 6 cathode has been heated to 1695 0 C. This temperature range is required for emission current densities in the 30 Acm 2 range. It is believed that the evaporation of lanthanum lowers the tungsten work function. In electron-gun use, the LaB 6 cathode has been operated up to 6.7 Acm 2 at 36 kV. A 120 kV Marx generator has been built to allow operation up to 40 Acm 2

  16. Structural and Mechanical Properties of Nanostructured C-Ag Thin Films Synthesized by Thermionic Vacuum Arc Method

    Directory of Open Access Journals (Sweden)

    Rodica Vladoiu

    2018-01-01

    Full Text Available Nanostructured C-Ag thin films of 200 nm thickness were successfully synthesized by the Thermionic Vacuum Arc (TVA method. The influence of different substrates (glass, silicon wafers, and stainless steel on the microstructure, morphology, and mechanical properties of nanostructured C-Ag thin films was characterized by High-Resolution Transmission Electron Microscopy (HRTEM, Scanning Electron Microscopy (SEM, Atomic Force Microscopy (AFM, and TI 950 (Hysitron nanoindenter equipped with Berkovich indenter, respectively. The film’s hardness deposited on glass (HC-Ag/Gl = 1.8 GPa was slightly lower than in the case of the C-Ag film deposited on a silicon substrate (HC-Ag/Si = 2.2 GPa. Also the apparent elastic modulus Eeff was lower for C-Ag/Gl sample (Eeff = 100 GPa than for C-Ag/Si (Eeff = 170 GPa, while the values for average roughness are Ra=2.9 nm (C-Ag/Si and Ra=10.6 (C-Ag/Gl. Using the modulus mapping mode, spontaneous and indentation-induced aggregation of the silver nanoparticles was observed for both C-Ag/Gl and C-Ag/Si samples. The nanocomposite C-Ag film exhibited not only higher hardness and effective elastic modulus, but also a higher fracture resistance toughness to the silicon substrate compared to the glass substrate.

  17. THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexei V.; Agustsson, R.; Boucher, S.; Campese, Tara; Chen, Y.C.; Hartzell, Josiah J.; Jocobson, B.T.; Murokh, A.; O' Shea, F.H.; Spranza, E.; Berg, W.; Borland, M.; Dooling, J. C.; Erwin, L.; Lindberg, R. R.; Pasky, S.J.; Sereno, N.; Sun, Y.; Zholents, A.

    2017-06-01

    Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes including conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.

  18. Spectrometric analog-to-digital converter

    International Nuclear Information System (INIS)

    Ormandzhiev, S.I.; Jordanov, V.T.

    1988-01-01

    Converter of digit-by-digit counterbalancing with slipping dial with number of channels equal to total number of states of the main digital-to-analog converter of digit-by-digit counterbalancing systems is presented. Algorithm for selection of digital-to-analog converters, which must be used by means of computer is suggested

  19. A novel series-resonant converter topology

    NARCIS (Netherlands)

    Tilgenkamp, N.V.; Haan, de S.W.H.; Huisman, H.

    1987-01-01

    A converter topology based on the principles of seriesresonant (SR) power conversion is described in which the input and output of this converter have one terminal in common, and the transformer is omitted. Both the underlying theory and associated waveforms are presented. The converter is suitable

  20. Layout Optimisation of Wave Energy Converter Arrays

    Directory of Open Access Journals (Sweden)

    Pau Mercadé Ruiz

    2017-08-01

    Full Text Available This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA, a genetic algorithm (GA and the glowworm swarm optimisation (GSO algorithm. The results show slightly higher performances for the latter two algorithms; however, the first turns out to be significantly less computationally demanding.

  1. Molten-salt converter reactors

    International Nuclear Information System (INIS)

    Perry, A.M.

    1975-01-01

    Molten-salt reactors appear to have substantial promise as advanced converters. Conversion ratios of 0.85 to 0.9 should be attainable with favourable fuel cycle costs, with 235 U valued at $12/g. An increase in 235 U value by a factor of two or three ($10 to $30/lb. U 3 O 8 , $75/SWU) would be expected to increase the optimum conversion ratio, but this has not been analyzed in detail. The processing necessary to recover uranium from the fuel salt has been partially demonstrated in the MSRE. The equipment for doing this would be located at the reactor, and there would be no reliance on an established recycle industry. Processing costs are expected to be quite low, and fuel cycle optimization depends primarily on inventory and burnup or replacement costs for the fuel and for the carrier salt. Significant development problems remain to be resolved for molten-salt reactors, notably the control of tritium and the elimination of intergranular cracking of Hastelloy-N in contact with tellurium. However, these problems appear to be amenable to solution. It is appropriate to consider separating the development schedule for molten-salt reactors from that for the processing technology required for breeding. The Molten-Salt Converter Reactor should be a useful reactor in its own right and would be an advance towards the achievement of true breeding in thermal reactors. (author)

