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Sample records for relativistic klystron two-beam

  1. Design of inductively detuned RF extraction cavities for the Relativistic Klystron Two Beam Accelerator

    SciTech Connect

    Henestroza, E.; Yu, S.S.; Li, H.

    1995-04-01

    An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Q{sub ext} and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes.

  2. Design of a 1-MV induction injector for the Relativistic Klystron Two-Beam Accelerator

    SciTech Connect

    Anderson, D.E.; Eylon, S.; Lidia, S.; Reginato, L.; Vanecek, D.; Yu, S.; Houck, T.; Westenskow, G.A.; Henestroza, E.

    1997-05-01

    A Relativistic Klystron Two-Beam Accelerator (RK-TBA) is envisioned as a rf power source upgrade of the Next Linear Collider. Construction of a prototype, called the RTA, based on the RK-TBA concept has commenced at the Lawrence Berkeley National Laboratory. This prototype will be used to study physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. The first half of the injector, a 1 MeV, 1.2 kA, 300 ns induction electron gun, has been built and is presently being tested. The design of the injector cells and the pulsed power drive units are presented in this paper.

  3. Relativistic-Klystron two-beam accelerator as a power source for future linear colliders

    SciTech Connect

    Lidia, S. M.; Anderson, D. E.; Eylon, S.; Henestroza, E.; Vanecek, D. L.; Yu, S. S.; Houck, T. L.; Westenskow, G. A.

    1999-05-07

    The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, 1-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1% energy variation), and a normalized edge emittance of less than 300 pi-mm-mr. The prototype accelerator will be used to study, physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented.

  4. Relativistic-Klystron two-beam accelerator as a power source for future linear colliders

    SciTech Connect

    Lidia, S.M.; Anderson, D.E.; Eylon, S.; Henestroza, E.; Vanecek, D.L.; Yu, S.S.; Westenskow, G.A.

    1999-05-01

    The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, 1-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1{percent} energy variation), and a normalized edge emittance of less than 300 pi-mm-mr. The prototype accelerator will be used to study, physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented. {copyright} {ital 1999 American Institute of Physics.}

  5. Relativistic-klystron two-beam accelerator as a power source for future linear colliders

    SciTech Connect

    Anderson, D E; Eylon, S; Henestroza, E; Houck, T L; Lidia, M; Vanecek, D L; Westenskow, G A; Yu, S S

    1998-10-05

    The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2&A, l-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1% energy variation), and a normalized edge emittance of less than 300 pi-mm-n-n. The prototype accelerator will be used to study physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented.

  6. The two-beam accelerator and the relativistic klystron power source

    SciTech Connect

    Sessler, A.M.

    1988-04-01

    This paper discusses the concept of a two-beam accelerator. Two versions are discussed; one employing a free electron laser, the second employing a branched beam sent through ''transfer cavities'' as in a klystron. 14 refs., 26 figs., 1 tab. (LSP)

  7. Studies of beam dynamics in relativistic klystron two-beam accelerators

    SciTech Connect

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band ({approximately}8-12 GHz) through Ka band ({approximately} 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional

  8. Relativistic klystrons

    SciTech Connect

    Allen, M.A.; Azuma, O.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Hoag, H.A.; Koontz, R.F.

    1989-03-01

    Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs.

  9. Low-field permanent magnet quadrupoles in a new relativistic-klystron two-beam accelerator design

    SciTech Connect

    Yu, S.; Sessler, A.

    1995-02-01

    Permanent magnets play a central role in the new relativistic klystron two-beam-accelerator design. The two key goals of this new design, low cost and the suppression of beam break-up instability are both intimately tied to the permanent magnet quadrupole focusing system. A recently completed systems study by a joint LBL-LLNL team concludes that a power source for a 1 TeV center-of-mass Next Linear Collider based on the new TBA design can be as low as $1 billion, and the efficiency (wall plug to rf) is estimated to be 36%. End-to-end simulations of longitudinal and transverse beam dynamics show that the drive beam is stable over the entire TBA unit.

  10. Design study of longitudinal dynamics of the drive beam in 1 TeV relativistic klystron two-beam accelerator

    SciTech Connect

    Li, H.; Yu, S.S.; Sessler, A.M.

    1994-10-01

    In this paper the authors present a design study on the longitudinal dynamics of a relativistic klystron two-beam accelerator (RK-TBA) scheme which has been proposed as a power source candidate for a 1 TeV next linear collider (NLC). They address the issue of maintaining stable power output at desired level for a 300-m long TBA with 150 extraction cavities and present their simulation results to demonstrate that it can be achieved by inductively detuning the extraction cavities to counter the space charge debunching effect on the drive beam. They then carry out simulation study to show that the beam bunches desired by the RK-TBA can be efficiently obtained by first chopping an initially uniform beam of low energy into a train of beam bunches with modest longitudinal dimension and then using the {open_quotes}adiabatic capture{close_quotes} scheme to bunch and accelerate these beam bunches into tight bunches at the operating energy of the drive beam. The authors have also examined the {open_quotes}after burner{close_quotes} scheme which is implemented in their RK-TBA design for efficiency enhancement.

  11. Design study of beam dynamics issues for 1 TeV next linear collider based upon the relativistic-klystron two-beam accelerator

    SciTech Connect

    Li, H.; Goffeney, N.; Henestroza, E.; Sessler, A.; Yu, S.; Houck, T.; Westenskow, G.

    1994-11-01

    A design study has recently been conducted for exploring the feasibility of a relativistic-klystron two-beam accelerator (RK-TBA) system as a rf power source for a 1 TeV linear collider. The author present, in this paper, the beam dynamics part of this study. They have achieved in their design study acceptable transverse and longitudinal beam stability properties for the resulting high efficiency and low cost RK-TBA.

  12. Relativistic-klystron two-beam-accelerator as a power source for a 1 TeV next linear collider: A systems study

    SciTech Connect

    Yu, S.; Goffeney, N.; Deadrick, F.

    1994-10-01

    A physics, engineering, and costing study has been conducted to explore the feasibility of a relativistic-klystron two-beam-accelerator system as a power source candidate for a 1 TeV linear collider. We present a point design example which has acceptable transverse and longitudinal beam stability properties. Preliminary ``bottom-up`` cost estimate yields the full power source system at less than 1 billion dollars. The overall efficiency for rf production is estimated to be 36%.

  13. Preliminary design report of a relativistic-Klystron two-beam-accelerator based power source for a 1 TeV center-of-mass next linear collider

    SciTech Connect

    Yu, S.; Goffeney, N.; Henestroza, E.

    1995-02-22

    A preliminary point design for an 11.4 GHz power source for a 1 TeV center-of-mass Next Linear Collider (NLC) based on the Relativistic-Klystron Two-Beam-Accelerator (RK-TBA) concept is presented. The present report is the result of a joint LBL-LLNL systems study. consisting of three major thrust areas: physics, engineering, and costing. The new RK-TBA point design, together with our findings in each of these areas, are reported.

  14. Relativistic klystron afterburner simulation techniques

    SciTech Connect

    Ryne, R.D.; Jong, R.A.; Westenskow, G.A.; Yu, S.S.

    1990-01-24

    We are developing computer codes for the numerical simulations of relativistic klystrons and relativistic klystron afterburners''. The purpose of this note is to discuss the main features of our numerical model. A relativistic klystron afterburner'' is a scheme to extract power from a spent FEL electron beam. Power is extracted from the beam by passing it through klystron output cavities. To study the feasibility of this concept, we are developing computer codes for the numerical simulation of relativistic klystrons and afterburners. The purpose of this note is to discuss the main features of our numerical model.

  15. Relativistic klystron research for linear colliders

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Koontz, R.F.

    1988-09-01

    Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron-positron colliders, compact accelerators, and FEL sources. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our relativistic klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 9 figs., 1 tab.

  16. A theory of the two-beam klystron

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.

    1993-08-01

    A theoretical model is developed for the two-beam klystron, where two concentric annular electron beams propagate through a grounded conducting tube. The beams premodulated at the first cavity enter the second cavity, exciting it. The induced voltage at the second cavity returns a part of the inner beam toward the first cavity, establishing a mutual communication between two cavities. The in-phase condition of the return current is obtained in terms of the intercavity distance. The maximum current-modulation condition at the second cavity is also obtained. These two conditions determine an optimum intercavity distance. The oscillation behavior of the first cavity is investigated, including influence of the intercavity distance on the induced gap voltage appearing on the cavity opening. The relationship between the induced voltage and the modulated return current in the opening is found from an equivalent circuit representation of the cavity impedance. The boundary between the oscillator and amplifier regions is described in the parameter space defined by the normalized return-current strength h and intercavity distance represented by the phase angle α. In the amplifier region (h sin α<1), the amplification occurs only for a narrow range of the phase angle α. The induced voltage grows exponentially in the oscillator region satisfying h sin α≳1. Introducing a nonlinear saturation term into the return current, the induced voltage is bounded in the oscillator operation.

  17. Relativistic klystron research at SLAC and LLNL

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Lavine, T.L.; Lee, T.G.; Loew, G.A.; Miller, R.H.; Morton, P.L.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Schwarz, H.D.; Takeuchi, Y.; Vlieks, A.E.; Wang, J.W.; Wilson, P.B.; Hopkins, D.B.; Sessler, A.M.; Barletta, W.A.; Birx, D.L.; Boyd, J.K.; Houck, T.; Westenskow, G.A.; Yu, S.S.

    1988-06-01

    We are developing relativistic klystrons as a power source for high gradient accelerator applications such as large linear electron-positron colliders and compact accelerators. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here briefly on our experiments so far. 5 refs., 1 fig., 1 tab.

  18. Relativistic klystron research for high gradient accelerators

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Lavine, T.L.; Lee, T.G.

    1988-06-01

    Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs.

  19. Recent progress in relativistic klystron research

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W.; Aalberts, D.P.; Boyd, J.K.; Houck, T.; Ryne, R.D.; Westenskow, G.A.; Yu, S.S.; Hopkins, D.B.; Sessler, A.M.; Haimson, J.; Mecklenburg, B.; Lawrence Livermore National Lab., CA (US

    1989-08-01

    Experimental work is now under way by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. We have learned how to overcome our previously reported problem of high-power rf pulse shortening and have achieved peak rf power levels of 290 MW. We have used the rf from a relativistic klystron to power a short, 11.4-GHz high-gradient accelerator. The measured momentum spectrum of the accelerated electron beam corresponds to an accelerating gradient of 84 MV/m. 5 refs., 7 figs.

  20. Relativistic klystrons for high-gradient accelerators

    SciTech Connect

    Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S. ); Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W. ); Haimson, J.; Mecklen

    1990-09-05

    Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. We have learned how to overcome or previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power.

  1. An X-band overmoded relativistic klystron

    NASA Astrophysics Data System (ADS)

    Xiao, Renzhen; Chen, Changhua; Deng, Yuqun; Li, Jiawei; Bai, Xianchen

    2014-11-01

    An X-band overmoded relativistic klystron is proposed, the operation mode of which is the TM02 mode. The drift tube could not cut off the TM01 mode; isolating the buncher cavity from the input cavity is achieved by introducing a sectional RF lossy material. Microwaves are extracted from the modulated electron beam using a cylindrical waveguide, rather than a coaxial waveguide; thereby, the output structure is significantly simplified. Particle-in-cell simulations show that microwaves with power of 1.28 GW and frequency of 9.30 GHz can be obtained, corresponding to an efficiency of 32% and relative bandwidth of about 8%.

  2. An X-band overmoded relativistic klystron

    SciTech Connect

    Xiao, Renzhen; Chen, Changhua; Li, Jiawei; Bai, Xianchen; Deng, Yuqun

    2014-11-15

    An X-band overmoded relativistic klystron is proposed, the operation mode of which is the TM{sub 02} mode. The drift tube could not cut off the TM{sub 01} mode; isolating the buncher cavity from the input cavity is achieved by introducing a sectional RF lossy material. Microwaves are extracted from the modulated electron beam using a cylindrical waveguide, rather than a coaxial waveguide; thereby, the output structure is significantly simplified. Particle-in-cell simulations show that microwaves with power of 1.28 GW and frequency of 9.30 GHz can be obtained, corresponding to an efficiency of 32% and relative bandwidth of about 8%.

  3. Anomalous electron loading in SLAC 5045 klystron and relativistic klystron input cavities

    SciTech Connect

    Koontz, R.F.; Fowkes, R.W.; Lavine, T.L.; Miller, R.H.; Vlieks, A.E.

    1989-03-01

    Recent studies of RF breakup and instability in the SLAC 5045 klystrons have revealed that many production klystrons show loading of the input cavity by low energy electrons even under cold cathode no beam conditions. Sometime after the onset of the RF drive pulse, the input cavity absorbs a portion of the incident RF drive that would otherwise be reflected from the not-beam-loaded cavity. This power absorption is a function of drive level, and of axial magnetic field surrounding the cavity. No power absorption is present when the axial magnetic field is zero. This same phenomenon has been observed in the input cavity of relativistic klystron experiments being conducted as part of the SLAC-LBL-LLNL development program. The phenomenon may be associated with RF breakup and RF instability in SLAC 5045 klystrons, and with unstable pulse shortening in the relativistic klystron experiments. This paper outlines some old and new observations of microwave beam device malfunctions that probably are associated with low energy electron fluxes in the vacuum environments of microwave power devices. 2 refs., 5 figs.

  4. High-current relativistic klystron research at Physics International

    SciTech Connect

    Levine, J.S.; Harteneck, B.D.; Lam, S.K.; Parks, C.W.

    1994-12-31

    The authors are developing an L-band (1.3 GHz) high-current relativistic klystron (5 kA, 500 kV) for repetitive (200 pps) pulsing. They have designed and tested an extraction cavity that removes energy from the modulated electron beam and radiates it into an anechoic chamber in the TM{sub 01} mode. Peak power in excess of 450 MW has been measured for a single shot and 275 MW for a sustained burst producing 3.3 kW of average power. This klystron is now being transitioned to a long pulse (> 500 ns), single shot facility.

  5. Simulation of pulse shortening in a relativistic klystron oscillator

    SciTech Connect

    Verboncoeur, J.P.; Mardahl, P.J.; Cartwright, K.L.; Birdsall, C.K.

    1996-12-31

    The relativistic klystron is a strong candidate for a high power microwave source for a number of applications, including accelerators and electronic warfare. In this work, the authors simulate a high power, high perveance relativistic klystron oscillator using a 2d PIC-MCC code. The experimental klystron is currently operating as an injection-locked oscillator at 1.25--1.35 GHz, with up to 1 GW rms output power for a 100 ns pulse. The beam voltage is 500 kV, with current of 10 kA, and a beam pulse length of 300 ns. Experimental evidence indicates the klystron behavior is azimuthally symmetric. Of particular interest for this device is the shortening of the rf pulse compared to the current pulse, which may be related to plasma formation near the extractor gap. Various gases liberated form the porous graphite beam dump may reach substantial pressures locally. The authors investigate the formation of plasma due to photoionization and electron impact ionization of the gas constituents, and its impact on the rf power output. The simulations are compared to the experimental data where available.

  6. Spontaneous emission and spectral properties of radiation by relativistic electrons in a gyro-klystron and optical-klystron undulator.

    PubMed

    Prakash, Bramha; Mishra, Ganeswar; Khullar, Roma

    2016-03-01

    In this paper spontaneous emission of radiation by relativistic electrons in a gyro-klystron is studied. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non-resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons. This leads to enhanced radiation due to klystron-type modulation as compared with a conventional gyrotron-type device driven by cyclotron maser interaction. It is shown that the klystron-modulated spectrum depends on the dispersive field strength, finite perpendicular velocity component and length of the solenoids but is independent of the axial magnetic field strength. A simple scheme to design a gyro-klystron is discussed. PMID:26917129

  7. Using traveling wave structures to extract power from relativistic klystrons

    SciTech Connect

    Ryne, R.D.; Yu, S.S.

    1990-09-19

    The purpose of this note is to analyze the excitation of traveling wave (TW) output structures by an RF current. Such structures are being used in relativistic klystron experiments at Lawrence Livermore National Laboratory. First we will preset a set of difference equations that describes the excitation of the cells of a TW structure. Next we will restrict our attention to structures that have identical cells, except possibly for the first and last cells. Under these circumstances one can obtain difference equations that have constant coefficients, and we will present the general solution of these equations. Lastly we will apply our results to the analysis of a TW output structure. We will show that, by appropriate choice of the quality factors (Qs) and eigenfrequencies of the first and last cells, it is possible to obtain a traveling wave solution for which there is no reflected wave and where the excitation grows linearly with cell number.

  8. Three-dimensional simulation analysis of the standing-wave free- electron laser two beam accelerator

    SciTech Connect

    Wang, C.; Sessler, A.

    1993-01-01

    We have modified a two-dimensional relativistic klystron code, developed by Ryne and Yu, to simulate both the standing-wave free- electron laser two-beam accelerator and the relativistic klystron two- beam accelerator. In this paper, the code is used to study a standing-wave free-electron laser with three cavities. The effect of the radius of the electron beam on the RF output power; namely, a three-dimensional effect is examined.

  9. High efficiency coaxial klystron-like relativistic backward wave oscillator with a premodulation cavity

    SciTech Connect

    Xiao Renzhen; Teng Yan; Chen Changhua; Sun Jun

    2011-11-15

    The klystron-like relativistic backward wave oscillator (RBWO) combines the transition radiation with Cerenkov radiation and has demonstrated microwave output of high power and high efficiency. The coaxial slow wave structure device can produce microwave with a lower frequency in a smaller cross section. For the purpose of high efficiency, low frequency, and miniaturization, a coaxial klystron-like RBWO with a premodulation cavity is presented. Particle-in-cell simulations show that a microwave with power of 1.15 GW and frequency of 2.1 GHz is generated with conversion efficiency of 48%, whereas for the device with a reflector, the efficiency is 38%.

  10. Long pulse and high repetition rate operation of a relativistic klystron amplifier

    SciTech Connect

    Levine, J.S.; Harteneck, B.D.

    1994-12-31

    The authors are developing an L-band (1.3 GHz) high current relativistic klystron amplifier for both long pulse ({ge} 500 ns) and high repetition rate ({ge} 200 pps) capabilities. In repetitive operation, it has produced 3.3 kW of average power in 80 ns FWHM pulses of 250 MW peak power at 200 pps. They are currently transferring this same klystron to a single-shot, long-pulse driver to demonstrate its operation with a {ge} 500 ns electrical pulse.

  11. Spontaneous emission of radiation by relativistic electrons in a gyro-klystron

    NASA Astrophysics Data System (ADS)

    Mishra, G.; Prakash, Bramha; Sharma, Geetanjali

    2016-03-01

    In this paper, we study spontaneous emission of radiation by relativistic electrons in a gyro-klystron. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons.This leads to enhanced radiation as compared to a conventional gyrotron type device driven by cyclotron maser interaction. It is shown that the klystron modulated spectrum depends on the dispersive field strength, finite perpendicular velocity component and length of the solenoids but do not depend on the axial magnetic field strength. The analysis is further extended to include the combined effects of the undulator aided gyrotron klystron radiation.

  12. Relativistic klystron driven compact high gradient accelerator as an injector to an X-ray synchrotron radiation ring

    DOEpatents

    Yu, David U. L.

    1990-01-01

    A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

  13. Investigation of an X-band gigawatt long pulse multi-beam relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Zhenbang; Huang, Hua; Lei, Lurong; Jin, Xiao; Zhu, Lei; Wang, Ganping; He, Hu; Wu, Yao; Ge, Yi; Yuan, Huan; Chen, Zhaofu

    2015-09-01

    To achieve a gigawatt-level long pulse radiation power in X-band, a multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes and extended interaction cavities, the power capacity of the device is increased. A radiation power of 1.23 GW with efficiency of 41% and amplifier gain of 46 dB is obtained in the particle-in-cell simulation. Under conditions of a 10 Hz repeat frequency and an input RF power of 30 kW, a radiation power of 0.9 GW, frequency of 9.405 GHz, pulse duration of 105 ns, and efficiency of 30% is generated in the experiment, and the amplifier gain is about 45 dB. Both the simulation and the experiment prove that the multi-beam relativistic klystron amplifier can generate a long pulse GW-level radiation power in X-band.

  14. Design of a C-band relativistic extended interaction klystron with coaxial output cavity

    NASA Astrophysics Data System (ADS)

    Yang, Wu; Zhao, De-Kui; Chen, Yong-Dong

    2015-07-01

    In order to overcome the disadvantages of conventional high frequency relativistic klystron amplifiers in power capability and RF conversion efficiency, a C-band relativistic extended interaction klystron amplifier with coaxial output cavity is designed with the aid of PIC code MAGIC. In the device, disk-loaded cavities are introduced in the input and intermediate cavity to increase the beam modulation depth, and a coaxial disk-loaded cavity is employed in the output cavity to enhance the RF conversion efficiency. In PIC simulation, when the beam voltage is 680 kV and current is 4 kA, the device can generate 1.11 GW output power at 5.64 GHz with an efficiency of 40.8%.

  15. High power operation of an X-band coaxial multi-beam relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Zhenbang; Huang, Hua; Jin, Xiao; Zhao, Yucong; He, Hu; Lei, Lurong; Chen, Zhaofu

    2013-11-01

    An X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase output microwave power and operating frequency of the amplifier tube. The experiment is performed on a Tesla-type accelerator. The amplifier is driven by an electron beam of 2.8 kA at 720 kV, and a microwave power of 30 kW and frequency of 9.384 GHz is injected into an input cavity by means of an external source, then a microwave power of over 800 MW is extracted, the amplifier gain is about 44 dB, and conversion efficiency is 40%. The experiment proves that output power of nearly GWs can be generated with the X-band coaxial multi-beam relativistic klystron amplifier driven by a kW-level input power.

  16. High power operation of an X-band coaxial multi-beam relativistic klystron amplifier

    SciTech Connect

    Liu, Zhenbang; Huang, Hua; Jin, Xiao; Zhao, Yucong; He, Hu; Lei, Lurong; Chen, Zhaofu

    2013-11-15

    An X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase output microwave power and operating frequency of the amplifier tube. The experiment is performed on a Tesla-type accelerator. The amplifier is driven by an electron beam of 2.8 kA at 720 kV, and a microwave power of 30 kW and frequency of 9.384 GHz is injected into an input cavity by means of an external source, then a microwave power of over 800 MW is extracted, the amplifier gain is about 44 dB, and conversion efficiency is 40%. The experiment proves that output power of nearly GWs can be generated with the X-band coaxial multi-beam relativistic klystron amplifier driven by a kW-level input power.

  17. Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

    SciTech Connect

    Wu, Y.; Xu, Z.; Li, Z. H.; Tang, C. X.

    2012-07-15

    In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

  18. A high efficiency Ku-band radial line relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Dang, Fangchao; Zhang, Xiaoping; Zhong, Huihuang; Zhang, Jun; Ju, Jinchuan

    2016-07-01

    To achieve the gigawatt-level microwave amplification output at Ku-band, a radial-line relativistic klystron amplifier is proposed and investigated in this paper. Different from the annular electron beam in conventional axial relativistic klystron amplifiers, a radial-radiated electron beam is employed in this proposed klystron. Owing to its radially spreading speciality, the electron density and space charge effect are markedly weakened during the propagation in the radial line drift tube. Additionally, the power capacity, especially in the output cavity, is enhanced significantly because of its large volume, which is profitable for the long pulse operation. Particle-in-cell simulation results demonstrate that a high power microwave with the power of 3 GW and the frequency of 14.25 GHz is generated with a 500 kV, 12 kA electron beam excitation and the 30 kW radio-frequency signal injection. The power conversion efficiency is 50%, and the gain is about 50 dB. Meanwhile, there is insignificant electron beam self-excitation in the proposed structure by the adoption of two transverse electromagnetic reflectors. The relative phase difference between the injected signals and output microwaves keeps stable after the amplifier saturates.

  19. Suppression of higher mode excitation in a high gain relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xu, Z.; Jin, X.; Li, Z. H.; Tang, C. X.

    2012-02-01

    Suppressing higher mode excitation is very important in the high gain relativistic klystron amplifier because higher mode can seriously degrade klystron performance and cause pulse shortening. The mechanism of higher mode self-excitation is explored in the PIC simulation, and it is shown the coupling between cavities is the main cause of higher mode self-excitation. The coupling forms the positive feedback loop for higher mode to be excited just like that in the oscillator circuit. The formula for startup current of higher mode self-excitation is developed based on the coupling between cavities. And the corresponding methods are taken to avoid higher mode self-excitation. Finally, mode control is realized in the RKA with output power up to 1.02 GW when driven power is only few kilowatts.

  20. Recent experimental results from a long-pulse J-band relativistic klystron amplifier developmental effort

    SciTech Connect

    Kato, K.G.; Crouch, D.D.; Sar, D.R.; Speciale, R.A.; Carlsten, B.E.; Fazio, M.V.; Haynes, W.B.; Stringfield, R.M.

    1994-12-31

    Recent experimental results, supporting simulations, and design modeling are presented from a developmental effort to a produce a long pulse ({approximately}1{mu}s) J-band (5.85-8.2 GHz) relativistic klystron amplifier (RKA) of the high current NRL genealogy. This RKA is designed to operate at approximately 6.6 GHz, with a desired RF output {approximately}700 MW. Conversion of electron beam energy to microwave energy is obtained by a mock magnetically insulated coaxial converter which, in various incarnations, can be made to be either a cavity gap extractor or an inverse cathode.

  1. Investigation of an X-band gigawatt long pulse multi-beam relativistic klystron amplifier

    SciTech Connect

    Liu, Zhenbang; Huang, Hua; Lei, Lurong; Jin, Xiao; Zhu, Lei; Wang, Ganping; He, Hu; Wu, Yao; Ge, Yi; Yuan, Huan; Chen, Zhaofu

    2015-09-15

    To achieve a gigawatt-level long pulse radiation power in X-band, a multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes and extended interaction cavities, the power capacity of the device is increased. A radiation power of 1.23 GW with efficiency of 41% and amplifier gain of 46 dB is obtained in the particle-in-cell simulation. Under conditions of a 10 Hz repeat frequency and an input RF power of 30 kW, a radiation power of 0.9 GW, frequency of 9.405 GHz, pulse duration of 105 ns, and efficiency of 30% is generated in the experiment, and the amplifier gain is about 45 dB. Both the simulation and the experiment prove that the multi-beam relativistic klystron amplifier can generate a long pulse GW-level radiation power in X-band.

  2. Utilization of a Vircator to drive a High Power Relativistic Klystron Amplifier

    NASA Astrophysics Data System (ADS)

    Gardelle, J.; Bardy, J.; Cassany, B.; Desanlis, T.; Eyl, P.; Galtié, A.; Modin, P.; Voisin, L.; Balleyguier, P.; Gouard, P.; Donohue, J.

    2002-11-01

    At CESTA, we have been producing electron beams for some fifteen years by using induction accelerators and pulse diodes. First we had performed Frre-Electron Lasers experiments and we are currently studying the production of High-Power microwaves in the S-band. Among the possible sources we have chosen to perform Relativistic Klystron (RK) experiments with a pulse diode capable of generating a 700kV, 15 kA, 100 ns annular electron beam. In an amplifier configuration, we are testing the idea of using a Vircator as the driver for the first cavity of the klystron. This Vircator uses a simple electrical generator (Marx capacitor bank) which operates in the S-band in the GW class. By reducing the power level to about 100 MW, a 200 ns reliable and reproducible input driver pulse is obtained. First, we present the results of a preliminary experiment for which a coaxial cavity has been built in order to be fed by the Vircator emission at 2.45 GHz. Secondly, we give the experimental results in an oscillator configuration which corresponds to the fisrt step of our RK studies. Comparisons with the results of numerical simulations performed with MAGIC and MAFIA will be given for both experiments.

  3. The long-pulse, high-current relativistic klystron at 500 MW and beyond

    SciTech Connect

    Fazio, M.V.; Haynes, W.B.; Carlsten, B.E.; Stringfield, R.M.

    1994-10-01

    This paper describes the development of an L-band annular beam, high-current relativistic klystron for producing a peak power of 1 GW at a pulse length of 1 {mu}s. The tube consists of three cavities: the input cavity driven by a 300 kW magnetron, an idler cavity, and an output cavity. The tube has produced 475 MW and an energy per pulse of 160 J. The microwave output pulse terminates prematurely, before the peak power in the electron beam pulse is reached. The pulse shortening is believed to be caused by too high a voltage across the gap of the output cavity. The result is electron reflection in the output gap leading to beam disruption and high voltage breakdown across the gap. Current experimental results are presented with an emphasis on the design of output cavities for coupling microwave power from high current, very low impedance modulated electron beams.

  4. An S-band high gain relativistic klystron amplifier with high phase stability

    SciTech Connect

    Wu, Y.; Li, Z. H.; Xu, Z.; Ma, Q. S.; Xie, H. Q.

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  5. Design and analysis of a radio frequency extractor in an S-band relativistic klystron amplifier

    SciTech Connect

    Zhang Zehai; Zhang Jun; Shu Ting; Qi Zumin

    2012-09-15

    A radio frequency (RF) extractor converts the energy of a strongly modulated intense relativistic electron beam (IREB) into the energy of high power microwave in relativistic klystron amplifier (RKA). In the aim of efficiently extracting the energy of the modulated IREB, a RF extractor with all round coupling structure is proposed. Due to the all round structure, the operating transverse magnetic mode can be established easily and its resonant property can be investigated with an approach of group delay time. Furthermore, the external quality factor can be low enough. The design and analysis of the extractor applied in an S-band RKA are carried out, and the performance of the extractor is validated with three-dimensional (3D) particle-in-cell simulations. The extraction efficiency reaches 27% in the simulation with a totally 3D model of the whole RKA. The primary experiments are also carried out and the results show that the RF extractor with the external quality factor of 7.9 extracted 22% of the beam power and transformed it into the high power microwave. Better results are expected after the parasitic mode between the input and middle cavities is suppressed.

  6. Design and analysis of a radio frequency extractor in an S-band relativistic klystron amplifier.

    PubMed

    Zhang, Zehai; Zhang, Jun; Shu, Ting; Qi, Zumin

    2012-09-01

    A radio frequency (RF) extractor converts the energy of a strongly modulated intense relativistic electron beam (IREB) into the energy of high power microwave in relativistic klystron amplifier (RKA). In the aim of efficiently extracting the energy of the modulated IREB, a RF extractor with all round coupling structure is proposed. Due to the all round structure, the operating transverse magnetic mode can be established easily and its resonant property can be investigated with an approach of group delay time. Furthermore, the external quality factor can be low enough. The design and analysis of the extractor applied in an S-band RKA are carried out, and the performance of the extractor is validated with three-dimensional (3D) particle-in-cell simulations. The extraction efficiency reaches 27% in the simulation with a totally 3D model of the whole RKA. The primary experiments are also carried out and the results show that the RF extractor with the external quality factor of 7.9 extracted 22% of the beam power and transformed it into the high power microwave. Better results are expected after the parasitic mode between the input and middle cavities is suppressed. PMID:23020400

  7. Design and analysis of a radio frequency extractor in an S-band relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Zhang, Zehai; Zhang, Jun; Shu, Ting; Qi, Zumin

    2012-09-01

    A radio frequency (RF) extractor converts the energy of a strongly modulated intense relativistic electron beam (IREB) into the energy of high power microwave in relativistic klystron amplifier (RKA). In the aim of efficiently extracting the energy of the modulated IREB, a RF extractor with all round coupling structure is proposed. Due to the all round structure, the operating transverse magnetic mode can be established easily and its resonant property can be investigated with an approach of group delay time. Furthermore, the external quality factor can be low enough. The design and analysis of the extractor applied in an S-band RKA are carried out, and the performance of the extractor is validated with three-dimensional (3D) particle-in-cell simulations. The extraction efficiency reaches 27% in the simulation with a totally 3D model of the whole RKA. The primary experiments are also carried out and the results show that the RF extractor with the external quality factor of 7.9 extracted 22% of the beam power and transformed it into the high power microwave. Better results are expected after the parasitic mode between the input and middle cavities is suppressed.

  8. A study on the high-order mode oscillation in a four-cavity intense relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Ying-Hui; Niu, Xin-Jian; Jia, Nan; Li, Zheng-Hong; Wang, Hui; Cheng, Hui; Yang, Xiao-Chuan; Duan, Yaoyong

    2016-07-01

    The high-order mode oscillation is studied in designing a four-cavity intense relativistic klystron amplifier. The reason for the oscillation caused by high-order modes and a method to suppress these kinds of spurious modes are found through theoretical analyses and the study on the influence of major parameters of a high frequency structure (such as the oscillation frequency of cavities, the cavity Q value, the length of drift tube section, and the characteristic impedance). Based on much simulation, a four-cavity intense relativistic klystron amplifier with a superior performance has been designed, built, and tested. An output power of 2.22 GW corresponding to 27.4% efficiency and 61 dB gain has been obtained. Moreover, the high-order mode oscillation is suppressed effectively, and an output power of 1.95 GW corresponding to 26% efficiency and 62 dB gain has been obtained in our laboratory.

  9. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Zhang, Zehai

    2015-03-01

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.

  10. Experimental study on parasitic mode suppression using FeSiAl in Relativistic Klystron Amplifier.

    PubMed

    Zhang, Zehai

    2015-03-01

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation. PMID:25832258

  11. Factors influencing the microwave pulse duration in a klystron-like relativistic backward wave oscillator

    SciTech Connect

    Xiao Renzhen; Zhang Xiaowei; Zhang Ligang; Li Xiaoze; Zhang Lijun

    2012-07-15

    In this paper, we analyze the factors that affect the microwave pulse duration in a klystron-like relativistic backward wave oscillator (RBWO), including the diode voltage, the guiding magnetic field, the electron beam collector, the extraction cavity, and the gap between the electron beam and the slow wave structure (SWS). The results show that the microwave pulse duration increases with the diode voltage until breakdown occurs on the surface of the extraction cavity. The pulse duration at low guiding magnetic field is generally 5-10 ns smaller than that at high magnetic field due to the asymmetric electron emission and the larger energy spread of the electron beam. The electron beam collector can affect the microwave pulse duration significantly because of the anode plasma generated by bombardment of the electron beam on the collector surface. The introduction of the extraction cavity only slightly changes the pulse duration. The decrease of the gap between the electron beam and the SWS can increase the microwave pulse duration greatly.

  12. Experimental study of a low radio frequency power driven relativistic klystron amplifier

    SciTech Connect

    Li Zhenghong

    2010-02-15

    Using particle in cell simulation codes, a low radio frequency (rf) power driven relativistic klystron amplifier is designed according to the beam with current of 7.5 kA and voltage of 750 kV with special measures to avoid the mode competition. Simulated power reaches 1.7 GW when the driven rf power is 7.0 kW, the corresponding gain is 53.9 dB. Also the experiment is carried out on a telsa-typed accelerator, whose beam is with current of 8 kA and voltage of 800 kV. The measured rf output power reaches 2.04 GW in the experiment when the input rf power is 62 kW and frequency 2.850 GHz, the corresponding gain is 45.1 dB and efficiency is 32%. The maximum gain reaches 46.7 dB when the input decreases to 39 kW, the corresponding output rf power is 1.84 GW.

  13. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    SciTech Connect

    Zhang, Zehai

    2015-03-15

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE{sub 11} is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.

  14. An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode

    NASA Astrophysics Data System (ADS)

    Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Qi, Zumin

    2015-11-01

    The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect.

  15. An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode

    SciTech Connect

    Zhu, Danni; Zhang, Jun Zhong, Huihuang; Qi, Zumin

    2015-11-15

    The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect.

  16. Three-dimensional relativistic field-electron interaction in a multicavity high-power klystron. Part 2: Working Equations

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1982-01-01

    A high power multicavity klystron amplifier was designed and a computation package containing all equations and procedures needed is presented. The rigorously derived three dimensional relativistic axisymmetric equations of motion are used to compute the bunched current and the induced RF gap voltage for all interaction cavities except the input and second cavities, where the linear space charge wave theory data are employed in order to reduce the computation time. Both distance step and time step integration methods are used to compute the Fourier coefficients of both the beam current and induced current.

  17. Gigawatt peak power generation in a relativistic klystron amplifier driven by 1 kW seed-power

    SciTech Connect

    Wu, Y.; Xie, H. Q.; Li, Z. H.; Zhang, Y. J.; Ma, Q. S.

    2013-11-15

    An S-band high gain relativistic klystron amplifier driven by kW-level RF power is proposed and studied experimentally. In the device, the RF lossy material is introduced to suppress higher mode excitation. An output power of 1.95 GW with a gain of 62.8 dB is obtained in the simulation. Under conditions of an input RF power of 1.38 kW, a microwave pulse with power of 1.9 GW, frequency of 2.86 GHz, and duration of 105 ns is generated in the experiment, and the corresponding gain is 61.4 dB.

  18. Mechanism of phase control in a klystron-like relativistic backward wave oscillator by an input signal

    NASA Astrophysics Data System (ADS)

    Xiao, Renzhen; Song, Zhimin; Deng, Yuqun; Chen, Changhua

    2014-09-01

    Theoretical analyses and particle-in-cell (PIC) simulations are carried out to understand the mechanism of microwave phase control realized by the external RF signal in a klystron-like relativistic backward wave oscillator (RBWO). Theoretical calculations show that a modulated electron beam can lead the microwave field with an arbitrary initial phase to the same equilibrium phase, which is determined by the phase factor of the modulated current, and the difference between them is fixed. Furthermore, PIC simulations demonstrate that the phase of input signal has a close relation to that of modulated current, which initiates the phase of the irregularly microwave during the build-up of oscillation. Since the microwave field is weak during the early time of starting oscillation, it is easy to be induced, and a small input signal is sufficient to control the phase of output microwave. For the klystron-like RBWO with two pre-modulation cavities and a reentrant input cavity, an input signal with 100 kW power and 4.21 GHz frequency can control the phase of 5 GW output microwave with relative phase difference less than 6% when the diode voltage is 760 kV, and beam current is 9.8 kA, corresponding to a power ratio of output microwave to input signal of 47 dB.

  19. Mechanism of phase control in a klystron-like relativistic backward wave oscillator by an input signal

    SciTech Connect

    Xiao, Renzhen; Song, Zhimin; Deng, Yuqun; Chen, Changhua

    2014-09-15

    Theoretical analyses and particle-in-cell (PIC) simulations are carried out to understand the mechanism of microwave phase control realized by the external RF signal in a klystron-like relativistic backward wave oscillator (RBWO). Theoretical calculations show that a modulated electron beam can lead the microwave field with an arbitrary initial phase to the same equilibrium phase, which is determined by the phase factor of the modulated current, and the difference between them is fixed. Furthermore, PIC simulations demonstrate that the phase of input signal has a close relation to that of modulated current, which initiates the phase of the irregularly microwave during the build-up of oscillation. Since the microwave field is weak during the early time of starting oscillation, it is easy to be induced, and a small input signal is sufficient to control the phase of output microwave. For the klystron-like RBWO with two pre-modulation cavities and a reentrant input cavity, an input signal with 100 kW power and 4.21 GHz frequency can control the phase of 5 GW output microwave with relative phase difference less than 6% when the diode voltage is 760 kV, and beam current is 9.8 kA, corresponding to a power ratio of output microwave to input signal of 47 dB.

  20. Improved power capacity in a high efficiency klystron-like relativistic backward wave oscillator by distributed energy extraction

    SciTech Connect

    Xiao, Renzhen; Chen, Changhua; Cao, Yibing; Sun, Jun

    2013-12-07

    With the efficiency increase of a klystron-like relativistic backward wave oscillator, the maximum axial electric field and harmonic current simultaneously appear at the end of the beam-wave interaction region, leading to a highly centralized energy exchange in the dual-cavity extractor and a very high electric field on the cavity surface. Thus, we present a method of distributed energy extraction in this kind of devices. Particle-in-cell simulations show that with the microwave power of 5.1 GW and efficiency of 70%, the maximum axial electric field is decreased from 2.26 MV/cm to 1.28 MV/cm, indicating a threefold increase in the power capacity.

  1. A high-efficiency overmoded klystron-like relativistic backward wave oscillator with low guiding magnetic field

    SciTech Connect

    Xiao Renzhen; Tan Weibing; Li Xiaoze; Song Zhimin; Sun Jun; Chen Changhua

    2012-09-15

    A klystron-like relativistic backward wave oscillator with a ratio of transverse dimension to free-space wavelength being about four is presented. In the beam-wave interaction region, the electron beam interacts with surface wave and volume wave simultaneously. The cathode holder plays an important role in the reflection of backward waves. A guard electrode, an electron collector ring, and a reflection ring are used to optimize the beam-wave interaction. The particle in cell simulation results reveal that microwaves with a power of 2 GW and a frequency of 12.3 GHz are generated with an efficiency of 42% when the diode voltage is 400 kV, the beam current 12 kA, and the magnetic field 0.48 T.

  2. Three-dimensional relativistic field-electron interaction in a multicavity high-power klystron. 1: Basic theory

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1982-01-01

    A theoretical investigation of three dimensional relativistic klystron action is described. The relativistic axisymmetric equations of motion are derived from the time-dependent Lagrangian function for a charged particle in electromagnetic fields. An analytical expression of the fringing RF electric and magnetic fields within and in the vicinity of the interaction gap and the space-charge forces between axially and radially elastic deformable rings of charges are both included in the formulation. This makes an accurate computation of electron motion through the tunnel of the cavities and the drift tube spaces possible. Method of analysis is based on Lagrangian formulation. Bunching is computed using a disk model of electron stream in which the electron stream is divided into axisymmetric disks of equal charge and each disk is assumed to consist of a number of concentric rings of equal charges. The Individual representative groups of electrons are followed through the interaction gaps and drift tube spaces. Induced currents and voltages in interacting cavities are calculated by invoking the Shockley-Ramo theorem.

  3. A second report on the experimental progress of the one microsecond, one kilojoule per pulse L-band relativistic klystron at Los Alamos

    SciTech Connect

    Haynes, W.B.; Carlsten, B.E.; Faehl, R.J.; Fazio, M.V.; Kwan, T.J.T.; Stringfield, R.M.

    1994-02-01

    Work is continuing on a high-current relativistic klystron amplifier (RKA) with the goal of producing 1 kJ per pulse with a 1 {mu}s pulsewidth and a peak power of 1 GW. The three cavity tube has already produced pulses with more than 150 J and over 450 MW peak power. The original output cavity was thought to be limiting the performance, and a new cavity has been designed, built, and is now on-line and being conditioned up towards high power. Current experimental results are presented.

  4. System parameters germane to relativistic klystron amplifiers: how the utility of pulse energy depends on pulse duration, the target, and the atmosphere

    NASA Astrophysics Data System (ADS)

    Myers, John M.

    1994-05-01

    Relativistic klystron amplifiers (RKAs) at a variety of carrier wavelengths and pulse durations appear feasible to supply microwave pulses to an array of antennas acting as a beam weapon against targets at or above 100 km in altitude. In order to avoid voltage breakdown in the atmosphere, the array area must be large enough to converge the beam, producing a higher energy flux on target than at intermediate altitudes susceptible to breakdown. The area required depends on the physics of atmospheric ionization and on the pulse duration and the carrier wavelength of the RKA. A quantitative statement of the dependence of array area on relevant parameters is presented. The energy per RKA pulse that is usable without delay lines is determined here as a function of RKA pulse duration and wavelength. Changing the pulse length from 160 ns to 1 microsecond(s) and shortening the wavelength raise the energy usable without delay lines by a factor of 1000.

  5. Development status of an intense beam klystron

    SciTech Connect

    Coleman, P.D.; Lemke, R.W.; Hendricks, K.J.; Arman, M.J.; Bowers, L.A.

    1994-10-01

    Investigations are being performed on a high current (16 kA), mildly relativistic (400kV), L-band klystron source. Experiments are in an early stage, and thus far have progressed to beam modulation studies. This paper discusses general klystron design considerations, beam propagation results, initial modulation results, and various extraction techniques being considered.

  6. Halo formation in high-power klystrons

    SciTech Connect

    Pakter, R.; Chen, C.

    1999-07-01

    Beam losses and radio-frequency (rf) pulse shortening are important issues in the development of high-power microwave (HPM) sources such as high-power klystrons and relativistic magnetrons. In this paper, the authors explore the formation and characteristics of halos around intense relativistic electron beams in a Periodic Permanent Magnet focusing klystron as well as in a uniform solenoidal focusing klystron. A self-consistent electrostatic model is used to investigate intense relativistic electron beam transport as an rf field induced mismatch between the electron beam and the focusing field develops. To model the effect of such mismatch in the PPM klystron experiment, they initialize the beam with an envelope mismatch. For zero canonical angular momentum and an initial mismatch of 100 percent, for example, the preliminary results show halo particles with a maximum radius extending up to several core radii at the rf output section. Transient effects and the influence of finite canonical angular momentum are being studied.

  7. Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

    SciTech Connect

    Bai Xianchen; Zhang Jiande; Yang Jianhua; Jin Zhenxing

    2012-12-15

    Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of {approx}22 MW, an output power of {approx}230 MW with the power gain of {approx}10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than {+-}15 Degree-Sign in a single shot, and phase jitter of {+-}11 Degree-Sign is obtained within a series of shots with duration of about 40 ns.

  8. Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Bai, Xianchen; Zhang, Jiande; Yang, Jianhua; Jin, Zhenxing

    2012-12-01

    Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of ˜22 MW, an output power of ˜230 MW with the power gain of ˜10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than ±15° in a single shot, and phase jitter of ±11° is obtained within a series of shots with duration of about 40 ns.

  9. Prospects for a soft x-ray FEL powered by a relativistic-klystron high-gradient accelerator (RK-HGA)

    SciTech Connect

    Shay, H.D.; Barletta, W.A.; Yu, S.S.; Schlueter, R.; Deis, G.A.

    1989-09-28

    We present here the concept of x-ray FELs using high gain, single-pass amplifiers with electron beams accelerated in high gradient structures powered by relativistic klystrons. Other authors have also considered x-ray FELs; the unique aspect of this paper is the use of high gradient acceleration. One of the authors has previously presented preliminary studies on this concept. The intent in this paper is to display the results of a top level design study on a high gain FEL, to present its sensitivity to a variety of fabrication and tuning errors, to discuss several mechanisms for increasing gain yet more, and to present explicitly the output characteristics of such an FEL. The philosophy of the design study is to find a plausible operating point which employs existing or nearly existing state-of-the-art technologies while minimizing the accelerator and wiggler lengths. The notion is to distribute the technical risk as evenly as possible over the several technologies so that each must advance only slightly in order to make this design feasible. This study entailed no systematic investigation of possible costs so that, for example, the sole criterion for balancing the trade-off between beam energy and wiggler length is that the two components have comparable lengths. 20 refs., 10 figs., 1 tab.

  10. Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

    NASA Astrophysics Data System (ADS)

    Bai, Xianchen; Yang, Jianhua; Zhang, Jiande

    2012-08-01

    By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

  11. Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

    SciTech Connect

    Bai Xianchen; Yang Jianhua; Zhang Jiande

    2012-08-15

    By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

  12. Multibeam klystron

    NASA Technical Reports Server (NTRS)

    Vancil, Bernard K. (Inventor); Wintucky, Edwin G. (Inventor)

    2006-01-01

    A multibeam, electrostatically focused klystron includes a plurality of conductive members, ones of which are recessed to provide input and output sections of microwave cavities, wherein focusing voltage is applied between those sections. The conductive members are either spaced along the path of multiple beams, or stacked in insulated relation, in either case being supported by glass rods within a glass envelope.

  13. Optical klystron SASE at FERMI

    NASA Astrophysics Data System (ADS)

    Penco, G.; Allaria, E. M.; De Ninno, G.; Ferrari, E.; Giannessi, L.

    2015-05-01

    The optical klystron enhancement to a self-amplified spontaneous emission (SASE) free electron laser (FEL) has been deeply studied in theory and in simulations. In this FEL scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. We report the first experiment that has been carried out at the FERMI facility in Trieste, of enhancement to a SASE FEL by using the optical klystron scheme. XUV photons have been produced with an intensity several orders of magnitude larger than in pure SASE mode. The impact of the uncorrelated energy spread of the electron beam on the optical klystron SASE performance has been also investigated.

  14. Triggering Klystrons

    SciTech Connect

    Stefan, Kelton D.; /Purdue U. /SLAC

    2010-08-25

    To determine if klystrons will perform to the specifications of the LCLS (Linac Coherent Light Source) project, a new digital trigger controller is needed for the Klystron/Microwave Department Test Laboratory. The controller needed to be programmed and Windows based user interface software needed to be written to interface with the device over a USB (Universal Serial Bus). Programming the device consisted of writing logic in VHDL (VHSIC (Very High Speed Integrated Circuits) hardware description language), and the Windows interface software was written in C++. Xilinx ISE (Integrated Software Environment) was used to compile the VHDL code and program the device, and Microsoft Visual Studio 2005 was used to compile the C++ based Windows software. The device was programmed in such a way as to easily allow read/write operations to it using a simple addressing model, and Windows software was developed to interface with the device over a USB connection. A method of setting configuration registers in the trigger device is absolutely necessary to the development of a new triggering system, and the method developed will fulfill this need adequately. More work is needed before the new trigger system is ready for use. The configuration registers in the device need to be fully integrated with the logic that will generate the RF signals, and this system will need to be tested extensively to determine if it meets the requirements for low noise trigger outputs.

  15. Theoretical examination of transfer cavities in a standing-wave free- electron laser Two-Beam Accelerator

    SciTech Connect

    Govil, R.; Sessler, A.

    1993-01-01

    Recent analysis of the Two-Beam Accelerator (TBA) by Wurtele, Whittum and Sessler has shown that the transfer cavities, both in the relativistic klystron version (RK/TBA) and the standing-wave free-electron laser version (SWFEL/TBA), can be characterized by a simple coupling impedance. In the two cases the radiation process is very similar: Only the modes that couple to the electron beam are different. As a result, computer programs that are able to handle realistic cavities (with beam ports and coupling ports, etc.) can be employed to evaluate the performance of either version of the TBA. We have employed the code URMEL to study the proper coupling impedance for a number of realistic cavities for a SWFEL.

  16. Two-beam accelerator

    SciTech Connect

    Selph, F.B.

    1984-09-01

    In the two-beam accelerator (TBA) concept, an electron linear accelerator structure is established in which two beams propagate. One is an intense low energy beam that is made to undergo free electron lasing to produce microwaves. These microwaves are then coupled to another part of the structure where they act to produce a high longitudinal electric gradient that is used to accelerate a second relatively low intensity electron beam to very high energies. The TBA was originally suggested by Sessler as a possible means for economically achieving linear collider energies of 100 GeV and above. Although still in a conceptual stage, the TBA is an inherently plausible concept that combines the free electron laser (FEL) with several well-known technologies - high current induction linacs, microwave waveguides, and traveling-wave linac structures - in a novel and interesting way. Two characteristics of the TBA that make it a particularly suitable candidate for achieving high energies are its ability to operate at higher frequencies than typical present-day linacs (say 30 GHz as compared with 3 GHz), and to be an efficient means for delivering power to a hitherto unattainable high-gradient structure (say 250 MV/m) that the higher frequency makes possible. These high accelerating gradients will permit much shorter linac structures for a given energy.

  17. Klystron-linac combination

    DOEpatents

    Stein, W.E.

    1980-04-24

    A combination klystron-linear accelerator which utilizes anti-bunch electrons generated in the klystron section as a source of electrons to be accelerated in the accelerator section. Electron beam current is controlled by second harmonic bunching, constrictor aperture size and magnetic focusing. Rf coupling is achieved by internal and external coupling.

  18. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    PubMed Central

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-01-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs. PMID:27481661

  19. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    NASA Astrophysics Data System (ADS)

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-08-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs.

  20. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier.

    PubMed

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-01-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs. PMID:27481661

  1. Mean life of klystrons

    SciTech Connect

    Sands, M.

    1985-10-30

    It would be useful to have the best possible estimate of this mean life-time of our new klystrons based on the most recent, available operating experience. A simple formula is given for this best estimate, based on the maximum likelihood method. This method also provides an indication of the reliability of the estimated lifetime. The results given here apply uniquely to a uniform klystron population for which we can assume that deaths occur randomly, and independently of the previous history (operating time) of any one klystron.

  2. METHOD FOR STABILIZING KLYSTRONS

    DOEpatents

    Magnuson, D.W.; Smith, D.F.

    1959-04-14

    High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.

  3. Klystron equalization for RF feedback

    SciTech Connect

    Corredoura, P.

    1993-01-01

    The next generation of colliding beam storage rings support higher luminosities by significantly increasing the number of bunches and decreasing the spacing between respective bunches. The heavy beam loading requires large RF cavity detuning which drives several lower coupled bunch modes very strongly. One technique which has proven to be very successful in reducing the coupled bunch mode driving impedance is RF feedback around the klystron-cavity combination. The gain and bandwidth of the feedback loop is limited by the group delay around the feedback loop. Existing klystrons on the world market have not been optimized for this application and contribute a large portion of the total loop group delay. This paper describes a technique to reduce klystron group delay by adding an equalizing filter to the klystron RF drive. Such a filter was built and tested on a 500 kill klystron as part of the on going PEP-II R D effort here at SLAC.

  4. Klystron equalization for RF feedback

    SciTech Connect

    Corredoura, P.

    1993-01-01

    The next generation of colliding beam storage rings support higher luminosities by significantly increasing the number of bunches and decreasing the spacing between respective bunches. The heavy beam loading requires large RF cavity detuning which drives several lower coupled bunch modes very strongly. One technique which has proven to be very successful in reducing the coupled bunch mode driving impedance is RF feedback around the klystron-cavity combination. The gain and bandwidth of the feedback loop is limited by the group delay around the feedback loop. Existing klystrons on the world market have not been optimized for this application and contribute a large portion of the total loop group delay. This paper describes a technique to reduce klystron group delay by adding an equalizing filter to the klystron RF drive. Such a filter was built and tested on a 500 kill klystron as part of the on going PEP-II R&D effort here at SLAC.

  5. Effects of angular misalignment on optical klystron undulator radiation

    NASA Astrophysics Data System (ADS)

    Mishra, G.; Prakash, Bramh; Gehlot, Mona

    2015-11-01

    In this paper ,we analyze the important effects of optical klystron undulator radiation with an angular offset of the relativistic electron beam in the second undulator section. An anlytical expression for the undulator radiation is obtained through a transparent and simple procedure.It is shown that the effects of the angular offset is more severe for longer undulator lengths and with higher dispersive field strengths.Both these effects are less pronounced for undulators with large K values.

  6. The Triaxial Klystron

    SciTech Connect

    Pasour, J.; Smithe, D.; Friedman, M.

    1999-05-01

    We describe a high-power, annular beam klystron, the Triaxial Klystron, that promises high efficiency at GW power levels and frequencies up to X band. Higher frequency operation should be possible at reduced power levels. The device consists of a thin annular electron beam propagating in an annular drift region, with cavity structures located inside and outside the beam. So long as the width of the drift region is less than half a wavelength (to cut off TM modes), the beam diameter can be as large as necessary to accommodate the required current and to reduce the RF surface fields to tolerable levels. Beam transport and stability are also facilitated in the annular channel. Simulations at X-band (using MRC{close_quote}s particle-in-cell code, MAGIC) show strong beam bunching and efficient energy extraction from specially designed radial cavity structures. Initial experiments at the Naval Research Laboratory have demonstrated transport of a 16-kA, 400-keV beam over a distance of {approximately}1 m with no evidence of instability or asymmetry. Strong bunching of such a beam has been produced at X band using a coaxially-driven input cavity and a multi-gap buncher cavity structure. The peak-to-peak modulated current amplitude from this simple structure exceeds the injected current amplitude and is stable throughout the 150 nsec pulse. {copyright} {ital 1999 American Institute of Physics.}

  7. One-dimensional disk model simulation for klystron design

    SciTech Connect

    Yonezawa, H.; Okazaki, Y.

    1984-05-01

    In 1982, one of the authors (Okazaki), of Toshiba Corporation, wrote a one-dimensional, rigid-disk model computer program <1> to serve as a reliable design tool for the 150 MW klystron development project. This is an introductory note for the users of this program. While reviewing the so-called disk programs presently available, hypotheses such as gridded interaction gaps, a linear relation between phase and position, and so on, were found. These hypotheses bring serious limitations and uncertainties into the computational results. JPNDISK was developed to eliminate these defects, to follow the equations of motion as rigorously as possible, and to obtain self-consistent solutions for the gap voltages and the electron motion. Although some inaccuracy may be present in the relativistic region, JPNDISK, in its present form, seems a most suitable tool for klystron design; it is both easy and inexpensive to use.

  8. Klystron beam-bunching lecture

    SciTech Connect

    Carlsten, B.

    1996-10-01

    Electron beam current modulation in a klystron is the key phenomenon that accounts for klystron gain and rf power generation. Current modulation results from the beams` interaction with the rf fields in a cavity, and in turn is responsible for driving modulation in the next rf cavity. To understand the impact of the current modulation in a klystron, we have to understand both the mechanism leading to the generation of the current modulation and the interaction of a current-modulated electron beam with an rf cavity. The cavity interaction is subtle, because the fields in the cavity modify the bunching of the beam within the cavity itself (usually very dramatically). We will establish the necessary formalism to understand klystron bunching phenomena which can be used to describe rf accelerator cavity/beam interactions. This formalism is strictly steady-state; no transient behavior will be considered. In particular, we will discuss the following: general description of klystron operation; beam harmonic current; how beam velocity modulation induced by an rf cavity leads to current modulation in both the ballistic and space-charge dominated regimes; use of Ramo`s theorem to define the power transfer between a bunched electron beam and the cavity; general cavity model with external coupling (including an external generator if needed), used to describe the input cavity, idler cavities, and the output cavity, including the definition of beam loaded-cavity impedance. Although all these are conceptually straight-forward, they represent a fair amount of physics, and to derive some elements of the formalism from first principles requires excessive steps. Our approach will be to present a self-consistent set of equations to provide a mechanism that leads to a quantifiable description of klystron behavior; derivations for moderately complex formulas will be outlined, and a relatively complex derivation of the self-consistent set of equations can be found in the Appendix. 6 figs.

  9. High power radial klystron oscillator

    SciTech Connect

    Arman, M.J.

    1995-11-01

    The advantages of the radial klystron amplifier over the conventional klystron amplifier have been reported by Arman et al. Briefly, the radial structure of this design allows for much smaller impedances and thus higher power, the beam-cavity coupling is stronger because the beam travels inside the cavity, and the source is much more compact because there is no need for external magnetic fields. Here the author reports on possible advantages of the radial klystron oscillator over the radial klystron amplifier. The amplifying nature of certain HPM sources is often mandated by the requirement for synchronization and phase-locking of a number of sources in specific applications. In situations where amplification is solely adhered to for the purpose of achieving higher powers, the oscillator will be a better choice if a mechanism can be found to grow the desired mode at the required frequency. By switching to the oscillator mode there will be no need for priming the cavity or maintaining the phase. This simplifies the design and reduces the operational and maintenance cost of the source. Here he reports that an oscillator version of the radial klystron is possible and in fact more suitable for many applications. The mechanism for exciting and growing the mode will be transit-time effects thus providing all the beneficial features of the transit-time oscillators. The complications due to the presence of thin foils in the radial design still persist and will be dealt with in subsequent works. Numerical simulations using the PIC codes MAGIC and SOS indicate the radial klystron oscillator is a viable and efficient means of rf generation.

  10. Sheet Beam Klystron Instability Analysis

    SciTech Connect

    Bane, K.L.F.; Jensen, A.; Li, Z.; Stupakov, G.; Adolphsen, C.; /SLAC

    2009-05-08

    Using the principle of energy balance we develop a 2D theory for calculating growth rates of instability in a two-cavity model of a sheet beam klystron. An important ingredient is a TE-like mode in the gap that also gives a longitudinal kick to the beam. When compared with a self-consistent particle-in-cell calculation, with sheet beam klystron-type parameters, agreement is quite good up to half the design current, 65 A; at full current, however, other, current-dependent effects come in and the results deviate significantly.

  11. High power W-band klystrons

    SciTech Connect

    Caryotakis, George; Scheitrum, Glenn; Jongewaard, Erik; Vlieks, Arnold; Fowkes, Randy; Li, Jeff

    1999-05-01

    The development of W-band klystrons is discussed. Modeling of the klystron performance predicts 100 kW output power from a single klystron. The permanent magnet focusing and small size of the circuit permit combination of multiple klystrons in a module. A six-klystron module in a single vacuum envelope is expected to produce 500 kW peak power and up to 5 kW average power. The critical issues in the W-band klystron development are the electron beam transport and the fabrication of the klystron circuit. Two microfabrication techniques, EDM and LIGA, are being evaluated to produce the W-band circuit. {copyright} {ital 1999 American Institute of Physics.}

  12. Klystron Gun Arcing and Modulator Protection

    SciTech Connect

    Gold, S

    2004-05-04

    The demand for 500 kV and 265 amperes peak to power an X-Band klystron brings up protection issues for klystron faults and the energy dumped into the arc from the modulator. This situation is made worse when more than one klystron will be driven from a single modulator, such as the existing schemes for running two and eight klystrons. High power pulsed klystrons have traditionally be powered by line type modulators which match the driving impedance with the load impedance and therefore current limit at twice the operating current. Multiple klystrons have the added problems of a lower modulator source impedance and added stray capacitance, which converts into appreciable energy at high voltages like 500kV. SLAC has measured the energy dumped into klystron arcs in a single and dual klystron configuration at the 400 to 450 kV level and found interesting characteristics in the arc formation. The author will present measured data from klystron arcs powered from line-type modulators in several configurations. The questions arise as to how the newly designed solid-state modulators, running multiple tubes, will react to a klystron arc and how much energy will be dumped into the arc.

  13. High efficiency SPS klystron design

    NASA Technical Reports Server (NTRS)

    Nalos, E. J.

    1980-01-01

    The most likely compact configuration to realize both high efficiency and high gain is a 5-6 cavity design focused by an electromagnet. An outline of a potential klystron configuration is given. The selected power output of 70 kW CW resulted from a maximum assumed operating voltage of 40 kV. The basic klystron efficiency cannot be expected to exceed 70-75% without collector depression. Although impressive gains were achieved in raising the basic efficiency from 50% to 70% or so with a multi-stage collector, the estimated efficiency improvement due to 5-stage collector at the 75% level is only about 8% resulting in an overall efficiency of about 83%.

  14. An immersed field cluster klystron

    SciTech Connect

    Palmer, R.B.; Herrmannsfeldt, W.B.; Eppley, K.R.

    1989-08-01

    Future linear colliders have a need for high power, high frequency, and short-pulse radio frequency sources. The proposed ''cluster klystron'' should give over 1 GW of 12 GHz radio frequency power, can employ direct current or a long high-voltage pulse, but can be gated to give pulses down to a few tens of nanoseconds. The device consists of 42 parallel 100 A channels. Each channel is fed from an individual magnetron-type gun employing a common 50 kV mod-anode. The beams are accelerated to 400 kV in common dc accelerating gaps and fed into the 42 separate klystron channels. Focusing of all channels is achieved by a single overall 4 kG magnetic field. Simulations of expected performance suggest that the efficiency could be above 70%. 10 refs., 6 figs., 5 tabs.

  15. Self-consistent klystron simulations

    SciTech Connect

    Carlsten, B.E.; Tallerico, P.J.

    1985-01-01

    A numerical analysis of large-signal klystron behavior based on general wave-particle interaction theory is presented. The computer code presented is tailored for the minimum amount of complexity needed in klystron simulation. The code includes self-consistent electron motion, space-charge fields, and intermediate and output fields. It also includes use of time periodicity to simplify the problem, accurate representation of the space-charge fields, accurate representation of the cavity standing-wave fields, and a sophisticated particle-pushing routine. In the paper, examples are given that show the effects of cavity detunings, of varying the magnetic field profile, of electron beam asymmetries from the gun, and of variations in external load impedance. 4 refs., 7 figs.

  16. Hardware upgrade for klystrons in the SLC

    SciTech Connect

    Jobe, R.K.; Browne, M.J.; Slattery, K.P.

    1985-05-01

    The control and monitoring of the klystrons in the first third of the SLAC linear accelerator has been commissioned, and a program to complete installation by summer 1985 is in progress. A general overview of the new control system for SLAC klystrons is presented along with a detailed description of the Modulator Klystron Support Unit. The MKSU contains all the devices necessary to interface klystron monitoring and control to the SLC control system through a dedicated intelligent CAMAC module. Controlled devices include RF phase and drive controls, the high power modulator status, associated RF signals, waterflow and magnet controls.

  17. Pulse to pulse klystron diagnosis system

    SciTech Connect

    Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

    1981-03-01

    This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 ..mu..s. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations.

  18. High efficiency SPS klystron design

    NASA Technical Reports Server (NTRS)

    Nalos, E. J.

    1980-01-01

    The most likely compact configuration to realize both high efficiency and high gain (approx. 40 dB) is a 5-6 cavity design focused by an electromagnet. The basic klystron efficiency cannot be expected to exceed 70-75% without collector depression. It was estimated that the net benefit of a 5 stage collector over a 2 stage collector is between 1.5 and 3.5 kW per tube. A modulating anode is incorporated in the design to enable rapid shutoff of the beam current in case the r.f. drive should be removed.

  19. Periodic permanent magnet focused klystron

    SciTech Connect

    Ferguson, Patrick; Read, Michael; Ives, R Lawrence

    2015-04-21

    A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

  20. Reliability and lifetime predictions of SLC klystrons

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Lee, T.G.; Vlieks, A.E.

    1989-03-01

    The energy upgrade of SLAC, with the first of the new 67 MW SLAC Linear Collider (SLC) klystrons, began over four years ago. Today there are over 200 of these klystrons in operation. As a result, there is a wealth klystron performance and failure information that enables reasonable predictions to be made on life expectancy and reliability. Data from initial tests, follow-up tests and daily operation monitoring on the accelerator is stores for analysis. Presented here are life expectancy predictions with particular emphasis on cathode life. Also, based on this data, we will discuss some of the principal modes of failure. 3 refs., 2 figs.

  1. X-BAND KLYSTRON DEVELOPMENT AT SLAC

    SciTech Connect

    Vlieks, Arnold E.; /SLAC

    2009-08-03

    The development of X-band klystrons at SLAC originated with the idea of building an X-band Linear Collider in the late 1980's. Since then much effort has been expended in developing a reliable X-band Power source capable of delivering >50 MW RF power in pulse widths >1.5 {micro}s. I will report on some of the technical issues and design strategies which have led to the current SLAC klystron designs.

  2. A new high-power klystron for the DSN

    NASA Technical Reports Server (NTRS)

    Goldfinger, A.; Gregg, M. A.; Hartop, R.

    1982-01-01

    A very high reliability 100 kW klystron for the Deep Space Network (DSN) high power transmitters in support of spacecrafts to the distant planets was studied. The last phases included electron gun fabrication and beam analyzer evaluation and klystron prototype fabrication, mechanical and electrical design improvements resulted in the delivery of a prototype klystron meeting all requirements. It is concluded that the development of a new high power klystron for the DSN was very successful as demonstrated by the prototype results.

  3. On a theory of two-beam mechanisms of charged particle acceleration in electrodynamic structures

    SciTech Connect

    Ostrovsky, A.O.

    1993-09-01

    This work is devoted to the theoretical studies of two-beam mechanisms of charged particle acceleration in electronic structures. The first section continues the outline of results of theoretical studies commenced in the intermediate report and considers the two-beam scheme of acceleration in the plasma waveguide. According to this scheme the strong current relativistic electron beam (REB) excites the intensive plasma waves accelerating the electrons of the second beam. The driving beam is assumed to be density-modulated. The preliminary modulation of the driving REB is shown to enhance substantially the acceleration efficiency of relativistic electrons of the driven beam. The second section deals with the two-beam acceleration in the vacuum corrugated waveguide. According to this scheme the excitation of electromagnetic waves and acceleration of driven beam electrons by them is accomplished under different Cherenkov resonances between the particles of beams and the corrugated waveguide field. The electromagnetic field in the periodic structure is known to be the superposition of spatial harmonics. With the small depth of the periodic nonuniformity the amplitudes of these harmonics decrease fast with their number increasing. Therefore, if the driving beam is in the Cherenkov resonance with the first spatial harmonic and the driven beam is in resonance with the zero space harmonic then the force accelerating the driven beam would be considerably bigger than the force decelerating the driving beam electrons.

  4. 1.5-GW S-band relativistic klystron amplifier

    NASA Astrophysics Data System (ADS)

    Ferguson, Patrick E.

    1992-04-01

    There is a strong symbiotic relationship between a developing technology and its applications. New technologies can generate applications previously either unrealizable or impractical. Conversely, applications can demand the development of new technological capability. Examples of both types of development can be found in the evolution of HPM. The high power and energy output made possible by HPM have created a technology driven interest in directed energy weapons and short pulse radar. On the other hand, the requirements for heating of fusion plasmas have resulted in an application driven program to develop high average power microwave devices. In this paper we address these and other applications such as RF electron linacs, laser pumping, and beaming of power. Emerging applications, such as ionispheric modification and environmental cleanup, are also touched upon. The approach of this paper will be to review each application separately and then compare the requirements of the applications in terms of the power, frequency and other key requirements necessary for HPM to usefully address the application.

  5. High power rf klystrons for linear accelerators

    SciTech Connect

    Konrad, G.T.

    1984-04-01

    Recent klystron developments at SLAC are described. The standard 40 MW klyston, which typically operates at 35 MW on the SLAC linac, is the starting point for the push to higher peak and average power. The standard tube is capable of a 2.5 ..mu..s rf pulse width at 360 pps. For the SLC a 50 MW klystron capable of 5 ..mu..s pulse width at 180 pps is under development. Another tube currently being worked on is a 150 MW klystron capable of 1 ..mu..s rf and 180 pps. Design criteria and actual operating experience for both developmental tubes are described. 10 references, 11 figures, 3 tables.

  6. Large-signal klystron simulations using KLSC

    SciTech Connect

    Carlsten, B.E.; Ferguson, P.

    1997-10-01

    The authors describe large-signal klystron simulations using the particle-in-cell code KLSC. This code uses the induced-current model to describe the steady-state cavity modulations and resulting rf fields, and advances the space-charge fields through maxwell`s equations. In this paper, an eight-cavity, high-power S-band klystron simulation is used to highlight various aspects of this simulation technique. In particular, there are specific issues associated with modeling the input cavity, the gain circuit, and the large-signal circuit (including the output cavities), that have to be treated carefully.

  7. A 75 MW S-Band Klystron

    SciTech Connect

    Ferguson, Patrick; Read, Michael; Ives, Robert Lawrence; Marsden, David

    2013-12-16

    This program performed computational and preliminary mechanical design for a klystron producing 75 MW at 2.856 GHz using periodic permanent magnet (PPM) focusing. The performance specifications achieved were those for the Matter-Radiation Interactions in the Extremes (MaRIE) project at Los Alamos National Laboratory. The klystron is designed to provide 10 microsecond pulses at 60 Hz with 56 dB gain. The PPM-Focusing eliminates requirements for solenoids and their associated power supplies, cooling systems, interlocks, control and diagnostic instrumentation, and maintenance. The represents a significant in both acquisition and operating costs. It also increases reliability by eliminating many potential failure modes.

  8. APS linac klystron and accelerating structure gain measurements and klystron PFN voltage regulation requirements

    SciTech Connect

    Sereno, N.S.

    1997-07-01

    This note details measurements of the APS positron linac klystron and accelerating structure gain and presents an analysis of the data using fits to simple mathematical models. The models are used to investigate the sensitivity of the energy dependence of the output positron beam to klystron parameters. The gain measurements are separated into two parts: first, the energy gains of the accelerating structures of the positron linac are measured as a function of output power of the klystron; second, the klystron output power is measured as a function of input drive power and pulse forming network (PFN) voltage. This note concentrates on the positron linac rf and its performance as it directly affects the energy stability of the positron beam injected into the positron accumulator ring (PAR). Ultimately it is important to be able to minimize beam energy variations to maximize the PAR accumulation efficiency.

  9. High efficiency klystron for the SPS application

    NASA Technical Reports Server (NTRS)

    Larue, A. D.

    1980-01-01

    The enhancement of klystron efficiency through the use of collector depression, that is by recovering energy from the spent electron beam after microwave amplification, was investigated. Design considerations included noise, harmonics, cooling, and service life. The mod anode, to be employed for beam control, and the depressed collector, used in spent electron beam energy recovery, are described.

  10. Klystron control software in the SLC

    SciTech Connect

    Jobe, R.K.; Thompson, K.; Phinney, N.

    1985-05-01

    Triggering, control, and monitoring of 240 high-power klystrons will be supported by the SLC control system this summer. The control software is distributed among a VAX host computer, a local microprocessor cluster, and a dedicated intelligent CAMAC module. The functions performed by these three components and the algorithms used are discussed.

  11. High-Efficiency Klystron For Television Transmitters

    NASA Technical Reports Server (NTRS)

    Ramins, Peter; Dayton, James; Mccune, Earl, Sr.; Kosmahl, Henry

    1990-01-01

    Improved klystron designed for use as final amplifier in ultrahigh-frequency (UHF) television transmitter. New device incorporates multistage depressed collector (MSDC) of advanced design to increase efficiency by recovering, from spent electron beam, some of residual kinetic energy otherwise dissipated as heat. Concept applied to increase efficiencies of microwave communication, equipment, radar systems, and particle-beam accelerators.

  12. Retrofitting the 5045 Klystron for Higher Efficiency

    SciTech Connect

    Jensen, Aaron; Fazio, Michael; Haase, Andy; Jongewaard, Erik; Kemp, Mark; Neilson, Jeff

    2015-04-15

    The 5045 klystron has been in production and accelerating particles at SLAC National Accelerator Laboratory for over 25 years. Although the design has undergone some changes there are still significant opportunities for improvement in performance. Retrofitting the 5045 for higher efficiencies and a more mono-energetic spent beam profile is presented.

  13. Klystron having electrostatic quadrupole focusing arrangement

    DOEpatents

    Maschke, Alfred W.

    1983-08-30

    A klystron includes a source for emitting at least one electron beam, and an accelerator for accelarating the beam in a given direction through a number of drift tube sections successively aligned relative to one another in the direction of the beam. A number of electrostatic quadrupole arrays are successively aligned relative to one another along at least one of the drift tube sections in the beam direction for focusing the electron beam. Each of the electrostatic quadrupole arrays forms a different quadrupole for each electron beam. Two or more electron beams can be maintained in parallel relationship by the quadrupole arrays, thereby enabling space charge limitations encountered with conventional single beam klystrons to be overcome.

  14. Klystron having electrostatic quadrupole focusing arrangement

    DOEpatents

    Maschke, A.W.

    1983-08-30

    A klystron includes a source for emitting at least one electron beam, and an accelerator for accelerating the beam in a given direction through a number of drift tube sections successively aligned relative to one another in the direction of the beam. A number of electrostatic quadrupole arrays are successively aligned relative to one another along at least one of the drift tube sections in the beam direction for focusing the electron beam. Each of the electrostatic quadrupole arrays forms a different quadrupole for each electron beam. Two or more electron beams can be maintained in parallel relationship by the quadrupole arrays, thereby enabling space charge limitations encountered with conventional single beam klystrons to be overcome. 4 figs.

  15. A crowbarless power supply for klystrons.

    PubMed

    Kozu, H; Jumonji, Y; Yamazaki, C; Shoji, Y; Hashimoto, S; Ando, A

    1998-05-01

    A new crowbarless power supply is to be installed at the New SUBARU storage ring. A high-power switching inverter unit eliminates the need for expensive and unstable crowbar circuits for the klystron power supply. It also realizes a very small voltage ripple in the low-frequency region. This is an important characteristic, especially in a quasi-isochronous storage ring such as New SUBARU. PMID:15263515

  16. FPGA Trigger System to Run Klystrons

    SciTech Connect

    Gray, Darius; /Texas A-M /SLAC

    2010-08-25

    The Klystron Department is in need of a new trigger system to update the laboratory capabilities. The objective of the research is to develop the trigger system using Field Programmable Gate Array (FPGA) technology with a user interface that will allow one to communicate with the FPGA via a Universal Serial Bus (USB). This trigger system will be used for the testing of klystrons. The key materials used consists of the Xilinx Integrated Software Environment (ISE) Foundation, a Programmable Read Only Memory (Prom) XCF04S, a Xilinx Spartan 3E 35S500E FPGA, Xilinx Platform Cable USB II, a Printed Circuit Board (PCB), a 100 MHz oscillator, and an oscilloscope. Key considerations include eight triggers, two of which have variable phase shifting capabilities. Once the project was completed the output signals were able to be manipulated via a Graphical User Interface by varying the delay and width of the signal. This was as planned; however, the ability to vary the phase was not completed. Future work could consist of being able to vary the phase. This project will give the operators in the Klystron Department more flexibility to run various tests.

  17. Investigation of the effects of returning electrons on klystron performance

    NASA Astrophysics Data System (ADS)

    Roybal, William Thomas

    The klystron, as part of an RF distribution system for an accelerator, is one of the most important components contributing to the cost, reliability, and longevity of the overall system. Operating cost is one of the primary concerns for klystrons. Achieving high direct current (DC) to radio frequency (RF) conversion efficiency, free of instabilities is very important. There is uncertainty concerning the effects of returning electrons within the klystron and the impact that they have on klystron performance. The effects of reverse traveling electrons on klystron performance, such as efficiency, are poorly defined. Classical and even modern klystron design avoids the consideration of return electrons, and thus the effects have not been numerically analyzed and quantified. A better understanding of the electron beam-to-RF conversion process and the effects of return electrons within the klystron output circuit is needed. Accurate klystron modeling and simulation of return electron effects are required to better understand the implications of the problem. This analysis identifies the influence that returning electrons have on the overall beam dynamics and self-consistent cavity voltages. Closer examination of the harmonic content within the reverse beam current, along with comparison to the nominal klystron design, reveals the effects that reverse flowing electrons can have on klystron performance and design. The results of this work include a description of the electron beam dynamics for a beam decelerated in the output cavity, with separation occurring between forward and reverse electrons. Varying the output parameter of the klystron causes an unexpected response in return current quantity and bunching quality, yielding periodic correlations and responses to two-stream interaction.

  18. Apparatus makes klystron operating frequency adjustable from remote point

    NASA Technical Reports Server (NTRS)

    Clauss, R. C.

    1967-01-01

    Apparatus makes possible proper frequency adjustment in a receiver using a pump klystron for a traveling-wave master. It incorporates a tunable overcoupled cavity with irises of appropriate size to accomplish frequency spread over the desired range and to maintain the Q of the klystron circuit at the optimum value.

  19. Modification of the control modulator (for a klystron)

    NASA Astrophysics Data System (ADS)

    Heine, Eric

    The modulators of the klystron units for pulse injection into an accelerator were modified in order to increase the peak power of the klystrons. The modulators were modified from 4 MW RF power out and 50 micro pulses to 10 MW RF power out and 5 microsec. The required modifications of the operator interface programming are explained.

  20. Design of a 50 MW klystron at X-band

    SciTech Connect

    Wright, E.; Callin, R.; Caryotakis, G.

    1995-07-01

    This paper describes the design and performance of the XL-1 klystron; a 50 MW klystron operating at a frequency of 11.424 GHz for use on the SLAC Next Linear Collider Test Accelerator (NLCTA). Problems associated with the development of high-power rf sources for NLC, and the solutions implemented on XL-1 are discussed.

  1. The Klynac: An Integrated Klystron and Linear Accelerator

    SciTech Connect

    Potter, J. M.; Schwellenbach, D.

    2013-04-01

    The Klynac concept integrates an electron gun, a radio frequency (RF) power source, and a coupled-cavity linear accelerator into a single resonant system. The klystron is essentially a conventional klystron structure with an input cavity, some number of intermediate cavities and an output cavity. The accelerator structure is, likewise, a conventional on-axis coupled structure. The uniqueness is the means of coupling the klystron output cavity to the accelerator. The coupler is a resonant coupler rather than an ordinary transmission line. The geometry of such a system need not be coaxial. However, if the klystron and accelerator are coaxial we can eliminate the need for a separate cathode for the accelerator by injecting some of the klystron beam into the accelerator. Such a device can be made cylindrical which is ideal for some applications.

  2. 250-kW CW klystron amplifier for planetary radar

    NASA Technical Reports Server (NTRS)

    Cormier, Reginald A.; Mizuhara, Albert

    1992-01-01

    The design, construction, and performance testing is described of two Varian klystrons, model VKX-7864A, which replaced the aging and less efficient VA-949J klystrons in the X band planetary radar transmitter on the Goldstone, CA, 70 meter antenna. The project was carried out jointly by the JPL and Varian Assoc. Output power was increased from 200 to 250 kW continuous wave per klystron, and full dc beam power is dissipated in the collector (it was not possible to operate the VA-949J klystrons without RF drive because of limited collector dissipation capability). Replacement were made with a minimum of transmitter modifciations. The planetary radar transmitter is now operating successfully with these two klystrons.

  3. The Klynac: An integrated klystron and linear accelerator

    SciTech Connect

    Potter, James M.; Schwellenbach, David; Meidinger, Alfred

    2013-04-19

    The Klynac concept integrates an electron gun, a radio frequency (RF) power source, and a coupled-cavity linear accelerator into a single resonant system. The klystron is essentially a conventional klystron structure with an input cavity, some number of intermediate cavities and an output cavity. The accelerator structure is, likewise, a conventional on-axis coupled structure. The uniqueness is the means of coupling the klystron output cavity to the accelerator. The coupler is a resonant coupler rather than an ordinary transmission line. The geometry of such a system need not be coaxial. However, if the klystron and accelerator are coaxial we can eliminate the need for a separate cathode for the accelerator by injecting some of the klystron beam into the accelerator. Such a device can be made cylindrical which is ideal for some applications.

  4. Performance of a 150-MW S-band klystron

    SciTech Connect

    Sprehn, D.; Phillips, R.M.; Caryotakis, G.