  2. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  3. Fuzzy Controlled Parallel AC-DC Converter for PFC

    Directory of Open Access Journals (Sweden)

    M Subba Rao

    2011-01-01

    Full Text Available Paralleling of converter modules is a well-known technique that is often used in medium-power applications to achieve the desired output power by using smaller size of high frequency transformers and inductors. In this paper, a parallel-connected single-phase PFC topology using flyback and forward converters is proposed to improve the output voltage regulation with simultaneous input power factor correction (PFC and control. The goal of the control is to stabilize the output voltage of the converter against the load variations. The paper presents the derivation of fuzzy control rules for the dc/dc converter circuit and control algorithm for regulating the dc/dc converter. This paper presents a design example and circuit analysis for 200 W power supply. The proposed approach offers cost effective, compact and efficient AC/DC converter by the use of parallel power processing. MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement.

  4. Reliability metrics extraction for power electronics converter stressed by thermal cycles

    DEFF Research Database (Denmark)

    Ma, Ke; Choi, Uimin; Blaabjerg, Frede

    2017-01-01

    Due to the continuous demands for highly reliable and cost-effective power conversion, the quantified reliability performances of the power electronics converter are becoming emerging needs. The existing reliability modelling approaches for the power electronics converter mainly focuses on the pr...... performance of power electronics system. The final predicted results showed good accuracy with much more reliability information compared to the existing approaches, and the quantified reliability correlation to the mission profiles of converter is mathematically established....

  5. Valuing Convertible Bonds Based on LSRQM Method

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2014-01-01

    Full Text Available Convertible bonds are one of the essential financial products for corporate finance, while the pricing theory is the key problem to the theoretical research of convertible bonds. This paper demonstrates how to price convertible bonds with call and put provisions using Least-Squares Randomized Quasi-Monte Carlo (LSRQM method. We consider the financial market with stochastic interest rates and credit risk and present a detailed description on calculating steps of convertible bonds value. The empirical results show that the model fits well the market prices of convertible bonds in China’s market and the LSRQM method is effective.

  6. Converting pest insects into food

    DEFF Research Database (Denmark)

    Offenberg, Hans Joachim; Wiwatwittaya, Decha

    2010-01-01

    Canopy dwelling weaver ants (Oecophylla spp.) are used to control a variety of pests in a number of tropical tree crops. What is less familiar is the existence of commercial markets where these ants and their brood are sold for (i) human consumption, (ii) pet food or (iii) traditional medicine...... on management, 32-115 kg ant brood (mainly new queens) was harvested per ha per year without detrimental effect on colony survival and worker ant densities. This suggest that ant biocontrol and ant harvest can be sustainable integrated in plantations and double benefits derived. As ant production is fuelled...... by pest insects, problematic pests are converted into food and additional earnings. To assess the profitability of providing additional food for the ants, O. smaragdina food conversion efficiency (ECI) was estimated in the laboratory. This estimate suggests the feeding of weaver ants in ant farms...

  7. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.

    2012-01-01

    This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging...... polypropylene film capacitor can be the equivalent capacitive load. Because of the voltage dependent characteristic, X7R MLCC cannot be used to replace the DEAP actuator. However, this type of capacitor can be used to substitute the capacitive actuator with voltage dependent property at the development phase....

  8. Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

    Directory of Open Access Journals (Sweden)

    Amir Ghorbani

    2018-05-01

    Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

  9. Power Generation Using Mechanical Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Srinivasan Chandrasekaran

    2012-03-01

    Full Text Available Ocean wave energy plays a significant role in meeting the growing demand of electric power. Economic, environmental, and technical advantages of wave energy set it apart from other renewable energy resources. Present study describes a newly proposed Mechanical Wave Energy Converter (MEWC that is employed to harness heave motion of floating buoy to generate power. Focus is on the conceptual development of the device, illustrating details of component level analysis. Employed methodology has many advantages such as i simple and easy fabrication; ii easy to control the operations during rough weather; and iii low failure rate during normal sea conditions. Experimental investigations carried out on the scaled model of MWEC show better performance and its capability to generate power at higher efficiency in regular wave fields. Design Failure Mode and Effect Analysis (FMEA shows rare failure rates for all components except the floating buoy.

  10. Generators for gearless wind energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Grauers, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    This paper discusses some design alternatives for directly driven generators, and one specific generator type is investigated for a wide range of rated power. First, the specification for a directly driven generator is presented, then different design alternatives are discussed. A radial-flux permanent magnet generator for frequency converter connection has been chosen for a more detailed investigation. The design, optimization and performance of that generator type are presented. Generators from 30 kW to 3 MW are designed and compared with conventional four-pole generators with gear. It is found that a directly driven generator can be more efficient than a conventional generator and gear and have a rather small diameter and a low active weight. 8 refs, 7 figs, 2 tabs

  11. Experimental Study on a Rotor for WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Marchalot, Tanguy

    This report presents the results of an experimental study of the power conversion capabilities of one single rotor of the WEPTOS wave energy converter. The investigation focuses mainly on defining the optimal weight distribution in the rotor in order to improve the hydraulic performance through...

  12. An Appraisal of the DEXA Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report has been requested by VækstFonden and aims at giving an overview of the experimental tests and a general appraisal of the DEXA wave energy converter (WEC). The reported results and findings were obtained during previously performed experimental tests by the Wave Energy Research Group...

  13. Optimization of Overtopping Wave Energy Converters by Geometry Control

    DEFF Research Database (Denmark)

    Victor, L.; Troch, P.; Kofoed, Jens Peter

    2011-01-01

    In this paper, the results of a study on the effects of geometry control on the performance of overtopping wave energy converters with a simple geometry built in coastal structures (simple OWECs) are presented. Empirical formulae, derived based on experimental tests on simple OWECs with varying...

  14. SCM Handbooks for dc-to-dc Converters

    Science.gov (United States)

    Lee, F.; Mohmoud, M.; Yu, Y.

    1984-01-01

    Two documents aid in design of control modules for dc-to-dc converters. Features of SCM include: Adaptive stability, power component stress limiting, implementation of various control laws, unified design approach. Analysis and quidelines contained in handbooks enable engineer to design SCM circuit and confidently predict resulting overall performance.

  15. Mismatch-Shaping Serial Digital-to-Analog Converter

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, Un-Ku; Temes, Gabor C.

    1999-01-01

    A simple but accurate pseudo-passive mismatch-shaping D/A converter is described. A digital state machine is used to control the switching sequence of a symmetric two-capacitor network that performs the D/A conversion. The error caused by capacitor mismatch is uncorrelated with the input signal...

  16. Circular waveguide mode converters at 140 GHz

    International Nuclear Information System (INIS)

    Trulsen, J.; Woskoboinikow, P.; Temkin, R.J.

    1986-01-01

    A unified derivation of the coupled mode equations for circular waveguide is presented. Also, approximate design criteria for TE/sub 0n/ to TE/sub 0n'/ axisymmetric, TE 01 to TE 11 wriggle, and TE 01 to TM 11 bend converters are reviewed. Numerically solving the coupled mode equations, an optimized set of mode converters has been designed for conversion of a 2 millimeter wave TE 03 mode into TE 11 . This set consists of axisymmetric TE 03 to TE 02 and TE 02 to TE 01 converters followed by a wriggle TE 01 to TE 11 converter. This mode converter set was fabricated and tested using a 3 kW, 137 GHz gyrotron. A TE 11 mode purity of better than 97% was achieved. The TE 01 to TE 11 wriggle converter was experimentally optimized for a measured conversion efficiency of better than 99% not including ohmic losses

  17. Thermal analysis of multi-MW two-level wind power converter

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Mogens, Lau

    2012-01-01

    In this paper, the multi-MW wind turbine of partial-scale and full-scale two-level power converter with DFIG and direct-drive PMSG are designed and compared in terms of their thermal performance. Simulations of different configurations regarding loss distribution and junction temperature...... in the power device in the whole range of wind speed are presented and analyzed. It is concluded that in both partial-scale and full-scale power converter the most thermal stressed power device in the generator-side converter will have higher mean junction temperature and larger junction temperature...... fluctuation compared to grid-side converter at the rated wind speed. Moreover, the thermal performance of the generator-side converter in the partial-scale power converter becomes crucial around the synchronous operating point and should be considered carefully....

  18. A Zero Input Current Ripple ZVS/ZCS Boost Converter with Boundary-Mode Control

    Directory of Open Access Journals (Sweden)

    Ching-Ming Lai

    2014-10-01

    Full Text Available In this paper, in order to achieve zero ripple conditions, the use of a ripple mirror (RM circuit for the boost converter is proposed. The operation modes are studied and steady-state analyses performed to show the merits of the proposed converter. It is found that the proposed RM circuit technique can provide much better flexibility than the two-phase interleaved boost converter for locating the zero ripple operating point in the design stage. In addition, the choice of using a boundary-mode control is mainly based on the consideration of achieving both ZVS (zero voltage switching/ZCS (zero current switching soft-switching and constant on-time control for the converter. To verify the performance of the proposed converter, a 48 V input and 200 W/200 V output prototype is constructed. Experimental results verify the effectiveness of the proposed converter.