    1994-09-01

    As part of an international collaboration, the Stanford Linear Accelerator Center (SLAC) klystron group has designed, fabricated, and tested a 60-Hz, 3-{mu}s, 150-MW S-band klystron built for Deutsches Elektronen Synchrotron (DESY). A test diode with a 535-kV, 700-A electron beam was constructed to verify the gun operation. The first klystron was built and successfully met design specifications. The 375-MW electron beam represents a new record for SLAC accelerator klystrons in terms of voltage, current, energy, and ruggedness of design. The rf output power is a 150% increase over the S-band tubes currently used in the two-mile-long linear accelerator at SLAC. This paper discusses design issues and experimental results of the diode and klystron.

  5. W-Band Sheet Beam Klystron Design

    SciTech Connect

    Scheitrum, G.; Caryotakis, G.; Burke, A.; Jensen, A.; Jongewaard, E.a Krasnykh, A.; Neubauer, M.; Phillips, R.; Rauenbuehler, K.; /SLAC

    2011-11-11

    Sheet beam devices provide important advantages for very high power, narrow bandwidth RF sources like accelerator klystrons [1]. Reduced current density and increased surface area result in increased power capabi1ity, reduced magnetic fields for focusing and reduced cathode loading. These advantages are offset by increased complexity, beam formation and transport issues and potential for mode competition in the ovennoded cavities and drift tube. This paper will describe the design issues encountered in developing a 100 kW peak and 2 kW average power sheet beam k1ystron at W-band including beam formation, beam transport, circuit design, circuit fabrication and mode competition.

  6. Nonlinear harmonic generation in distributed optical klystrons

    SciTech Connect

    H.P. Freund; George R. Neil

    2001-12-01

    A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5{angstrom} fundamental and a 1.5{angstrom} harmonic is discussed.

  7. Adaptive control system for pulsed megawatt klystrons

    DOEpatents

    Bolie, Victor W.

    1992-01-01

    The invention provides an arrangement for reducing waveform errors such as errors in phase or amplitude in output pulses produced by pulsed power output devices such as klystrons by generating an error voltage representing the extent of error still present in the trailing edge of the previous output pulse, using the error voltage to provide a stored control voltage, and applying the stored control voltage to the pulsed power output device to limit the extent of error in the leading edge of the next output pulse.

  8. W-band sheet beam klystron simulation

    SciTech Connect

    Colby, E.R.; Caryotakis, G.; Fowkes, W.R.; Smithe, D.N.

    1999-05-01

    With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat}{approximately}{lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focussing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35{percent} beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry. {copyright} {ital 1999 American Institute of Physics.}

  9. W-Band Sheet Beam Klystron Simulation

    SciTech Connect

    Colby, E.R.; Caryotakis, G.; Fowkes, W.R.; Smithe, D.N.; /Mission Res., Newington

    2005-09-12

    With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat} {approx} {lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focusing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35% beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry.

  10. Wavelength switching in an optical klystron

    SciTech Connect

    Berryman, K.W.; Smith, T.I.

    1995-12-31

    A symmetric optical klystron consists of two identical undulator sections separated a dispersive section. For a device of a given length, an optical klystron is capable of producing much more bunching, and therefore more gain, than a traditional undulator. Another consequence of introducing dispersion between two undulator sections is that the overall spontaneous radiation pattern results from the interference between the two undulator sections, and as such resembles a standard undulator radiation pattern modulated by a sinusoidal interference term. The presence of several wavelength peaks in the spontaneous lineshape implies an equal number of peaks in the gain spectrum. If the strength of the dispersion section is adjusted to provide nearly equal gain on the two largest of these peaks, then they will compete, and the FEL may switch wavelengths based on noise, cavity length, or other perturbations. We provide the first observations of this behavior, using the FIREFLY system at the Stanford Picosecond FEL Center. In FIREFLY, relative wavelength switching by more than 3%--more than twice the laser linewidth-has been observed by varying dispersion section strength, while at intermediate points stable switching has also been observed as a function of cavity length.

  11. A Unique Power Supply for the PEPII Klystron at SLAC

    NASA Astrophysics Data System (ADS)

    Cassel, R. L.; Nguyen, M. N.

    1997-05-01

    Each of the eight 1.2 MW RF klystrons for the PEP-II storage rings require a 2.5 MVA DC power supply of 83 kv at 23 amps. The design for the supply was base on three factors low cost, small size to fit existing substation pads, and good protection against damage to the klystron including klystron gun arcs. The supply uses a 12 pulse 12.5 KV primary thyristor ``star point controller'' with primary filter inductor to provide rapid voltage control, good voltage regulation, and fast turn off during klystron tube faults. The supply also uses a unique secondary rectifier, filter capacitor configuration to minimize the energy available under a klystron fault. The voltage control is from 0-90 KV with a regulation of < 0.1 % and voltage ripple of < 1 % P-P, (< 0.2 % RMS.) above 60 KV. The supply utilizes a thyristor crowbar, which under a klystron tube arc limits the energy in the klystron arc to < 5 joules. If the thyristor crowbar is disabled the energy supplied is < 40 joules into the arc. The size of the supply was reduced small enough to fit the existing PEP transformer yard pads. The cost of the power supply was < $ 140 per KVA.

  12. Efficiency enhancement of a two-beam free-electron laser

    SciTech Connect

    Rouhani, M. H.; Maraghechi, B.; Saberi, H.

    2009-12-15

    A local and nonlinear simulation of two-beam and tapered free-electron laser (FEL) is presented self-consistently. The slippage of the electromagnetic wave with respect to the electron beam is ignored and the relativistic electron beams are assumed to be cold. The fundamental resonance and the third harmonic radiation of the beam with lower energy are considered, in which the third harmonic is at the fundamental resonance of the beam with higher energy. The wiggler field is set to decrease linearly when the radiation of the third harmonic saturates. The optimum starting point of tapering and the slope of the reduction in the amplitude of wiggler are found by successive run of the code. Using the slowly varying envelope approximation, a set of nonlinear equations is derived which describes this system. These equations are solved numerically by the Runge-Kutta method. This method can be used to improve the efficiency of the two-beam FEL in the extreme ultraviolet and x-ray regions of spectrum.

  13. Phase synchronization of multiple klystrons in RF system

    SciTech Connect

    Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

    1998-12-31

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of the Acceleration Production of Tritium (APT) accelerator. The first LEDA RF system includes three, 1.2 MW, 350 MHz, continuous wave, klystrons driving a radio frequency quadrupole (RFQ). A phase control loop is necessary for each individual klystron in order to guarantee the phase matching of these klystrons. To meet this objective, they propose adaptive PI controllers which are based on simple adaptive control. These controllers guarantee not only phase matching but also amplitude matching.

  14. The klystron: A microwave source of surprising range and endurance

    SciTech Connect

    Caryotakis, G.

    1998-04-01

    This year marks the 60th anniversary of the birth of the klystron at Stanford University. The tube was the first practical source of microwaves and its invention initiated a search for increasingly more powerful sources, which continues to this day. This paper reviews the scientific uses of the klystron and outlines its operating principles. The history of the device is traced, from its scientific beginnings, to its role in World War II and the Cold War, and to its current resurgence as the key component in a major accelerator project. Finally, the paper describes the development of a modular klystron, which may someday power future accelerators at millimeter wavelengths.

  15. Evaluation of the effects of optical klystrons on the selene free electron laser oscillator. Master`s thesis

    SciTech Connect

    Kelsey, E.A.

    1995-06-01

    Lasers have been incorporated into many parts of society including heavy industrial work military defense, light displays, scientific research, and everyday household appliances. Free Electron Lasers (FELs) use relativistic electrons traveling in an alternating magnetic field to produce coherent radiation. One particular application for a FEL is to beam power to satellites. The United States and Russia have agreed to pursue this effort together. The installation in the United States is the SpacE Laser ENErgy (SELENE) project scheduled for installation at China Lake, California. The SELENE laser system consists of an oscillator and a radiator. The electrons are bunched in the oscillator in preparation for entering the radiator. The use of a three-section optical klystron has been proposed for the SELENE oscillator. An optical klystron FEL is composed of multiple undulator sections, each separated from the next by a dispersive section. The dispersive section allows for larger gain from a shorter total length of undulator. The effects of the optical klystrons in the SELENE oscillator using the proposed SELENE FEL parameters will be investigated through the use of simulations of two and three-section undulators.

  16. Numerical Simulation of Transient and Steady State Nonlinear Beam-Cavity Dynamics in High Power Klystrons.

    NASA Astrophysics Data System (ADS)

    Zambre, Yadunath Bhagvantrao

    1988-03-01

    A 2-1over2 dimensional analysis of klystrons, assuming cylindrical space symmetry but retaining all velocity effects, is presented. The model handles all relativistic, electromagnetic, and non-linear effects. The klystron geometry is viewed as a conducting cylinder (the tube) to which are attached a number of resonant cavities at various locations. Within this tube, particle in cell plasma simulation techniques are used to model the electron beam dynamics and electromagnetic fields. The effects of the cavities are then "patched in" by the use of eigenmode expansions over the cavity geometries. These expansions reduce the effects of the cavity fields into relatively simple time varying boundary conditions on the tube. The plasma simulation in the tube is carried out using a number of "macroparticles," each representing many electrons and each obeying the equations of motion for an electron. A time centered cycloid fitting algorithm is used to move the particles. A time centered spectral method using Fourier series in z and Chebyschev polynomials in r is used to advance the fields. A non-uniform grid permits the use of FFT's to carry out the Chebyschev expansions. A method for finding time periodic solutions is also presented. This method will compute a qualitatively correct transient solution and yield a quantitatively correct steady state solution.

  17. Klystron 'efficiency loop' for the ALS storage ring RF system

    SciTech Connect

    Kwiatkowski, Slawomir; Julian, Jim; Baptiste, Kenneth

    2002-05-20

    The recent energy crisis in California has led us to investigate the high power RF systems at the Advanced Light Source (ALS) in order to decrease the energy consumption and power costs. We found the Storage Ring Klystron Power Amplifier system operating as designed but with significant power waste. A simple proportional-integrator (PI) analog loop, which controls the klystron collector beam current, as a function of the output RF power, has been designed and installed. The design considerations, besides efficiency improvement, were to interface to the existing system without major expense. They were to also avoid the klystron cathode power supply filter's resonance in the loop's dynamics, and prevent a conflict with the existing Cavity RF Amplitude Loop dynamics. This efficiency loop will allow us to save up to 700 MW-hours of electrical energy per year and increase the lifetime of the klystron.

  18. Engineering Features: Klystron Tubes and Utilidors Clear Air Force ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Engineering Features: Klystron Tubes and Utilidors - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  19. Optical Klystron Enhancement to SASE X-ray FELs

    SciTech Connect

    Ding, Yuantao; Emma, Paul; Huang, Zhirong; Kumar, Vinit

    2006-04-07

    The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 A) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.

  20. Experimental demonstration of enhanced self-amplified spontaneous emission by an optical klystron.

    PubMed

    Penco, G; Allaria, E; De Ninno, G; Ferrari, E; Giannessi, L

    2015-01-01

    We report the first experimental evidence of enhancement of self-amplified spontaneous emission, due to the use of an optical klystron. In this free-electron laser scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. The experiment has been carried out at the FERMI facility in Trieste. Powerful radiation has been produced in the extreme ultraviolet range, with an intensity a few orders of magnitude larger than in pure self-amplified spontaneous emission mode. Data have been benchmarked with an existing theoretical model. PMID:25615469

  1. Experimental Demonstration of Enhanced Self-Amplified Spontaneous Emission by an Optical Klystron

    NASA Astrophysics Data System (ADS)

    Penco, G.; Allaria, E.; De Ninno, G.; Ferrari, E.; Giannessi, L.

    2015-01-01

    We report the first experimental evidence of enhancement of self-amplified spontaneous emission, due to the use of an optical klystron. In this free-electron laser scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. The experiment has been carried out at the FERMI facility in Trieste. Powerful radiation has been produced in the extreme ultraviolet range, with an intensity a few orders of magnitude larger than in pure self-amplified spontaneous emission mode. Data have been benchmarked with an existing theoretical model.

  2. CARM-klystron amplifier for accelerator applications

    NASA Astrophysics Data System (ADS)

    Gold, Steven H.; Fliflet, Arne W.

    2001-05-01

    We consider the possibility of a cyclotron-autoresonance-maser (CARM) klystron configuration for accelerator applications as an alternative to the gyroklystron amplifier. The potential advantages, compared to gyroklystrons, include: 1) comparable efficiencies at lower values of the electron beam pitch ratio α, which should improve the beam quality and make the device substantially more stable against the excitation of parasitic mode, 2) operation far from cutoff, which should reduce the fields at cavity walls, allowing higher power operation, and 3) operation at lower magnetic fields for the same cyclotron harmonic number. However, there are two significant issues associated with the design of efficient, high-power CARMs. First, because of the higher value of kZ, compared to gyroklystrons, CARMs are substantially more sensitive to parallel velocity spread (pitch-angle spread). Second, conventional cavities support a variety of near-cutoff modes, which can compete with the CARM interaction. Therefore, one must consider either Bragg resonators or quasioptical cavity configurations.

  3. 100 MW klystron development at SLAC

    SciTech Connect

    Vlieks, A.E.; Callin, R.S.; Caryotakis, G.; Fant, K.S.; Fowkes, W.R.; Lee, T.G.; Wright, E.L.

    1991-05-01

    A klystron designed to operate at 11.4 GHz and 440 kV is presently SLAC's strongest rf power source candidate for the Next Linear Collider. It is expected to provide 100 MW of rf power with a pulse width of 1 microsecond. Many of the conventional tube technologies are being pushed to their limits. High electron beam power densities, rf electric gradients in cavity gaps and stresses on the ceramic rf output windows are among the most severe problems to be dealt with. This paper describes progress in the development of this device including results from single and double gap output cavities and various styles of rf output windows. 6 refs., 3 figs., 1 tab.

  4. Thermal effect on prebunched two-beam free electron laser

    SciTech Connect

    Mirian, N. S.; Maraghechi, B.

    2013-08-15

    A numerical simulation in one-dimension is conducted to study the two-beam free electron laser. The fundamental resonance of the fast electron beam coincides with the fifth harmonic of the slow electron beam in order to generate extreme ultraviolet radiation. Thermal effect in the form of the longitudinal velocity spread is included in the analysis. In order to reduce the length of the wiggler, prebunched slow electron beam is considered. The evaluation of the radiation power, bunching parameter, distribution function of energy, and the distribution function of the pondermotive phase is studied. Sensitivity of the power of the fifth harmonic to the jitter in the energy difference between the two beams is also studied. A phase space is presented that shows the trapped electrons at the saturation point.

  5. 66. Building 102, view of Klystron tubes located in test ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. Building 102, view of Klystron tubes located in test systems located at first floor level with top of tubes protruding through second floor and ready to be lit and installed through top of Klystron tube vaults to ready position. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  6. Two-beam interferometer for fourier spectroscopy with rigid pendulum

    SciTech Connect

    Burkert, P.

    1983-05-17

    A two-beam interferometer for fourier spectroscopy includes a rigid pendulum structure mounting at least one of the movable retroreflectors in a fully compensated optical system immune to tilt and lateral movement distortions. The swing of the rotatably journaled pendulum accurately confines the retroreflector(s) to movement in a single plane during scanning and, due to the low heat generated in the pendulum bearings, the simple and compact structure is well adapted to be housed in a cryostat aboard a spacecraft.

  7. FPGA-based klystron linearization implementations in scope of ILC

    NASA Astrophysics Data System (ADS)

    Omet, M.; Michizono, S.; Matsumoto, T.; Miura, T.; Qiu, F.; Chase, B.; Varghese, P.; Schlarb, H.; Branlard, J.; Cichalewski, W.

    2015-04-01

    We report the development and implementation of four FPGA-based predistortion-type klystron linearization algorithms. Klystron linearization is essential for the realization of ILC, since it is required to operate the klystrons 7% in power below their saturation. The work presented was performed in international collaborations at the Fermi National Accelerator Laboratory (FNAL), USA and the Deutsches Elektronen Synchrotron (DESY), Germany. With the newly developed algorithms, the generation of correction factors on the FPGA was improved compared to past algorithms, avoiding quantization and decreasing memory requirements. At FNAL, three algorithms were tested at the Advanced Superconducting Test Accelerator (ASTA), demonstrating a successful implementation for one algorithm and a proof of principle for two algorithms. The functionality of the algorithm implemented at DESY was demonstrated successfully in a simulation. Besides this, a proof of principle of an FPGA-based klystron and cavity simulator implemented at the High Energy Accelerator Research Organization (KEK), Japan was demonstrated. Its purpose is to allow the development and test of digital LLRF control systems including klystron linearization algorithms when no actual klystron and cavity are available.

  8. FPGA-based klystron linearization implementations in scope of ILC

    NASA Astrophysics Data System (ADS)

    Omet, M.; Michizono, S.; Matsumoto, T.; Miura, T.; Qiu, F.; Chase, B.; Varghese, P.; Schlarb, H.; Branlard, J.; Cichalewski, W.

    2014-12-01

    We report the development and implementation of four FPGA-based predistortion-type klystron linearization algorithms. Klystron linearization is essential for the realization of ILC, since it is required to operate the klystrons 7% in power below their saturation. The work presented was performed in international collaborations at the Fermi National Accelerator Laboratory (FNAL), USA and the Deutsches Elektronen Synchrotron (DESY), Germany. With the newly developed algorithms, the generation of correction factors on the FPGA was improved compared to past algorithms, avoiding quantization and decreasing memory requirements. At FNAL, three algorithms were tested at the Advanced Superconducting Test Accelerator (ASTA), demonstrating a successful implementation for one algorithm and a proof of principle for two algorithms. The functionality of the algorithm implemented at DESY was demonstrated successfully in a simulation. Besides this, a proof of principle of an FPGA-based klystron and cavity simulator implemented at the High Energy Accelerator Research Organization (KEK), Japan, was demonstrated. Its purpose is to allow the development and test of digital LLRF control systems including klystron linearization algorithms when no actual klystron and cavity are available.

  9. A non-uniform three-gap buncher cavity with suppression of transverse-electromagnetic mode leakage in the triaxial klystron amplifier

    SciTech Connect

    Qi, Zumin; Zhang, Jun Zhong, Huihuang; Zhu, Danni; Qiu, Yongfeng

    2014-01-15

    The triaxial klystron amplifier is an efficient high power relativistic klystron amplifier operating at high frequencies due to its coaxial structure with large radius. However, the coaxial structures result in coupling problems among the cavities as the TEM mode is not cut-off in the coaxial tube. Therefore, the suppression of the TEM mode leakage, especially the leakage from the buncher cavity to the input cavity, is crucial in the design of a triaxial klystron amplifier. In this paper, a non-uniform three-gap buncher cavity is proposed to suppress the TEM mode leakage. The cold cavity analysis shows that the non-uniform three-gap buncher cavity can significantly suppress the TEM mode generation compared to a uniform three-gap buncher cavity. Particle-in-cell simulation shows that the power leakage to the input cavity is less than 1.5‰ of the negative power in the buncher cavity and the buncher cavity can efficiently modulate an intense relativistic electron beam free of self-oscillations. A fundamental current modulation depth of 117% is achieved by employing the proposed non-uniform buncher cavity into an X-band triaxial amplifier, which results in the high efficiency generation of high power microwave.

  10. The X-band klystron program at SLAC

    SciTech Connect

    Caryotakis, G.

    1996-04-01

    The X-band rf source development at SLAC can be considered a qualified success. A total of twelve klystrons were built. Six of them are still in use. The latest tube, XL4, produced 75 MW at an efficiency of 47.5 percent. However, victory cannot be declared as yet, since an NLC prototype has not been fully designed and the decision between permanent magnet focusing and a super-conducting solenoid has not been formally made. Daryl Sprehn`s paper will present the status of the PPM klystron development. The authors believe that a PPM X-band source will work, at 50 as well as at 75 megawatts. But they are prepared to adapt the XL4 design to a super-conducting solenoid, should the PPM klystron develop unexpected problems. The SLAC program is now in its seventh year. It may well be the longest and most expensive microwave tube development on record, in a government laboratory or in industry. Direct and related costs for the total effort are probably of the order of $10 million. In these circumstances it is perhaps not surprising that it has been possible to produce a klystron with the performance of XL4. At the same time, it must be said that the necessary leap in technology from the SLAC 60-megawatt S-band production klystrons to a klystron of comparable performance at four times the frequency could not be realized without some very careful experimentation and, most importantly, without the infrastructure for tube fabrication and testing available at SLAC. The design of an 11.4 GHz 50--100 MW klystron, with microsecond pulses and a pulse repetition frequency of 180 Hz presents a number of technical challenges which are listed here.

  11. Evaluation of two-beam spectroscopy as a plasma diagnostic

    SciTech Connect

    Billard, B.D.

    1980-04-01

    A two-beam spectroscopy (TBS) system is evaluated theoretically and experimentally. This new spectroscopic technique uses correlations between components of emitted light separated by a small difference in angle of propagation. It is thus a non-perturbing plasma diagnostic which is shown to provide local (as opposed to line-of-sight averaged) information about fluctuations in the density of light sources within a plasma - information not obtainable by the usual spectroscopic methods. The present design is an improvement on earlier systems proposed in a thesis by Rostler.

  12. A theory of two-beam acceleration of charged particles in a plasma waveguide

    SciTech Connect

    Ostrovsky, A.O.

    1993-11-01

    The progress made in recent years in the field of high-current relativistic electron beam (REB) generation has aroused a considerable interest in studying REB potentialities for charged particle acceleration with a high acceleration rate T = 100MeV/m. It was proposed, in particular, to employ high-current REB in two-beam acceleration schemes (TBA). In these schemes high current REB (driving beam) excites intense electromagnetic waves in the electrodynamic structure which, in their turn, accelerate particles of the other beam (driven beam). The TBA schemes can be divided into two groups. The first group includes the schemes, where the two beams (driving and driven) propagate in different electrodynamic structures coupled with each other through the waveguides which ensure the microwave power transmission to accelerate driven beam particles. The second group includes the TBA schemes, where the driving and driven beams propagate in one electrodynamic structure. The main aim of this work is to demonstrate by theory the possibility of realizing effectively the TBA scheme in the plasma waveguide. The physical model of the TBA scheme under study is formulated. A set of equations describing the excitation of RF fields by a high-current REB and the acceleration of driven beam electrons is also derived. Results are presented on the the linear theory of plasma wave amplification by the driving beam. The range of system parameters, at which the plasma-beam instability develops, is defined. Results of numerical simulation of the TBA scheme under study are also presented. The same section gives the description of the dynamics of accelerated particle bunching in the high-current REB-excited field. Estimates are given for the accelerating field intensities in the plasma and electron acceleration rates.

  13. High-gradient two-beam electron accelerator

    SciTech Connect

    Hirshfield, Jay L.

    2014-11-04

    The main goal for this project was to design, build, and evaluate a detuned-cavity, collinear, two-beam accelerator structure. Testing was to be at the Yale University Beam Physics Laboratory, under terms of a sub-grant from Omega-P to Yale. Facilities available at Yale for this project include a 6-MeV S-band RF gun and associated beam line for forming and transporting a ~1 A drive beam , a 300 kV beam source for use as a test beam, and a full panoply of laboratory infrastructure and test equipment. During the first year of this project, availability and functionality of the 6-MeV drive beam and 300 kV test beam were confirmed, and the beam line was restored to a layout to be used with the two-beam accelerator project. Major efforts during the first year were also focused on computational design and simulation of the accelerator structure itself, on beam dynamics, and on beam transport. Effort during the second year was focussed on building and preparing to test the structure, including extensive cold testing. Detailed results from work under this project have been published in twelve archival journal articles, listed in Section IV of the technical report.

  14. Development of X-band klystron technology at SLAC

    SciTech Connect

    Caryotakis, G.

    1997-05-01

    The SLAC design for a 1-TeV collider (NLC) requires klystrons with a performance which is well beyond the state-of-the-art for microwave tubes in the United States or abroad. The electrical specifications for the NLC klystrons are not fully established, but they are approximately as follows: Frequency, 11.4 GHz; Peak Power, 75 MW; Pulse Length, 1.5 {mu}s; Repetition Rate, 180 Hz; Gain, 50 dB; Efficiency, (including beam focusing) 50%. SLAC is in the seventh year of a program to develop these klystrons. The choice of X-band as the operating frequency, along with the sheer size of the NLC, have resulted in some new, most demanding standards for the klystrons which may power this future machine. These are related to the overall efficiency required, to the high rf gradients that must be supported at the output circuit without vacuum breakdown, and to the manufacturing cost of the 5,000-10,000 klystrons needed for the collider.

  15. Development of a 50 MW Multiple Beam Klystron

    SciTech Connect

    Ives, R Lawrence; Ferguson, Patrick; Read, Michael; Collins, George

    2007-10-31

    The goal of this program was to develop a 50 MW, multiple beam klystron at 11.424 GHz. The device uses eight electron guns and beam lines to achieve the required power level at a beam voltage of 190 kV, consistent with solid state power supplies. The electron gun operates with confined flow focusing, which is unique among current multiple beam sources, and allows operation at power levels consistent with producing 10s of MWs of pulsed RF power. The circuit consists of a ring resonator input cavity, eight sets of buncher cavities, and a ring resonator output cavity. The RF output power is coupled into four rectangular waveguides equally spaced around the klystron. Eight individual collectors absorb the spent beam power in each beam. The klystron operates in a solenoid. The principle challenges in the design included development of the beam optics using confined flow focusing, shaping of the magnetic field in the gun region to avoid beam spiraling, coupling input power equally to all eight beam lines from a single input, and obtaining the required frequency and Q in the output cavity. The mechanical design was particularly complex due to the large parts count, number of braze and weld joints, and close proximity of the beam lines that limited access. Addressing vacuum leaks and cold testing the complex structures was particularly troublesome. At the conclusion of the program, the klystron is experiencing several vacuum leaks that are under repair. Efforts will continue to seal and test the klystron.

  16. Latest Results in SLAC 75-MW PPM Klystrons

    SciTech Connect

    Sprehn, D.; Caryotakis, G.; Haase, A.; Jongewaard, E.; Laurent, L.; Pearson, C.; Phillips, R.; /SLAC

    2006-03-06

    75 MW X-band klystrons utilizing Periodic Permanent Magnet (PPM) focusing have been undergoing design, fabrication and testing at the Stanford Linear Accelerator Center (SLAC) for almost nine years. The klystron development has been geared toward realizing the necessary components for the construction of the Next Linear Collider (NLC). The PPM devices built to date which fit this class of operation consist of a variety of 50 MW and 75 MW devices constructed by SLAC, KEK (Tsukuba, Japan) and industry. All these tubes follow from the successful SLAC design of a 50 MW PPM klystron in 1996. In 2004 the latest two klystrons were constructed and tested with preliminary results reported at EPAC2004. The first of these two devices was tested to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW average power operation came with a tube efficiency >50%. The most recent testing of these last two devices will be presented here. Design and manufacturing issues of the latest klystron, due to be tested by the Fall of 2005, are also discussed.

  17. 3-D simulations of multiple beam klystrons

    SciTech Connect

    Smithe, David N.; Bettenhausen, Mike; Ludeking, Larry; Caryotakis, G.; Sprehn, Daryl; Scheitrum, Glenn

    1999-05-07

    The MAGIC3D simulation code is being used to assess the multi-dimensional physics issues relating to the design and operation of multiple beam klystrons. Investigations, to date, include a detailed study of the mode structure of the cavities in the 19-beam hexagonally packed geometry and a study of the velocity spread caused by the cavity mode's field profile. Some attempts to minimize this effect are investigated. Additional simulations have provided quantification of the beam loading Q in a dual input cavity, and optimization of a dual output cavity. An important goal of the simulations is an accurate picture of beam transport along the length of the MBK. We have quantified the magnitude and spatial variation of the beam-line space charge interactions within a cavity gap. Present simulations have demonstrated the transport of the beam through three cavities (the present limits of our simulation size) without difficulty; additional length simulations are expected. We have also examined unbalanced beam-line scenarios, e.g., one beam-line suppressed, and find little disturbance to the transport in individual cavity tests, with results for multiple cavity transport expected.

  18. Refocusing of the spent axisymmetric beam in klystron tubes

    NASA Technical Reports Server (NTRS)

    Branch, G. M.; Neugebauer, W.

    1972-01-01

    Analytic methods were developed and employed to optimize the magnetic field transition region between the output interaction gap of a klystron and a multi-stage depressed potential electrostatic beam collector, in order to enhance the power conversion efficiency of satellite-borne broadcast transmitters. Permanent magnet structures were designed to provide the magnetic field distributions required to expand and recollimate the spent electron beam of the power amplifier klystron for proper entry into the beam collector. These design criteria for magnetic field distributions for expanding and recollimating spent-beam electrons for optimal entry into a multi-stage depressed potential collector are generally applicable to traveling-wave tubes as well as klystrons.

  19. FPGA-based Klystron linearization implementations in scope of ILC

    DOE PAGESBeta

    Omet, M.; Michizono, S.; Matsumoto, T.; Miura, T.; Qiu, F.; Chase, B.; Varghese, P.; Schlarb, H.; Branlard, J.; Cichalewski, W.

    2015-01-23

    We report the development and implementation of four FPGA-based predistortion-type klystron linearization algorithms. Klystron linearization is essential for the realization of ILC, since it is required to operate the klystrons 7% in power below their saturation. The work presented was performed in international collaborations at the Fermi National Accelerator Laboratory (FNAL), USA and the Deutsches Elektronen Synchrotron (DESY), Germany. With the newly developed algorithms, the generation of correction factors on the FPGA was improved compared to past algorithms, avoiding quantization and decreasing memory requirements. At FNAL, three algorithms were tested at the Advanced Superconducting Test Accelerator (ASTA), demonstrating a successfulmore » implementation for one algorithm and a proof of principle for two algorithms. Furthermore, the functionality of the algorithm implemented at DESY was demonstrated successfully in a simulation.« less

  20. The klystron: A microwave source of surprising range and endurance

    NASA Astrophysics Data System (ADS)

    Caryotakis, George

    1998-05-01

    This year marks the 60th anniversary of the birth of the klystron at Stanford University. The tube was the first practical source of microwaves and its invention initiated a search for increasingly more powerful sources, which continues to this day. This paper reviews the scientific uses of the klystron and outlines its operating principles. The history of the device is traced from its scientific beginnings to its role in WWII and the Cold War, its subsequent decline in use for military systems, and to its current resurgence as the key component in a major accelerator project. Finally, the paper describes the development of a modular klystron, which may someday power future accelerators at millimeter wavelengths.

  1. FPGA-based Klystron linearization implementations in scope of ILC

    SciTech Connect

    Omet, M.; Michizono, S.; Varghese, P.; Schlarb, H.; Branlard, J.; Cichalewski, W.

    2015-01-23

    We report the development and implementation of four FPGA-based predistortion-type klystron linearization algorithms. Klystron linearization is essential for the realization of ILC, since it is required to operate the klystrons 7% in power below their saturation. The work presented was performed in international collaborations at the Fermi National Accelerator Laboratory (FNAL), USA and the Deutsches Elektronen Synchrotron (DESY), Germany. With the newly developed algorithms, the generation of correction factors on the FPGA was improved compared to past algorithms, avoiding quantization and decreasing memory requirements. At FNAL, three algorithms were tested at the Advanced Superconducting Test Accelerator (ASTA), demonstrating a successful implementation for one algorithm and a proof of principle for two algorithms. Furthermore, the functionality of the algorithm implemented at DESY was demonstrated successfully in a simulation.

  2. Two-beam, Multi-mode Detuned Accelerating Structure

    SciTech Connect

    Kazakov, S. Yu.; Kuzikov, S. V.; Yakovlev, V. P.; Hirshfield, J. L.

    2009-01-22

    A two-beam accelerator structure is described having several novel features including all metal construction, no transfer structures required between the drive and accelerator channels, symmetric fields at the axes of each channel, RF micropulse widths on cavity irises that are less than half those for a conventional cavity at the same fundamental frequency by virtue of using several harmonically-related cavity modes, and a transformer ratio much greater than unity by the use of detuned cavities. Detuning is also shown to allow either parallel or anti-parallel directions for the drive and accelerated beams. A preliminary calculation for the dilution of emittance due to short-range wakes for drive beam parameters similar to those for CLIC shows this effect to be acceptably small.

  3. Experimental demonstration of dielectric structure based two beam acceleration.

    SciTech Connect

    Gai, W.; Conde, M. E.; Konecny, R.; Power, J. G.; Schoessow, P.; Sun, X.; Zou, P.

    2000-11-28

    We report on the experimental results of the dielectric based two beam accelerator (step-up transformer). By using a single high charge beam, we have generated and extracted a high power RF pulse from a 7.8 GHz primary dielectric structure and then subsequently transferred to a second accelerating structure with higher dielectric constant and smaller transverse dimensions. We have measured the energy change of a second (witness) beam passing through the acceleration stage. The measured gradient is >4 times the deceleration gradient. The detailed experiment of set-up and results of the measurements are dimmed. Future plans for the development of a 100 MeV demonstration accelerator based on this technique is presented.

  4. A Solid State Modulator for Driving SLAC 5045 Klystrons

    SciTech Connect

    Lamare, Jeffrey E

    2002-09-19

    A test is ongoing at the Stanford Linear Accelerator Center (SLAC) where a solid state induction modulator is driving a SLAC 5045 klystron. The modulator generates 22 kV, 6 kA pulses that are stepped up by a 15.1 transformer that is a part of the klystron's pulse tank. The modulator's pulse duration is adjustable up to the volt-second limit of its cores, and it is capable of a pulse repetition frequency up to 120 Hz. The modulator's design, construction, and experimental results are the focus of this paper.

  5. High Power Klystrons: Theory and Practice at the Stanford Linear Accelerator CenterPart I

    SciTech Connect

    Caryotakis, G.

    2004-12-15

    This is Part I of a two-part report on design and manufacturing methods used at SLAC to produce accelerator klystrons. Chapter 1 begins with the history and applications for klystrons, in both of which Stanford University was extensively involved. The remaining chapters review the theory of klystron operation, derive the principal formulae used in their design, and discuss the assumptions that they involve. These formulae are subsequently used in small-signal calculations of the frequency response of a particular klystron, whose performance is also simulated by two different computer codes. The results of calculations and simulations are compared to the actual performance of the klystron.

  6. Amended proposal for R&D on a cluster klystron

    SciTech Connect

    Fernow, R.C.; Fischer, J.; Gallardo, J.C.; Kirk, H.G.; Ko, S.K.; Palmer, R.B.; Ulc, S.; Wang, H.

    1993-01-01

    This Proposal is an updated version of FWP submitted in March 1992. Significant work has been done since the original proposal, and much of this is reported on in this update. In addition there have been several changes made, some in response to suggestions made by the three reviews sent to us in December, 1992. The new information and changes include: Technical information on the proposed design of the magnetron gun, the magnet, acceleration gap, and electrical system (including a comment on efficiency loss due to high-voltage leakage current). Modification of the phase I and II tests to allow operation of the gun and klystron off the axis of the magnet, thus simulating the magnet situation when multiple beams are used. Modification of phases III and IV to test a cluster of three beams: first a three beam gun, and then three beams with a klystron on one of them. We have added a phase V which would be the testing of a full three-beam demonstration klystron. The mod-anode pulser would now be located on the high voltage deck instead of externally. Power for the pulser and other high voltage components would now be provided by an isolation transformer instead of from a lead battery. We believe these changes have improved the proposed program and thank the reviewers for their constructive suggestions. The design is still evolving. Relatively little work has been done on the detailed klystron design, and none on the beam dump.

  7. Klystron based high power rf system for proton accelerator

    SciTech Connect

    Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Patel, Niranjan; Handu, Verander E-mail: manjiri08@gmail.com

    2011-07-01

    As a part of ADS program a proton accelerator (20 MeV, 30 mA) and its high power RF systems (HPRF) are being developed in BARC. This paper explains design details of this klystron based HPRF system. (author)

  8. Intracavity Single Lens for Focusing of a Klystron Electron Beam

    NASA Astrophysics Data System (ADS)

    Daumenov, T. D.; Khizirova, M. A.

    2016-05-01

    The possibility of application of a single lens for focusing in the vertical direction of an electron flux in superhigh frequency klystron-type devices is shown. This problem is considered in the first approximation by solving a differential equation for the trajectory of particles moving in an electrostatic field with rotational symmetry.

  9. Pulsed klystrons with feedback controlled mod-anode modulators

    SciTech Connect

    Reass, William A; Baca, David M; Jerry, Davis L; Rees, Daniel E

    2009-01-01

    This paper describes a fast rise and fall, totem-pole mod-anode modulators for klystron application. Details of these systems as recently installed utilizing a beam switch tube ''on-deck'' and a planar triode ''off-deck'' in a grid-catch feedback regulated configuration will be provided. The grid-catch configuration regulates the klystron mod-anode voltage at a specified set-point during switching as well as providing a control mechanism that flat-top regulates the klystron beam current during the pulse. This flat-topped klystron beam current is maintained while the capacitor bank droops. In addition, we will review more modern on-deck designs using a high gain, high voltage planar triode as a regulating and switching element. These designs are being developed, tested, and implemented for the Los Alamos Neutron Science Center (LANSCE) accelerator refurbishment project, ''LANSCE-R''. An advantage of the planar triode is that the tube can be directly operated with solid state linear components and provides for a very compact design. The tubes are inexpensive compared to stacked semiconductor switching assemblies and also provide a linear control capability. Details of these designs are provided as well as operational and developmental results.

  10. Inverse Marx modulators for self-biasing klystron depressed collectors

    SciTech Connect

    Kemp, Mark A.

    2014-07-31

    A novel pulsed depressed collector biasing scheme is proposed. This topology feeds forward energy recovered during one RF pulse for use on the following RF pulse. The presented ''inverse'' Marx charges biasing capacitors in series, and discharges them in parallel. Simulations are shown along with experimental demonstration on a 62kW klystron.

  11. 72. View of test system showing Klystron tube installed in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. View of test system showing Klystron tube installed in test position on first floor of transmitter building no. 102. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  12. 65. Building 102, view of Klystron tube in amplifier housing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    65. Building 102, view of Klystron tube in amplifier housing showing top of tube connecting conductors. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  13. 64. Building 102, view of Klystron tube amplifier housing with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    64. Building 102, view of Klystron tube amplifier housing with tube removed and showing waveguide entrances at top of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  14. AN INVESTIGATION OF THE BEAM MONITOR FOR THE CLUSTER KLYSTRON.

    SciTech Connect

    ZHAO,Y.

    2001-08-21

    The cluster klystron project required a beam monitor to check the quality of the hollow beam shape. Since the power density of the beam is very large, a common phosphorescent screen doesn't work. We investigated varies types of monitors. The related problems were also discussed.

  15. 63. View of Klystron tube cutaway exhibit located at mezzanine ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. View of Klystron tube cut-away exhibit located at mezzanine level transmitter building no. 102, directly above RF power generation systems located on first floor. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  16. A Gridded Electron Gun for a Sheet Beam Klystron

    SciTech Connect

    Read, M.E.; Miram, G.; Ives, R.L.; Ivanov, V.; Krasnykh, A.; /SLAC

    2008-04-25

    This paper describes the development of an electron gun for a sheet beam klystron. Initially intended for accelerator applications, the gun can operate at a higher perveance than one with a cylindrically symmetric beam. Results of 2D and 3D simulations are discussed.

  17. Klystron Linearizer for Use with 1.2 MW 476 MHz Klystrons in PEP-II RF Systems

    SciTech Connect

    Fox, J.; Mastorides, T.; Teytelman, D.; Van Winkle, D.; Zhou, Y.; Gallo, A.; /Frascati

    2005-06-15

    The direct and comb loop feedback around the RF cavities in PEP-II is critical in reducing longitudinal instabilities driven by the cavity impedance. The non-linear 1.2 MW klystron is in the signal path for these feedback loops. As a result, the effective small-signal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power amplifier. A klystron linearizer circuit has been developed which operates in series with the power amplifier and acts to equalize the small and large signal gains through the combination. The technique must implement a 1 MHz linear control bandwidth over roughly 15 dB of RF signal level variation. The dynamics of this system is operating point dependent, and the channel must have dynamic gain compensation to keep the linearity compensation loop stable over changes in operating point. The design of this non-linear signal processing channel (incorporating RF and DSP techniques) and measured results from full-power klystron testing are presented.

  18. Design for a One-Gigawatt, Annular-Beam Klystron

    SciTech Connect

    Arfin, Bernard

    2001-01-23

    A one-gigawatt, annular beam klystron (ABK) is being developed by Los Alamos National Laboratory in collaboration with the Stanford Linear Accelerator Center (SLAC). The pulse length is 1 {micro}s, the pulse repetition frequency is 5 Hz, and the operating frequency is 1.3 GHz. The beam voltage and current are 800 kV and 4 kA. Since the electron beam parameters are considerably beyond the state-of the-art, an aggressive cathode and electron gun design is required. The magnetron injection gun (MIG) configuration was chosen over the standard Pierce geometry that is typically used in klystrons. The tube design, design issues, and status are presented.

  19. NLC Reliability Analysis Notes: Klystron-Modulator System (LCC-0029)

    SciTech Connect

    Wilson, Z.