  19. Image-converter streak cameras with very high gain

    International Nuclear Information System (INIS)

    1975-01-01

    A new camera is described with slit scanning and very high photonic gain (G=5000). Development of the technology of tubes and microchannel plates has enabled integration of such an amplifying element in an image converter tube which does away with the couplings and the intermediary electron-photon-electron conversions of the classical converter systems having external amplification. It is thus possible to obtain equal or superior performance while retaining considerable gain for the camera, great compactness, great flexibility in use, and easy handling. (author)

  20. CMOS sigma-delta converters practical design guide

    CERN Document Server

    De la Rosa, Jose M

    2013-01-01

    A comprehensive overview of Sigma-Delta Analog-to-Digital Converters (ADCs) and a practical guide to their design in nano-scale CMOS for optimal performance. This book presents a systematic and comprehensive compilation of sigma-delta converter operating principles, the new advances in architectures and circuits, design methodologies and practical considerations - going from system-level specifications to silicon integration, packaging and measurements, with emphasis on nanometer CMOS implementation. The book emphasizes practical design issues - from high-level behavioural modelling i

  1. Ocean floor mounting of wave energy converters

    Science.gov (United States)

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  2. Vacuum-insulated catalytic converter

    Science.gov (United States)

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  3. Semi-automatic logarithmic converter of logs

    International Nuclear Information System (INIS)

    Gol'dman, Z.A.; Bondar's, V.V.

    1974-01-01

    Semi-automatic logarithmic converter of logging charts. An original semi-automatic converter was developed for use in converting BK resistance logging charts and the time interval, ΔT, of acoustic logs from a linear to a logarithmic scale with a specific ratio for subsequent combining of them with neutron-gamma logging charts in operative interpretation of logging materials by a normalization method. The converter can be used to increase productivity by giving curves different from those obtained in manual, pointwise processing. The equipment operates reliably and is simple in use. (author)

  4. Commutation Processes in Multiresonant ZVS Bridge Converter

    Directory of Open Access Journals (Sweden)

    Miroslaw Luft

    2008-01-01

    Full Text Available The analysis of the multiresonant ZVS DC/DC bridge converter is presented. The control system of the converter is basedon the method of frequency control at the constant time of transistor turn-off with a phase shift. The operation of the circuit is givenand the operating range of the converter is defined where ZVS switching operation is assured. Control characteristics are given andthe converter’s efficiency is defined. The circuit’s operation is analysed on the basis of results of the converter simulation tests using Simplorer programme.

  5. Energy savings assessment for digital-to-analog converter boxes

    International Nuclear Information System (INIS)

    Cheung, Hoi Ying; Meier, Alan; Brown, Richard

    2011-01-01

    The Digital Television (DTV) Converter Box Coupon Program was administered by the U.S. government to subsidize purchases of digital-to-analog converter boxes, with up to two $40 coupons for each eligible household. In order to qualify as Coupon Eligible Converter Boxes (CECBs), these devices had to meet a number of minimum performance specifications, including energy efficiency standards. The Energy Star Program also established voluntary energy efficiency specifications that are more stringent than the CECB requirements. In this study, we measured the power and energy consumptions for a sample of 12 CECBs (including 6 Energy Star labeled models) in-use in homes and estimated aggregate energy savings produced by the energy efficiency policies. Based on the 35 million coupons redeemed through the end of the program, our analysis indicates that between 2500 and 3700 GWh per year are saved as a result of the energy efficiency policies implemented on digital-to-analog converter boxes. The energy savings generated are equivalent to the annual electricity use of 280,000 average US homes. - Research highlights: → We examined energy efficiency policies on digital-to-analog converter boxes in US. → The government assistance program resulted in high participation. → 35 million coupons were redeemed for the purchases of energy efficient DTAs. → Between 2500 and 3700 GWh per year are saved as a result of the policies. → Savings are equivalent to the annual electricity use of 280,000 average US homes.

  6. Electric converters of electromagnetic strike machine with battery power

    Science.gov (United States)

    Usanov, K. M.; Volgin, A. V.; Kargin, V. A.; Moiseev, A. P.; Chetverikov, E. A.

    2018-03-01

    At present, the application of pulse linear electromagnetic engines to drive strike machines for immersion of rod elements into the soil, strike drilling of shallow wells, dynamic probing of soils is recognized as quite effective. The pulse linear electromagnetic engine performs discrete consumption and conversion of electrical energy into mechanical work. Pulse dosing of a stream transmitted by the battery source to the pulse linear electromagnetic engine of the energy is provided by the electrical converter. The electric converters with the control of an electromagnetic strike machine as functions of time and armature movement, which form the unipolar supply pulses of voltage and current necessary for the normal operation of a pulse linear electromagnetic engine, are proposed. Electric converters are stable in operation, implement the necessary range of output parameters control determined by the technological process conditions, have noise immunity and automatic disconnection of power supply in emergency modes.

  7. Half bridge resonant converter for ignition of thermal plasmas

    International Nuclear Information System (INIS)

    Pena E, L.

    1997-01-01

    In this work the background, design, implementation and performance of a half bridge resonant converter (HBRC) used as an electronic ignition system for arc plasma torch generation is presented. The significance of the design lies in its simplicity, versatility and low cost. The system operates like a high voltage supply attached to electrodes before gaseous breakdown and like open circuit when electric arc is established. Resonant converter is implemented with a high voltage and high speed power driver intended for control the power MOSFET transistors connected in half bridge topology with L C load. The HBRC operates besides interference into domestic electric supply line (120 V, 60 Hz) as well electric measurement devices. Advantages and limitations of the converter are reviewed. Experimental impedance variation in the medium as a function of frequency operation and some experiences in striking arcs are also presented. (Author)

  8. Direct Torque Control of Matrix Converter Fed Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    JAGADEESAN Karpagam

    2011-10-01

    Full Text Available This paper presents the Direct TorqueControl (DTC of induction motor drive using matrixconverters. DTC is a high performance motor controlscheme with fast torque and flux responses. However,the main disadvantage of conventional DTC iselectromagnetic torque ripple. In this paper, directtorque control for Induction Motors using MatrixConverters is analysed and points out the problem ofthe electromagnetic torque ripple which is one of themost important drawbacks of the Direct TorqueControl. Besides, the matrix converter is a single-stageac-ac power conversion device without dc-link energystorage elements. Matrix converter (MC may becomea good alternative to voltage-source inverter (VSI.This work combines the advantages of the matrixconverter with those of the DTC technique, generatingthe required voltage vectors under unity input powerfactor operation. Simulation results demonstrates theeffectiveness of the torque control.

  9. Ripple Mitigation with Improved Line-Load Transients Response in Two-Stage DC-DC-AC Converter

    DEFF Research Database (Denmark)

    Gautam, Aditya R.; Gaurav, Kumar; Guerrero, Josep M.

    2018-01-01

    . The front-end boost converter in the considered two-stage converter interfaces a battery bank and single phase inverter fed loads. The control shapes the output impedance of boost converter to reduce the ripple component at battery input. Secondly, the proposed controller achieves good dynamic performance...

  10. Design and evaluation of cellular power converter architectures

    Science.gov (United States)

    Perreault, David John

    Power electronic technology plays an important role in many energy conversion and storage applications, including machine drives, power supplies, frequency changers and UPS systems. Increases in performance and reductions in cost have been achieved through the development of higher performance power semiconductor devices and integrated control devices with increased functionality. Manufacturing techniques, however, have changed little. High power is typically achieved by paralleling multiple die in a sing!e package, producing the physical equivalent of a single large device. Consequently, both the device package and the converter in which the device is used continue to require large, complex mechanical structures, and relatively sophisticated heat transfer systems. An alternative to this approach is the use of a cellular power converter architecture, which is based upon the parallel connection of a large number of quasi-autonomous converters, called cells, each of which is designed for a fraction of the system rating. The cell rating is chosen such that single-die devices in inexpensive packages can be used, and the cell fabricated with an automated assembly process. The use of quasi-autonomous cells means that system performance is not compromised by the failure of a cell. This thesis explores the design of cellular converter architectures with the objective of achieving improvements in performance, reliability, and cost over conventional converter designs. New approaches are developed and experimentally verified for highly distributed control of cellular converters, including methods for ripple cancellation and current-sharing control. The performance of these techniques are quantified, and their dynamics are analyzed. Cell topologies suitable to the cellular architecture are investigated, and their use for systems in the 5-500 kVA range is explored. The design, construction, and experimental evaluation of a 6 kW cellular switched-mode rectifier is also addressed

  11. High-Repeatable Data Acquisition Systems for Pulsed Power Converters in Particle Accelerator Structures

    CERN Document Server

    AUTHOR|(CDS)2087245; Martino, Michele; Zinno, Raffaele

    In this Ph.D. thesis, the issues related to the metrological characterization of high-performance pulsed power converters are addressed. Initially, a background and a state of the art on the measurement systems needed to correctly operate a high-performance power converter are presented. As a matter of fact, power converters usually exploits digital control loops to enhance their performance. In this context the final performance of a power converter has to be validated by a reference instrument with higher metrological characteristics. In addition, an on-line measurement systemis also needed to digitize the quantity to be controlled with high accuracy. Then, in industrial applications of power converters metrology, specifications are given in terms of Worst-Case Uncertainty (WCU). Therefore, an analytical model for predicting the Worst-Case Uncertainty (WCU) of a measurement system is discussed and detailed for an instrument affected by Gaussian noise. Furthermore, the study and the design of a Reference Acq...