    2004-03-23

    This paper address the reliability and availability issues to be faced in deploying and operating the klystron modulator assemblies proposed for the Next Linear Collider (NLC). The rf power sources are a major system of the NLC and require a high uptime in order to reach the goal of 0.85 availability. Since the NLC is made up of several systems, not just klystron-modulator assemblies, the availability goal for the assemblies must be higher than 0.85. Currently this goal is at least 0.95. This short paper summarizes the analysis currently under way to determine whether the design of the rf power system will meet the design availability goal.

  20. Development and Production of a 201 MHz, 5.0 MW Peak Power Klystron

    SciTech Connect

    Aymar, Galen; Eisen, Edward; Stockwell, Brad; Begum, rasheda; Lenci, Steve; Eisner, Rick; Cesca, Eugene

    2016-01-01

    Communications & Power Industries LLC has designed and manufactured the VKP-8201A, a high peak power, high gain, VHF band klystron. The klystron operates at 201.25 MHz, with 5.0 MW peak output power, 34 kW average output power, and a gain of 36 dB. The klystron is designed to operate between 1.0 MW and 4.5 MW in the linear range of the transfer curve. The klystron utilizes a unique magnetic field which enables the use of a proven electron gun design with a larger electron beam requirement. Experimental and predicted performance data are compared.

  1. Periodic permanent magnet development for linear collider X-band klystrons

    SciTech Connect

    Sprehn, D.; Caryotakis, G.; Jongewaard, E.; Phillips, R.

    1999-05-01

    The Stanford Linear Accelerator Center (SLAC) klystron group is currently designing, fabricating and testing 11.424 GHz klystrons with peak output powers from 50 to 75 MW at 1 to 2 {mu}s rf pulsewidths as part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). In order to eliminate the projected operational-year energy bill for klystron solenoids, Periodic Permanent Magnet (PPM) focusing has been employed on our latest X-band klystron designs. A PPM beam tester has operated at the same repetition rate, voltage and average beam power required for a 75-MW NLC klystron. Prototype 50 and 75-MW PPM klystrons were built and tested during 1996 and 1997 which operate from 50 to 70 MW at efficiencies greater than 55{percent}. Construction and testing of 75-MW research klystrons will continue while the design and reliability is perfected. This paper will discuss the design of these PPM klystrons and the results of testing to date along with future plans for the development of a low-cost Design for Manufacture (DFM) 75-MW klystron and invitation for industry participation. {copyright} {ital 1999 American Institute of Physics.}

  2. Periodic permanent magnet development for linear collider X-band klystrons

    SciTech Connect

    Sprehn, D.; Caryotakis, G.; Jongewaard, E.; Phillips, R.

    1999-05-07

    The Stanford Linear Accelerator Center (SLAC) klystron group is currently designing, fabricating and testing 11.424 GHz klystrons with peak output powers from 50 to 75 MW at 1 to 2 {mu}s rf pulsewidths as part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). In order to eliminate the projected operational-year energy bill for klystron solenoids, Periodic Permanent Magnet (PPM) focusing has been employed on our latest X-band klystron designs. A PPM beam tester has operated at the same repetition rate, voltage and average beam power required for a 75-MW NLC klystron. Prototype 50 and 75-MW PPM klystrons were built and tested during 1996 and 1997 which operate from 50 to 70 MW at efficiencies greater than 55%. Construction and testing of 75-MW research klystrons will continue while the design and reliability is perfected. This paper will discuss the design of these PPM klystrons and the results of testing to date along with future plans for the development of a low-cost Design for Manufacture (DFM) 75-MW klystron and invitation for industry participation.

  3. Design of a Ku band miniature multiple beam klystron

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Ayan Kumar; Pal, Debasish; Saini, Anil; Kant, Deepender; Saha, Sukalyan; Joshi, Lalit Mohan

    2016-03-01

    The design of a miniature multiple beam klystron (MBK) working in the Ku-band frequency range is presented in this article. Starting from the main design parameters, design of the electron gun, the input and output couplers and radio frequency section (RF-section) are presented. The design methodology using state of the art commercial electromagnetic design tools, analytical formulae as well as noncommercial design tools are briefly presented in this article.

  4. Advanced Klystrons for High Efficiency Accelerator Systems - Final Report

    SciTech Connect

    Read, Michael; Ives, Robert Lawrence

    2014-03-26

    This program explored tailoring of RF pulses used to drive accelerator cavities. Simulations indicated that properly shaping the pulse risetime to match accelerator cavity characteristics reduced reflected power and increased total efficiency. Tailoring the pulse requires a high power, gridded, klystron to shape the risetime while also controlling the beam current. The Phase I program generated a preliminary design of a gridded electron gun for a klystron producing 5-10 MW of RF power. This required design of a segmented cathode using Controlled Porosity Reservoir cathodes to limit power deposition on the grid. The program was successful in computationally designing a gun producing a high quality electron beam with grid control. Additional analysis of pulse tailoring indicated that technique would only be useful for cavity drive pulses that were less than approximately 2-3 times the risetime. Otherwise, the efficiency gained during the risetime of the pulse became insignificant when considering the efficiency over the entire pulse. Consequently, it was determined that a Phase II program would not provide sufficient return to justify the cost. Never the less, other applications for a high power gridded gun are currently being pursued. This klystron, for example, would facilitate development inverse Comptom x-ray sources by providing a high repetition rate (10 -100 kHz) RF source.

  5. Klystron Cluster Scheme for ILC High Power RF Distribution

    SciTech Connect

    Nantista, Christopher; Adolphsen, Chris; /SLAC

    2009-07-06

    We present a concept for powering the main linacs of the International Linear Collider (ILC) by delivering high power RF from the surface via overmoded, low-loss waveguides at widely spaced intervals. The baseline design employs a two-tunnel layout, with klystrons and modulators evenly distributed along a service tunnel running parallel to the accelerator tunnel. This new idea eliminates the need for the service tunnel. It also brings most of the warm heat load to the surface, dramatically reducing the tunnel water cooling and HVAC requirements. In the envisioned configuration, groups of 70 klystrons and modulators are clustered in surface buildings every 2.5 km. Their outputs are combined into two half-meter diameter circular TE{sub 01} mode evacuated waveguides. These are directed via special bends through a deep shaft and along the tunnel, one upstream and one downstream. Each feeds approximately 1.25 km of linac with power tapped off in 10 MW portions at 38 m intervals. The power is extracted through a novel coaxial tap-off (CTO), after which the local distribution is as it would be from a klystron. The tap-off design is also employed in reverse for the initial combining.

  6. Relativistic diffusion

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  7. Relativistic diffusion.

    PubMed

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed. PMID:19391727

  8. Charge density harmonics generation in free-electron relativistic parametric devices.

    PubMed

    Baccaro, S; Demartini, F; Ghigo, A

    1982-04-01

    A single-particle theory of the evolution of the harmonic content of a bunched beam in a relativistic optical klystron is reported. The equations of motion of the electrons in the dispersive-magnetic-drift space are solved analytically, including the effects of the energy and angular spreads of the beam. The theory enables one to predict the optical efficiency of a coherent relativistic scatterer designed for the generation of the third harmonics of the charge density wave (lambda(sc) = 1766 A) induced on the electron beam of the Frascati storage ring, Adone, with gamma = 1200. PMID:19710862

  9. Design and Operation of a 100 kW CW X-band Klystron for Spacecraft Communications

    NASA Technical Reports Server (NTRS)

    Balkcum, Adam; Mizuhara, Al; Stockwell, Brad; Begum, Rasheda; Cox, Lydia; Forrest, Scott; Perrin, Mark; Zitelli, Lou; Hoppe, Dan; Britcliffe, Mike; Vodonos, Yakov; Liou, R. Roland; Stone, Ernest

    2012-01-01

    A 7.19 GHz klystron producing 100 kW CW of output power over 90 MHz of bandwidth has been designed and three klystrons manufactured for use in a new JPL/NASA transmitter for spacecraft communications. The klystron was fully characterized including its phase pushing figures.

  10. SPALLATION NEUTRON SOURCE SUPERCONDUCTING LINAC KLYSTRON TO CAVITY MISMATCH EFFECTS AND COMPENSATION*

    SciTech Connect

    McCarthy, Mike; Kim, Sang-Ho; Crofford, Mark T

    2009-01-01

    Abstract Observations of several of the 81 klystron output waveforms into their respective superconducting cavities do not correspond with their rectangular klystron inputs in open loop mode. This can't be completely explained by a drooping high voltage power supply especially when the waveform is parabolic. Some possible causes and effects of these anomalies are presented.

  11. Analysis of optical klystron wave guide free electron laser with betatron oscillation effects

    NASA Astrophysics Data System (ADS)

    Jain, Deepi; Mishra, G.

    2014-12-01

    In this paper, we analyze the effect of the betatron oscillation on spontaneous emission and gain spectrum of an optical klystron wave guide free electron laser. The analysis also includes the effects of length mismatch of the two undulator sections of the klystron configuration. We observe that intensity and gain can be change with length mismatch parameter without changing the central emission frequency.

  12. S-Band Waveguide Reconfiguration Options for the LCLS RF Gun and L0 Klystron Feeds

    SciTech Connect

    McIntosh, P.

    2005-01-28

    This note highlights the possible re-configuration options for the existing WR284 S-band waveguide in the klystron gallery, to enable those existing 5045 klystrons to power the RF Gun and the L0 accelerating structures for LCLS. A reconfiguration decision based on the pros and cons for each option is subsequently identified.

  13. SLAC 5045 klystron technical specification SC-700-866-45-R3 (Engineering Materials)

    SciTech Connect

    Not Available

    1984-05-09

    The purpose of this specification is to define the performance characteristics of improved klystrons for operation at the Stanford Linear Accelerator Center. Each klystron shall be capable of supplying 50 megawatts peak, 45 kilowatts average rf power at 2856 Megahertz. It is expected that over the next few years, existing SLAC klystrons will be replaced by the improved klystrons covered by this specification. It is desirable that the klystrons covered by this specification be usable with magnets designed by SLAC under specification No. SC-700-866-46. Recently SLAC has been able to achieve a klystron efficiency in excess of 45% and design information of tubes which have exhibited this efficiency is available. It must be emphasized that one of the most important features of tubes designed to operate to these specifications must be long life. The overall economy of the SLAC linear accelerator program is strongly influenced by klystron life and it is expected that the design of this tube can lead to a minimum operating life equal to that experienced with the older klystrons. In order to increase the probability of long life, SLAC expects to operate the tubes conservatively at 315 kV beam voltage which is approximately 5 kV below the maximum allowed by the specifications. However, it is expected that from time to time, as required by physics experiments, the tubes will be operated at the maximum power allowed.

  14. The 5K70SK automatically tuned, high power, S-band klystron

    NASA Technical Reports Server (NTRS)

    Goldfinger, A.

    1977-01-01

    Primary objectives include delivery of 44 5K70SK klystron amplifier tubes and 26 remote tuner assemblies with spare parts kits. Results of a reliability demonstration on a klystron test cavity are discussed, along with reliability tests performed on a remote tuning unit. Production problems and one design modification are reported and discussed. Results of PAT and DVT are included.

  15. X-Band Multi-Beam Klystron Design and Progress Report

    SciTech Connect

    Jensen, Aaron; Neilson, Jeff; Tantawi, Sami

    2015-04-15

    Progress on the development of a 5MW 16 beam x-band multi-beam klystron is presented. The power from each of the 16 klystrons is combined using a matched waveguide network. Mechanical and electric models and simulations are discussed. The status of procuring and assembling parts is presented.

  16. A 12 GHZ 50 MW Klystron for Support of Accelerator Research

    SciTech Connect

    Sprehn, Daryl; Haase, Andrew; Jensen, Aaron; Jongewaard, Erik; Nantista, Christopher; Vlieks, Arnold; /SLAC

    2011-05-31

    A 12 GHz 50MW X-band klystron is under development at the SLAC National Accelerator Laboratory Klystron Department. The klystron will be fabricated to support programs currently underway at three European Labs; CERN, PSI, and INFN Trieste. The choice of frequency selection was due to the CLIC RF frequency changing from 30 GHz to the European X-band frequency of 11.99 GHz in 2008. Since the Klystron Department currently builds 50MW klystrons at 11.424 GHz known collectively as the XL4 klystrons, it was deemed cost-effective to utilize many XL4 components by leaving the gun, electron beam transport, solenoid magnet and collector unchanged. To realize the rf parameters required, the rf cavities and rf output hardware were necessarily altered. Some improvements to the rf design have been made to reduce operating gradients and increase reliability. Changes in the multi-cell output structure, waveguide components, and the window will be discussed along with testing of the devices. Five klystrons known as XL5 klystrons are scheduled for production over the next two years.

  17. Improvements in X-band transmitter phase stability through Klystron body temperature regulation

    NASA Technical Reports Server (NTRS)

    Perez, R. M.

    1992-01-01

    This article describes the techniques used and experimental results obtained in improving transmitter stability by control of the klystron body temperature. Related work in the measurement of klystron phase control parameters (pushing factors) is also discussed. The contribution of wave guide temperature excursions to uplink phase stability is presented. Suggestions are made as to the direction of future work in this area.

  18. Improvements in X-band transmitter phase stability through klystron body temperature regulation

    NASA Technical Reports Server (NTRS)

    Perez, R. M.

    1992-01-01

    This article describes the techniques used and experimental results obtained in improving transmitter stability by control of the klystron body temperature. Related work in the measurement of klystron phase control parameters (pushing factors) is also discussed. The contribution of waveguide temperature excursions to uplink phase stability is presented. Suggestions are made as to the direction of future work in this area.

  19. Simulation of conditions for the maximal efficiency of decimeter-wave klystrons

    NASA Astrophysics Data System (ADS)

    Baikov, A. Yu.; Grushina, O. A.; Strikhanov, M. N.

    2014-03-01

    Using the mathematical model of electron beam transformation in a narrow tube developed by the authors and the KlypWin program suite, conditions for the maximal efficiency of decimeter-wave klystrons having from three to six amplification stages are simulated. Simulation is based on a real electron-optical system and real parameters of the cavities. It is shown that the maximal efficiency (across the load) is 83% for a four-cavity klystron, 86% for a five-cavity klystron, 88% for a six-cavity klystron, and 90% for a seven-cavity one. The electronic efficiency of the simulated seven-cavity klystron equals 94%, which implies the achievement of a global extremum.

  20. The 250-kW CW klystron amplifier for planetary radar

    NASA Technical Reports Server (NTRS)

    Cormier, R.; Mizuhara, A.

    1992-01-01

    The design, construction, and performance testing is described of two Varian klystrons, model VKX-7864A, which replaced the aging and less efficient VA-949J klystrons in the X band planetary radar transmitter on the Goldstone, CA, 70 meter antenna. The project was carried out jointly by the JPL and Varian Assoc. Output power was increased from 200 to 250 kW continuous wave per klystron, and full dc beam power is dissipated in the collector (it was not possible to operate the VA-949J klystrons without RF drive because of limited collector dissipation capability). Replacements were made with a minimum of transmitter modifications. The planetary radar transmitter is now operating successfully with these two klystrons.

  1. Development of a 10 MW Sheet Beam Klystron for the ILC

    SciTech Connect

    Sprehn, D.; Jongewaard, E.; Haase, A.; Jensen, A.; Martin, D.; Burke, A.; /SAIC, Sunnyvale

    2009-05-07

    SLAC is developing a 10 MW, 5 Hz, 1.6 ms, L-band (1.3 GHz) Sheet-Beam Klystron as a less expensive and more compact alternative to the ILC baseline Multiple-Beam Klystron. The Klystron is intended as a plug-compatible device of the same beam current and operating voltage as existing Multiple-Beam Klystrons. At this time, a beam tester has been constructed and currently is in test. The beam tester includes an intercepting cup for making beam quality measurements of the 130 A, 40-to-1 aspect ratio beam. Measurements will be made of the electrostatic beam and of the beam after transporting through a drift tube and magnetic focusing system. General theory of operation, design trade-offs, and manufacturing considerations of both the beam tester and klystron will be discussed.

  2. Development of a 10 kW, 2.815 GHz Klystron

    SciTech Connect

    Ives, Robert Lawrence; Read, Michael; Patrick, Ferguson

    2015-05-15

    Development of a Periodic Permanent Magnet (PPM) focused klystron is described. The klystron was designed to produce 10 kW CW at 2.815 GHz. The program developed an innovative PPM circuit that provided extremely uniform magnetic fields at the electron beam location while providing unprecedented access to the RF circuit for tuners and water cooling. Simulations indicated the klystron would produce more than 11 kW with an efficiency exceeding 65%. Problems with the mechanical design prevented successful testing of the initial prototype; however, a new design was successfully developed and implemented in a 6 MW klystron developed in a follow-on program. Funding is being pursued to rebuild the 10 kW RF circuit and complete the klystron development.

  3. Study program for design improvements of the X-3060 klystron. Phase 3: Electron gun fabrication and beam analyzer evaluation. Phase 4: Klystron prototype fabrication and testing

    NASA Technical Reports Server (NTRS)

    Goldfinger, A.

    1981-01-01

    A full scale model was produced to verify suggested design changes. Through beam analyzer study, the correct electron beam diameter and cross sectional profile were established in conjunction with the desired confining magnetic field. Comparative data on the performance of the X-3060 klystron, design predictions for the improved klystron, and performance data taken during acceptance testing of the prototype VKS-8274 JPL are presented.

  4. Relativistic geodesy

    NASA Astrophysics Data System (ADS)

    Flury, J.

    2016-06-01

    Quantum metrology enables new applications in geodesy, including relativistic geodesy. The recent progress in optical atomic clocks and in long-distance frequency transfer by optical fiber together pave the way for using measurements of the gravitational frequency redshift for geodesy. The remote comparison of frequencies generated by calibrated clocks will allow for a purely relativistic determination of differences in gravitational potential and height between stations on Earth surface (chronometric leveling). The long-term perspective is to tie potential and height differences to atomic standards in order to overcome the weaknesses and inhomogeneity of height systems determined by classical spirit leveling. Complementarily, gravity measurements with atom interferometric setups, and satellite gravimetry with space borne laser interferometers allow for new sensitivities in the measurement of the Earth's gravity field.

  5. Relativistic Astrophysics

    NASA Astrophysics Data System (ADS)

    Jones, Bernard J. T.; Markovic, Dragoljub

    1997-06-01

    Preface; Prologue: Conference overview Bernard Carr; Part I. The Universe At Large and Very Large Redshifts: 2. The size and age of the Universe Gustav A. Tammann; 3. Active galaxies at large redshifts Malcolm S. Longair; 4. Observational cosmology with the cosmic microwave background George F. Smoot; 5. Future prospects in measuring the CMB power spectrum Philip M. Lubin; 6. Inflationary cosmology Michael S. Turner; 7. The signature of the Universe Bernard J. T. Jones; 8. Theory of large-scale structure Sergei F. Shandarin; 9. The origin of matter in the universe Lev A. Kofman; 10. New guises for cold-dark matter suspects Edward W. Kolb; Part II. Physics and Astrophysics Of Relativistic Compact Objects: 11. On the unification of gravitational and inertial forces Donald Lynden-Bell; 12. Internal structure of astrophysical black holes Werner Israel; 13. Black hole entropy: external facade and internal reality Valery Frolov; 14. Accretion disks around black holes Marek A. Abramowicz; 15. Black hole X-ray transients J. Craig Wheeler; 16. X-rays and gamma rays from active galactic nuclei Roland Svensson; 17. Gamma-ray bursts: a challenge to relativistic astrophysics Martin Rees; 18. Probing black holes and other exotic objects with gravitational waves Kip Thorne; Epilogue: the past and future of relativistic astrophysics Igor D. Novikov; I. D. Novikov's scientific papers and books.

  6. Preliminary performance of the MKII 17 GHz traveling wave relativistic klystron

    SciTech Connect

    Haimson, J.; Mecklenburg, B.; Stowell, G.; Kreischer, K.E.; Mastovsky, I.

    1999-05-01

    Initial test results are presented of an upgraded RF source developed for high peak power 17 GHz linear accelerator applications. The objectives of this upgrade program were (a) to increase the output capability of the existing vacuum demountable prototype tube so that RF power could also be supplied to a future 2 MeV photoinjector system without appreciable loss of input power to the 17 GHz linac and (b) to investigate the performance of a new design traveling wave output circuit incorporating a racetrack shaped dual output coupler with 5{percent} bandwidth high peak power ceramic RF windows. These recently installed devices are presently being conditioned and tested at the MIT Plasma Science and Fusion Center. {copyright} {ital 1999 American Institute of Physics.}

  7. Preliminary performance of the MKII 17 GHz traveling wave relativistic klystron

    SciTech Connect

    Haimson, J.; Mecklenburg, B.; Stowell, G.; Kreischer, K. E.; Mastovsky, I.

    1999-05-07

    Initial test results are presented of an upgraded RF source developed for high peak power 17 GHz linear accelerator applications. The objectives of this upgrade program were (a) to increase the output capability of the existing vacuum demountable prototype tube so that RF power could also be supplied to a future 2 MeV photoinjector system without appreciable loss of input power to the 17 GHz linac and (b) to investigate the performance of a new design traveling wave output circuit incorporating a racetrack shaped dual output coupler with 5% bandwidth high peak power ceramic RF windows. These recently installed devices are presently being conditioned and tested at the MIT Plasma Science and Fusion Center.

  8. High-Q toroidal cavities for high frequency klystrons.

    NASA Technical Reports Server (NTRS)

    Branch, G. M.

    1972-01-01

    A toroidal cavity developed for a 4-KW 12 GHz satellite-borne television transmitter klystron is described. The cavity has an internal Q 40% higher than that of a conventional cylindrical doubly reentrant cavity, thus yielding higher circuit efficiency and conserving energy which cannot be recovered in multistage depressed potential beam collectors. As a result of optimization studies with a digital computer program for obtaining cavity field distributions by a relaxation method and for computing the intrinsic cavity parameters, a particular cavity configuration with conical reentrant tunnel tips and toroidal walls is shown to provide good thermal characteristics and mechanical rigidity as well as low internal losses.

  9. A Gridded Electron Gun for a Sheet Beam Klystron

    NASA Astrophysics Data System (ADS)

    Read, M. E.; Miram, G.; Ives, R. L.; Ivanov, V.; Krasnykh, A.

    2003-12-01

    Calabazas Creek Research, Inc.(CCR) is developing rectangular, gridded, thermionic, dispenser-cathode guns for sheet beam devices. The first application is expected to be klystrons for advanced particle accelerators and colliders. The current generation of accelerators typically use klystrons with a cylindrical beam generated by a Pierce-type electron gun. As RF power is pushed to higher levels, space charge forces in the electron beam limit the amount of current that can be transmitted at a given voltage. The options are to increase the beam voltage, leading to problems with X-Ray shielding and modulator and power supply design, or to develop new techniques for lowering the space charge forces in the electron beam. In this device, the beam has a rectangular cross section. The thickness is constrained as it would in a normal, cylindrically symmetric klystron with a Pierce gun. However, the width of the beam is many times the thickness, and the resulting cross sectional area is much larger than in the conventional device. This allows much higher current and/or a lower voltage before space charge forces become too high. The current program addresses issues related to beam formation at the emitter surface, design and implementation of shadow and control grids in a rectangular geometry. It is directed toward a robust, cost-effective, and reliable mechanical design. A prototype device will be developed that will operate at 415 kV, 250 A for an 80 MW, X-Band, sheet-beam klystron. The cathode will have 100 cm2 of cathode area with an average cathode current loading of 2.5 A/cm2. For short pulse formation, the use of a grid was chosen. The gun has been designed with a combination of 2-D and 3-D codes. 2-D codes were used to determine the starting point for the electrodes to produce the compression (which is in only 1 direction.) These results showed that a very high quality beam could be achieved even in the presence of the shadow grid. 3-D results have shown that the

  10. Theoretical and experimental research on multi-beam klystron

    SciTech Connect

    Ding Yaogen; Peng Jun; Zhu Yunshu; Shi Shaoming

    1999-05-07

    Theoretical and experimental research work on multi-beam klystron (MBK) conducted in Institute of Electronics, Chinese Academy of Sciences (IECAS) is described in this paper. Research progress on Interaction between multi-electron beam and microwave electric field, multi-beam cavity, filter loaded double gap cavity broadband output circuit, multi-beam electron gun, and periodic reversal focusing system is presented. Performance and measurement results of five types of MBK are also given out. The key technical problems for present MBK are discussed in this paper.

  11. A Sheet-Beam Klystron Paper Design Development of a Sheet-Beam Klystron for the NLC

    SciTech Connect

    Caryotakis, G

    2004-03-25

    What may be the first detailed cold test and computer simulation analysis of a Double Sheet Beam Klystron (DSBK) was performed at SLAC. The device was conceptually designed mechanically, and evaluated electrically for beam formation, gain, stability and efficiency. It is believed that the DSBK can be built at a relatively low cost for a future NLC collider and can produce at least 150 MW at 11.4 GHz with PPM focusing. Voltage and current are 450 kV and 640 A, respectively.

  12. Towards intense attosecond pulses: using two beams for high order harmonic generation from solid targets

    NASA Astrophysics Data System (ADS)

    Tarasevitch, A. P.; Kohn, R.; von der Linde, D.

    2009-07-01

    The advantages of using two beam high order harmonic generation (HOHG) from solids are discussed. The two-pulse technique allows additional control of the parameters essential for the attosecond pulse generation. We show that spectral filtering is not necessary for the generation of attosecond pulses. The simple oscillating mirror model is in qualitative agreement with the computer simulations. We present the results of first experiments using two beams for HOHG.

  13. Low Beam Voltage, 10 MW, L-Band Cluster Klystron

    SciTech Connect

    Teryaev, V.; Yakovlev, V.P.; Kazakov, S.; Hirshfield, J.L.; /Yale U. /Omega-P, New Haven

    2009-05-01

    Conceptual design of a multi-beam klystron (MBK) for possible ILC and Project X applications is presented. The chief distinction between this MBK design and existing 10-MW MBK's is the low operating voltage of 60 kV. There are at least four compelling reasons that justify development at this time of a low-voltage MBK, namely (1) no pulse transformer; (2) no oil tank for high-voltage components and for the tube socket; (3) no high-voltage cables; and (4) modulator would be a compact 60-kV IGBT switching circuit. The proposed klystron consists of four clusters containing six beams each. The tube has common input and output cavities for all 24 beams, and individual gain cavities for each cluster. A closely related optional configuration, also for a 10 MW tube, would involve four totally independent cavity clusters with four independent input cavities and four 2.5 MW output ports, all within a common magnetic circuit. This option has appeal because the output waveguides would not require a controlled atmosphere, and because it would be easier to achieve phase and amplitude stability as required in individual SC accelerator cavities.

  14. Fifty megawatt klystron for the Stanford Linear Collider

    SciTech Connect

    Lee, T.G.; Lebacqz, J.V.; Konrad, G.T.

    1983-09-01

    The proposed Stanford Linear Collider (SLC) has been designed to provide 50 on 50 GeV electron-positron collisions. The performance of the 240 klystrons driving the two-mile long linac must be upgraded to achieve at least 50 Megawatts of peak power output at a pulse of 5 ..mu..sec and a pulse repetition frequency of 180 pulses per second. The operating frequency of the upgraded linac will continue to be 2856 MHz. A klystron amplifier meeting these new requirements has been designed to operate at 315 kV, ..mu..k = 2, with a computed efficiency of slightly greater than 50%. Initial tests indicate the achievement of the basic power objectives; however, observed parasitic instabilities make beam focusing, RF drive frequency and drive level extremely critical. High electric fields in the electron gun, output gap and output window are all potential problems. Steps taken in the design to overcome these problems are discussed and test results are presented.

  15. Investigation of a 94 GHz Pseudospark-Sourced Klystron

    NASA Astrophysics Data System (ADS)

    Bowes, David; Yin, Huabi; Cross, Adrian; He, Wenlong; Phelps, Alan; Ronald, Kevin; Chen, Xiaodong; Li, Daohui

    2010-11-01

    Work is ongoing at the University of Strathclyde to design, construct and test a klystron amplifier with an operating frequency of 94 GHz using a pseudospark discharge beam source. A pseudospark is a form of low-pressure, high-current discharge which produces an electron beam possessing high brightness and self-focusing properties during the final stages of the discharge. Single-gap pseudospark experiments were performed in order to assess the feasibility of scaling down in size previous work carried out at the University of Strathclyde. Using 1mm cathode and anode apertures with 3mm separation, a 10kV voltage applied at a pressure of 100mTorr resulted in a 4 A beam current, which compares favourably with previous discharges. A 3-cavity 94 GHz klystron has been simulated with the particle-in-cell code MAGIC-2D with pulsed voltage and current inputs in keeping with possible pseudospark discharge traces. Efficiency and gain were simulated at 7.38% and 16.5 dB respectively.

  16. A unique power supply for the PEP II klystron at SLAC

    SciTech Connect

    Cassel, R.; Nguyen, M.N.

    1997-07-01

    Each of the eight 1.2 MW RF klystrons for the PEP-II storage rings require a 2.5 MVA DC power supply of 83 Kv at 23 amps. The design for the supply was base on three factors, low cost, small size to fit existing substation pads, and good protection against damage to the klystron including klystron gun arcs. The supply uses a 12 pulse 12.5 KV primary thyristor star point controller with primary filter inductor to provide rapid voltage control, good voltage regulation, and fast turn off during klystron tube faults. The supply also uses a unique secondary rectifier, filter capacitor configuration to minimize the energy available under a klystron fault. The voltage control is from 0--90 KV with a regulation of < 0.1% and voltage ripple of < 1% P-P, (< 0.2% RMS) above 60 KV. The supply utilizes a thyristor crowbar, which under a klystron tube arc limits the energy in the klystron arc to < 5 joules. If the thyristor crowbar is disabled the energy supplied is < 40 joules into the arc. The size of the supply was reduced small enough to fit the existing PEP transformer yard pads. The cost of the power supply was < $140 per KVA.

  17. Spectral modulation of higher harmonic spontaneous emission from an optical klystron.

    PubMed

    Sei, Norihiro; Ogawa, Hiroshi; Yamada, Kawakatsu; Koike, Masaki; Ohgaki, Hideaki

    2014-07-01

    Higher harmonics of spontaneous emission from an optical klystron have been observed. The modulation factor of the spontaneous emission spectrum for the higher harmonics can be described by considering the observation system. When the dispersive gap of the optical klystron was fixed, the microstructure interval of the spontaneous emission spectrum at a certain resonant wavelength became narrower as the order of the higher harmonic became larger. Some unique characteristics of the higher harmonics have been clarified, and these studies are likely to contribute to the development of free-electron lasers using higher harmonics of an optical klystron in the shorter-wavelengths region. PMID:24971958

  18. Generation of dissipative temporal solitons in ring self-oscillating systems with amplifier klystrons

    NASA Astrophysics Data System (ADS)

    Grishin, S. V.; Dmitriev, B. S.; Skorokhodov, V. N.; Sharaevskii, Yu. P.

    2015-09-01

    Theoretical and experimental results are presented that show the possibility of forming periodic pulsed signal sequences with a profile similar to that of bright solitons in a ring self-oscillating system with an amplifier klystron. The generated pulse sequences are dissipative temporal solitons formed in the ring due to the establishment of balance both between gain and loss and between time dispersion and cubic nonlinearity of the klystron. Analytical solutions have been obtained for a generator model with a two-cavity amplifier klystron and an additional cavity resonator, which confirm the possibility of forming these dissipative structures.

  19. 1.2 MW klystron for Asymmetric Storage Ring B Factory

    SciTech Connect

    Fowkes, W.R.; Caryotakis, G.; Doyle, E.

    1995-03-01

    A cw klystron operating at 476 MHz has been developed jointly by SLAC and Varian Associates. The unique set of characteristics of this tube were strongly guided by requirements of the fast feedback necessary to prevent oscillations of the storage ring beams caused by the detuned accelerating cavity. This requires a combination of bandwidth and short group delay within the klystron. The RF feedback stabilization scheme also requires amplitude modulation making it necessary to operate the klystron about 10% below saturation. Performance specifications and initial operating results are presented.

  20. Relativistic causality

    NASA Astrophysics Data System (ADS)

    Valente, Giovanni; Owen Weatherall, James

    2014-11-01

    Relativity theory is often taken to include, or to imply, a prohibition on superluminal propagation of causal processes. Yet, what exactly the prohibition on superluminal propagation amounts to and how one should deal with its possible violation have remained open philosophical problems, both in the context of the metaphysics of causation and the foundations of physics. In particular, recent work in philosophy of physics has focused on the causal structure of spacetime in relativity theory and on how this causal structure manifests itself in our most fundamental theories of matter. These topics were the subject of a workshop on "Relativistic Causality in Quantum Field Theory and General Relativity" that we organized (along with John Earman) at the Center for Philosophy of Science in Pittsburgh on April 5-7, 2013. The present Special Issue comprises contributions by speakers in that workshop as well as several other experts exploring different aspects of relativistic causality. We are grateful to the journal for hosting this Special Issue, to the journal's managing editor, Femke Kuiling, for her help and support in putting the issue together, and to the authors and the referees for their excellent work.

  1. PPM focused X-band klystron development at the Stanford Linear Accelerator Center

    SciTech Connect

    Sprehn, D.; Caryotakis, G.; Eppley, K.; Phillips, R.M.

    1996-07-01

    X-band klystrons capable of 50 MW and utilizing Periodic Permanent Magnet (PPM) focusing are undergoing design and fabrication at the Stanford Linear Accelerator Center (SLAC). The klystron development is part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). The first klystron to be tested this year has a 0.6 microK beam at 465 kV, a 5 cells traveling wave output structure and a predicted efficiency of 63%. A 465 kV, 190 A beam stick with 12 periods of PPM focusing has recently operated to verify the gun optics and transmission of the beam in the absence of rf bunching. Beam transmission greater than 99.8% has been measured. Design and simulation of the beam stick and klystron are discussed, along with performance of the beam stick under confined flow and shielded conditions.

  2. Computer control of the energy output of a klystron in the SLC

    SciTech Connect

    Jobe, R.K.; Browne, M.J.; Flores, M.; Phinney, N.; Schwarz, H.D.; Sheppard, J.C.

    1987-02-01

    Hardware and software have been developed to permit computer control of the output of high power klystrons on a pulsed basis. Control of the klystron output is accomplished by varying the input drive via a pulsed rf attenuator. Careful power calibrations permit accurate calculation of the available energy, as seen by the beam, over the full range of the klystron output. The ability to control precisely the energy output allows for energy feed-forward as well as energy feedback applications. Motivation for this work has been the need to adjust the energy of beams launched into various regions of the SLC. Vernier klystrons play a crucial role in the energy delivered from the SLC injector, linac, and positron source. This paper discusses the hardware development, energy calculations, and software implementation. Operational results are presented.

  3. 50-MW X-band klystron sources for the next generation of linear colliders

    SciTech Connect

    Caryotakis, G.; Eppley, K.; Fant, K.; Fowkes, R.; Phillips, R.; Tantawi, S.; Vlieks, A.; Wright, E.

    1994-06-01

    The first in a new series of high-power pulsed klystrons has been tested with the following results: Frequency = 11.4 GHz, beam voltage = 415 kV, power output = 51 MW, pulse length = 1.5 {mu}s, and efficiency = 37%. Several tubes of this type will be used in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. The rf performance of the klystron, which employs a standing-wave extended-interaction output circuit, is closely approximated by simulations performed with the SLAC CONDOR code. The same code predicts considerably higher efficiency, using a traveling-wave output circuit. A klystron with such a circuit will be constructed in the future. Another klystron is also planned in which beam confinement is accomplished by a periodic permanent magnet (PPM) stack, for which simulations also predict good performance.

  4. Relativistic fluid dynamics. Proceedings.

    NASA Astrophysics Data System (ADS)

    Anile, A. M.; Choquet-Bruhat, Y.

    Contents: 1. Covariant theory of conductivity in ideal fluid or solid media (B. Carter). 2. Hamiltonian techniques for relativistic fluid dynamics and stability theory (D. D. Holm). 3. Covariant fluid mechanics and thermodynamics: an introduction (W. Israel). 4. Relativistic plasmas (H. Weitzner). 5. An improved relativistic warm plasma model (A. M. Anile, S. Pennisi). 6. Relativistic extended thermodynamics II (I. Müller). 7. Relativistic extended thermodynamics: general assumptions and mathematical procedure (T. Ruggeri). 8. Relativistic hydrodynamics and heavy ion reactions (D. Strottman). 9. Some problems in relativistic hydrodynamics (C. G. van Weert).

  5. Multi-stage Depressed Collectors (MDC) for efficiency improvements of UHF broadcast klystrons

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1982-01-01

    The consumed primary power is reduced and the efficiency of traveling wave tubes is raised through the use of depressed collectors which passively convert potential energy into electric energy. Efficiency was kept with constant within a 3 dB range while the output power varied by 10 dB. Aspects to be considered in transferring this technology to UHF klystrons are the electron energy spectrum of the klystron and the magnitude of the injection angle required.

  6. Investigation of a klystron with a pseudospark-sourced electron beam

    NASA Astrophysics Data System (ADS)

    Bowes, D.; Yin, H.; Cross, A. W.; He, W.; Phelps, A. D. R.; Ronald, K.; Chen, X.; Li, D.

    2014-05-01

    Investigation has been undertaken at the University of Strathclyde to simulate, design and construct a klystron amplifier with an operating frequency of 94 GHz. A novel beam source shall be utilized in the form of a pseudospark discharge, a form of low-pressure, high-current plasma discharge which produces an electron beam possessing high brightness as well as self-focusing properties. The seed signal for the klystron will be fed in using a tapered dielectric-lined iris coupling system.

  7. Final Design of the SLAC P2 Marx Klystron Modulator

    SciTech Connect

    Kemp, M.A.; Benwell, A.; Burkhart, C.; Larsen, R.; MacNair, D.; Nguyen, M.; Olsen, J.; /SLAC

    2011-11-08

    The SLAC P2 Marx has been under development for two years, and follows on the P1 Marx as an alternative to the baseline klystron modulator for the International Linear Collider. The P2 Marx utilizes a redundant architecture, air-insulation, a control system with abundant diagnostic access, and a novel nested droop correction scheme. This paper is an overview of the design of this modulator. There are several points of emphasis for the P2 Marx design. First, the modulator must be compatible with the ILC two-tunnel design. In this scheme, the modulator and klystron are located within a service tunnel with limited access and available footprint for a modulator. Access to the modulator is only practical from one side. Second, the modulator must have high availability. Robust components are not sufficient alone to achieve availability much higher than 99%. Therefore, redundant architectures are necessary. Third, the modulator must be relatively low cost. Because of the large number of stations in the ILC, the investment needed for the modulator components is significant. High-volume construction techniques which take advantage of an economy of scale must be utilized. Fourth, the modulator must be simple and efficient to maintain. If a modulator does become inoperable, the MTTR must be small. Fifth, even though the present application for the modulator is for the ILC, future accelerators can also take advantage of this development effort. The hardware, software, and concepts developed in this project should be designed such that further development time necessary for other applications is minimal.

  8. Final Report 200 MW L-Band Annular Beam Klystron for Accelerators

    SciTech Connect

    Read, Michael; Ferguson, Patrick; Ives, Lawrence; Song, Liqun; Carlsten, Bruce; Fazio, Michael

    2009-02-11

    This program developed a 200 MW, 1.3 GHz, Annular Beam Klystron (ABK) for accelerator systems. An ABK provides lower impedance than a conventional klystron, making it possible to produce higher RF powers with lower voltages. With a higher power per unit, fewer klystrons would be required for a large accelerator. Lower voltage also simplifies and reduces the cost of the power supply system. Both features will significantly lower the cost of an RF system. This device operates at 475 kV. The klystron uses a magnetron injection gun producing 1100 A in one microsecond pulses. Power is extracted into fundamental rectangular waveguide through two output windows. The predicted gain is approximately 45 dB with estimated efficiency of 45%. The klystron was assembled, but no facility was available for testing. Consequently, no high power performance measurements are available. Because the assembled klystron is approximately 15 feet long, it was disassembled for storage. It can be reassembled should a use materialize.

  9. Current Status of the Next Linear Collider X-Band Klystron Development Program

    SciTech Connect

    Caryotakis, G.; Haase, A.A.; Jongewaard, E.N.; Pearson, C.; Sprehn, D.W.; /SLAC

    2005-05-09

    Klystrons capable of driving accelerator sections in the Next Linear Collider (NLC) have been developed at SLAC during the last decade. In addition to fourteen 50 MW solenoid-focused devices and a 50 MW Periodic Permanent Magnet focused (PPM) klystron, a 500 kV 75 MW PPM klystron was tested in 1999 to 80 MW with 3 {micro}s pulses, but very low duty. Subsequent 75 MW prototypes aimed for low-cost manufacture by employing reusable focusing structures external to the vacuum, similar to a solenoid electromagnet. During the PPM klystron development, several partners (CPI, EEV and Toshiba) have participated by constructing partial or complete PPM klystrons. After early failures during testing of the first two devices, SLAC has recently tested this design (XP3-3) to the full NLC specifications of 75 MW, 1.6 {micro}s pulse length, and 120 Hz. This 14.4 kW average power operation came with an efficiency of 50%. The XP3-3 average and peak output power, together with the focusing method, arguably makes it the most advanced high power klystron ever built anywhere in the world. Design considerations and test results for these latest prototypes will be presented.