  12. Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad

    2010-01-01

    DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

  13. Analysis of Topaz-II reactor performance using MCNP and TFEHX

    International Nuclear Information System (INIS)

    Lee, H.H.; Klein, A.C.

    1993-01-01

    Data reported by Russian scientist and engineers for the TOPAZ-II Space Nuclear Power is compared with analytical results calculated using the Monte Carlo Neutron and Photon (MCNP) and TFEHX computer codes. The results of these comparisons show good agreement with the TOPAZ-II neutronics, thermionic and thermal hydraulics performance. A detailed description of the TOPAZ-II reactor and of the TFE should enhance the performance of the both codes in modeling the reactor and TFE performances

  14. Program to Research Laser-Driven Thermionic Electron Sources for Free Electron Lasers.

    Science.gov (United States)

    1988-01-01

    by sinal I lengths of coaxial cable. With the ’. corresponding charge to the diode also reduced, a series of temporall y sho rter -Ioctron pulse-s was...e combination of approximately 1.6 eV. With the Nd:glass laser beam pulse heating the cathode " and the charge supplied by 0.5/ F capacitor, a series ...available charge stored in the h-arg ing ’apar i tor. A series of experiments was performed wilh lowetr capacitances of sevoral tens of picofarads furnished

  15. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...

  16. Present trends in HVDC converter station design

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Lennart; Asplund, Gunnar; Bjorklund, Hans; Flisberg, Gunnar [ABB Power Systems AB, Ludvika (Sweden)

    1994-12-31

    HVDC converter station technology has developed rapidly to satisfy increasing requirements during past 10 - 15 years, but there has not been any dramatic changes since thyristor valves were introduced in the mid 70s. This paper describes some recent and expected future developments, that will substantiality change and simplify future converter stations. (author) 4 refs., 7 figs.

  17. Luminescent converter of neodymium laser radiation

    International Nuclear Information System (INIS)

    Ryba-Romanowski, W.; Golab, S.

    1992-01-01

    The new luminescent converter of neodymium laser radiation has been worked out. Activated inorganic compounds of ytterbium and erbium ions has been used as luminescent agent. The multi-component inorganic glass containing tellurium oxide as well as boron, sodium, magnesium and zinc oxides has been applied as a converter matrix

  18. Time-Interleaved Analog to Digital Converters

    NARCIS (Netherlands)

    Louwsma, S.M.; van Tuijl, Adrianus Johannes Maria; Nauta, Bram

    2010-01-01

    This book describes the research carried out by our PhD student Simon Louwsma at the University of Twente, The Netherlands in the field of high-speed Analogto- Digital (AD) converters. AD converters are crucial circuits for modern systems where information is stored or processed in digital form. Due

  19. Switched-mode converters (one quadrant)

    CERN Document Server

    Barrade, P

    2006-01-01

    Switched-mode converters are DC/DC converters that supply DC loads with a regulated output voltage, and protection against overcurrents and short circuits. These converters are generally fed from an AC network via a transformer and a conventional diode rectifier. Switched-mode converters (one quadrant) are non-reversible converters that allow the feeding of a DC load with unipolar voltage and current. The switched-mode converters presented in this contribution are classified into two families. The first is dedicated to the basic topologies of DC/DC converters, generally used for low- to mid-power applications. As such structures enable only hard commutation processes, the main drawback of such topologies is high commutation losses. A typical multichannel evolution is presented that allows an interesting decrease in these losses. Deduced from this direct DC/DC converter, an evolution is also presented that allows the integration of a transformer into the buck and the buck–boost structure. This enables an int...

  20. Controller for a wave energy converter

    Science.gov (United States)

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  1. Full range ZVS DC-DC converter

    International Nuclear Information System (INIS)

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

    2011-01-01

    A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)

  2. Passive Resonant Bidirectional Converter with Galvanic Barrier

    Science.gov (United States)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  3. Modeling and Simulation of Matrix Converter

    DEFF Research Database (Denmark)

    Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...

  4. A TECHNIQUE OF EXPERIMENTAL INVESTIGATIONS OF LINEAR IMPULSE ELECTROMECHANICAL CONVERTERS

    Directory of Open Access Journals (Sweden)

    V.F. Bolyukh

    2017-04-01

    Full Text Available Purpose. Development of a technique of experimental studies linear pulse electromechanical converters parameters, which are used as shock-power devices and electromechanical accelerators, and comparing the experimental results with the calculated indices obtained using the mathematical model. Methodology. Method of experimental investigations of linear electromechanical converter is that the electrical parameters are recorded simultaneously (inductor winding current and mechanical parameters characterizing the power and speed indicators of the joke with actuator. Power indicators are primarily important for shock-power devices, and high velocity - for electromechanical accelerators. Power indices were investigated using piezoelectric sensors, a system of strain sensors, pressure pulsation sensor and high-speed videorecording. Velocity indicators were investigated using a resistive movement sensor which allows to record character of the armature movement with actuating element in each moment. Results. The technique of experimental research, which is the simultaneous recording of electrical and mechanical power and velocity parameters of the linear electromechanical converter pulse, is developed. In the converter as a shock-power device power indicators are recorded using a piezoelectric transducer, strain sensors system, pressure pulsation sensor and high-speed video. The parameters of the inductor winding current pulse, the time lag of mechanical processes in relation to the time of occurrence of the inductor winding current, the average speed of the joke, the magnitude and momentum of electrodynamics forces acting on the plate strikes are experimentally determined. In the converter as an electromechanical accelerator velocity performance recorded using resistive displacement sensors. It is shown that electromechanical converter processes have complex spatial-temporal character. The experimental results are in good agreement with the calculated

  5. A novel power converter for photovoltaic applications

    Science.gov (United States)

    Yuvarajan, S.; Yu, Dachuan; Xu, Shanguang

    A simple and economical power conditioner to convert the power available from solar panels into 60 Hz ac voltage is described. The raw dc voltage from the solar panels is converted to a regulated dc voltage using a boost converter and a large capacitor and the dc output is then converted to 60 Hz ac using a bridge inverter. The ratio between the load current and the short-circuit current of a PV panel at maximum power point is nearly constant for different insolation (light) levels and this property is utilized in designing a simple maximum power point tracking (MPPT) controller. The controller includes a novel arrangement for sensing the short-circuit current without disturbing the operation of the PV panel and implementing MPPT. The switching losses in the inverter are reduced by using snubbers. The results obtained on an experimental converter are presented.

  6. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage......DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which......-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques....

  7. A review of Indirect Matrix Converter Topologies

    Directory of Open Access Journals (Sweden)

    Salem Rahmani

    2015-08-01

    Full Text Available Abstract—Matrix Converter (MC is a modern direct AC/AC electrical power converter without dc-link capacitor. MC is operated in four quadrant, assuring a control of the output voltage, amplitude and frequency. The matrix converter has recently attracted significant attention among researchers and it has become increasing attractive for applications of wind energy conversion, military power supplies, induction motor drives, etc. Recently, different MC topologies have been proposed and developed which have their own advantages and disadvantages. Matrix converter can be classified as direct and indirect structures. The direct one has been elaborated in previous work. In this paper the indirect MCs are reviewed. Different characteristics of the indirect MC topologies are mentioned to show the strengths and weaknesses of such converter topologies.

  8. Formation of an interface layer in thermionic oxide cathodes for CRT applications

    International Nuclear Information System (INIS)

    Hashim, A A; Barratt, D S; Ray, A K; Hassan, A K

    2004-01-01

    Scanning electron microscopic techniques were employed to study the surface morphological changes of oxide cathodes and nickel caps as a result of cathode activation extending over periods of 1-12 h. Elemental analysis of barium, strontium, tungsten, magnesium and aluminium was performed using energy dispersion x-ray spectroscopy. An abrupt change was observed after activation longer than 3 h. Conduction through well activated cathode assemblies was found to be due to intergranular electron tunnelling at low temperatures (T ≤ 500 K), while trapping and detrapping at grain boundaries becomes the dominant mechanism at high temperatures (T ≥ 500 K). The contribution of the interfacial layer to conductivity was found to be significant for cathodes activated for smaller periods

  9. 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

  10. High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

    2017-01-01

    This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

  11. The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

    DEFF Research Database (Denmark)

    Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

    2017-01-01

    A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

  12. Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2016-01-01

    in the dc-link of the power converter to improve system performance, but also ensure the grid-side current balancing to increase the generated power of the wind turbine under the unbalanced grid fault, in comparison with the conventional VSWT based on BTB three-level NPC converters. The simulation studies......The modular multilevel converter (MMC) becomes attractive in the medium- and high-power application with high modularity. In this paper, the MMC is proposed to be applied in the variable speed wind turbine (VSWT) based on the full-scale back-to-back (BTB) power converter, where the generator...

  13. The application of standardized control and interface circuits to three dc to dc power converters.

    Science.gov (United States)

    Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

    1973-01-01

    Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

  14. Lifetime estimation for the power semiconductors considering mission profiles in wind power converter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    for the reliability improvement and also for cost reduction of wind power technology. Unfortunately, the existing lifetime estimation methods for the power electronic converter are not yet suitable in the wind power application, because the comprehensive mission profiles are not well specified and included......As a key component in the wind turbine system, power electronic converter and its power semiconductors suffer from adverse power loadings related to environment, and are proven to have certain failure rates. Therefore, correct lifetime estimation of wind power converter is crucial...... estimation, more detailed information for the reliability performance of wind power converter can be obtained....