  10. Investigation of the Long-Term Performance of the 324 MHz Klystrons for Achieving the Efficient Operation of the Linac at J-PARC

    NASA Astrophysics Data System (ADS)

    Hori, T.; Shinozaki, S.; Chishiro, E.; Sato, F.; Kawamura, M.; Futatsukawa, K.; Fukui, Y.; Oguri, H.

    As a part of the researches of the reliability and life time of klystrons, the cathode performance test of 324 MHz klystrons operated for 32000 hours on line has been performed at the klystron test stand. The experimental results coincide approximately with the data both reported in the literature for the cathode performance and the one obtained from the data base of RF data acquisition system. In this test, two parameters such as klystron beam perveance and knee-point were used to investigate the emission performance. It turned out that klystron beam perveance is most suitable parameter for understanding the klystron performance under operating condition on line.

  11. Two-beam high-order harmonics from solids: Coupling mechanisms

    SciTech Connect

    Tarasevitch, A.; Wieczorek, J.; Kohn, R.; Bovensiepen, U.; Linde, D. von der

    2010-11-15

    The polarization of the two beam (driver-probe) high-order harmonic generation from solids is measured. The experiments, together with computer simulations, allow us to distinguish two different coupling mechanisms of the driver and the probe, resulting in different harmonic efficiencies and spectral slopes. We find that in the nonrelativistic regime the coupling is mostly due to the nonlinear plasma density modulation.

  12. Relativistic electron beam generator

    DOEpatents

    Mooney, L.J.; Hyatt, H.M.

    1975-11-11

    A relativistic electron beam generator for laser media excitation is described. The device employs a diode type relativistic electron beam source having a cathode shape which provides a rectangular output beam with uniform current density.

  13. Phase locking and frequency locking of a 140 GHz klystron and a 280 GHz carcinotron

    SciTech Connect

    Sprehn, D.W.; Rettig, C.L.; Luhmann, N.C. Jr. )

    1992-10-01

    A phase and frequency-locked loop to synchronize two microwave tube oscillators for a high density plasma collective scattering diagnostic has been designed, assembled, and tested. A Varian (VRT2121A16) reflex klystron was down converted by mixing with the eighth harmonic of a 17.437 GHz phase-locked Gunn oscillator, and the resulting baseband was used to lock the klystron phase to a 200 MHz crystal. The down-converted 140 GHz klystron frequency spectrum shows a linewidth {lt}50 Hz and sideband power {lt}50 dB below the carrier (dBc). Frequency locking of a Thomson CSF TH4224S 280 GHz carcinotron was performed and the klystron was then down converted by the stabilized carcinotron and phase locked to the 200 MHz crystal. The klystron would track the frequency excursions of the carcinotron when the system was perturbed by direct modulation with frequencies of up to 10 MHz and remained locked as long as modulation sidebands were kept {lt}15 dBc. The locked states of both configurations show 3 to 4 orders of magnitude improvement in short and long term stability over the unlocked states.

  14. Design of a multi beam klystron cavity from its single beam parameters

    NASA Astrophysics Data System (ADS)

    Kant, Deepender; Joshi, L. M.; Janyani, Vijay

    2016-03-01

    The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam cavities. Design of the desired multi beam cavity can be optimized through iterative simulations in CST Microwave Studio.

  15. Recent Upgrade of the Klystron Modulator at SLAC

    SciTech Connect

    Nguyen, M.N.; Burkhart, C.P.; Lam, B.K.; Morris, B.; /SLAC

    2011-11-04

    The SLAC National Accelerator Laboratory employs 244 klystron modulators on its two-mile-long linear accelerator that has been operational since the early days of the SLAC establishment in the sixties. Each of these original modulators was designed to provide 250 kV, 262 A and 3.5 {mu}S at up to 360 pps using an inductance-capacitance resonant charging system, a modified type-E pulse-forming network (PFN), and a pulse transformer. The modulator internal control comprised of large step-start resistor-contactors, vacuum-tube amplifiers, and 120 Vac relays for logical signals. A major, power-component-only upgrade, which began in 1983 to accommodate the required beam energy of the SLAC Linear Collider (SLC) project, raised the modulator peak output capacity to 360 kV, 420 A and 5.0 {mu}S at a reduced pulse repetition rate of 120 pps. In an effort to improve safety, performance, reliability and maintainability of the modulator, this recent upgrade focuses on the remaining three-phase AC power input and modulator controls. The upgrade includes the utilization of primary SCR phase control rectifiers, integrated fault protection and voltage regulation circuitries, and programmable logic controllers (PLC) -- with an emphasis on component physical layouts for safety and maintainability concerns. In this paper, we will describe the design and implementation of each upgraded component in the modulator control system. We will also report the testing and present status of the modified modulators.

  16. W-band LiGA fabricated klystron

    NASA Astrophysics Data System (ADS)

    Song, Liqun

    2002-01-01

    Klystrino-W-band klystron was proposed by scientists at SLAC to satisfy recent applications in advanced accelerators, medical treatment, radars and communications. LiGA (a German acronym for lithographe, galvanoformung, and abformung) is introduced in the fabrication of klystrino for the first time in the history of microwave tube fabrication. The cold test experiments show that LiGA fabrication yields best surface smoothness compared with an alternative way EDM (Electrical Discharge Machining). Resultantly LiGA fabricated klystrino has the smallest wall loss which maximizes the circuit efficiency of the output structure. A multiple-gap coupled cavity is motivated to be employed as the klystrino output cavity for maximizing the efficiency. Klytrino is simulated by 1-D, 2-D and 3-D simulation codes. Particularly a complete klystrino is simulated intensively using 2-D MAGIC Particle-in-Cell (PIC) code either for beam absence or beam presence. Many simulation techniques are developed such as model transformation from 3-D to 2-D, circuit parameter simulation, dispersion characteristic analysis, pre bunched electron beam mode and so on. Klystrino, as a 3-D structure, is modeled by 3-D MAFIA for analyzing the cold circuit properties. 3-D MAGIC is explored to simulate klystrino for the actual structure analysis and actual beam interaction process observation.

  17. Time-dependent simulation of prebunched one and two-beam free electron laser

    SciTech Connect

    Mirian, N. S.; Maraghechi, B.

    2014-04-15

    A numerical simulation in one-dimension is conducted to study the slippage effects on prebunched free electron laser. A technique for the simulation of time dependent free electron lasers (FEL) to model the slippage effects is introduced, and the slowly varying envelope approximation in both z and t is used to illustrate the temporal behaviour in the prebunched FEL. Slippage effect on prebunched two-beam FEL is compared with the one-beam modeling. The evaluation of the radiation pulse energy, thermal and phase distribution, and radiation pulse shape in one-beam and two-beam modeling is studied. It was shown that the performance is considerably undermined when the slippage time is comparable to the pulse duration. However, prebunching reduces the slippage. Prebunching also leads to the radiation pulse with a single smooth spike.

  18. Demonstration of two-beam acceleration and 30 GHz power production in the CLIC Test Facility

    SciTech Connect

    Bossart, R.; Braun, H. H.; Carron, G.; Chanudet, M.; Chautard, F.; Delahaye, J. P.; Godot, J. C.; Hutchins, S.; Martinez, C.; Suberlucq, G.; Tenenbaum, P.; Thorndahl, L.; Trautner, H.; Valentini, M.; Wilson, I.; Wuensch, W.

    1999-05-07

    The Compact Linear Collider (CLIC) Test Facility (CTF II) at CERN has recently demonstrated Two-Beam power production and acceleration at 30 GHz. With 41 MW of 30 GHz power produced in 14 ns pulses at a repetition rate of 5 Hz, the main beam has been accelerated by 28 MeV. The 30 GHz RF power is extracted in low impedance decelerating structures from a low-energy, high-current 'drive beam' which runs parallel to the main beam. The average current in the drive-beam train is 25 A, while the peak current exceeds 2 kA. Crosschecks between measured drive-beam charge, 30 GHz power and main-beam energy gain are in good agreement. In this paper, some relevant experimental and technical issues on drive-beam generation, two-beam power production and acceleration are presented.

  19. Numerical Verification of the Power Transfer and Wakefield Coupling in the Clic Two-Beam Accelerator

    SciTech Connect

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN

    2011-08-19

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its two-beam accelerator (TBA) concept envisions complex 3D structures, which must be modeled to high accuracy so that simulation results can be directly used to prepare CAD drawings for machining. The required simulations include not only the fundamental mode properties of the accelerating structures but also the Power Extraction and Transfer Structure (PETS), as well as the coupling between the two systems. Time-domain simulations will be performed to understand pulse formation, wakefield damping, fundamental power transfer and wakefield coupling in these structures. Applying SLAC's parallel finite element code suite, these large-scale problems will be solved on some of the largest supercomputers available. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel two-beam accelerator scheme.

  20. Resolving two beams in beam splitters with a beam position monitor

    SciTech Connect

    Kurennoy, S.

    2002-01-01

    The beam transport system for the Advanced Hydrotest Facility (AHF) anticipates multiple beam splitters. Monitoring two separated beams in a common beam pipe in the splitter sections imposes certain requirements on diagnostics for these sections. In this note we explore a two-beam system in a generic beam monitor and study the feasibility of resolving the positions of the two beams with a single diagnostic device. In the Advanced Hydrotest Facility (AHF), 20-ns beam pulses (bunches) are extracted from the 50-GeV main proton synchrotron and then are transported to the target by an elaborated transport system. The beam transport system splits the beam bunches into equal parts in its splitting sections so that up to 12 synchronous beam pulses can be delivered to the target for the multi-axis proton radiography. Information about the transverse positions of the beams in the splitters, and possibly the bunch longitudinal profile, should be delivered by some diagnostic devices. Possible candidates are the circular wall current monitors in the circular pipes connecting the splitter elements, or the conventional stripline BPMs. In any case, we need some estimates on how well the transverse positions of the two beams can be resolved by these monitors.

  1. Test Results of a Compact Conventional Modulator for Two-Klystron Operation

    SciTech Connect

    Gold, S

    2004-05-04

    Modulator technology has not advanced greatly over the last 30 years. Today, with the advent of the High Voltage, High Power IGBT there are several approaches for a solid state ON/OFF switched modulator. Klystron and accelerator technology is forcing voltages and peak powers higher such as the demand for 500 kV and 500 amperes peak to power two X-Band klystrons. Conventional technology (line-type modulators) were never overly concerned about rise time and efficiency. A few years ago, the klystron department at Stanford Linear Accelerator Center (SLAC) undertook an investigation into what could be done in a conventional modulator at 500 kV. We have reported on test bed measurements and shown both conceptual and hardware pictures during design and construction. We have now completed the modulator tank.

  2. Spontaneous emission of the Super-ACO fel optical klystron domino

    NASA Astrophysics Data System (ADS)

    Couprie, M. E.; Bazin, C.; Billardon, M.; Velghe, M.

    1989-12-01

    New free electron laser experiments are planned on the Orsay storage ring Super-ACO, which has been commisioned in 1987 at LURE (Laboratoire d'Utilisation du Rayonnement Electromagnétique). For this purpose, a new insertion device, DOMINO, was set up on Super-ACO in January 1988; it consists of a permanent magnet optical klystron composed of two undulators separated by a dispersive section; the magnetic gaps can be changed independently. Here, the parameters of the optical klystron are specified, and the main steps of the optimization are described. Then, the effect of the insertion device on the stored beam is discussed. The spontaneous emission of the optical klystron has been observed and analysed. Consequently, with the ring parameters measurements, the free electron laser gain versus the current can be evaluated.

  3. Measurement of klystron phase modulation due to ac-powered filaments

    NASA Technical Reports Server (NTRS)

    Finnegan, E. J.

    1977-01-01

    A technique for determining the intermodulation components in the RF spectrum of the S-band radar transmitter generated by having the klystron filaments heated by 400-Hz ac power is described. When the klystron is being operated with 400-Hz (ac) on the filament, the IPM is buried in the 400-Hz equipment interference noise. The modulation sidebands were separated and identified and found to be-67 db below the main carrier. This is well below the transmitter specifications, and operating the filaments on ac would not degrade the spectrum to where it would be detrimental to the radiated RF.

  4. Solar power satellite 50 kW VKS-7773 cw klystron evaluation

    NASA Technical Reports Server (NTRS)

    Larue, A. D.

    1977-01-01

    A test program for evaluating the electrical characteristics of a cw, 50 kW power output klystron at 2.45 GHz is described. The tube tested was an 8-cavity klystron, the VKS-7773 which had been in storage for seven years. Tests included preliminary testing of the tube, cold tests of microwave components, tests of the electromagnet, and first and second hot tests of the tube. During the second hot test, the tuner in the fifth cavity went down to air, preventing any further testing. Cause of failure is not known, and recommendations are to repair and modify the tube, then proceed with testing as before to meet program objectives.

  5. Calculation of the frequency spectrum of an electron beam in a klystron with premodulation

    NASA Astrophysics Data System (ADS)

    Alekseev, Iu. K.; Kostienko, A. I.

    1982-12-01

    The combined modulation of the electron beam in a klystron with a triode gun is considered. Amplitude modulation of current density (static control) is followed by modulation of electron velocities (dynamic control). The spectral characteristics of the convection current at the input of the energy-extraction device are calculated for large ratios of the dynamic and static control frequencies. Calculations point to the possibility of using low-frequency preliminary amplitude modulation to enhance the electronic efficiency of pulsed klystrons, operating both in the amplification and frequency-multiplication modes.

  6. Recent performance, lifetime, and failure modes of the 5045 klystron population at SLAC

    SciTech Connect

    Koontz, R.F.; Lee, T.G.; Pearson, C.; Vlieks, A.E.

    1992-08-01

    The 65 MW S-Band klystrons (5045) used to power SLC have been in service for over seven years. Currently, 244 of these tubes are in place on the accelerator, operating full power at 120 pulses per second. Enough tubes have now reached end of life, or experienced other failures to allow a good analysis of failure modes, and to project average lifetime for this type of tube. This paper describes the various modes of failure seen in klystrons rammed from SLC service, and provides data on expected lifetime from current production based on accumulated SLC operating experience.

  7. Relativistic Guiding Center Equations

    SciTech Connect

    White, R. B.; Gobbin, M.

    2014-10-01

    In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.

  8. Relativistic Linear Restoring Force

    ERIC Educational Resources Information Center

    Clark, D.; Franklin, J.; Mann, N.

    2012-01-01

    We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…

  9. A possible pole problem in the formula for klystron gap fields

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1977-01-01

    In isolated cases a pole may be encountered in a previously published solution for the fields in a klystron gap. Formulas, permitting the critical combinations of parameters to be defined, are presented. It is noted that the region of inaccuracy surrounding the pole is sufficiently small and that a 0.1% change in the field changing parameter is enough to avoid it.

  10. Three-dimensional evaluation of energy extraction in output cavities of klystron amplifiers

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.; Albers, L. U.

    1973-01-01

    Description of an accurate three-dimensional mathematical model and computer program for calculating electronic interaction, electron trajectories, beam interception, and efficiency in the output cavity of a klystron amplifier. The highest computed efficiency for an optimally bunched beam was 80.3% with 6% ideal interception. Efficiency is shown to increase initially with interception.

  11. A theoretical model of phase changes of a klystron due to variation of operating parameters

    NASA Technical Reports Server (NTRS)

    Kupiszewski, A.

    1980-01-01

    A mathematical model for phase changes of the VA-876 CW klystron amplifier output is presented and variations of several operating parameters are considered. The theoretical approach to the problem is based upon a gridded gap modeling with inclusion of a second order correction term so that actual gap geometry is reflected in the formulation. Physical measurements are contrasted to theoretical calculations.

  12. Photorefractive two-beam coupling joint transform correlator: modeling and performance evaluation.

    PubMed

    Nehmetallah, G; Khoury, J; Banerjee, P P

    2016-05-20

    The photorefractive two-beam coupling joint transform correlator combines two features. The first is embedded semi-adaptive optimality, which weighs the correlation against clutter and noise in the input, and the second is the intrinsic dynamic range compression nonlinearity, which improves several metrics simultaneously without metric trade-off. Although the two beam coupling correlator was invented many years ago, its outstanding performance was recognized on only relatively simple images. There was no study about the performance of this correlator on complicated images and using different figures of merit. In this paper, the study is extended to more complicated images. For the first time, to our knowledge, we demonstrate simultaneous improvement in metrics performance without metric trade-off. The performance was evaluated compared to the classical joint transform correlator. A typical experimental result to validate the simulation results was also shown in this work. The best performing operation parameters were identified to guide the experimental work and for future comparison with other well-known optimal correlation filters. PMID:27411127

  13. Non-relativistic leptogenesis

    NASA Astrophysics Data System (ADS)

    Bödeker, Dietrich; Wörmann, Mirco

    2014-02-01

    In many phenomenologically interesting models of thermal leptogenesis the heavy neutrinos are non-relativistic when they decay and produce the baryon asymmetry of the Universe. We propose a non-relativistic approximation for the corresponding rate equations in the non-resonant case, and a systematic way for computing relativistic corrections. We determine the leading order coefficients in these equations, and the first relativistic corrections. The non-relativistic approximation works remarkably well. It appears to be consistent with results obtained using a Boltzmann equation taking into account the momentum distribution of the heavy neutrinos, while being much simpler. We also compute radiative corrections to some of the coefficients in the rate equations. Their effect is of order 1% in the regime favored by neutrino oscillation data. We obtain the correct leading order lepton number washout rate in this regime, which leads to large ( ~ 20%) effects compared to previous computations.

  14. Design and development of a 6 MW peak, 24 kW average power S-band klystron

    SciTech Connect

    Joshi, L.M.; Meena, Rakesh; Nangru, Subhash; Kant, Deepender; Pal, Debashis; Lamba, O.S.; Jindal, Vishnu; Jangid, Sushil Kumar; Chakravarthy, D.P.; Dixit, Kavita

    2011-07-01

    A 6 MW peak, 24 kW average power S-band Klystron is under development at CEERI, Pilani under an MoU between BARC and CEERI. The design of the klystron has been completed. The electron gun has been designed using TRAK and MAGIC codes. RF cavities have been designed using HFSS and CST Microwave Studio while the complete beam wave interaction simulation has been done using MAGIC code. The thermal design of collector and RF window has been done using ANSYS code. A Gun Collector Test Module (GCTM) was developed before making actual klystron to validate gun perveance and thermal design of collector. A high voltage solid state pulsed modulator has been installed for performance valuation of the tube. The paper will cover the design aspects of the tube and experimental test results of GCTM and klystron. (author)

  15. Adaptive frequency comb illumination for interferometry in the case of nested two-beam cavities

    SciTech Connect

    Harder, Irina; Leuchs, Gerd; Mantel, Klaus; Schwider, Johannes

    2011-09-01

    The homogeneity test of glass plates in a Fizeau interferometer is hampered by the superposition of multiple interference signals coming from the surfaces of the glass plate as well as the empty Fizeau cavity. To evaluate interferograms resulting from such nested cavities, various approaches such as the use of broadband light sources have been applied. In this paper, we propose an adaptive frequency comb interferometer to accomplish the cavity selection. An adjustable Fabry-Perot resonator is used to generate a variable frequency comb that can be matched to the length of the desired cavity. Owing to its flexibility, the number of measurements needed for the homogeneity test can be reduced to four. Furthermore, compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher if a Fabry-Perot filter is applied.

  16. Neutron spectra at two beam ports of a TRIGA Mark III reactor loaded with HEU fuel.

    PubMed

    Vega-Carrillo, H R; Hernández-Dávila, V M; Aguilar, F; Paredes, L; Rivera, T

    2014-01-01

    The neutron spectra have been measured in two beam ports, one radial and another tangential, of the TRIGA Mark III nuclear reactor from the National Institute of Nuclear Research in Mexico. Measurements were carried out with the reactor core loaded with high enriched uranium fuel. Two reactor powers, 5 and 10 W, were used during neutron spectra measurements using a Bonner sphere spectrometer with a (6)LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter high-density polyethylene spheres. The neutron spectra were unfolded using the NSDUAZ unfolding code. For each spectrum total flux, mean energy and ambient dose equivalent were determined. Measured spectra show fission, epithermal and thermal neutrons, being harder in the radial beam port. PMID:23746708

  17. Two-beam interferometer for optical constants measurements at near-millimeter wavelengths

    NASA Astrophysics Data System (ADS)

    Jones, C. R.; Dutta, J. M.; Davé, H.

    1984-03-01

    A simple and versatile instrument for the measurement of optical constants in the near millimeter spectral region is described. Studies of quasi-optical components used in this instrument for effective beam transmission and control are reported. These studies include transmission characteristics of dielectric waveguides and performance of a variable coupler based on frustrated total internal reflection. Operation of this instrument as a two-beam interferometer for determining the index of refraction or as a device to measure transmission for determining the absorption coefficient are described. Values measured with this instrument at 245 GHz, using an optically pumped molecular laser as the source, are reported for several low-loss materials. Appropriate corrections and error estimates are discussed. The potential for improvement and increased accuracies are discussed.

  18. Standing-Wave Free-Electron Laser Two-Beam Accelerator

    SciTech Connect

    Sessler, Andrew M.; Whittum, D.H.; Wurtele, Jonathan S.; Sharp, W.M.; Makowski, M.A.

    1991-02-01

    A free-electron laser (FEL) two-beam accelerator (TBA) is proposed, in which the FEL interaction takes place in a series of drive cavities, rather than in a waveguide. Each drive cavity is 'beat-coupled' to a section of the accelerating structure. This standing-wave TBA is investigated theoretically and numerically, with analyses included of microwave extraction, growth of the FEL signal through saturation, equilibrium longitudinal beam dynamics following saturation, and sensitivity of the microwave amplitude and phase to errors in current and energy. It is found that phase errors due to current jitter are substantially reduced from previous versions of the TBA. Analytic scalings and numerical simulations are used to obtain an illustrative TBA parameter set.

  19. Stacked insulator induction accelerator gaps

    SciTech Connect

    Houck, T.I.; Westenskow, G.A.; Kim, J.S.; Eylon, S.; Henestroza, E.; Yu, S.S.; Vanecek, D.

    1997-05-01

    Stacked insulators, with alternating layers of insulating material and conducting film, have been shown to support high surface electrical field stresses. We have investigated the application of the stacked insulator technology to the design of induction accelerator modules for the Relativistic-Klystron Two-Beam Accelerator program. The rf properties of the accelerating gaps using stacked insulators, particularly the impedance at frequencies above the beam pipe cutoff frequency, are investigated. Low impedance is critical for Relativistic-Klystron Two-Beam Accelerator applications where a high current, bunched beam is trsnsported through many accelerating gaps. An induction accelerator module designs using a stacked insulator is presented.

  20. Environmental influences contributing to window failure of the SLAC 50 MW klystron

    SciTech Connect

    Krienen, F.

    1984-03-01

    The additional heating of the klystron window is due to the intense x-ray level, produced inside the klystron, illuminating the entrance of the output wave guide. Photo-electric effect, although of low efficiency, produces enough electrons at the right location and right phase to start multipactor, which progresses with increasing intensity towards the window. The intercepted charge and the concomitant x-radiation heat the window, but the heating is not the cause of the breakdown per se. The accumulated charge on the window creates electric stress, which comes in addition to the RF stress. It could therefore be a major cause of electrical breakdown. The coating, which is intended to carry this charge off, should have a relaxation time constant small compared to the pulse duration. Unfortunately the coating can not be made conducting enough because it conflicts with the Joule heating in the RF field.

  1. Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems

    SciTech Connect

    Van Winkle, D.; Browne, J.; Fox, J.D.; Mastorides, T.; Rivetta, C.; Teytelman, D.; /SLAC

    2006-07-18

    The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2A (HER) on 4A (LER) currents, we estimate that longitudinal growth rates will be comparable to the damping rates currently achieved in the existing low level RF and longitudinal feedback systems. Prior to having a good non-linear time domain model [1] it was postulated that klystron small signal gain non-linearity may be contributing to measured longitudinal growth rates being higher than linearly predicted growth rates. Five prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 476 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development plans, conclusions from beam testing and ideas for future use of this linearization technique are presented.

  2. Design of a wiggler-focused, sheet beam X band klystron

    SciTech Connect

    Eppley, K.R.; Herrmannsfeldt, W.B.; Miller, R.H.

    1987-02-01

    An X band klystron using a sheet beam and wiggler focusing was simulated using the 2 + 1/2 dimensional particle in cell code MASK. Simulation of the rf cavities was by means of the port approximation used in modelling of standard klystrons. The wigglers, which would need permanent magnets to achieve the required field strengths, were modelled using an idealized analytic expression with an exponential rise and a linear taper superimposed on a sinusoidal variation. Cavity locations and tunings were varied for maximum output power. Beam voltage and current were also varied to explore the effect on efficiency. Both an idealized laminar beam and a more realistic beam from a gun design code were studied. For a voltage of 200 kV and current of 20 amp per linear cm efficiencies of approximately 50% were calculated.

  3. Study of the emission performance of high-power klystrons: SLAC XK-5

    SciTech Connect

    Zhao, Y.

    1981-07-01

    There are hundreds of high power klystrons operated in the Linac gallery and about fifty to sixty tubes fail every year. The lifetime ranges from a few thousand up to seventy thousand hours except those which fail during an early period. The overall percentage of failures due to emission problems is approximately 25%. It is also noted that a 10% increase in mean lifetime of klystrons will reduce the overall cost per hour as much as a 10% increase in efficiency. Therefore, it is useful to find some method to predict the expected life of an individual tube. The final goal has not been attained yet, but some useful information was obtained. It is thought that this information might be helpful for those people who will study this subject further.

  4. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  5. Relativistic Hall effect.

    PubMed

    Bliokh, Konstantin Y; Nori, Franco

    2012-03-23

    We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes. PMID:22540559

  6. RF Feedback Analysis for 4 cavities per klystron in PEP-II

    SciTech Connect

    Corredoura, P.; Tighe, R.

    1994-06-01

    Lattice changes in the PEP-II high energy ring have made the concept of driving four cavities with a single klystron an attractive option. This paper examines the topology from a RF feedback point of view. Sources of error are identified and their magnitudes are estimated. The effect on the performance of the longitudinal impedance reducing feedback loops is calculated using control theory and Mathematica.

  7. The pulse modulator for the mod-anode of the cluster klystron

    SciTech Connect

    Zhao, Y.; Palmer, R.; Wang, H.

    1996-05-01

    A high voltage pulse generator using a Zarem type modulator was developed. The Zarem type circuit doesn`t require a matched load, making it suitable to drive the mod-anode of the cluster klystron, which has a capacitive load. The principle and the experiments, as well as the analyses and the simulations of the observed phenomena, (ringing, pulse {open_quotes}skirt{close_quotes} and {open_quotes}deficiency{close_quotes}) are presented.

  8. Exact Relativistic `Antigravity' Propulsion

    NASA Astrophysics Data System (ADS)

    Felber, Franklin S.

    2006-01-01

    The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload.

  9. Relativistic Quantum Scars

    SciTech Connect

    Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard

    2009-07-31

    The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.

  10. Relativistic viscoelastic fluid mechanics

    SciTech Connect

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-15

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  11. A 200 MHz 35 MW Multiple Beam Klystron for Accelerator Applications Final Report

    SciTech Connect

    R. Lawrence Ives; Michael Read; Patrick Ferguson; David Marsden

    2011-11-28

    Calabazas Creek Research, Inc. (CCR) performed initial development of a compact and reliable 35 MW, multiple beam klystron (MBK) at 200 MHz with a pulse length of 0.125 ms and a 30 Hz repetition rate. The device was targeted for acceleration and ionization cooling of a muon collider, but there are several other potential applications in this frequency range. The klystron uses multiple beams propagating in individual beam tunnels to reduce space charge and allow reduction in the accelerating voltage. This allows a significant reduction in length over a single beam source. More importantly this allows more efficient and less expensive power supplies. At 200 MHz, the interaction circuit for a single beam klystron would be more than six meters long to obtain 50% efficiency and 50 dB gain. This would require a beam voltage of approximately 400 kV and current of 251 A for a microperveance of 1.0. For an eight beam MBK with the same beam perveance, a three meter long interaction circuit achieves the same power and gain. Each beam operates at 142 kV and 70A. The Phase I demonstrated that this device could be fabricated with funding available in a Phase II program and could achieve the program specifications.

  12. Klystron Modulator Design for the Los Alamos Neutron Science Center Accelerator

    SciTech Connect

    Reass, William A.; Baca, David M.; Partridge, Edward R.; Rees, Daniel E.

    2012-06-22

    This paper will describe the design of the 44 modulator systems that will be installed to upgrade the Los Alamos Neutron Science Center (LANSCE) accelerator RF system. The klystrons can operate up to 86 kV with a nominal 32 Amp beam current with a 120 Hz repetition rate and 15% duty cycle. The klystrons are a mod-anode design. The modulator is designed with analog feedback control to ensure the klystron beam current is flat-top regulated. To achieve fast switching while maintaining linear feedback control, a grid-clamp, totem-pole modulator configuration is used with an 'on' deck and an 'off' deck. The on and off deck modulators are of identical design and utilize a cascode connected planar triode, cathode driven with a high speed MOSFET. The derived feedback is connected to the planar triode grid to enable the flat-top control. Although modern design approaches suggest solid state designs may be considered, the planar triode (Eimac Y-847B) is very cost effective, is easy to integrate with the existing hardware, and provides a simplified linear feedback control mechanism. The design is very compact and fault tolerant. This paper will review the complete electrical design, operational performance, and system characterization as applied to the LANSCE installation.

  13. Progress on a particle-in-cell model of a W-band klystron

    NASA Astrophysics Data System (ADS)

    Mardahl, Peter J.; Verboncoeur, John P.; Birdsall, C. K.

    1999-11-01

    Design and initial implementation of an extension from two to three dimensions (x-y-z and r-θ-z) is described for the XOOPIC( J. P. Verboncoeur, A. B. Langdon, and N. T. Gladd, ``An object-oriented electromagnetic PIC code.'' Computer Physics Communications 87) (1995) 199-211. code. The klystron ( G. Caryotakis, E. Jongewaard, G. Schietrum, A. Vlieks, R.L. Kustom, N.C. Luhmann, M.I. Petelin, ``W-Band Micro-fabricated Modular Klystrons.'' --Private communication) of interest is to operate at 91GHz, with a 125kW peak power, 120kV, 2.5A, 1us pulse, and 0.8mm drift tube diameter. This klystron uses periodic permanent magnetic focussing to contain the beam within the drift tube. Initially, the device will be modelled in 2d, and this will be extended to a 3d model. A 3d model is preferred because the drift tube is circular, while the cavities are rectangular. The circular drift tube will be modelled using stair-stepped boundaries.

  14. Low crosstalk optical hierarchical authentication with a fixed random phase lock based on two beams interference

    NASA Astrophysics Data System (ADS)

    Lu, Dajiang; He, Wenqi; Peng, Xiang

    2015-09-01

    We propose a novel method to achieve the purpose of hierarchical authentication based on two beams interference. In this method, different target images indicating different authentication levels are analytically encoded into corresponding phase-only masks (phase keys) and amplitude-only masks (amplitude keys) with the help of a random phase mask, which is created in advance and acts as the fixed lock of this authentication system. For the authentication process, a legal user can obtain a specified target image at the output plane if his/her phase key, and amplitude key, which should be settled close against the fixed internal phase lock, are respectively illuminated by two coherent beams. By comparing the target image with all the standard certification images in the database, the system can thus verify the user's identity. In simple terms, this system can not only confirm the legality of a user but also distinguish his/her identity level. Moreover, in despite of the internal phase lock of this system being fixed, the crosstalk between different pairs of keys hold by different users is low. Theoretical analysis and numerical simulation are both provided to demonstrate the validity of this method.

  15. A new method for RF power generation for two-beam linear colliders

    SciTech Connect

    Braun, H.; Corsini, R.; DAmico, T.; Delahaye, J.P.; Guignard, G.; Johnson, C.; Millich, A.; Pearce, P.; Rinolfi, L.; Riche, A.; Schulte, D.; Thorndahl, L.; Valentini, M.; Wilson, I.; Ruth, R.D.

    1999-05-01

    In this paper we discuss a new approach to two-beam acceleration. The energy for RF production is initially stored in a long-pulse electron beam which is efficiently accelerated to about 1.2 GeV by a fully loaded, conventional, low frequency ({approximately}1 GHz) linac. The beam pulse length is twice the length of the high-gradient linac. Segments of this long pulse beam are compressed using combiner rings to create a sequence of higher peak power drive beams with gaps in between. This train of drive beams is distributed from the end of the linac against the main beam direction down a common transport line so that each drive beam can power a section of the main linac. After a 180-degree turn, each high-current, low-energy drive beam is decelerated in low-impedance decelerator structures, and the resulting power is used to accelerate the low-current, high-energy beam in the main linac. The method discussed here seems relatively inexpensive, is very flexible and can be used to accelerate beams for linear colliders over the entire frequency and energy range. {copyright} {ital 1999 American Institute of Physics.}

  16. A new method for RF power generation for two-beam linear colliders

    SciTech Connect

    Braun, H.; Corsini, R.; D'Amico, T.; Delahaye, J. P.; Guignard, G.; Johnson, C.; Millich, A.; Pearce, P.; Rinolfi, L.; Riche, A.; Schulte, D.; Thorndahl, L.; Valentini, M.; Wilson, I.; Ruth, R. D.

    1999-05-07

    In this paper we discuss a new approach to two-beam acceleration. The energy for RF production is initially stored in a long-pulse electron beam which is efficiently accelerated to about 1.2 GeV by a fully loaded, conventional, low frequency ({approx}1 GHz) linac. The beam pulse length is twice the length of the high-gradient linac. Segments of this long pulse beam are compressed using combiner rings to create a sequence of higher peak power drive beams with gaps in between. This train of drive beams is distributed from the end of the linac against the main beam direction down a common transport line so that each drive beam can power a section of the main linac. After a 180-degree turn, each high-current, low-energy drive beam is decelerated in low-impedance decelerator structures, and the resulting power is used to accelerate the low-current, high-energy beam in the main linac. The method discussed here seems relatively inexpensive, is very flexible and can be used to accelerate beams for linear colliders over the entire frequency and energy range.

  17. Fully phase multiple information encoding based on superposition of two beams and Fresnel-transform domain

    NASA Astrophysics Data System (ADS)

    Abuturab, Muhammad Rafiq

    2015-12-01

    A novel asymmetric multiple information encoding using superposition of two beams and Fresnel transform, is proposed. In this scheme, each channel of individual user image is separately phase encoded and then modulated by random phase mask. The three modulated user channels are independently multiplied to produce three complex user channels. They are individually multiplied with three channels of carrier image and Fresnel transformed, and then phase- and amplitude truncated to produce first set of three encrypted channels and three asymmetric keys. Now each channel of secret image is normalized, phase-only masked, and then independently multiplied by corresponding modulated user channels. The three resultant channels are separately multiplied to construct three complex secret channels. Afterward, the three encrypted channels are multiplied with corresponding three complex secret channels and Fresnel transformed, and then phase- and amplitude truncated to obtain second set of three encrypted channels and three asymmetric keys. The wavelengths and propagation distances of two Fresnel transforms, and two asymmetric keys are common keys to all authorized-users, while two individual keys are provided to each authorized-user. The encryption process is implemented digitally while the decryption process can be performed optoelectronically. The proposed method is asymmetric, noniterative and larger multiplexing capacity without any cross-talk noise effects. Owing to the individual user image based method, high robustness against existing attacks can be achieved. Numerical simulation results demonstrate that the proposed method is feasible and efficient.

  18. A new three-band, two beam astronomical photo-polarimeter

    NASA Astrophysics Data System (ADS)

    Srinivasulu, G.; Raveendran, A. V.; Muneer, S.; Mekkaden, M. V.; Jayavel, N.; Somashekar, M. R.; Sagayanathan, K.; Ramamoorthy, S.; Rosario, M. J.; Jayakumar, K.

    2014-09-01

    We designed and built a new astronomical photo-polarimeter that can measure linear polarization simultaneously in three spectral bands. It has a Calcite beam-displacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral bands are quasi-simultaneously detected by the same photomultiplier by using a high speed rotating chopper. A rotating superachromatic Pancharatnam halfwave plate is used to modulate the light incident on the analyzer. The spectral bands are isolated using appropriate dichroic and glass filters. We show that the reduction of 50% in the efficiency of the polarimeter because of the fact that the intensities of the two beams are measured alternately is partly compensated by the reduced time to be spent on the observation of the sky background. The use of a beam-displacement prism as the analyzer completely removes the polarization of background skylight, which is a major source of error during moonlit nights, especially, in the case of faint stars. The field trials that were carried out by observing several polarized and unpolarized stars show the performance of the polarimeter to be satisfactory.

  19. On coupled transversal and axial motions of two beams with a joint

    NASA Astrophysics Data System (ADS)

    Burns, J. A.; Cliff, E. M.; Liu, Z.; Spies, R. D.

    2008-03-01

    In this paper we develop and analyze a mathematical model for combined axial and transverse motions of two Euler-Bernoulli beams coupled through a joint composed of two rigid bodies. The motivation for this problem comes from the need to accurately model damping and joints for the next generation of inflatable/rigidizable space structures. We assume Kelvin-Voigt damping in the two beams whose motions are coupled through a joint which includes an internal moment. The resulting equations of motion consist of four, second-order in time, partial differential equations, four second-order ordinary differential equations, and certain compatibility boundary conditions. The system is re-cast as an abstract second-order differential equation in an appropriate Hilbert space, consisting of function spaces describing the distributed beam deflections, and a finite-dimensional space that projects important features at the joint boundary. Semigroup theory is used to prove the system is well posed, and that with positive damping parameters the resulting semigroup is analytic and exponentially stable. The spectrum of the infinitesimal generator is characterized.

  20. A new optical image cryptosystem based on two-beam coherent superposition and unequal modulus decomposition

    NASA Astrophysics Data System (ADS)

    Chen, Linfei; Gao, Xiong; Chen, Xudong; He, Bingyu; Liu, Jingyu; Li, Dan

    2016-04-01

    In this paper, a new optical image cryptosystem is proposed based on two-beam coherent superposition and unequal modulus decomposition. Different from the equal modulus decomposition or unit vector decomposition, the proposed method applies common vector decomposition to accomplish encryption process. In the proposed method, the original image is firstly Fourier transformed and the complex function in spectrum domain will be obtained. The complex distribution is decomposed into two vector components with unequal amplitude and phase by the common vector decomposition method. Subsequently, the two components are modulated by two random phases and transformed from spectrum domain to spatial domain, and amplitude parts are extracted as encryption results and phase parts are extracted as private keys. The advantages of the proposed cryptosystem are: four different phase and amplitude information created by the method of common vector decomposition strengthens the security of the cryptosystem, and it fully solves the silhouette problem. Simulation results are presented to show the feasibility and the security of the proposed cryptosystem.

  1. Rf transfer in the Coupled-Cavity Free-Electron Laser Two-Beam Accelerator

    SciTech Connect

    Makowski, M.A.

    1991-01-01

    A significant technical problem associated with the Coupled-Cavity Free-Electron Laser Two-Beam Accelerator is the transfer of RF energy from the drive accelerator to the high-gradient accelerator. Several concepts have been advanced to solve this problem. This paper examines one possible solution in which the drive and high-gradient cavities are directly coupled to one another by means of holes in the cavity walls or coupled indirectly through a third intermediate transfer cavity. Energy cascades through the cavities on a beat frequency time scale which must be made small compared to the cavity skin time but large compared to the FEL pulse length. The transfer is complicated by the fact that each of the cavities in the system can support many resonant modes near the chosen frequency of operation. A generalized set of coupled-cavity equations has been developed to model the energy transfer between the various modes in each of the cavities. For a two cavity case transfer efficiencies in excess of 95% can be achieved. 3 refs., 2 figs.

  2. Horizontal geometrical reaction time model for two-beam nacelle LiDARs

    NASA Astrophysics Data System (ADS)

    Beuth, Thorsten; Fox, Maik; Stork, Wilhelm

    2015-06-01

    Wind energy is one of the leading sustainable energies. To attract further private and state investment in this technology, a broad scaled drop of the cost of energy has to be enforced. There is a trend towards using Laser Doppler Velocimetry LiDAR systems for enhancing power output and minimizing downtimes, fatigue and extreme forces. Since most used LiDARs are horizontally setup on a nacelle and work with two beams, it is important to understand the geometrical configuration which is crucial to estimate reaction times for the actuators to compensate wind gusts. In the beginning of this article, the basic operating modes of wind turbines are explained and the literature on wind behavior is analyzed to derive specific wind speed and wind angle conditions in relation to the yaw angle of the hub. A short introduction to the requirements for the reconstruction of the wind vector length and wind angle leads to the problem of wind shear detection of angled but horizontal homogeneous wind fronts due to the spatial separation of the measuring points. A distance is defined in which the wind shear of such homogeneous wind fronts is not present which is used as a base to estimate further distance calculations. The reaction time of the controller and the actuators are having a negative effect on the effective overall reaction time for wind regulation as well. In the end, exemplary calculations estimate benefits and disadvantages of system parameters for wind gust regulating LiDARs for a wind turbine of typical size. An outlook shows possible future improvements concerning the vertical wind behavior.

  3. Comparison of free-electron laser amplifiers based on a step-tapered optical klystron and a conventional tapered wiggler

    NASA Astrophysics Data System (ADS)

    Freund, H. P.

    2013-06-01

    Free-electron laser amplifiers have been operated at high efficiency at wavelengths from the microwave through the visible. Typically, these amplifiers require long tapered sections and produce spent beams with large energy spreads that are 4-5 times the electronic efficiency. In addition, while optical guiding during exponential growth in the uniform wiggler section confines the optical mode, the guiding disappears in the tapered wiggler section resulting in a relatively large optical mode at the wiggler exit. Optical klystrons consist of a Modulator wiggler that induces a velocity modulation on the electron beam followed by a magnetic dispersive section that enhances the velocity modulation prior to injection into a second, radiator wiggler. Optical klystrons have been operated over a broad spectral range; however, no optical klystron has been built with a tapered radiator wiggler. A comparison between a optical klystron with a step-tapered Radiator wiggler and a conventional tapered wiggler amplifier is analyzed in this paper. The purpose of the step taper is to both enhance the efficiency and to extend the range of the exponential gain and so preserve the optical guiding over a longer interaction length. The step-tapered optical klystron and a tapered wiggler amplifier are compared for a nominal set of parameters to determine the differences in the efficiency, interaction length, spent beam energy spread, and the size of the optical mode at the wiggler exit.

  4. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

    The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for trelativistic) Gaussian diffusion, for t>t{c} . Implications of this crossover between different diffusion regimes are discussed for some explicit examples. The study of such an explicit and simple Markov chain can shed some light on several results obtained in much more involved contexts. PMID:20866862

  5. SAMPEX Relativistic Microbursts Observation

    NASA Astrophysics Data System (ADS)

    Liang, X.; Comess, M.; Smith, D. M.; Selesnick, R. S.; Sample, J. G.; Millan, R. M.

    2012-12-01

    Relativistic (>1 MeV) electron microburst precipitation is thought to account for significant relativistic electron loss. We present the statistical and spectral analysis of relativistic microbursts observed by the Proton/Electron Telescope (PET) on board the Solar Anomalous Magnetospheric Particle Explorer(SAMPEX) satellite from 1992 to 2004. Spectrally we find that microbursts are well fit by an exponential energy distribution in the 0.5-4 MeV range with a spectral e-folding energy of E0 < 375 keV. We also discuss the comparison of morning microbursts with events at midnight, which were first identified as microbursts by O'Brien et al. (2004). Finally, we compare the loss-rates due to microbursts and non-microburst precipitation during storm times and averaged over all times.

  6. Relativistic nuclear dynamics

    SciTech Connect

    Coester, F.

    1985-01-01

    A review is presented of three distinct approaches to the construction of relativistic dynamical models: (1) Relativistic canonical quantum mechanics. (The Hilbert space of states is independent of the interactions, which are introduced by modifying the energy operator.) (2) Hilbert spaces of manifestly covariant wave functions. (The interactions modify the metric of the Hilbert space.) (3) Covariant Green functions. In each of the three approaches the focus is on the formulation of the two-body dynamics, and problems in the construction of the corresponding many-body dynamics are discussed briefly. 21 refs.

  7. Perspective: relativistic effects.

    PubMed

    Autschbach, Jochen

    2012-04-21

    This perspective article discusses some broadly-known and some less broadly-known consequences of Einstein's special relativity in quantum chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. The treatment of the electron correlation problem in relativistic quantum chemistry methods, and expanding the reach of the available relativistic methods to calculate all kinds of energy derivative properties, in particular spectroscopic and magnetic properties, requires on-going efforts. PMID:22519307

  8. An improved suppression method of the transverse-electromagnetic mode leakage with two reflectors in the triaxial klystron amplifier

    SciTech Connect

    Qi, Zumin; Zhang, Jun; Zhong, Huihuang; Zhang, Qiang; Zhu, Danni

    2014-07-15

    Suppression of the transverse-electromagnetic (TEM) mode leakage is crucial in the design of a triaxial klystron amplifier with high gain, because a small microwave leakage from the buncher or the output cavity could overwhelm the input signal with low power. In this paper, a specially designed reflector is proposed to suppress the TEM mode leakage, whose axial electric field is approximately zero at the beam radial position. Theoretical analysis indicates that the reflector introduces little influence on the normal modulation of the beam while keeping a high reflection coefficient. By using two such reflectors with different eigen frequencies located in front of the buncher cavity and the output cavity, respectively, an improved triaxial klystron amplifier is presented. The simulation results show that the reflectors substantially decrease the TEM mode leakage power and achieve very good isolation among the cavities. The improved triaxial klystron amplifier can operate normally with 10's kW microwave injection without self-oscillations.

  9. Broadband power amplifier tube: Klystron tube 5K70SK-WBT and step tuner VA-1470S

    NASA Technical Reports Server (NTRS)

    Cox, H. R.; Johnson, J. O.

    1974-01-01

    The design concept, the fabrication, and the acceptance testing of a wide band Klystron tube and remotely controlled step tuner for channel selection are discussed. The equipment was developed for the modification of an existing 20 KW Power Amplifier System which was provided to the contractor as GFE. The replacement Klystron covers a total frequency range of 2025 to 2120 MHz and is tuneable to six (6) each channel with a band width of 22 MHz or greater per channel. A 5 MHz overlap is provided between channels. Channels are selected at the control panel located in the front of the Klystron magnet or from one of three remote control stations connected in parallel with the step tuner. Included in this final report are the results of acceptance tests conducted at the vendor's plant and of the integrated system tests.

  10. An improved suppression method of the transverse-electromagnetic mode leakage with two reflectors in the triaxial klystron amplifier

    NASA Astrophysics Data System (ADS)

    Qi, Zumin; Zhang, Jun; Zhong, Huihuang; Zhang, Qiang; Zhu, Danni

    2014-07-01

    Suppression of the transverse-electromagnetic (TEM) mode leakage is crucial in the design of a triaxial klystron amplifier with high gain, because a small microwave leakage from the buncher or the output cavity could overwhelm the input signal with low power. In this paper, a specially designed reflector is proposed to suppress the TEM mode leakage, whose axial electric field is approximately zero at the beam radial position. Theoretical analysis indicates that the reflector introduces little influence on the normal modulation of the beam while keeping a high reflection coefficient. By using two such reflectors with different eigen frequencies located in front of the buncher cavity and the output cavity, respectively, an improved triaxial klystron amplifier is presented. The simulation results show that the reflectors substantially decrease the TEM mode leakage power and achieve very good isolation among the cavities. The improved triaxial klystron amplifier can operate normally with 10's kW microwave injection without self-oscillations.

  11. Relativistic impulse dynamics.

    PubMed

    Swanson, Stanley M

    2011-08-01

    Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion. PMID:21929132

  12. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  13. A relativistic spherical vortex

    PubMed Central

    Pekeris, C. L.

    1976-01-01

    This investigation is concerned with stationary relativistic flows of an inviscid and incompressible fluid. In choosing a density-pressure relation to represent relativistic “incompressibility,” it is found that a fluid in which the velocity of sound equals the velocity of light is to be preferred for reasons of mathematical simplicity. In the case of axially symmetric flows, the velocity field can be derived from a stream function obeying a partial differential equation which is nonlinear. A transformation of variables is found which makes the relativistic differential equation linear. An exact solution is obtained for the case of a vortex confined to a stationary sphere. One can make all three of the components of velocity vanish on the surface of the sphere, as in the nonrelativistic Hicks spherical vortex. In the case of an isolated vortex on whose surface the pressure is made to vanish, it is found that the pressure at the center of the sphere becomes negative, as in the nonrelativistic case. A solution is also obtained for a relativistic vortex advancing in a fluid. The sphere is distorted into an oblate spheroid. The maximum possible velocity of advance of the vortex is (2/3) c. PMID:16578745

  14. The Relativistic Rocket

    ERIC Educational Resources Information Center

    Antippa, Adel F.

    2009-01-01

    We solve the problem of the relativistic rocket by making use of the relation between Lorentzian and Galilean velocities, as well as the laws of superposition of successive collinear Lorentz boosts in the limit of infinitesimal boosts. The solution is conceptually simple, and technically straightforward, and provides an example of a powerful…

  15. A novel technique for tuning of co-axial cavity of multi-beam klystron

    NASA Astrophysics Data System (ADS)

    Saha, Sukalyan; Bandyopadhyay, Ayan Kumar; Pal, Debashis; Kant, Deepender; Joshi, Lalit Mohan; Kumar, Bijendra; Meena, Rakesh; Rawat, Vikram

    2016-03-01

    Multi-beam Klystrons (MBKs) have gained wide acceptances in the research sector for its inherent advantages. But developing a robust tuning technique for an MBK cavity of coaxial type has still remained a challenge as these designs are very prone to suffer from asymmetric field distribution with inductive tuning of the cavity. Such asymmetry leads to inhomogeneous beam-wave interaction, an undesirable phenomenon. Described herein is a new type of coaxial cavity that has the ability to suppress the asymmetry, thereby allowing tuning of the cavity with a single tuning post.

  16. Hyperbolic chaos in the klystron-type microwave vacuum tube oscillator.

    PubMed

    Emel'yanov, V V; Kuznetsov, S P; Ryskin, N M

    2010-12-01

    The ring-loop oscillator consisting of two coupled klystrons which is capable of generating hyperbolic chaotic signal in the microwave band is considered. The system of delayed-differential equations describing the dynamics of the oscillator is derived. This system is further reduced to the two-dimensional return map under the assumption of the instantaneous build-up of oscillations in the cavities. The results of detailed numerical simulation for both models are presented showing that there exists large enough range of control parameters where the sustained regime corresponds to the structurally stable hyperbolic chaos. PMID:21198074

  17. Suppression of third-order intermodulation in a klystron by third-order injection.

    PubMed

    Bhattacharjee, S; Marchewka, C; Welter, J; Kowalczyk, R; Wilsen, C B; Lau, Y Y; Booske, J H; Singh, A; Scharer, J E; Gilgenbach, R M; Neumann, M J; Keyser, M W

    2003-03-01

    The first observations and measurements are reported on suppression of the third-order intermodulation (IM3) product arising from nonlinear mixing of two drive frequencies in a klystron, by externally injecting a wave at the IM3 product frequency. Optimum amplitude and phase of the injected wave for maximum suppression are examined. Results indicate that suppression of the IM3 product by as much as 30 dB can be achieved. Experimental results compare favorably with predictions of a 1D simulation code that takes into account all kinematical and dynamical effects including charge overtaking and space charge forces. PMID:12689260

  18. Nonlinear, nonlaminar - 3D computation of electron motion through the output cavity of a klystron.

    NASA Technical Reports Server (NTRS)

    Albers, L. U.; Kosmahl, H. G.

    1971-01-01

    The accurate computation is discussed of electron motion throughout the output cavity of a klystron amplifier. The assumptions are defined whereon the computation is based, and the equations of motion are reviewed, along with the space charge fields derived from a Green's function potential of a solid cylinder. The integration process is then examined with special attention to its most difficult and important aspect - namely, the accurate treatment of the dynamic effect of space charge forces on the motion of individual cell rings of equal volume and charge. The correct treatment is demonstrated upon four specific examples, and a few comments are given on the results obtained.-

  19. Towards a PEBB-Based Design Approach for a Marx-Topology ILC Klystron Modulator

    SciTech Connect

    Macken, K

    2009-10-17

    Introduced by the U.S. Navy more than a decade ago, the concept of Power Electronic Building Blocks (PEBBs) has been successfully applied in various applications. It is well accepted within the power electronics arena that this concept offers the potential to achieve increased levels of modularity and compactness. This approach is thus ideally suited for applications where easy serviceability and high availability are key, such as the ILC. This paper presents a building block approach for designing a Marx-topology ILC klystron modulator.

  20. Design And Construction of a W-Band Sheet Beam Klystron

    SciTech Connect

    Scheitrum, G.; /SLAC

    2006-02-14

    The design and construction of a 100 kW peak power, 2% duty, PCM focused, Wband sheet beam klystron is discussed. The elliptical cross section beam is produced by a new electron gun design using a cylindrical cathode and a racetrack shaped focus electrode. The multi-gap cavities produce acceptable values of R/Q and are designed to produce a uniform electric field over the width of the 12:1 aspect ratio beam. The prototype cavities are produced using normal machining however, LIGA will be used to fabricate the cavities in production versions.

  1. FEL and Optical Klystron Gain for an Electron Beam with Oscillatory Energy Distribution

    SciTech Connect

    Stupakov, G.; Ding, Y.; Huang, Z.; /SLAC

    2009-12-09

    If the energy spread of a beam is larger then the Pierce parameter, the FEL gain length increases dramatically and the FEL output gets suppressed. We show that if the energy distribution of such a beam is made oscillatory on a small scale, the gain length can be considerably decreased. Such an oscillatory energy distribution is generated by first modulating the beam energy with a laser via the mechanism of inverse FEL, and then sending it through a strong chicane. We show that this approach also works for the optical klystron enhancement scheme. Our analytical results are corroborated by numerical simulations.

  2. Hyperbolic chaos in the klystron-type microwave vacuum tube oscillator

    NASA Astrophysics Data System (ADS)

    Emel'yanov, V. V.; Kuznetsov, S. P.; Ryskin, N. M.

    2010-12-01

    The ring-loop oscillator consisting of two coupled klystrons which is capable of generating hyperbolic chaotic signal in the microwave band is considered. The system of delayed-differential equations describing the dynamics of the oscillator is derived. This system is further reduced to the two-dimensional return map under the assumption of the instantaneous build-up of oscillations in the cavities. The results of detailed numerical simulation for both models are presented showing that there exists large enough range of control parameters where the sustained regime corresponds to the structurally stable hyperbolic chaos.

  3. Relativistic effects on plasma expansion

    SciTech Connect

    Benkhelifa, El-Amine; Djebli, Mourad

    2014-07-15

    The expansion of electron-ion plasma is studied through a fully relativistic multi-fluids plasma model which includes thermal pressure, ambipolar electrostatic potential, and internal energy conversion. Numerical investigation, based on quasi-neutral assumption, is performed for three different regimes: nonrelativistic, weakly relativistic, and relativistic. Ions' front in weakly relativistic regime exhibits spiky structure associated with a break-down of quasi-neutrality at the expanding front. In the relativistic regime, ion velocity is found to reach a saturation limit which occurs at earlier stages of the expansion. This limit is enhanced by higher electron velocity.

  4. Dynamics of relativistic jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Frank, J.; Christodoulou, D. M.; Koide, S.; Sakai, J.-I.; Sol, Hélène; Mutel, Robert L.

    1998-12-01

    We discuss the structure and relativistic kinematics that develop in three spatial dimensions when a moderately hot, supersonic jet propagates into a denser background medium and encounters resistance from an oblique magnetic field. Our simulations incorporate relativistic MHD in a four-dimensional spacetime and clearly show that (a) relatively weak, oblique fields (at 1/16 of the equipartition value) have only a negligible influence on the propagating jet and they are passively pushed away by the relativistically moving head; (b) oblique fields in equipartition with the ambient plasma provide more resistance and cause bending at the jet head, but the magnitude of this deflection and the associated backflow are small compared to those identified by previous studies. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently during the simulations. The effect is analogous to pushing Japanese "noren" or vertical Venetian blinds out of the way while the slats are allowed to bend and twist in 3-D space. Applied to relativistic extragalactic jets from blazars, the new results are encouraging since superluminal outflows exhibit bending near their sources and their environments are profoundly magnetized - but observations do not provide support for irregular kinematics such as large-scale vortical motions and pronounced reverse flows near the points of origin.

  5. A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION

    SciTech Connect

    W.A. REASS; J.D. DOSS; R.F. GRIBBLE

    2001-06-01

    This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented.

  6. Ultra Stable Capacitor charging Power Supply of Klystron-Modulator for PAL XFEL

    SciTech Connect

    Son, Y. G.; Kwon, S. J.; Jang, S. D.; Suh, J. H.; Oh, J. S.

    2007-01-19

    The PAL (Pohang Accelerator Laboratory) 2.5-GeV linac is planed to be converted to a SASE-XFEL facility (PAL XFEL) that supplies coherent X-rays down to 0.3-nm wavelength. The electron beams has to have an emittance of 1.0 mm-mrad, a peak current of 3 kA, and a low energy spread of 1.0 MeV. In order to provide reasonably stable SASE output, the RF stability of 0.02% rms is required for both RF phase and amplitude. This stability is mainly determined by a low level RF drive system and klystron-modulators. The stability level of the modulator has to be improved 10 times better to meet the pulse stability of 0.02%. This is a technologically challenging issue for PAL XFEL. An inverter technology is to be applied to charge the PFN of a new modulator. Therefore, a new inverter system should provide very stable charging performances. This paper presents the development of an ultra stable klystron-modulator with an inverter power.

  7. Three-dimensional particle-in-cell simulations of 300 GHz reflex klystrons

    SciTech Connect

    Jeon, S. G.; Jin, Y. S.; Kim, J. I.; Kim, G. J.; Shon, C. H.

    2007-03-01

    Three-dimensional (3D) particle-in-cell simulations of 300 GHz reflex klystrons are presented. 300 GHz electromagnetic wave generation in a resonant cavity is analyzed by using a 3D simulation model in which all the geometric parameters (such as the grid thickness, repeller shape, beam radius, etc.) are described. When an electron beam of an energy of 1.0 keV and a net current of 8.9 mA is used, the maximum electronic efficiency of energy transfer is observed when the gap transit angle is 0.7{pi} rad, and the efficiency saturates when the beam current is over 10 mA. Space charge forces produce a shift in the optimum repeller voltage. It is also shown that the effect of the beam temperature is not critical, even though the bunching wavelength of the electron beam is several times smaller than that in conventional vacuum electron devices. Our simulation results show that a microfabricated 300 GHz reflex klystron can directly generate electromagnetic waves with output power levels of several tens of milliwatts.

  8. Relativistic radiative transfer and relativistic plane-parallel flows

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2015-04-01

    Relativistic radiative transfer and relativistic plane-parallel flows accelerated from their base like accretion disk winds are numerically examined under the special relativistic treatment. We first solve the relativistic transfer equation iteratively, using a given velocity field, and obtain specific intensities as well as moment quantities. Using the obtained flux, we then solve the hydrodynamical equation, and obtain the new velocity field and the mass-loss rate as an eigen value. We repeat these double-iteration processes until both the intensity and velocity profiles converge. Under this double iteration, we solve the relativistic radiative transfer equation and relativistic flows in the vertical direction, simultaneously. The flows are gradually accelerated, as the optical depth decreases towards the surface. The mass-loss rate dot{J} is roughly expressed in terms of the optical depth τb and terminal speed βs of the flow as dot{J} ˜ 10 τ_b β _s^{-3/4}.

  9. Local relativistic exact decoupling.

    PubMed

    Peng, Daoling; Reiher, Markus

    2012-06-28

    We present a systematic hierarchy of approximations for local exact decoupling of four-component quantum chemical Hamiltonians based on the Dirac equation. Our ansatz reaches beyond the trivial local approximation that is based on a unitary transformation of only the atomic block-diagonal part of the Hamiltonian. Systematically, off-diagonal Hamiltonian matrix blocks can be subjected to a unitary transformation to yield relativistically corrected matrix elements. The full hierarchy is investigated with respect to the accuracy reached for the electronic energy and for selected molecular properties on a balanced test molecule set that comprises molecules with heavy elements in different bonding situations. Our atomic (local) assembly of the unitary exact-decoupling transformation--called local approximation to the unitary decoupling transformation (DLU)--provides an excellent local approximation for any relativistic exact-decoupling approach. Its order-N(2) scaling can be further reduced to linear scaling by employing a neighboring-atomic-blocks approximation. Therefore, DLU is an efficient relativistic method well suited for relativistic calculations on large molecules. If a large molecule contains many light atoms (typically hydrogen atoms), the computational costs can be further reduced by employing a well-defined nonrelativistic approximation for these light atoms without significant loss of accuracy. We also demonstrate that the standard and straightforward transformation of only the atomic block-diagonal entries in the Hamiltonian--denoted diagonal local approximation to the Hamiltonian (DLH) in this paper--introduces an error that is on the order of the error of second-order Douglas-Kroll-Hess (i.e., DKH2) when compared with exact-decoupling results. Hence, the local DLH approximation would be pointless in an exact-decoupling framework, but can be efficiently employed in combination with the fast to evaluate DKH2 Hamiltonian in order to speed up calculations

  10. Development of a high-power solid-state switch using static induction thyristors for a klystron modulator

    NASA Astrophysics Data System (ADS)

    Tokuchi, Akira; Kamitsukasa, Fumiyoshi; Furukawa, Kazuya; Kawase, Keigo; Kato, Ryukou; Irizawa, Akinori; Fujimoto, Masaki; Osumi, Hiroki; Funakoshi, Sousuke; Tsutsumi, Ryouta; Suemine, Shoji; Honda, Yoshihide; Isoyama, Goro

    2015-01-01

    We developed a solid-state switch with static induction thyristors for the klystron modulator of the L-band electron linear accelerator (linac) at the Institute of Scientific and Industrial Research, Osaka University. This switch is designed to have maximum specifications of a holding voltage of 25 kV and a current of 6 kA at the repetition frequency of 10 Hz for forced air cooling. The turn-on time of the switch was measured with a matched resistor to be 270 ns, which is sufficiently fast for the klystron modulator. The switch is retrofitted in the modulator to generate 1.3 GHz RF pulses with durations of either 4 or 8 μs using a 30 MW klystron, and the linac is successfully operated under maximum conditions. This finding demonstrates that the switch can be used as a high-power switch for the modulator. Pulse-to-pulse variations of the klystron voltage are measured to be less than 0.015%, and those of RF power and phase are lower than 0.15% and 0.1°, respectively. These values are significantly smaller than those obtained with a thyratron; hence, the stability of the main RF system is improved. The solid-state switch has been used in normal operation of the linac for more than a year without any serious trouble. Thus, we confirmed the switch's robustness and long-term reliability.

  11. Test and Development of a 10 MW 1.3 GHz Sheet Beam Klystron for the ILC

    SciTech Connect

    Sprehn, Daryl; Haase, Andrew; Jensen, Aaron; Jongewaard, Erik; Martin, David; /SLAC

    2012-07-03

    The SLAC National Accelerator Laboratory Klystron Department is developing a 10 MW, 5 Hz, 1.6 ms, 1.3 GHz plug-compatible Sheet-Beam Klystron as a less expensive and more compact alternative to the ILC baseline Multiple-Beam Klystron. Earlier this year a beam tester was constructed and began test. Device fabrication issues have complicated the analysis of the data collected from an intercepting cup for making beam quality measurements of the 130 A, 40-to-1 aspect ratio beam. Since the goal of the beam tester is to confirm 3d beam simulations it was necessary to rebuild the device in order to mitigate unwanted effects due to imperfect focusing construction. Measurements are underway to verify the results of this latest incarnation. Measurement will then be made of the beam after transporting through a drift tube and magnetic focusing system. In the klystron design, a TE oscillation was discovered during long simulation runs of the entire device which has since prompted two design changes to eliminate the beam disruption. The general theory of operation, the design choices made, and results of testing of these various devices will be discussed.

  12. Optimization of the permanent magnet optical klystron for the SUPER-ACO storage ring free electron laser

    NASA Astrophysics Data System (ADS)

    Couprie, M. E.; Bazin, C.; Billardon, M.

    1989-06-01

    A permanent magnet optical klystron has been optimized for free electron laser experiments and optical harmonic generation on the new storage ring SUPER-ACO at Orsay. The conditions of the optimization and the different steps of the field characterization measurements of this insertion device are discussed. Its effects on the stored beam and the undulator radiation measurements are described.

  13. Relativistic tidal disruption events

    NASA Astrophysics Data System (ADS)

    Levan, A.

    2012-12-01

    In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like) galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s-1 at peak), rapid X-ray variability (factors of >100 on timescales of 100 seconds) and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ˜ 2 - 5), created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  14. Point form relativistic quantum mechanics and relativistic SU(6)

    NASA Technical Reports Server (NTRS)

    Klink, W. H.

    1993-01-01

    The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.

  15. Relativistic kinetic theory of magnetoplasmas

    SciTech Connect

    Beklemishev, Alexei; Nicolini, Piero; Tessarotto, Massimo

    2005-05-16

    Recently, an increasing interest in astrophysical as well as laboratory plasmas has been manifested in reference to the existence of relativistic flows, related in turn to the production of intense electric fields in magnetized systems. Such phenomena require their description in the framework of a consistent relativistic kinetic theory, rather than on relativistic MHD equations, subject to specific closure conditions. The purpose of this work is to apply the relativistic single-particle guiding-center theory developed by Beklemishev and Tessarotto, including the nonlinear treatment of small-wavelength EM perturbations which may naturally arise in such systems. As a result, a closed set of relativistic gyrokinetic equations, consisting of the collisionless relativistic kinetic equation, expressed in hybrid gyrokinetic variables, and the averaged Maxwell's equations, is derived for an arbitrary four-dimensional coordinate system.

  16. Relativistic interactions and realistic applications

    SciTech Connect

    Hoch, T.; Madland, D.; Manakos, P.; Mannel, T.; Nikolaus, B.A.; Strottman, D. |

    1992-12-31

    A four-fermion-coupling Lagrangian (relativistic Skyrme-type) interaction has been proposed for relativistic nuclear structure calculations. This interaction, which has the merit of simplicity, is from the outset tailored as an effective interaction for relativistic Hartree-Fock calculations. Various extensions of such a model are discussed and compared with Walecka`s meson-nucleon mean field approach. We also present results of the calculation of nuclear ground state properties with an extended (density dependent) version of the four fermion interaction in a relativistic Hartree-Fock approximation.

  17. Relativistic Quantum Communication

    NASA Astrophysics Data System (ADS)

    Hosler, Dominic

    In this Ph.D. thesis, I investigate the communication abilities of non-inertial observers and the precision to which they can measure parametrized states. I introduce relativistic quantum field theory with field quantisation, and the definition and transformations of mode functions in Minkowski, Schwarzschild and Rindler spaces. I introduce information theory by discussing the nature of information, defining the entropic information measures, and highlighting the differences between classical and quantum information. I review the field of relativistic quantum information. We investigate the communication abilities of an inertial observer to a relativistic observer hovering above a Schwarzschild black hole, using the Rindler approximation. We compare both classical communication and quantum entanglement generation of the state merging protocol, for both the single and dual rail encodings. We find that while classical communication remains finite right up to the horizon, the quantum entanglement generation tends to zero. We investigate the observers' abilities to precisely measure the parameter of a state that is communicated between Alice and Rob. This parameter was encoded to either the amplitudes of a single excitation state or the phase of a NOON state. With NOON states the dual rail encoding provided greater precision, which is different to the results for the other situations. The precision was maximum for a particular number of excitations in the NOON state. We calculated the bipartite communication for Alice-Rob and Alice-AntiRob beyond the single mode approximation. Rob and AntiRob are causally disconnected counter-accelerating observers. We found that Alice must choose in advance with whom, Rob or AntiRob she wants to create entanglement using a particular setup. She could communicate classically to both.

  18. Frequency agile relativistic magnetrons

    SciTech Connect

    Levine, J.S.; Harteneck, B.D.; Price, H.D.

    1995-11-01

    The authors are developing a family of frequency agile relativistic magnetrons to continuously cover the bands from 1 to 3 GHz. They have achieved tuning ranges of > 33%. The magnetrons have been operated repetitively in burst mode at rates up to 100 pps for 10 sec. Power is extracted from two resonators, and is in the range of 400--600 MW, fairly flat across the tuning bandwidth. They are using a network of phase shifters and 3-dB hybrids to combine the power into a single arm and to provide a continuously adjustable attenuator.

  19. Republication of: Relativistic cosmology

    NASA Astrophysics Data System (ADS)

    Robertson, H. P.

    2012-08-01

    This is a reprinting of the paper by Howard Percy Robertson, first published in 1933 in Rev. Mod. Phys., that is a very authoritative summary of relativistic cosmology at the stage at which it was up to 1933. The paper has been selected by the Editors of General Relativity and Gravitation for re-publication in the Golden Oldies series of the journal. This republication is accompanied by an editorial note written by George Ellis, and by Robertson's biography, compiled by Andrzej Krasinski from printed sources.

  20. Newtonian and relativistic cosmologies

    NASA Astrophysics Data System (ADS)

    Green, Stephen R.; Wald, Robert M.

    2012-03-01

    Cosmological N-body simulations are now being performed using Newtonian gravity on scales larger than the Hubble radius. It is well known that a uniformly expanding, homogeneous ball of dust in Newtonian gravity satisfies the same equations as arise in relativistic Friedmann-Lemaître-Robinson-Walker cosmology, and it also is known that a correspondence between Newtonian and relativistic dust cosmologies continues to hold in linearized perturbation theory in the marginally bound/spatially flat case. Nevertheless, it is far from obvious that Newtonian gravity can provide a good global description of an inhomogeneous cosmology when there is significant nonlinear dynamical behavior at small scales. We investigate this issue in the light of a perturbative framework that we have recently developed [S. R. Green and R. M. Wald, Phys. Rev. DPRVDAQ1550-7998 83, 084020 (2011).10.1103/PhysRevD.83.084020], which allows for such nonlinearity at small scales. We propose a relatively straightforward dictionary—which is exact at the linearized level—that maps Newtonian dust cosmologies into general relativistic dust cosmologies, and we use our “ordering scheme” to determine the degree to which the resulting metric and matter distribution solve Einstein’s equation. We find that, within our ordering scheme, Einstein’s equation fails to hold at “order 1” at small scales and at “order ɛ” at large scales. We then find the additional corrections to the metric and matter distribution needed to satisfy Einstein’s equation to these orders. While these corrections are of some interest in their own right, our main purpose in calculating them is that their smallness should provide a criterion for the validity of the original dictionary (as well as simplified versions of this dictionary). We expect that, in realistic Newtonian cosmologies, these additional corrections will be very small; if so, this should provide strong justification for the use of Newtonian simulations

  1. Relativistic nuclear collisions: theory

    SciTech Connect

    Gyulassy, M.

    1980-07-01

    Some of the recent theoretical developments in relativistic (0.5 to 2.0-GeV/nucleon) nuclear collisions are reviewed. The statistical model, hydrodynamic model, classical equation of motion calculations, billiard ball dynamics, and intranuclear cascade models are discussed in detail. Inclusive proton and pion spectra are analyzed for a variety of reactions. Particular attention is focused on how the complex interplay of the basic reaction mechanism hinders attempts to deduce the nuclear matter equation of state from data. 102 references, 19 figures.

  2. Ultrabaric relativistic superfluids

    NASA Astrophysics Data System (ADS)

    Papini, G.; Weiss, M.

    1985-09-01

    Ultrabaric superfluid solutions are obtained for Einstein's equations to examine the possibility of the existence of superluminal sound speeds. The discussion is restricted only by requiring the energy-momentum tensor and the equation of state of matter to be represented by full relativistic equations. Only a few universes are known to satisfy the conditions, and those exhibit tension and are inflationary. Superluminal sound velocities are shown, therefore, to be possible for the interior Schwarzchild metric, which has been used to explain the red shift of quasars, and the Stephiani solution (1967). The latter indicates repeated transitions between superluminal and subliminal sound velocities in the hyperbaric superfluid of the early universe.

  3. Modeling relativistic nuclear collisions.

    SciTech Connect

    Anderlik, C.; Magas, V.; Strottman, D.; Csernai, L. P.

    2001-01-01

    Modeling Ultra-Relativistic Heavy Ion Collisioiis at RHIC and LHC energies using a Multi Module Model is presented. The first Module is the Effective String Rope Model for the calculation of the initial stages of the reaction; the output of this module is used as the initial state for the subsequent one-fluid hydrodynainical calculation module. It is shown that such an initial state leads to the creation of the third flow component. The hydrodynamical evolution of the energy density distribution is presented for RHIC energies. The final module describing the Freeze Out; and Hadronization is also discussed.

  4. Parametric analysis of micromachined reflex klystrons for operation at millimeter and submillimeter wavelengths

    NASA Astrophysics Data System (ADS)

    García-García, J.; Martín, F.; Miles, R. E.; Steenson, D. P.; Chamberlain, J. M.; Fletcher, J. R.; Thorpe, J. R.

    2002-12-01

    A tool for the simulation of high frequency reflex klystrons is presented. Based on the Monte Carlo technique, this simulation includes loss mechanisms (due to the opacity of the grids) and takes into account the main peculiarities expected for device operation at millimeter and submillimeter wave frequencies. The tool has been used to study the effects of device parameters which are critical to the optimization of output power in a prototype 100 GHz micromachined structure based on a field emission electron source, namely, the electric field in the drift region and the grid distance. The results also show that this device can be used for direct generation of useful amounts of power at these frequencies.

  5. Pulse propagation and optical-klystron free-electron-laser devices.

    PubMed

    Dattoli, G; Mezi, L; Bucci, L

    2000-06-01

    We derive the equation governing the evolution of the optical field amplitude of a free-electron-laser oscillator operating in the optical-klystron configuration. The equation includes short pulse effects, due to the finite length of the electron bunches, and are valid under the assumption of small signal regime and low gain. Stationary solutions of the supermode type, analogous to those of conventional free-electron-laser configurations, are shown to exist for this case, too. Analytical expressions for the optical pulse shape are derived, without any assumption of dominance of the dispersive section, in the case of the long bunch regime, namely when the bunch length is larger than the slippage length. We present useful gain formulas, including the combined effect of dispersive section and pulse effects, and discuss the limits of validity of our treatment. PMID:11088401

  6. Start-to-end modelling of a mode-locked optical klystron free electron laser amplifier

    SciTech Connect

    Dunning, D. J.; Thompson, N. R.; Mc Neil, B. W. J.; Williams, P. H.

    2011-07-15

    A free electron laser (FEL) in a mode-locked optical klystron (MLOK) configuration is modelled using start-to-end simulations that simulate realistic electron beam acceleration and transport before input into a full three-dimensional FEL simulation code. These simulations demonstrate that the MLOK scheme is compatible with the present generation of radiofrequency accelerator designs. A train of few-optical cycle pulses is predicted with peak powers similar to those of the equivalent conventional FEL amplifier. The role of electron beam energy modulation in these results is explained and the limitations of some simulation codes discussed. It is shown how seeding the FEL interaction using a High Harmonic seed laser can improve the coherence properties of the output.

  7. A Simple Relativistic Bohr Atom

    ERIC Educational Resources Information Center

    Terzis, Andreas F.

    2008-01-01

    A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…

  8. Nonlinear optics in relativistic plasmas.

    PubMed

    Umstadter, D; Chen, S Y; Wagner, R; Maksimchuk, A; Sarkisov, G

    1998-03-30

    We review our recent work on the various nonlinear optical processes that occur as an intense laser propagates through a relativistic plasma. These include the experimental observations of electron acceleration driven by laser-wakefield generation, relativistic self-focusing, waveguide formation and laser self-channeling. PMID:19377614

  9. relline: Relativistic line profiles calculation

    NASA Astrophysics Data System (ADS)

    Dauser, Thomas

    2015-05-01

    relline calculates relativistic line profiles; it is compatible with the common X-ray data analysis software XSPEC (ascl:9910.005) and ISIS (ascl:1302.002). The two basic forms are an additive line model (RELLINE) and a convolution model to calculate relativistic smearing (RELCONV).

  10. Two-beam coupling correlation synthetic aperture radar image recognition with power-law scattering centers pre-enhancement

    NASA Astrophysics Data System (ADS)

    Haji-saeed, Bahareh; Khoury, Jed; Woods, Charles L.; Kierstead, John

    2008-03-01

    Synthetic radar image recognition is an area of interest for military applications including automatic target recognition, air traffic control, and remote sensing. Here a dynamic range compression two-beam coupling joint transform correlator for detecting synthetic aperture radar (SAR) targets is utilized. The joint input image consists of a pre-power-law, enhanced scattering center of the input image and a linearly synthesized power-law enhanced scattering center template. Enhancing the scattering center of both the synthetic template and the input image furnishes the conditions for achieving dynamic range compression correlation in two-beam coupling. Dynamic range compression: (a) enhances the signal to noise ratio, (b) enhances the high frequencies relative to low frequencies, and (c) converts the noise to high frequency components. This improves the correlation peak intensity to the mean of the surrounding noise significantly. Dynamic range compression correlation has already been demonstrated to outperform many optimal correlation filters in detecting signals in severe noise environments. The performance is evaluated via established metrics, such as peak-to-correlation energy (PCE), Horner efficiency and correlation peak intensity. The results showed significant improvement as the power increased.

  11. Two-beam Laser Brazing of Thin Sheet Steel for Automotive Industry Using Cu-base Filler Material

    NASA Astrophysics Data System (ADS)

    Mittelstädt, C.; Seefeld, T.; Reitemeyer, D.; Vollertsen, F.

    This work shows the potential of two-beam laser brazing for joining both Zn-coated steel and 22MnB5. Brazing of Zn-coated steel sheets using Cu-Si filler wire is already state of the art in car manufacturing. New press-hardened steels like 22MnB5 are more and more used in automotive industry, offering high potential to save costs and improve structural properties (reduced weight / higher stiffness). However, for joining of these ultra-high strength steels investigations are mandatory. In this paper, a novel approach using a two-beam laser brazing process and Cu-base filler material is presented. The use of Cu-base filler material leads to a reduced heat input, compared to currently applied welding processes, which may result in benefits concerning distortion, post processing and tensile strength of the joint. Reliable processing at desired high speeds is attained by means of laser-preheating. High feed rates prevent significant diffusion of copper into the base material.

  12. Relativistic jets in astrophysics

    NASA Astrophysics Data System (ADS)

    Derishev, E. V.; Zheleznyakov, V. V.; Koryagin, S. A.; Kocharovsky, Vl. V.

    The properties of the plasma state of matter are determined by the motion and the electromagnetic emission of the non-bound electrically charged particles --- electrons, positrons, protons and ions. It is not easy to create plasma in a laboratory. However this state is typical for the cosmic conditions --- at the stars and in the interstellar space. The properties of the laboratory as well as the space plasma are investigated at the Institute of Applied Physics of the Russian Academy of Sciences. The research is focused on the mechanisms of generation and propagation of the electromagnetic radiation --- from the radio waves to the gamma-rays --- in the planetary and stellar atmospheres and at the other astrophysical objects. The extreme physical conditions for a plasma are realized near the compact objects like black holes, neutron stars and collapsing nuclei of the massive stars. The plasma could be strongly non-equlibrium and can produce strong electromagnetic fields. Its bulk motion as well as the chaotic motion of the constituting particles can be relativistic, i. e. the motion can achieve velocities close to the speed of light. The relativistic plasma is frequently observed in the form of jets.

  13. A relativistic trolley paradox

    NASA Astrophysics Data System (ADS)

    Matvejev, Vadim N.; Matvejev, Oleg V.; Grøn, Ø.

    2016-06-01

    We present an apparent paradox within the special theory of relativity, involving a trolley with relativistic velocity and its rolling wheels. Two solutions are given, both making clear the physical reality of the Lorentz contraction, and that the distance on the rails between each time a specific point on the rim touches the rail is not equal to 2 π R , where R is the radius of the wheel, but 2 π R / √{ 1 - R 2 Ω 2 / c 2 } , where Ω is the angular velocity of the wheels. In one solution, the wheel radius is constant as the velocity of the trolley increases, and in the other the wheels contract in the radial direction. We also explain two surprising facts. First that the shape of a rolling wheel is elliptical in spite of the fact that the upper part of the wheel moves faster than the lower part, and thus is more Lorentz contracted, and second that a Lorentz contracted wheel with relativistic velocity rolls out a larger distance between two successive touches of a point of the wheel on the rails than the length of a circle with the same radius as the wheels.

  14. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  15. Relativistic Continuum Shell Model

    NASA Astrophysics Data System (ADS)

    Grineviciute, Janina; Halderson, Dean

    2011-04-01

    The R-matrix formalism of Lane and Thomas has been extended to the relativistic case so that the many-coupled channels problem may be solved for systems in which binary breakup channels satisfy a relative Dirac equation. The formalism was previously applied to the relativistic impulse approximation RIA and now we applied it to Quantum Hadrodynamics QHD in the continuum Tamm-Dancoff approximation TDA with the classical meson fields replaced by one-meson exchange potentials. None of the published QHD parameters provide a decent fit to the 15 N + p elastic cross section. The deficiency is also evident in inability of the QHD parameters with the one meson exchange potentials to reproduce the QHD single particle energies. Results with alternate parameters sets are presented. A. M. Lane and R. G. Thomas, R-Matrix Theory of Nuclear Reactions, Reviews of Modern Physics, 30 (1958) 257

  16. Role of dc space charge field in the optimization of microwave conversion efficiency from a modulated intense relativistic electron beam

    SciTech Connect

    Xiao, Renzhen; Chen, Changhua; Wu, Ping; Song, Zhimin; Sun, Jun

    2013-12-07

    We demonstrate an efficiency of 70% with 5.1 GW microwave power for a diode voltage of 770 kV and a current modulation coefficient of 1.67 in a klystron-like relativistic backward wave oscillator. The device combines the advantages of reducing electron beam radius, adopting dual-cavity extractor, and introducing two pre-modulation cavities. A large dc space charge field is present due to the conversion of considerable potential energy to kinetic energy at the end of beam-wave interaction region. A nonlinear theory is developed to show that the dc space charge field can increase the current modulation coefficient and microwave conversion efficiency significantly.