  15. DC-DC Converter Topology Assessment for Large Scale Distributed Photovoltaic Plant Architectures

    Energy Technology Data Exchange (ETDEWEB)

    Agamy, Mohammed S; Harfman-Todorovic, Maja; Elasser, Ahmed; Sabate, Juan A; Steigerwald, Robert L; Jiang, Yan; Essakiappan, Somasundaram

    2011-07-01

    Distributed photovoltaic (PV) plant architectures are emerging as a replacement for the classical central inverter based systems. However, power converters of smaller ratings may have a negative impact on system efficiency, reliability and cost. Therefore, it is necessary to design converters with very high efficiency and simpler topologies in order not to offset the benefits gained by using distributed PV systems. In this paper an evaluation of the selection criteria for dc-dc converters for distributed PV systems is performed; this evaluation includes efficiency, simplicity of design, reliability and cost. Based on this evaluation, recommendations can be made as to which class of converters is best fit for this application.

  16. The 77 K operation of a multi-resonant power converter

    Science.gov (United States)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The liquid-nitrogen temperature (77 K) operation of a 55 W, 200 kHz, 48/28 V zero-voltage switching multi-resonant dc/dc converter designed with commercially available components is reported. Upon dipping the complete converter (power and control circuits) into liquid-nitrogen, the converter performance improved as compared to the room-temperature operation. The switching frequency, resonant frequency, and the characteristic impedance did not change significantly. Accordingly, the zero-voltage switching was maintained from no-load to full-load for the specified line variations. Cryoelectronics can provide high density power converters, especially for high power applications.

  17. Control of a resonant d.c.-link converter for a.c. motor drives

    Directory of Open Access Journals (Sweden)

    Astrid Petterteig

    1992-10-01

    Full Text Available This paper presents the control of the resonant d.c.-link converter for a.c. motor drives. This is a low loss converter with higher efficiency than a conventional PWM converter, but it requires complex control. It needs a special control of the resonant d.c.-link voltage in addition to the discrete control of the a.c. side currents. Simulations show how the control of the a.c. currents, the modulation principle, influences the overall performance of the converter.

  18. Development and implementation of a compound converter in solar energy systems

    Directory of Open Access Journals (Sweden)

    S. J. B. Hartman

    1992-07-01

    Full Text Available The converter proposed here is a compound photovoltaic converter system that has been implemented with a power rating of 1,5 kVA at an array voltage of 96 V, using a 24 V battery bank. The converter system combines the functions of inversion, battery regulation and maximum power point tracking of the solar array into a single cost-effective converter. Maximum power point tracking is performed by controlling the voltage and frequency of the AC output. A description of this converter, and an explanation of the control strategy employed, are provided together with practical results measured on the prototype converter. This compound topology has a high conversion efficiency from solar array to load.

  19. A new converter for improving efficiency of multi-actuators fluid power system

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yong; Shang, JianZhong; Yang, JunHong; Wang Zhuo [National University of Defense Technology, Changsha (China)

    2016-05-15

    This paper is concerned with the application of energy efficient fluid power in mobile robots system and proposes a new fluid power converter system which is analogous to a boost converter in power electronics. The fluid power converter system is based on the principle of pulse-width modulation. The fluid power converter has an effect akin to an electrical switched inductance transformer, wherein the output pressure or flow rate can be stepped up or down. Using an inductive reactance device (an inertia mass-block), the output flow and pressure can be varied to meet the load by a means that does not rely on dissipation of power (the resistance control). The simulation model based on the mathematics models of the components is built to analyse the performance of the fluid power converter. It is clearly shown that the fluid power converter has higher energy efficiency than conventional resistance control manners.

  20. A wideband fractal-inspired piezoelectric energy converter: design, simulation and experimental characterization

    International Nuclear Information System (INIS)

    Castagnetti, Davide

    2013-01-01

    In order to develop self-powered wireless sensor nodes, many energy harvesting devices that are able to convert available ambient energy into electrical energy have been proposed in the literature. A promising technique, in terms of simplicity and high conversion efficiency, is the harvesting of ambient kinetic energy through piezoelectric materials. The aim of this work is to design and investigate the modal response and power output of a fractal-inspired, multi-frequency, piezoelectric energy converter. The converter is a square, thin sheet structure, characterized by a fractal geometry obtained through a pattern of cuts in the plate. There are two steps involved. First, a computational analysis of the converter is performed. Second, a physical prototype of the converter is built and its eigenfrequencies and power generation under different resistive loads are experimentally examined in the range from 0 to 120 Hz. The converter exhibits three eigenfrequencies and a good power output, particularly at the first eigenfrequency. (paper)