  17. Relativistic astrophysics explorer

    NASA Astrophysics Data System (ADS)

    Kaaret, P.

    2004-01-01

    The great success of the Rossi X-Ray Timing Explorer (RXTE) has shown that X-ray timing is an excellent tool for the study of strong gravitational fields and the measurement of fundamental physical properties of black holes and neutron stars. Here, we describe a next-generation X-ray timing mission, the Relativistic Astrophysics Explorer (RAE), designed to fit within the envelope of a medium-sized mission. The instruments will be a narrow-field X-ray detector array with an area of 6 m 2 equal to 10 times that of RXTE and a wide-field X-ray monitor. We describe the science made possible with this mission, the design of the instruments, and results on prototype large-area X-ray detectors.

  18. The Relativistic Astrophysics Explorer

    NASA Astrophysics Data System (ADS)

    Kaaret, P.

    The great success of the Rossi X-Ray Timing Explorer (RXTE) has shown that X-ray timing is an excellent tool for the study of strong gravitational fields and the measurement of fundamental physical properties of black holes and neutron stars. Here, we describe a next-generation X-ray timing mission, the Relativistic Astrophysics Explorer (RAE), designed to fit within the envelope of a medium-sized mission. The instruments will be a narrow-field X-ray detector array with an area of 60,000 cm2 equal to ten times that of RXTE and a wide-field X-ray monitor. We describe the science made possible with this mission, the design of the instruments, and results on prototype large-area X-ray detectors.

  19. Relativistic Jets in Collapsars

    NASA Astrophysics Data System (ADS)

    Zhang, Weiqun; Woosley, S. E.; MacFadyen, A. I.

    2003-04-01

    We examine the propagation of two-dimensional relativistic jets through the stellar progenitor in the collapsar model for gamma-ray bursts. In agreement with previous studies, we find that the jet is collimated by its passage. Moreover, interaction of the jet with the star causes mixing that sporadically decelerates the jet, leading to a highly variable Lorentz factor. The jet that finally emerges has a moderate Lorentz factor, but a very large internal energy loading. In a second series of calculations we follow the emergence of such enegy-loaded jets from the star. For the initial conditions chosen, conversion of the remaining internal energy gives a terminal Lorentz factor of approximately 150. Implications of our calculations for GRB light curves, the luminosity-variability relation, and the GRB-supernova association are discussed.

  20. Photodetachment of relativistic ions

    SciTech Connect

    Donahue, J.B.; Gram, P.A.M.; Hamm, M.E.; Hamm, R.W.; Bryant, H.C.; Butterfield, K.B.; Clark, D.A.; Frost, C.A.; Smith, W.W.

    1980-01-01

    A series of fundamental laser ion beam experiments has been made feasible by the high-quality, relativistic (..beta.. = 0.842) H/sup -/ ion beam available at the Clinton P. Anderson Meson Physics Facility (LAMPF). The relatavistic Doppler shift of the light from an ordinary ultraviolet laser provides what is, in effect, a continuously tunable vacuum-ultraviolet laser in the rest frame of the moving ions. The Lorentz transformation of a modest laboratory magnetic field provides an electric field of several megavolts/centimeter. The latest results of photo-detachment work with H/sup -/ beams and our spectroscopic work with H/sup 0/ beams are presented. Plans for future work are discussed.

  1. Relativistic quantum cryptography

    NASA Astrophysics Data System (ADS)

    Molotkov, S. N.; Nazin, S. S.

    2003-07-01

    The problem of unconditional security of quantum cryptography (i.e. the security which is guaranteed by the fundamental laws of nature rather than by technical limitations) is one of the central points in quantum information theory. We propose a relativistic quantum cryptosystem and prove its unconditional security against any eavesdropping attempts. Relativistitic causality arguments allow to demonstrate the security of the system in a simple way. Since the proposed protocol does not empoly collective measurements and quantum codes, the cryptosystem can be experimentally realized with the present state-of-art in fiber optics technologies. The proposed cryptosystem employs only the individual measurements and classical codes and, in addition, the key distribution problem allows to postpone the choice of the state encoding scheme until after the states are already received instead of choosing it before sending the states into the communication channel (i.e. to employ a sort of "antedate" coding).

  2. Relativistic Heavy Ion Collider

    SciTech Connect

    Willen, E.H.

    1986-01-01

    The Relativistic Heavy Ion Collider (RHIC) is a proposed research facility at Brookhaven National Laboratory to study the collision of beams of heavy ions, up to gold in mass and at beam energies up to 100 GeV/nucleon. The physics to be explored by this collider is an overlap between the traditional disciplines of nuclear physics and high energy physics and is a continuation of the planned program of light and heavy ion physics at BNL. The machine is to be constructed in the now-empty tunnel built for the former CBA project. Various other facilities to support the collider are either in place or under construction at BNL. The collider itself, including the magnets, is in an advanced state of design, and a construction start is anticipated in the next several years.

  3. Hydrodynamics of Relativistic Fireballs

    NASA Technical Reports Server (NTRS)

    Piran, Tsvi; Shemi, Amotz; Narayan, Ramesh

    1993-01-01

    Many models of gamma-ray bursts involve a fireball, which is an optically thick concentration of radiation energy with a high ratio of energy density to rest mass. We examine analytically and numerically the evolution of a relativistic fireball. We show that, after an early rearrangement phase, most of the matter and energy in the fireball is concentrated within a narrow shell. The shell propagates at nearly the speed of light, with a frozen radial profile, and according to a simple set of scaling laws. The spectrum of the escaping radiation is harder at early times and softer later on. Depending on the initial energy-to-mass ratio, the final outcome of a fireball is either photons with roughly the initial temperature or ultrarelativistic baryons. In the latter case, the energy could be converted back to gamma-rays via interaction with surrounding material.

  4. SU-E-E-08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)

    SciTech Connect

    Ulmer, W

    2015-06-15

    Purpose: During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm’s resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung. Methods: The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation. Results: The cross-section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents. Conclusions: The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to

  5. Two-beam ultrabroadband coherent anti-Stokes Raman spectroscopy for high resolution gas-phase multiplex imaging

    SciTech Connect

    Bohlin, Alexis; Kliewer, Christopher J.

    2014-01-20

    We propose and develop a method for wideband coherent anti-Stokes Raman spectroscopy (CARS) in the gas phase and demonstrate the single-shot measurement of N{sub 2}, H{sub 2}, CO{sub 2}, O{sub 2}, and CH{sub 4}. Pure-rotational and vibrational O-, Q-, and S- branch spectra are collected simultaneously, with high spectral and spatial resolution, and within a single-laser-shot. The relative intensity of the rotational and vibrational signals can be tuned arbitrarily using polarization techniques. The ultrashort 7 fs pump and Stokes pulses are automatically overlapped temporally and spatially using a two-beam CARS technique, and the crossed probe beam allows for excellent spatial sectioning of the probed location.

  6. Fabrication of 2-inch nano patterned sapphire substrate with high uniformity by two-beam laser interference lithography

    NASA Astrophysics Data System (ADS)

    Dai, LongGui; Yang, Fan; Yue, Gen; Jiang, Yang; Jia, Haiqiang; Wang, Wenxin; Chen, Hong

    2014-11-01

    Generally, nano-scale patterned sapphire substrate (NPSS) has better performance than micro-scale patterned sapphire substrate (MPSS) in improving the light extraction efficiency of LEDs. Laser interference lithography (LIL) is one of the powerful fabrication methods for periodic nanostructures without photo-masks for different designs. However, Lloyd's mirror LIL system has the disadvantage that fabricated patterns are inevitably distorted, especially for large-area twodimensional (2D) periodic nanostructures. Herein, we introduce two-beam LIL system to fabricate consistent large-area NPSS. Quantitative analysis and characterization indicate that the high uniformity of the photoresist arrays is achieved. Through the combination of dry etching and wet etching techniques, the well-defined NPSS with period of 460 nm were prepared on the whole sapphire substrate. The deviation is 4.34% for the bottom width of the triangle truncated pyramid arrays on the whole 2-inch sapphire substrate, which is suitable for the application in industrial production of NPSS.

  7. Some problems in relativistic thermodynamics

    SciTech Connect

    Veitsman, E. V.

    2007-11-15

    The relativistic equations of state for ideal and real gases, as well as for various interface regions, have been derived. These dependences help to eliminate some controversies in the relativistic thermodynamics based on the special theory of relativity. It is shown, in particular, that the temperature of system whose velocity tends to the velocity of light in vacuum varies in accordance with the Ott law T = T{sub 0}/{radical}1 - v{sup 2}/c{sup 2}. Relativistic dependences for heat and mass transfer, for Ohm's law, and for a viscous flow of a liquid have also been derived.

  8. Relativistic spin effects in the baryon spectrum

    SciTech Connect

    Garcilazo, Humberto

    2005-04-01

    We study the nonstrange baryon spectrum within a three-body theory that treats relativistically both the space and the spin variables. The relativistic effects of the spin are about one order of magnitude smaller than those due to the use of relativistic momentum variables. The relativistic treatment of the spin breaks the degenerancy that is present in the nonrelativistic model and in the model with only relativistic momentum variables.

  9. Relativistic Transformation of Solid Angle.

    ERIC Educational Resources Information Center

    McKinley, John M.

    1980-01-01

    Rederives the relativistic transformations of light intensity from compact sources (stars) to show where and how the transformation of a solid angle contributes. Discusses astrophysical and other applications of the transformations. (Author/CS)

  10. Simulating relativistic binaries with Whisky

    NASA Astrophysics Data System (ADS)

    Baiotti, L.

    We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.

  11. Conductivity of a relativistic plasma

    SciTech Connect

    Braams, B.J.; Karney, C.F.F.

    1989-03-01

    The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

  12. Interference in multilayer relativistic mirrors

    NASA Astrophysics Data System (ADS)

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Babaei, Javad; Taghipour, Meisam; Mohammadzadeh, Zahra

    2015-10-01

    In this paper, reflection coefficient of a relativistic ultra-thin electron multilayer is calculated using electromagnetic interference procedures. The relativistic electron layers are assumed to be formed by nonlinear plasma wake waves that constitute the electron density cusps. It is shown that the interference between successive relativistic mirrors is restricted by the condition, τ p ≫ ( 2 γ 0 ) 5 / 2 / ω p 0 , where τp is the laser pulse duration. The results showed that tailoring the pulse amplitude, incident wave frequency value, incidence angle, and plasma density leads to increasing reflection coefficient a few orders of magnitudes. This constructive interference condition can be used for increasing conversion efficiency in the reflected energy from relativistic mirrors for the purpose of generating ultra-short coherence pulses in the extreme ultraviolet and x-ray regions. We also performed reflection from relativistic thin electron layers using relativistic 1D3V electromagnetic particle-in-cell (PIC) simulation. It was found that the results of PIC simulation are in agreement with analytical considerations.

  13. Relativistic magnetohydrodynamics in one dimension.

    PubMed

    Lyutikov, Maxim; Hadden, Samuel

    2012-02-01

    We derive a number of solutions for one-dimensional dynamics of relativistic magnetized plasma that can be used as benchmark estimates in relativistic hydrodynamic and magnetohydrodynamic numerical codes. First, we analyze the properties of simple waves of fast modes propagating orthogonally to the magnetic field in relativistically hot plasma. The magnetic and kinetic pressures obey different equations of state, so that the system behaves as a mixture of gases with different polytropic indices. We find the self-similar solutions for the expansion of hot strongly magnetized plasma into vacuum. Second, we derive linear hodograph and Darboux equations for the relativistic Khalatnikov potential, which describe arbitrary one-dimensional isentropic relativistic motion of cold magnetized plasma and find their general and particular solutions. The obtained hodograph and Darboux equations are very powerful: A system of highly nonlinear, relativistic, time-dependent equations describing arbitrary (not necessarily self-similar) dynamics of highly magnetized plasma reduces to a single linear differential equation. PMID:22463331

  14. Relativistic theory of gravitation

    SciTech Connect

    Logunov, A.A.; Mestvirishvili, M.A.

    1986-01-01

    In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday--Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly fulfilled for the energy-moment and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just ''flat.'' This suggests that in the universe a ''missing mass'' should exist in a form of matter.

  15. Design and Construction of a 500 KW CW, 400 MHZ Klystron To Be Used As RF Power Source For LHC/RF Component Tests

    SciTech Connect

    Pearson, Chris

    2003-05-05

    A 500 kW cw klystron operating at 400 MHz was developed and constructed jointly by CERN and SLAC for use as a high-power source at CERN for testing LHC/RF components such as circulators, RF absorbers and superconducting cavities with their input couplers. The design is a modification of the 353 MHz SLAC PEP-I klystron. More than 80% of the original PEP-I tube parts could thus be incorporated in the LHC test klystron which resulted in lower engineering costs as well as reduced development and construction time. The physical length between cathode plane and upper pole plate was kept unchanged so that a PEP-I tube focusing solenoid, available at CERN, could be re-used. With the aid of the klystron simulation codes JPNDISK and CONDOR, the design of the LHC tube was accomplished, which resulted in a tube with noticeably higher efficiency than its predecessor, the PEP-I klystron. The integrated cavities were redesigned using SUPERFISH and the output coupling circuit, which also required redesigning, was done with the aid of MAFIA. Details of the tube development and test results are presented.

  16. Design and Construction of a 500 kW CW, 400 MHz Klystron to be used as RF Power Source for LHC/RF Component Tests

    NASA Astrophysics Data System (ADS)

    Frischholz, H.; Fowkes, W. R.; Pearson, C.

    1997-05-01

    A 500 kW CW klystron operating at 400 MHz was jointly developed and constructed by CERN and SLAC for use as a high power source at CERN for testing LHC/RF components such as circulators, RF absorbers and superconducting cavities with their input couplers. The design is a modification of the 353 MHz SLAC PEP-I klystron which resulted in lower engineering costs as well as reduced development and construction time. More than 80% of the original PEP-I tube parts could be incorporated in the LHC test klystron. The physical length between cathode plane and upper pole plate was kept unchanged so that a PEP-I tube focusing frame, available at CERN, could be re-used. With the aid of the klystron simulation codes JPNDISK and CONDOR, the design of the LHC tube was accomplished, which resulted in a tube with noticeably higher efficiency than its predecessor, the PEP-I klystron. The integrated cavities were redesigned by using SUPERFISH and the output coupling circuit, which also required redesigning, was done with the aid of MAFIA. Details of the tube development and test results are presented. Finally the set-up of the LHC/RF test stand and the features of its auxiliary high-power RF equipment, such as circulator and absorber, are described.

  17. A ten-stage electrostatic depressed collector for improving klystron efficiency.

    NASA Technical Reports Server (NTRS)

    Neugebauer, W.; Mihran, T. G.

    1972-01-01

    A ten-stage electrostatic depressed collector, designed with the aid of an analog computer, was tested on a 1-kW CW 750-MHz klystron. Excellent correlation was achieved between computed and measured performance under varying conditions of RF drive. At full RF power output approximately 60 per cent of the spent beam energy was recovered by use of the depressed collector. The net power conversion efficiency of the tube was raised from its undepressed value of 54.3 per cent to approximately 70.9 per cent. At one-half full power output, a collector efficiency of 70 per cent was measured. At zero RF power output collector efficiency was 80 per cent. To achieve these results it was necessary to install a small focusing coil between the final drift tube and the collector. No spurious oscillations or instabilities were detected when collector depression was employed, nor was electron backstreaming increased significantly. Intentional short circuiting of adjacent collector electrode pairs was shown to cause only minor degradation in collector performance.

  18. Design Considerations for a PEBB-Based Marx-Topology ILC Klystron Modulator

    SciTech Connect

    Macken, K.; Beukers, T.; Burkhart, C.; Kemp, M.A.; Nguyen, M.N.; Tang, T.; /SLAC

    2009-12-09

    The concept of Power Electronic Building Blocks (PEBBs) has its origin in the U.S. Navy during the last decade of the past century. As compared to a more conventional or classical design approach, a PEBB-oriented design approach combines various potential advantages such as increased modularity, high availability and simplified serviceability. This relatively new design paradigm for power conversion has progressively matured since then and its underlying philosophy has been clearly and successfully demonstrated in a number of real-world applications. Therefore, this approach has been adopted here to design a Marx-topology modulator for an International Linear Collider (ILC) environment where easy serviceability and high availability are crucial. This paper describes various aspects relating to the design of a 32-cell Marx-topology ILC klystron modulator. The concept of nested droop correction is introduced and illustrated. Several design considerations including cosmic ray withstand, power cycling capability, fault tolerance, etc., are discussed. Details of the design of a Marx cell PEBB are included.

  19. High Voltage EPC for 94 GHz Klystron for Cloud Profiling Radar

    NASA Astrophysics Data System (ADS)

    Gambarara, Marcello; Ceruti, Luca; Cantamessa, Marco; Bartola, Furio

    2008-09-01

    The Cloud Profiling Radar (CPR) operating at 94 GHz is one of the payload instruments to be flown on the EarthCare mission in the time frame of year 2013. An important part of the CPR is the High Power Transmitter (HPT) that is composed by an Electronic Power Conditioner (EPC) and an Extended Interaction Klystron (EIK).The EIK, developed by CPI-Canada, has been selected as promising radio frequency power transmitter. This EIK is already flying on board of the Cloud Sat satellite and is recognised to be reliable for commercial and military applications throughout the world.This paper will be mainly focused on the EPC, developed in the frame of two subsequent ESA contracts, with particular attentions to the presentation of the activities performed, the design solutions adopted, the testing activities and main achieved performances.The activities of the contracts has been concluded on July 2007 with the realization of an elegant breadboard (EBB) of the EPC (see Fig. 1) that has been extensively tested (both alone and integrated with the EIK) and submitted to an accelerated life test.

  20. Remote coupling between a probe and a superconducting klystron cavity for use in gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    de Paula, L. A. N.; Aguiar, O. D.; Oliveira, N. F., Jr.

    2013-08-01

    In this work the main task was to measure the remote coupling between a probe and some niobium superconducting reentrant cavities for use in parametric transducers of gravitational wave detectors. The cavities were manufactured from RRR300 niobium and cryogenically tested to determine the electromagnetic coupling among other parameters. These cavities were also closed using a RRR300 niobium cover forming a narrow axial gap with the post top. A hole was made at the base opposite the cover in order to the probe reach the cavity. Generally, the critical coupling (β ≈ 1) is achieved with the probe inside the cavity. The mechanical connection of the probe with the transducer and the external circuit introduces an unwanted seismic noise in the transducer. The microstrip antennas have been traditionally employed to make a wireless connection. However, this study has demonstrated coupling factor β ≈ 1 with the probe moved away 4.0 mm from the cavity with a 3.0 mm diameter hole. Couplings with the probe moved away 1.0 mm and 7.0 mm from cavities with 1.5 mm and 3.5 mm diameter holes, respectively, have also been obtained. These results have revealed the influence of the hole diameter with the remote coupling between an electric field probe and the klystron mode of a superconducting reentrant cavity. Due to the practicalities, this effect may replace the microstrip antennas making it possible to implement high sensitivity parametric transducers.

  1. Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows

    NASA Astrophysics Data System (ADS)

    Bernstein, J. P.; Hughes, P. A.

    2009-09-01

    We have undertaken the simulation of hydrodynamic flows with bulk Lorentz factors in the range 102-106. We discuss the application of an existing relativistic, hydrodynamic primitive variable recovery algorithm to a study of pulsar winds, and, in particular, the refinement made to admit such ultra-relativistic flows. We show that an iterative quartic root finder breaks down for Lorentz factors above 102 and employ an analytic root finder as a solution. We find that the former, which is known to be robust for Lorentz factors up to at least 50, offers a 24% speed advantage. We demonstrate the existence of a simple diagnostic allowing for a hybrid primitives recovery algorithm that includes an automatic, real-time toggle between the iterative and analytical methods. We further determine the accuracy of the iterative and hybrid algorithms for a comprehensive selection of input parameters and demonstrate the latter’s capability to elucidate the internal structure of ultra-relativistic plasmas. In particular, we discuss simulations showing that the interaction of a light, ultra-relativistic pulsar wind with a slow, dense ambient medium can give rise to asymmetry reminiscent of the Guitar nebula leading to the formation of a relativistic backflow harboring a series of internal shockwaves. The shockwaves provide thermalized energy that is available for the continued inflation of the PWN bubble. In turn, the bubble enhances the asymmetry, thereby providing positive feedback to the backflow.

  2. Superhydrophobic SERS Substrates Based on Silver-Coated Reduced Graphene Oxide Gratings Prepared by Two-Beam Laser Interference.

    PubMed

    Yan, Zhao-Xu; Zhang, Yong-Lai; Wang, Wei; Fu, Xiu-Yan; Jiang, Hao-Bo; Liu, Yu-Qing; Verma, Prabhat; Kawata, Satoshi; Sun, Hong-Bo

    2015-12-16

    Reported here is the fabrication of reduced graphene oxide (RGO) grating structures by two-beam laser interference (TBLI) for the development of highly efficient SERS substrates via simple physical vapor deposition (PVD) coating of silver. TBLI has been utilized to make hierarchical RGO grating structures with microscale gratings and nanoscale folders through a laser treatment induced ablation and photoreduction process. The hierarchical structures contribute to the formation of plasmonic structures after silver coating, giving rise to the formation of plenty of SERS "hot spots", while the RGO substrate would provide chemical enhancement of Raman signal through interaction with analytes molecules. The significantly increased roughness with respect to the hierarchical structures in combination with the removal of hydrophilic oxygen-containing groups endow the resultant substrates with unique superhydrophobicity, which leads to the enrichment of analytes and further lowers the detection limit. The synergistic effects make the silver coated RGO gratings a highly efficient SERS substrate; in the detection of Rhodamine B, our SERS substrates showed high SERS enhancement and good reproducibility, a detection limit of 10(-10) M has been achieved. PMID:26595745

  3. Relativistic dynamical collapse model

    NASA Astrophysics Data System (ADS)

    Pearle, Philip

    2015-05-01

    A model is discussed where all operators are constructed from a quantum scalar field whose energy spectrum takes on all real values. The Schrödinger picture wave function depends upon space and time coordinates for each particle, as well as an inexorably increasing evolution parameter s which labels a foliation of spacelike hypersurfaces. The model is constructed to be manifestly Lorentz invariant in the interaction picture. Free particle states and interactions are discussed in this framework. Then, the formalism of the continuous spontaneous localization (CSL) theory of dynamical collapse is applied. The collapse-generating operator is chosen to be the particle number space-time density. Unlike previous relativistically invariant models, the vacuum state is not excited. The collapse dynamics depends upon two parameters, a parameter Λ which represents the collapse rate/volume and a scale factor ℓ. A common example of collapse dynamics, involving a clump of matter in a superposition of two locations, is analyzed. The collapse rate is shown to be identical to that of nonrelativistic CSL when the GRW-CSL choice of ℓ=a =1 0-5 cm , is made, along with Λ =λ /a3 (GRW-CSL choice λ =1 0-16s-1). The collapse rate is also satisfactory with the choice ℓ as the size of the Universe, with Λ =λ /ℓa2. Because the collapse narrows wave functions in space and time, it increases a particle's momentum and energy, altering its mass. It is shown that, with ℓ=a , the change of mass of a nucleon is unacceptably large but, when ℓ is the size of the Universe, the change of mass over the age of the Universe is acceptably small.

  4. Relativistic breakdown in planetary atmospheres

    SciTech Connect

    Dwyer, J. R.

    2007-04-15

    In 2003, a new electrical breakdown mechanism involving the production of runaway avalanches by positive feedback from runaway positrons and energetic photons was introduced. This mechanism, which shall be referred to as 'relativistic feedback', allows runaway discharges in gases to become self-sustaining, dramatically increasing the flux of runaway electrons, the accompanying high-energy radiation, and resulting ionization. Using detailed Monte Carlo calculations, properties of relativistic feedback are investigated. It is found that once relativistic feedback fully commences, electrical breakdown will occur and the ambient electric field, extending over cubic kilometers, will be discharged in as little as 2x10{sup -5} s. Furthermore, it is found that the flux of energetic electrons and x rays generated by this mechanism can exceed the flux generated by the standard relativistic runaway electron model by a factor of 10{sup 13}, making relativistic feedback a good candidate for explaining terrestrial gamma-ray flashes and other high-energy phenomena observed in the Earth's atmosphere.

  5. Theory of relativistic cyclotron masers

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Latham, P. E.; Dumbrajs, O.

    1995-07-01

    In this paper we have made an attempt to review the present status of the theory of cyclotron masers with relativistic electron beams. After discussing the basic features of electron-cyclotron radiation under conditions of normal and anomalous Doppler frequency shifts, we consider particle deceleration by a constant amplitude electromagnetic wave in a constant magnetic field using the formalism developed earlier for cyclotron autoresonance acceleration of electrons. An optimal cyclotron resonance mismatch was found that corresponds to the possibility of complete deceleration of relativistic electrons. Then, interaction of relativistic electrons with resonator fields is considered and the efficiency increase due to electron prebunching is demonstrated in a simple model. Since an efficient interaction of relativistic electrons with the large amplitude electromagnetic field of a resonator occurs at a short distance, where electrons make a small number of electron orbits, the issue of the simultaneous interaction of electrons with the field at several cyclotron harmonics is discussed. Finally, we consider deceleration of a prebunched electron beam by a traveling electromagnetic wave in a tapered magnetic field. This simple modeling is illustrated with a number of simulations of relativistic gyroklystrons and gyrotwistrons (gyrodevices in which the bunching cavity of the gyroklystron is combined with the output waveguide of the gyro-traveling-wave-tube).

  6. Particle Acceleration at Relativistic and Ultra-Relativistic Shock Waves

    NASA Astrophysics Data System (ADS)

    Meli, A.

    We perform Monte Carlo simulations using diffusive shock acceleration at relativistic and ultra-relativistic shock waves. High upstream flow gamma factors are used, Γ=(1-uup2/c2)-0.5, which are relevant to models of ultra-relativistic particle shock acceleration in the central engines and relativistic jets of Active Galactic Nuclei (AGN) and in Gamma-Ray Burst (GRB) fireballs. Numerical investigations are carried out on acceleration properties in the relativistic and ultra-relativistic flow regime (Γ ˜ 10-1000) concerning angular distributions, acceleration time scales, particle energy gain versus number of crossings and spectral shapes. We perform calculations for both parallel and oblique sub-luminal and super-luminal shocks. For parallel and oblique sub-luminal shocks, the spectra depend on whether or not the scattering is represented by pitch angle diffusion or by large angle scattering. The large angle case exhibits a distinctive structure in the basic power-law spectrum not nearly so obvious for small angle scattering. However, both cases yield a significant 'speed-up' of acceleration rate when compared with the conventional, non-relativistic expression, tacc=[c/(uup-udown)] (λup/uup+λdown/udown). An energization by a factor Γ2 for the first crossing cycle and a large energy gains for subsequent crossings as well as the high 'speed-up' factors found, are important in supporting past works, especially the models developed by Vietri and Waxman on ultra-high energy cosmic ray, neutrino and gamma-ray production in GRB. For oblique super-luminal shocks, we calculate the energy gain and spectral shape for a number of different inclinations. For this case the acceleration of particles is 'pictured' by a shock drift mechanism. We use high gamma flows with Lorentz factors in the range 10-40 which are relevant to ultra-relativistic shocks in AGN accretion disks and jets. In all investigations we closely follow the particle's trajectory along the magnetic field

  7. Design, construction and evaluation of a 12.2 GHz, 4.0 kW-CW high efficiency klystron amplifier. [for satellite-borne TV broadcast transmitters

    NASA Technical Reports Server (NTRS)

    Vishida, J. M.; Brodersen, L. K.

    1974-01-01

    An analytical and experimental program is described, for studying design techniques for optimizing the conversion efficiency of klystron amplifiers, and to utilize these techniques in the development and fabrication of an X-band 4 kW cw klystron, for use in satellite-borne television broadcast transmitters. The design is based on a technique for increasing the RF beam current by using the second harmonic space charge forces in the bunched beam. Experimental analysis was also made of a method to enhance circuit efficiency in the klystron cavities. The design incorporates a collector which is demountable from the tube to facilitate multistage depressed collector experiments employing an axisymmetric, electrostatic collector for linear beam microwave tubes.

  8. Fluctuations in relativistic causal hydrodynamics

    NASA Astrophysics Data System (ADS)

    Kumar, Avdhesh; Bhatt, Jitesh R.; Mishra, Ananta P.

    2014-05-01

    Formalism to calculate the hydrodynamic fluctuations by applying the Onsager theory to the relativistic Navier-Stokes equation is already known. In this work, we calculate hydrodynamic fluctuations within the framework of the second order hydrodynamics of Müller, Israel and Stewart and its generalization to the third order. We have also calculated the fluctuations for several other causal hydrodynamical equations. We show that the form for the Onsager-coefficients and form of the correlation functions remain the same as those obtained by the relativistic Navier-Stokes equation and do not depend on any specific model of hydrodynamics. Further we numerically investigate evolution of the correlation function using the one dimensional boost-invariant (Bjorken) flow. We compare the correlation functions obtained using the causal hydrodynamics with the correlation function for the relativistic Navier-Stokes equation. We find that the qualitative behavior of the correlation functions remains the same for all the models of the causal hydrodynamics.

  9. Non-Relativistic Superstring Theories

    SciTech Connect

    Kim, Bom Soo

    2007-12-14

    We construct a supersymmetric version of the 'critical' non-relativistic bosonic string theory [1] with its manifest global symmetry. We introduce the anticommuting bc CFT which is the super partner of the {beta}{gamma} CFT. The conformal weights of the b and c fields are both 1/2. The action of the fermionic sector can be transformed into that of the relativistic superstring theory. We explicitly quantize the theory with manifest SO(8) symmetry and find that the spectrum is similar to that of Type IIB superstring theory. There is one notable difference: the fermions are non-chiral. We further consider 'noncritical' generalizations of the supersymmetric theory using the superspace formulation. There is an infinite range of possible string theories similar to the supercritical string theories. We comment on the connection between the critical non-relativistic string theory and the lightlike Linear Dilaton theory.

  10. Polyanalytic relativistic second Bargmann transforms

    SciTech Connect

    Mouayn, Zouhaïr

    2015-05-15

    We construct coherent states through special superpositions of eigenstates of the relativistic isotonic oscillator. In each superposition, the coefficients are chosen to be L{sup 2}-eigenfunctions of a σ-weight Maass Laplacian on the Poincaré disk, which are associated with the eigenvalue 4m(σ−1−m), m∈Z{sub +}∩[0,(σ−1)/2]. For each nonzero m, the associated coherent states transform constitutes the m-true-polyanalytic extension of a relativistic version of the second Bargmann transform, whose integral kernel is expressed in terms of a special Appel-Kampé de Fériet’s hypergeometric function. The obtained results could be used to extend the known semi-classical analysis of quantum dynamics of the relativistic isotonic oscillator.

  11. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  12. Theory of the relativistic gyrotwistron

    NASA Astrophysics Data System (ADS)

    Nusinovich, G. S.; Li, H.

    1992-04-01

    A generalized theory of the relativistic gyrotwistron, the device combining the elements of the gyroklystron and the gyro-traveling wave tube, is presented. A modulation of electrons in the input cavity is considered with the account of modulation in an electron axial momentum that is important for relativistic particles passing through a short cavity. A comprehensive study of large-signal operation of the output waveguide section in the cases of gyroresonance at the fundamental and second cyclotron harmonics has demonstrated a wide variety of electron bunching phenomena and the possibility of achieving high electron efficiency in a wide range of gyrotwistron parameters.

  13. Analytical investigation of efficiency and performance limits in klystron amplifiers using multidimensional computer programs; multi-stage depressed collectors; and thermionic cathode life studies

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1980-01-01

    An extensive parametric investigation was performed of the extraction of energy in output gaps of klystron amplifiers, using 3-D computer programs. Due to complexity of the program which used a hydrodynamic, axially and radially deformable disk ring model and the resulting long computing time, the investigation was limited to the output gap, by far the most important and difficult part of the klystron interaction. Results show that, for a confined flow focused beam throughout the penultimate cavity, radial velocities remain very small and the beam is highly laminar. It was, therefore, concluded that possible errors resulting from treating only the output cavity in 3-D would remain small.

  14. 180 MW/180 KW pulse modulator for S-band klystron of LUE-200 linac of IREN installation of JINR

    NASA Astrophysics Data System (ADS)

    Su, Kim Dong; Sumbaev, A. P.; Shvetsov, V. N.

    2014-09-01

    The offer on working out of the pulse modulator with 180 MW pulse power and 180 kW average power for pulse S-band klystrons of LUE-200 linac of IREN installation at the Laboratory of neutron physics (FLNP) at JINR is formulated. Main requirements, key parameters and element base of the modulator are presented. The variant of the basic scheme on the basis of 14 (or 11) stage 2 parallel PFN with the thyratron switchboard (TGI2-10K/50) and six parallel high voltage power supplies (CCPS Power Supply) is considered.

  15. Generalized representation of electric fields in interaction gaps of klystrons and traveling wave tubes with axial symmetry

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1972-01-01

    Analytic expressions for axial and radial electric fields in axisymmetric interaction gaps of klystrons and coupled cavity traveling wave tubes are derived. Introduction of the field shape parameter m results in both limiting cases of the field at the tunnel tips, that is, E equal to a constant and E approaching infinity as well as a continuous transition between these two limits. The transition represents actual, practical fields. This representation may be used to replace the somewhat arbitrary expressions being applied by various researchers to describe the fields.

  16. Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier

    NASA Astrophysics Data System (ADS)

    Kemp, Thomas F.; Dannatt, Hugh R. W.; Barrow, Nathan S.; Watts, Anthony; Brown, Steven P.; Newton, Mark E.; Dupree, Ray

    2016-04-01

    A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to 1H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90 K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90 K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement.

  17. Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier.

    PubMed

    Kemp, Thomas F; Dannatt, Hugh R W; Barrow, Nathan S; Watts, Anthony; Brown, Steven P; Newton, Mark E; Dupree, Ray

    2016-04-01

    A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to (1)H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement. PMID:26867091

  18. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  19. Relativistic treatment of inertial spin effects

    NASA Astrophysics Data System (ADS)

    Ryder, Lewis

    1998-03-01

    A relativistic spin operator for Dirac particles is identified and it is shown that a coupling of spin to angular velocity arises in the relativistic case, just as Mashhoon had speculated, and Hehl and Ni had demonstrated, in the non-relativistic case.

  20. Energy transfer between injection-locked single-mode diode lasers by two-beam coupling in BaTiO/sub 3/

    SciTech Connect

    Christian, W.R.; Beckwith, P.H.; McMichael, I.

    1989-01-01

    Two-beam coupling in photorefractive BaTiO/sub 3/ is used to combine beams coherently from two injection-locked single-mode diode lasers operating at 830 nm. We are able to transfer more than 70% of the power in one beam to the other beam with this method.

  1. Klystron-like cavity with mode transformation for high-harmonic terahertz gyrotrons

    NASA Astrophysics Data System (ADS)

    Bandurkin, I. V.; Kalynov, Yu. K.; Savilov, A. V.

    2013-01-01

    A novel cavity scheme of a gyrotron is proposed and investigated. As it provides low Ohmic losses and high mode selectivity, it can be especially prospective for realization in gyrotrons operating in the THz frequency range. Numerical simulations show that it allows three-fold increase in the efficiency of the low-relativistic 500 GHz fourth-harmonic gyrotron as compared to conventional two-section scheme with modes transformation.

  2. Klystron-like cavity with mode transformation for high-harmonic terahertz gyrotrons

    SciTech Connect

    Bandurkin, I. V.; Kalynov, Yu. K.; Savilov, A. V.

    2013-01-15

    A novel cavity scheme of a gyrotron is proposed and investigated. As it provides low Ohmic losses and high mode selectivity, it can be especially prospective for realization in gyrotrons operating in the THz frequency range. Numerical simulations show that it allows three-fold increase in the efficiency of the low-relativistic 500 GHz fourth-harmonic gyrotron as compared to conventional two-section scheme with modes transformation.

  3. Relativistic Transverse Gravitational Redshift

    NASA Astrophysics Data System (ADS)

    Mayer, A. F.

    2012-12-01

    symmetric energy potential exists between the frames that is quantified by the instantaneous Δ {v} = v\\cdot{d}φ between them; in order for either frame to become indistinguishable from the other, such that their respective velocity and acceleration vectors are parallel, a change in velocity is required. While the qualitative features of general relativity imply this phenomenon (i.e., a symmetric potential difference between two points on a Newtonian `equipotential surface' that is similar to a friction effect), it is not predicted by the field equations due to a modeling error concerning time. This is an error of omission; time has fundamental geometric properties implied by the principles of relativity that are not reflected in the field equations. Where b is the radius and g is the gravitational acceleration characterizing a spherical geoid S of an ideal point-source gravitational field, an elegant derivation that rests on first principles shows that for two points at rest on S separated by a distance d << b, a symmetric relativistic redshift exists between these points of magnitude z = gd2/bc^2, which over 1 km at Earth sea level yields z ˜{10-17}. It can be tested with a variety of methods, in particular laser interferometry. A more sophisticated derivation yields a considerably more complex predictive formula for any two points in a gravitational field.

  4. The Highest Redshift Relativistic Jets

    SciTech Connect

    Cheung, C.C.; Stawarz, L.; Siemiginowska, A.; Harris, D.E; Schwartz, D.A.; Wardle, J.F.C.; Gobeille, D.; Lee, N.P.

    2007-12-18

    We describe our efforts to understand large-scale (10's-100's kpc) relativistic jet systems through observations of the highest-redshift quasars. Results from a VLA survey search for radio jets in {approx} 30 z > 3.4 quasars are described along with new Chandra observations of 4 selected targets.

  5. Proper-time relativistic dynamics

    NASA Technical Reports Server (NTRS)

    Gill, Tepper L.; Zachary, W. W.; Lindesay, James

    1993-01-01

    Proper-time relativistic single-particle classical Hamiltonian mechanics is formulated using a transformation from observer time to system proper time which is a canonical contact transformation on extended phase space. It is shown that interaction induces a change in the symmetry structure of the system which can be analyzed in terms of a Lie-isotopic deformation of the algebra of observables.

  6. Future relativistic heavy ion experiments

    SciTech Connect

    Pugh, H.G.

    1980-12-01

    Equations of state for nuclear matter and ongoing experimental studies are discussed. Relativistic heavy ion physics is the only opportunity to study in the laboratory the properties of extended multiquark systems under conditions such that quarks might run together into new arrangements previously unobserved. Several lines of further study are mentioned. (GHT)

  7. Particle Acceleration in Relativistic Outflows

    NASA Technical Reports Server (NTRS)

    Bykov, Andrei; Gehrels, Neil; Krawczynski, Henric; Lemoine, Martin; Pelletier, Guy; Pohl, Martin

    2012-01-01

    In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae. We highlight the possible contributions of these sources to ultra-high-energy cosmic rays.

  8. BOOK REVIEW: Relativistic Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Antoine, J.-P.

    2004-01-01

    The aim of relativistic quantum mechanics is to describe the finer details of the structure of atoms and molecules, where relativistic effects become nonnegligible. It is a sort of intermediate realm, between the familiar nonrelativistic quantum mechanics and fully relativistic quantum field theory, and thus it lacks the simplicity and elegance of both. Yet it is a necessary tool, mostly for quantum chemists. Pilkuhn's book offers to this audience an up-to-date survey of these methods, which is quite welcome since most previous textbooks are at least ten years old. The point of view of the author is to start immediately in the relativistic domain, following the lead of Maxwell's equations rather than classical mechanics, and thus to treat the nonrelativistic version as an approximation. Thus Chapter 1 takes off from Maxwell's equations (in the noncovariant Coulomb gauge) and gradually derives the basic aspects of Quantum Mechanics in a rather pedestrian way (states and observables, Hilbert space, operators, quantum measurement, scattering,. Chapter 2 starts with the Lorentz transformations, then continues with the Pauli spin equation and the Dirac equation and some of their applications (notably the hydrogen atom). Chapter 3 is entitled `Quantum fields and particles', but falls short of treating quantum field theory properly: only creation/annihilation operators are considered, for a particle in a box. The emphasis is on two-electron states (the Pauli principle, the Foldy--Wouthuysen elimination of small components of Dirac spinors, Breit projection operators. Chapter 4 is devoted to scattering theory and the description of relativistic bound states. Chapter 5, finally, covers hyperfine interactions and radiative corrections. As we said above, relativistic quantum mechanics is by nature limited in scope and rather inelegant and Pilkuhn's book is no exception. The notation is often heavy (mostly noncovariant) and the mathematical level rather low. The central topic

  9. Cost optimization of induction linac drivers for linear colliders

    SciTech Connect

    Barletta, W.A.

    1986-12-29

    Recent developments in high reliability components for linear induction accelerators (LIA) make possible the use of these devices as economical power drives for very high gradient linear colliders. A particularly attractive realization of this ''two-beam accelerator'' approach is to configure the LIA as a monolithic relativistic klystron operating at 10 to 12 GHz with induction cells providing periodic reacceleration of the high current beam. Based upon a recent engineering design of a state-of-the-art, 10- to 20-MeV LIA at Lawrence Livermore National Laboratory, this paper presents an algorithm for scaling the cost of the relativistic klystron to the parameter regime of interest for the next generation high energy physics machines. The algorithm allows optimization of the collider luminosity with respect to cost by varying the characteristics (pulse length, drive current, repetition rate, etc.) of the klystron. It also allows us to explore cost sensitivities as a guide to research strategies for developing advanced accelerator technologies.

  10. Fast Lattice Boltzmann Solver for Relativistic Hydrodynamics

    SciTech Connect

    Mendoza, M.; Herrmann, H. J.; Boghosian, B. M.; Succi, S.

    2010-07-02

    A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows.

  11. Relativistic formulation of the Voigt profile

    NASA Astrophysics Data System (ADS)

    Wcisło, P.; Amodio, P.; Ciuryło, R.; Gianfrani, L.

    2015-02-01

    The relativistic formulation of the Voigt profile is reported for the spontaneous emission from an atomic or molecular cloud, in coincidence with a given spectral line. We considered the simultaneous occurrence of homogeneous broadening and thermal broadening, this latter being determined by the relativistic Doppler effect. Our formula for the relativistic Voigt profile reproduces those characterizing the two available limit cases, namely, the relativistic Gaussian profile and the classical Voigt convolution. The relativistic deformation of the Voigt profile was carefully quantified at different temperatures, in the case of the molecular hydrogen spectrum.

  12. Simulations of Relativistic Extragalactic Jets

    NASA Astrophysics Data System (ADS)

    Hughes, P. A.; Duncan, G. C.

    1994-05-01

    We present results for 2-D, axisymmetric simulations of flows with Lorentz factors ~ 5 -- 10, typical of values inferred for superluminal BL Lacs and QSOs. The simulations were performed with a numerical hydrodynamic code that admits relativistic flow speed. We exploit the property that the relativistic Euler equations for mass, momentum and total energy densities in the laboratory frame have the same form as the nonrelativistic equations, to solve for laboratory frame variables using a conventional Godunov-type scheme with approximate Riemann solver: the HLLE method. The relativistic nature of the flow is incorporated by performing a Lorentz transformation at every step, at each cell center or cell boundary where pressure, sound speed or velocity are required. Determination of the velocity in this manner is a robust algebraic procedure within which we can ensure that vrelativistic flows exhibit a less pronounced pattern of incident and reflection shocks on axis. For flows which have propagated to a fixed number of jet radii, the Kelvin-Helmholtz instability at the contact surface is much less evident in the high Lorentz factor cases, supporting the contention that relativistic flows are less prone to such instability. We describe how the morphology of the cocoon and shocked ambient gas change with increasing Lorentz factor. This work was supported by NSF grant AST 9120224 and by the Ohio Supercomputer Center from a Cray Research Software Development Grant.

  13. Operational results of the spallation neutron source (SNS) polyphase converter-modulator for the 140 KV klystron RF system

    SciTech Connect

    Reass, W. A.; Doss, James D.; Gribble, R. F.; Lynch, M. T.; Rees, D. E.; Tallerico, P. J.; Borovina, D. L.

    2001-01-01

    This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltageswitching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three 'H-Bridge' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.

  14. OPERATIONAL RESULTS OF THE SPALLATION NEUTRON SOURCE (SNS) POLYPHASE CONVERTER-MODULATOR FOR THE 140 KV KLYSTRON RF SYSTEMS

    SciTech Connect

    W.A. REASS; J.D. DOSS; ET AL

    2001-06-01

    This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.

  15. Investigation of ultra-high sensitivity klystron cavity transducers for broadband resonant-mass gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Pimentel, G. L.; Aguiar, O. D.; Barroso, J. J.; Tobar, M. E.

    2008-07-01

    Since the Stanford pioneering work of Paik in the 1970s, cryogenic resonant-mass gravitational wave detectors have used resonant transducers, which have the effect of increasing both the detector sensitivity and bandwidth. Now nanotechnology is opening new possibilities towards the construction of ultra-high sensitivity klystron cavity transducers. It might be feasible to construct TeraHz/micron parametric transducers in a near future. They would be so sensitive that there would be no need for multimode resonant transducers. The resonant-antenna would act as a broadband detector for gravitational waves. A spherical antenna, such as Schenberg or Mini-Grail, could add to this quality the advantage of wave position and polarity determination. Here we propose an extreme geometry for a re-entrant klystron cavity (df/dg ~ 1018 Hz/m, where f stands for the microwave pump frequency and g for variations in the cavity gap), obtaining a frequency response for the strain sensitivity of the Schenberg gravitational wave detector such that its bandwidth increases from 50 Hz (using the so-called resonant mode coupling) to ~4000 Hz when operating @ 20 mK, and, when compared to LIGO experimental curve, shows a competitive band of about 2000 Hz. We also study some of the technological complications that can be foreseen to design such a resonant cavity.

  16. Relativistic ionization fronts in gas jets

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Dias, J. M.; Gallacher, J. G.; Issac, R. C.; Fonseca, R. A.; Lopes, N. C.; Silva, L. O.; Mendonça, J. T.; Jaroszynski, D. A.

    2006-10-01

    A high-power ultra-short laser pulse propagating through a gas jet, ionizes the gas by tunnelling ionization, creating a relativistic plasma-gas interface. The relativistic ionization front that is created can be used to frequency up-shift electromagnetic radiation either in co-propagation or in counter-propagation configurations. In the counter-propagation configuration, ionization fronts can act as relativistic mirrors for terahertz radiation, leading to relativistic double Doppler frequency up-shift to the visible range. In this work, we identified and explored, the parameters that optimize the key features of relativistic ionization fronts for terahertz radiation reflection. The relativistic ionization front generated by a high power laser (TOPS) propagating in a supersonic gas jet generated by a Laval nozzle has been fully characterized. We have also performed detailed two-dimensional relativistic particle-in-cell simulations with Osiris 2.0 to analyze the generation and propagation of the ionization fronts.

  17. Progress Toward a Gigawatt-Class Annular Beam Klystron with a Thermionic Electron Gun

    NASA Astrophysics Data System (ADS)

    Fazio, M.; Carlsten, B.; Farnham, J.; Habiger, K.; Haynes, W.; Myers, J.; Nelson, E.; Smith, J.; Arfin, B.; Haase, A.

    2002-08-01

    In an effort to reach the gigawatt power level in the microsecond pulse length regime Los Alamos, in collaboration with SLAC, is developing an annular beam klystron (ABK) with a thermionic electron gun. We hope to address the causes of pulse shortening in very high peak power tubes by building a "hard-vacuum" tube in the 10-10 Torr range with a thermionic electron gun producing a constant impedance electron-beam. The ABK has been designed to operate at 5 Hz pulse repetition frequency to allow for RF conditioning. The electron gun has a magnetron injection gun configuration and uses a dispenser cathode running at 1100 degC to produce a 4 kA electron beam at 800 kV. The cathode is designed to run in the temperature-limited mode to help maintain beam stability in the gun. The beam-stick consisting of the electron gun, an input cavity, an idler cavity, and drift tube, and the collector has been designed collaboratively, fabricated at SLAC, then shipped to Los Alamos for testing. On the test stand at Los Alamos a low voltage emission test was performed, but unfortunately as we prepared for high voltage testing a problem with the cathode heater was encountered that prevented the cathode from reaching a high enough temperature for electron emission. A post-mortem examination will be done shortly to determine the exact cause of the heater failure. The RF design has been proceeding and is almost complete. The output cavity presents a challenging design problem in trying to efficiently extract energy from the low impedance beam while maintaining a gap voltage low enough to avoid breakdown and a Q high enough to maintain mode purity. In the next iteration, the ABK will have a new cathode assembly installed along with the remainder of the RF circuit. This paper will discuss the electron gun and the design of the RF circuit along with a report on the status of the work.

  18. Relativistic stars in bigravity theory

    NASA Astrophysics Data System (ADS)

    Aoki, Katsuki; Maeda, Kei-ichi; Tanabe, Makoto

    2016-03-01

    Assuming static and spherically symmetric spacetimes in the ghost-free bigravity theory, we find a relativistic star solution, which is very close to that in general relativity. The coupling constants are classified into two classes: Class [I] and Class [II]. Although the Vainshtein screening mechanism is found in the weak gravitational field for both classes, we find that there is no regular solution beyond the critical value of the compactness in Class [I]. This implies that the maximum mass of a neutron star in Class [I] becomes much smaller than that in general relativity (GR). On the other hand, for the solution in Class [II], the Vainshtein screening mechanism works well even in a relativistic star and the result in GR is recovered.

  19. Relativistic hydrodynamics on graphic cards

    NASA Astrophysics Data System (ADS)

    Gerhard, Jochen; Lindenstruth, Volker; Bleicher, Marcus

    2013-02-01

    We show how to accelerate relativistic hydrodynamics simulations using graphic cards (graphic processing units, GPUs). These improvements are of highest relevance e.g. to the field of high-energetic nucleus-nucleus collisions at RHIC and LHC where (ideal and dissipative) relativistic hydrodynamics is used to calculate the evolution of hot and dense QCD matter. The results reported here are based on the Sharp And Smooth Transport Algorithm (SHASTA), which is employed in many hydrodynamical models and hybrid simulation packages, e.g. the Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). We have redesigned the SHASTA using the OpenCL computing framework to work on accelerators like graphic processing units (GPUs) as well as on multi-core processors. With the redesign of the algorithm the hydrodynamic calculations have been accelerated by a factor 160 allowing for event-by-event calculations and better statistics in hybrid calculations.

  20. Magnetohydrodynamics of chiral relativistic fluids

    NASA Astrophysics Data System (ADS)

    Boyarsky, Alexey; Fröhlich, Jürg; Ruchayskiy, Oleg

    2015-08-01

    We study the dynamics of a plasma of charged relativistic fermions at very high temperature T ≫m , where m is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magnetohydrodynamical description of the evolution of such a plasma. We show that, compared to conventional magnetohydronamics (MHD) for a plasma of nonrelativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudoscalar field originating in a local asymmetry in the densities of left-handed and right-handed fermions. This field can be interpreted as an effective axion field. Taking into account the chiral anomaly we present dynamical equations for the evolution of this field, as well as of other fields appearing in the MHD description of the plasma. Due to its nonlinear coupling to helical magnetic fields, the axion field significantly affects the dynamics of a magnetized plasma and can give rise to a novel type of inverse cascade.

  1. Relativistic rocket: Dream and reality

    NASA Astrophysics Data System (ADS)

    Semyonov, Oleg G.

    2014-06-01

    The dream of interstellar flights persists since the first pioneers in astronautics and has never died. Many concepts of thruster capable to propel a rocket to the stars have been proposed and the most suitable among them are thought to be photon propulsion and propulsion by the products of proton-antiproton annihilation in magnetic nozzle. This article addresses both concepts allowing for cross-section of annihilation among other issues in order to show their vulnerability and to indicate the problems. The concept of relativistic matter propulsion is substantiated and discussed. The latter is argued to be the most straightforward way to build-up a relativistic rocket firstly because it is based on the existing technology of ion generators and accelerators and secondly because it can be stepped up in efflux power starting from interplanetary spacecrafts powered by nuclear reactors to interstellar starships powered by annihilation reactors. The problems imposed by thermodynamics and heat disposal are accentuated.

  2. A novel simultaneous photoelastic and two-beam interferometric system: I. Dynamic full-field evaluation of the elasticity modulus profile of polymeric fibres.

    PubMed

    Hamza, A A; Sokkar, T Z N; El-Farahaty, K A; Raslan, M I

    2014-06-01

    A novel optical setup for simultaneous capturing of photoelastic and two-beam interference patterns was designed. The designed optical setup was used to simultaneously record two types of patterns. The first pattern is two-beam interference pattern, and the second one is photoelastic interference pattern produced by objects under stress. This simultaneous capturing of the two patterns allowed us to calculate the full-field distribution of the elasticity modulus profile of fibres. A mathematical expression of the profile of the elasticity modulus was derived. This was applied to evaluate the elasticity modulus of anisotropic isotactic polypropylene fibres during stretching processes. The profile of the elasticity modulus was determined for both static and dynamic in situ cases where the propagation of different structural deformations was observed and studied using the designed optical setup. Patterns were given for illustration. PMID:24666238

  3. Fully relativistic lattice Boltzmann algorithm

    SciTech Connect

    Romatschke, P.; Mendoza, M.; Succi, S.

    2011-09-15

    Starting from the Maxwell-Juettner equilibrium distribution, we develop a relativistic lattice Boltzmann (LB) algorithm capable of handling ultrarelativistic systems with flat, but expanding, spacetimes. The algorithm is validated through simulations of a quark-gluon plasma, yielding excellent agreement with hydrodynamic simulations. The present scheme opens the possibility of transferring the recognized computational advantages of lattice kinetic theory to the context of both weakly and ultrarelativistic systems.

  4. Dynamics of Relativistic Magnetized Explosions

    NASA Astrophysics Data System (ADS)

    Lyutikov, M.

    2001-11-01

    The dynamics of (i) relativistic blast waves propagating through magnetized medium, (ii) magnetic explosions (when most energy is released in a form of toroidal magnetic field) is considered taking into account possible inhomogeneities of density and external magnetic field and additional energy supply. Self-similar solutions for the internal structure in the bulk flow and in the strongly magnetized sheath near contact discontinuity are found.

  5. Soft X-Ray Stimulated Bremsstrahlung In Traveling Longitudinal Electric Wake-Fields Of Two-Beam Pill-Box Cavities

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Chen, K. W.; Wilhelm, H. E.

    1986-01-01

    The amplification of laser light in a free electron laser (FEL) due to stimulated bremsstrahlung in a traveling longitudinal undulating electric field is derived. It is shown that this FEL provides sufficient gain to be used as a coherent radiation source down to the soft x-ray regime. It is suggested that, among other possibilities, the wake-field produced in a two-beam elliptical or annular pill-box cavity is suitable for the required traveling longitudinal undulating electric field.

  6. Soft X-ray stimulated bremsstrahlung in traveling longitudinal electric wake-fields of two-beam pill-box cavities

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Chen, K. W.; Wilhelm, H. E.

    The amplification of laser light in a free electron laser (FEL) due to stimulated bremsstrahlung in a traveling longitudinal undulating electric field is derived. It is shown that this FEL provides sufficient gain to be used as a coherent radiation source down to the soft X-ray regime. It is suggested that, among other possibilities, the wake-field produced in a two-beam elliptical or annular pill-box cavity is suitable for the required traveling longitudinal undulating electric field.

  7. Double-sided Relativistic Magnetron

    NASA Astrophysics Data System (ADS)

    Agafonov, A. V.; Krastelev, E. G.

    1997-05-01

    A new scheme of a symmetricaly powered relativistic magnetron and several methods of localised electron flow forming in an interaction region are proposed to increase an efficiency of relativistic magnetrons. As will be shown, a very important reason is the effect of nonsymmetric feeding of power from one side of a magnetron, which is typical for experiments. One-sided powering leads to the axial drift of electrons, to the transformation of transverse velocities of electrons to longitudinal one and to the generation of a parasitic e-beam which does not take part in energy exchange between electrons and waves at all. A special driver was designed for double-sided powering of relativistic magnetrons. The proposed system is compact, rigid and capable of reliable operation at high repetition rates, which is advantageous for many applications. Several smooth-bore magnetrons were tested by means of computer simulations using PIC code KARAT. The results showed a dramatical difference between the dynamics of electron flow for one- and two-sided power feeding of a structure under test. Design of a driver and computer simulation results are presented.

  8. Relativistic opacities for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Fontes, C. J.; Fryer, C. L.; Hungerford, A. L.; Hakel, P.; Colgan, J.; Kilcrease, D. P.; Sherrill, M. E.

    2015-09-01

    We report on the use of the Los Alamos suite of relativistic atomic physics codes to generate radiative opacities for the modeling of astrophysically relevant plasmas under local thermodynamic equilibrium (LTE) conditions. The atomic structure calculations are carried out in fine-structure detail, including full configuration interaction. Three example applications are considered: iron opacities at conditions relevant to the base of the solar convection zone, nickel opacities for the modeling of stellar envelopes, and samarium opacities for the modeling of light curves produced by neutron star mergers. In the first two examples, comparisons are made between opacities that are generated with the fully and semi-relativistic capabilities in the Los Alamos suite of codes. As expected for these highly charged, iron-peak ions, the two methods produce reasonably similar results, providing confidence that the numerical methods have been correctly implemented. However, discrepancies greater than 10% are observed for nickel and investigated in detail. In the final application, the relativistic capability is used in a preliminary investigation of the complicated absorption spectrum associated with cold lanthanide elements.

  9. Relativistic Tennis Using Flying Mirror

    SciTech Connect

    Pirozhkov, A. S.; Kando, M.; Ma, J.; Fukuda, Y.; Chen, L.-M.; Daito, I.; Ogura, K.; Homma, T.; Hayashi, Y.; Kotaki, H.; Sagisaka, A.; Mori, M.; Koga, J. K.; Kawachi, T.; Daido, H.; Kimura, T.; Kato, Y.; Tajima, T.; Esirkepov, T. Zh.; Bulanov, S. V.

    2008-06-24

    Upon reflection from a relativistic mirror, the electromagnetic pulse frequency is upshifted and the duration is shortened by the factor proportional to the relativistic gamma-factor squared due to the double Doppler effect. We present the results of the proof-of-principle experiment for frequency upshifting of the laser pulse reflected from the relativistic 'flying mirror', which is a wake wave near the breaking threshold created by a strong driver pulse propagating in underdense plasma. Experimentally, the wake wave is created by a 2 TW, 76 fs Ti:S laser pulse from the JLITE-X laser system in helium plasma with the electron density of {approx_equal}4-6x10{sup 19} cm{sup -3}. The reflected signal is observed with a grazing-incidence spectrograph in 24 shots. The wavelength of the reflected radiation ranges from 7 to 14 nm, the corresponding frequency upshifting factors are {approx}55-115, and the gamma-factors are y = 4-6. The reflected signal contains at least 3x10{sup 7} photons/sr. This effect can be used to generate coherent high-frequency ultrashort pulses that inherit temporal shape and polarization from the original (low-frequency) ones. Apart from this, the reflected radiation contains important information about the wake wave itself, e.g. location, size, phase velocity, etc.

  10. Relativistic Navigation: A Theoretical Foundation

    NASA Technical Reports Server (NTRS)

    Turyshev, Slava G.

    1996-01-01

    We present a theoretical foundation for relativistic astronomical measurements in curved space-time. In particular, we discuss a new iterative approach for describing the dynamics of an isolated astronomical N-body system in metric theories of gravity. To do this, we generalize the Fock-Chandrasekhar method of the weak-field and slow-motion approximation (WFSMA) and develop a theory of relativistic reference frames (RF's) for a gravitationally bounded many-extended-body problem. In any proper RF constructed in the immediate vicinity of an arbitrary body, the N-body solutions of the gravitational field equations are formally presented as a sum of the Riemann-flat inertial space-time, the gravitational field generated by the body itself, the unperturbed solutions for each body in the system transformed to the coordinates of this proper RF, and the gravitational interaction term. We develop the basic concept of a general WFSMA theory of the celestial RF's applicable to a wide class of metric theories of gravity and an arbitrary model of matter distribution. We apply the proposed method to general relativity. Celestial bodies are described using a perfect fluid model; as such, they possess any number of internal mass and current multipole moments that explicitly characterize their internal structures. The obtained relativistic corrections to the geodetic equations of motion arise because of a coupling of the bodies' multiple moments to the surrounding gravitational field. The resulting relativistic transformations between the different RF's extend the Poincare group to the motion of deformable self-gravitating bodies. Within the present accuracy of astronomical measurements we discuss the properties of the Fermi-normal-like proper RF that is defined in the immediate vicinity of the extended compact bodies. We further generalize the proposed approximation method and include two Eddington parameters (gamma, Beta). This generalized approach was used to derive the

  11. Relativistic radiation transport in dispersive media

    SciTech Connect

    Kichenassamy, S.; Krikorian, R.A.

    1985-10-15

    A general-relativistic radiative transfer equation in an isotropic, weakly absorbing, nonmagnetized dispersive medium is derived using the kinetic-theoretical approach and the relativistic Hamiltonian theory of geometrical optics in those media. It yields the generally accepted classical equation in the special-relativistic approximation and in stationary conditions. The influence of the gravitational field and of space-time variations of the refractive index n on the radiation distribution is made explicit in the case of spherical symmetry.

  12. Mesoscopic Superposition States in Relativistic Landau Levels

    SciTech Connect

    Bermudez, A.; Martin-Delgado, M. A.; Solano, E.

    2007-09-21

    We show that a linear superposition of mesoscopic states in relativistic Landau levels can be built when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily superpositions of coherent states involving the particle orbital quanta in a well-defined mesoscopic regime. We demonstrate that these mesoscopic superpositions have a purely relativistic origin and disappear in the nonrelativistic limit.

  13. Loading relativistic Maxwell distributions in particle simulations

    SciTech Connect

    Zenitani, Seiji

    2015-04-15

    Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

  14. Loading relativistic Maxwell distributions in particle simulations

    NASA Astrophysics Data System (ADS)

    Zenitani, Seiji

    2015-04-01

    Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50 % for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

  15. Relativistic and non-relativistic magnetohydrodynamic flows around compact stars

    NASA Astrophysics Data System (ADS)

    Mobarry, Clark Matthew

    A set of theoretical tools are developed for studying the magnetized accretion disks and astrophysical jets in active galaxies. A general theory is developed for the steady axisymmetric flow of an ideal general-relativistic fluid around a Schwarzschild black hole. The theory leads to a second-order partial differential equation, a Grad-Shafranov equation, for the magnetic flux function psi(R, theta). The magnetic surface functions of the Grad-Shafranov method are shown to be the Lagrange multipliers of an energy principle. Thus, the magnetic surface functions are not arbitrary functions, but must be chosen consistent with physically stable equilibria. From the energy principle, a numerical artificial friction method is developed to solve the general relativistic Grad-Shafranov equation with fluid flow. This method is suited for the internal boundaries between elliptic and hyperbolic behavior present in magnetospheres with fluid flow. The friction method is shown to be compatible with a theory for the slow dissipative evolution of a nearly ideal MagnetoHydroDynamic (MHD) fluid. A virial theorem is derived from the basic equations of general relativistic MHD. It is used to obtain an upper bound on the total energy in the electromagnetic field in terms of the total gravitational binding energy between the black hole and the matter (and energy) outside it. An analysis is made of the motion of a charged test particle in the electromagnetic field of a magnetized accretion disk surrounding a black hole. The results are consistent with stable orbits close to the event horizon. A semi-analytical model is developed for the evolution and dissipation of narrow magnetized jets from an active galaxy. This model exhibits the acceleration and expansion of the jets with increasing axial distance from the central object.

  16. Laser hosing in relativistically hot plasmas.

    PubMed

    Li, G; Mori, W B; Ren, C

    2013-04-12

    Electron response in an intense laser is studied in the regime where the electron temperature is relativistic. Equations for laser envelope and plasma density evolution, both in the electron plasma wave and ion acoustic wave regimes, are rederived from the relativistic fluid equations to include relativistic plasma temperature effect. These equations are used to study short-pulse and long-pulse laser hosing instabilities using a variational method approach. The analysis shows that relativistic electron temperatures reduce the hosing growth rates and shift the fastest-growing modes to longer wavelengths. These results resolve a long-standing discrepancy between previous nonrelativistic theory and simulations or experiments on hosing. PMID:25167277

  17. What is the relativistic spin operator?

    NASA Astrophysics Data System (ADS)

    Bauke, Heiko; Ahrens, Sven; Keitel, Christoph H.; Grobe, Rainer

    2014-04-01

    Although the spin is regarded as a fundamental property of the electron, there is no universally accepted spin operator within the framework of relativistic quantum mechanics. We investigate the properties of different proposals for a relativistic spin operator. It is shown that most candidates are lacking essential features of proper angular momentum operators, leading to spurious zitterbewegung (quivering motion) or violation of the angular momentum algebra. Only the Foldy-Wouthuysen operator and the Pryce operator qualify as proper relativistic spin operators. We demonstrate that ground states of highly charged hydrogen-like ions can be utilized to identify a legitimate relativistic spin operator experimentally.

  18. Dissipation in Relativistic Pair-Plasma Reconnection

    NASA Technical Reports Server (NTRS)

    Hesse, Michael; Zenitani, Seiji

    2007-01-01

    We present an investigation of the relativistic dissipation in magnetic reconnection. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm's law is derived. We analyze a set of numerical simulations, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For anti-parallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.

  19. Dissipation in relativistic pair-plasma reconnection

    SciTech Connect

    Hesse, Michael; Zenitani, Seiji

    2007-11-15

    An investigation into the relativistic dissipation in magnetic reconnection is presented. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm's law is derived. A set of numerical simulations is analyzed, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For antiparallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.

  20. Relativistic Bernstein waves in a degenerate plasma

    SciTech Connect

    Ali, Muddasir; Hussain, Azhar; Murtaza, G.

    2011-09-15

    Bernstein mode for a relativistic degenerate electron plasma is investigated. Using relativistic Vlasov-Maxwell equations, a general expression for the conductivity tensor is derived and then employing Fermi-Dirac distribution function a generalized dispersion relation for the Bernstein mode is obtained. Two limiting cases, i.e., non-relativistic and ultra-relativistic are discussed. The dispersion relations obtained are also graphically presented for some specific values of the parameters depicting how the propagation characteristics of Bernstein waves as well as the Upper Hybrid oscillations are modified with the increase in plasma number density.

  1. Analysis of the SERSE Ion Output by Using Klystron-based or TWT-based Microwave generators

    SciTech Connect

    Celona, L.; Gammino, S.; Ciavola, G.; Consoli, F.; Galata, A.

    2005-03-15

    A set of measurements has been carried out in order to confirm the previously observed enhancement of the SERSE source performances, when microwaves are fed by means of a TWT generator instead of a Klystron generator, which has been commonly used. An increase in the extracted currents takes place for the highest charge states by using a TWT at 14 GHz, while higher extracted currents were obtained for every charge state by using a TWT at 18 GHz. A description of the experimental set-up and of the obtained results is given in the following. The data will be analysed and a qualitative explanation in terms of ECRIS plasma model will be proposed.

  2. MM-wave cavity/klystron developments using deep x-ray lithography at the Advanced Photon Source.

    SciTech Connect

    Song, J.J.; Decarlo, F.; Kang, Y.W.; Kustom, R.L.; Mancini, D.c.; Nassiri, A.; Lai, B.; Caryotakis, G.; Jongewaard, E.N.; Feinerman, A.D.; White, V.

    1998-03-31

    Recent microfabrication technologies based on LIGA (German acronym for Li thographe, G alvanoformung, und A bformung) have been applied to build high-aspect-ratio, metallic or dielectric, planar structures suitable for high frequency rf cavity structures. The cavity structures would be used as parts of linear accelerators, microwave undulators, and mm-wave amplifiers. The microfabrication process includes manufacturing of precision x-ray masks, exposure of positive resist by x-rays through the mask, resist development, and electroforming of the final microstructure. Prototypes of a 32-cell, 108-GHz constant impedance cavity and a 66-cell, 94-GHz constant-gradient cavity were fabricated using the synchrotron radiation sources at APS. Preliminary design parameters for a 91- GHz modulator klystron along with an overview of the new technology are discussed.

  3. MM-Wave Cavity/Klystron Developments Using Deep X-Ray Lithography at the Advanced Photon Source

    SciTech Connect

    Song, J.J.; Kang, Y.W.; Kustom, R.L.; Mancini, D.C.; Nassiri, A.; Lai, B.; Jongwaard, E.N.; Caryotakis, G.; Feinerman, A.D.; White, V.; /Wisconsin U., Madison

    2006-10-25

    Recent microfabrication technologies based on LIGA (German acronym for Lithographe, Galvanoformung, und Abformung) have been applied to build high-aspect-ratio, metallic or dielectric, planar structures suitable for high-frequency rf cavity structures. The cavity structures would be used as parts of linear accelerators, microwave undulators, and mm-wave amplifiers. The microfabrication process includes manufacturing of precision x-ray masks, exposure of positive resist by x-rays through the mask, resist development, and electroforming of the final microstructure. Prototypes of a 32-cell, 108-GHz constant impedance cavity and a 66-cell, 94-GHz constant-gradient cavity were fabricated using the synchrotron radiation sources at APS. Preliminary design parameters for a 91-GHz modulator klystron along with an overview of the new technology are discussed.

  4. Eulerian method for computing multivalued solutions of the Euler-Poisson equations and applications to wave breaking in klystrons.

    PubMed

    Li, Xiantao; Wöhlbier, John G; Jin, Shi; Booske, John H

    2004-01-01

    We provide methods of computing multivalued solutions to the Euler-Poisson system and test them in the context of a klystron amplifier. An Eulerian formulation capable of computing multivalued solutions is derived from a kinetic description of the Euler-Poisson system and a moment closure. The system of the moment equations may be closed due to the special structure of the solution in phase space. The Eulerian moment equations are computed for a velocity modulated electron beam, which has been shown by prior Lagrangian theories to break in a finite time and form multivalued solutions. The results of the Eulerian moment equations are compared to direct computation of the kinetic equations and a Lagrangian method also developed in the paper. We use the Lagrangian formulation for the explicit computation of wave breaking time and location for typical velocity modulation boundary conditions. PMID:15324179

  5. High-gain lasing and polarization switch with a distributed optical-klystron free-electron laser.

    PubMed

    Wu, Y K; Vinokurov, N A; Mikhailov, S; Li, J; Popov, V

    2006-06-01

    This Letter reports the first experimental results from the world's first distributed optical-klystron (DOK) free-electron laser (FEL), the DOK-1 FEL, at Duke University. The DOK-1 FEL is a hybrid system, comprised of four wigglers: two horizontal and two helical. With the DOK-1 FEL, we have obtained the highest FEL gain among all storage ring based FELs at 47.8% (+/-2.7%) per pass. We have also demonstrated that the FEL gain can be enhanced by increasing electron bunching using wigglers with a different polarization. Furthermore, we have realized controlled polarization switches of the FEL beam by a nonoptical means through the manipulation of a buncher magnet. PMID:16803315

  6. Experimental Study of a Gyrotron with a Sectioned Klystron-Type Cavity Operated at Higher Cyclotron Harmonics

    NASA Astrophysics Data System (ADS)

    Bandurkin, I. V.; Kalynov, Yu. K.; Savilov, A. V.

    2016-02-01

    We are planning to use extended cavities in order to excite gyrotrons with large electron orbits, which are operated at higher cyclotron harmonics in the terahertz frequency range. This is determined by both the weakness of the electron-wave interaction, and relatively low operating currents. Since the diffraction Q-factor of such cavities is high, a significant part of the highfrequency power produced by the electron beam is lost due to the ohmic loss in the cavity walls. As a way to solve this problem, we proposed a sectioned klystron-type cavity, where an extended length of the electron-wave interaction region can be combined with a relatively low diffraction Q-factor of the system. This work presents the results of the first experiment on a gyrotron with a sectioned cavity, where selective excitation of higher (second and third) cyclotron harmonics was observed in the terahertz frequency range (0 .55 and 0 .74 THz).

  7. Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency.

    PubMed

    Stark, David J; Bhattacharjee, Chinmoy; Arefiev, Alexey V; Toncian, Toma; Hazeltine, R D; Mahajan, S M

    2015-07-10

    3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. For an anisotropic electron distribution, propagation characteristics, like the critical density, will depend on the polarization of the electromagnetic wave. Despite the onset of the Weibel instability in such plasmas, the anisotropy can persist long enough to affect laser propagation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization. PMID:26207473

  8. Relativistic and non-relativistic solitons in plasmas

    NASA Astrophysics Data System (ADS)

    Barman, Satyendra Nath

    This thesis entitled as "Relativistic and Non-relativistic Solitons in Plasmas" is the embodiment of a number of investigations related to the formation of ion-acoustic solitary waves in plasmas under various physical situations. The whole work of the thesis is devoted to the studies of solitary waves in cold and warm collisionless magnetized or unmagnetized plasmas with or without relativistic effect. To analyze the formation of solitary waves in all our models of plasmas, we have employed two established methods namely - reductive perturbation method to deduce the Korteweg-de Vries (KdV) equation, the solutions of which represent the important but near exact characteristic concepts of soliton-physics. Next, the pseudopotential method to deduce the energy integral with total nonlinearity in the coupling process for exact characteristic results of solitons has been incorporated. In Chapter 1, a brief description of plasma in nature and laboratory and its generation are outlined elegantly. The nonlinear differential equations to characterize solitary waves and the relevant but important methods of solutions have been mentioned in this chapter. The formation of solitary waves in unmagnetized and magnetized plasmas, and in relativistic plasmas has been described through mathematical entity. Applications of plasmas in different fields are also put forwarded briefly showing its importance. The study of plasmas as they naturally occur in the universe encompasses number of topics including sun's corona, solar wind, planetary magnetospheres, ionospheres, auroras, cosmic rays and radiation. The study of space weather to understand the universe, communications and the activities of weather satellites are some useful areas of space plasma physics. The surface cleaning, sterilization of food and medical appliances, killing of bacteria on various surfaces, destroying of viruses, fungi, spores and plasma coating in industrial instruments ( like computers) are some of the fields

  9. Magnetogenesis through Relativistic Velocity Shear

    NASA Astrophysics Data System (ADS)

    Miller, Evan

    Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday's law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic 'battery' arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.

  10. Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency

    NASA Astrophysics Data System (ADS)

    Hazeltine, R. D.; Stark, David J.; Bhattacharjee, Chinmoy; Arefiev, Alexey V.; Toncian, Toma; Mahajan, S. M.

    2015-11-01

    3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. We consider here the simplest problem: the propagation of a low amplitude pulse through a preformed relativistically hot anisotropic electron plasma to explore its intrinsic dielectric properties. We find that: 1) the critical density for propagation depends strongly on the pulse polarization, 2) two plasmas with the same density and average energy per electron can exhibit profoundly different responses to electromagnetic pulses, 3) the anisotropy-driven Weibel instability develops as expected; the timescales of the growth and back reaction (on anisotropy), however, are long enough that sufficient anisotropy persists for the entire duration of the simulation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization. This work was supported by the U.S. DOE Contract Nos. DE-FG02-04ER54742 and DE-AC05-06OR23100 (D. J. S.) and NNSA Contract No. DE-FC52-08NA28512.

  11. Relativistic radiative transfer and relativistic spherical shell flows

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2016-06-01

    We examine a radiatively driven spherical flow from a central object, whose thickness is smaller than the radius of the central object, and a plane-parallel approximation can be used-a spherical shell flow. We first solve the relativistic radiative transfer equation iteratively, using a given velocity field, and obtain specific intensities as well as moment quantities. Using the obtained comoving flux, we then solve the relativistic hydrodynamical equation, and obtain a new velocity field. We repeat these double iteration processes until both the intensity and velocity profiles converge. We found that the flow speed v(τ) is roughly approximated as β ≡ v/c = βs(1 - τ/τb), where τ is the optical depth, τb the flow total optical depth, and c the speed of light. We further found that the flow terminal speed vs is roughly expressed as β _s ≡ v_s/c = (Γ hat{F}_0-1)τ_b/dot{m} , where Γ is the central luminosity normalized by the Eddington luminosity, hat{F}_0 the comoving flux normalized by the incident flux, and of the order of unity, and dot{m} the mass-loss rate normalized by the critical mass loss.

  12. Relativistic radiative transfer and relativistic spherical shell flows

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2016-04-01

    We examine a radiatively driven spherical flow from a central object, whose thickness is smaller than the radius of the central object, and a plane-parallel approximation can be used-a spherical shell flow. We first solve the relativistic radiative transfer equation iteratively, using a given velocity field, and obtain specific intensities as well as moment quantities. Using the obtained comoving flux, we then solve the relativistic hydrodynamical equation, and obtain a new velocity field. We repeat these double iteration processes until both the intensity and velocity profiles converge. We found that the flow speed v(τ) is roughly approximated as β ≡ v/c = βs(1 - τ/τb), where τ is the optical depth, τb the flow total optical depth, and c the speed of light. We further found that the flow terminal speed vs is roughly expressed as β _s ≡ v_s/c = (Γ hat{F}_0-1)τ_b/dot{m} , where Γ is the central luminosity normalized by the Eddington luminosity, hat{F}_0 the comoving flux normalized by the incident flux, and of the order of unity, and dot{m} the mass-loss rate normalized by the critical mass loss.

  13. Relativistic mean-field theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Ring, Peter; Zhao, Pengwei

    In this chapter, the covariant energy density functional is constructed with both the meson-exchange and the point-coupling pictures. Several widely used functionals with either nonlinear or density-dependent effective interactions are introduced. The applications of covariant density functional theory are demonstrated for infinite nuclear matter and finite nuclei with spherical symmetry, axially symmetric quadrupole deformation, and triaxial quadrupole shapes. Finally, a relativistic description of the nuclear landscape has been discussed, which is not only important for nuclear structure, but also important for nuclear astrophysics, where we are facing the problem of a reliable extrapolation to the very neutron-rich nuclei.

  14. Thermodynamics of polarized relativistic matter

    NASA Astrophysics Data System (ADS)

    Kovtun, Pavel

    2016-07-01

    We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

  15. Einstein Toolkit for Relativistic Astrophysics

    NASA Astrophysics Data System (ADS)

    Collaborative Effort

    2011-02-01

    The Einstein Toolkit is a collection of software components and tools for simulating and analyzing general relativistic astrophysical systems. Such systems include gravitational wave space-times, collisions of compact objects such as black holes or neutron stars, accretion onto compact objects, core collapse supernovae and Gamma-Ray Bursts. The Einstein Toolkit builds on numerous software efforts in the numerical relativity community including CactusEinstein, Whisky, and Carpet. The Einstein Toolkit currently uses the Cactus Framework as the underlying computational infrastructure that provides large-scale parallelization, general computational components, and a model for collaborative, portable code development.

  16. Vortices in relativistic electron beams

    PubMed

    Jovanovic; Fedele; Shukla

    2000-08-01

    We demonstrate that a relativistic electron beam is properly described in the moving frame by the electron-magnetohydrodynamic equations of plasma physics. For large beam currents, the accelerator magnetic field is expected to be unstable to the fast magnetic reconnection. We present a plausible saturated state of the fast reconnection, in the form of a complex vortex pattern. The nonlinear dispersion equations of the vortex are derived and the relationship between the vortex structure and the background magnetic field is discussed. PMID:11088759

  17. Relativistic heavy ion facilities: worldwide

    SciTech Connect

    Schroeder, L.S.

    1986-05-01

    A review of relativistic heavy ion facilities which exist, are in a construction phase, or are on the drawing boards as proposals is presented. These facilities span the energy range from fixed target machines in the 1 to 2 GeV/nucleon regime, up to heavy ion colliders of 100 GeV/nucleon on 100 GeV/nucleon. In addition to specifying the general features of such machines, an outline of the central physics themes to be carried out at these facilities is given, along with a sampling of the detectors which will be used to extract the physics. 22 refs., 17 figs., 3 tabs.

  18. Relativistic atomic beam spectroscopy II

    SciTech Connect

    1989-12-31

    The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, high excitations and double charge escape in H{sup -}, and multiphoton detachment of electrons from H{sup -}.

  19. Relativistic jets and star formation

    NASA Astrophysics Data System (ADS)

    Bicknell, Geoffrey Vincent; Mukherjee, Dipanjan; Wagner, Alex; Slatyer Sutherland, Ralph

    2015-08-01

    We are conducting simulations of jets interacting with molecular and atomic gas on scales of a few kpc in forming galaxies. Competing processes, such as the dispersion of gas in the galaxy and star formation in the high-pressure environment determine whether positive or negative feedback predominates. We shall present our new simulations including an assessment of these different effects. Our simulations also predict the velocity and velocity dispersion of atomic and molecular gas in galaxies, which are undergoing interaction with relativistic jets. These results are of interest to radio and optical spectral imaging observations of galaxies undergoing feedback.

  20. Relativistic quantum private database queries

    NASA Astrophysics Data System (ADS)

    Sun, Si-Jia; Yang, Yu-Guang; Zhang, Ming-Ou

    2015-04-01

    Recently, Jakobi et al. (Phys Rev A 83, 022301, 2011) suggested the first practical private database query protocol (J-protocol) based on the Scarani et al. (Phys Rev Lett 92, 057901, 2004) quantum key distribution protocol. Unfortunately, the J-protocol is just a cheat-sensitive private database query protocol. In this paper, we present an idealized relativistic quantum private database query protocol based on Minkowski causality and the properties of quantum information. Also, we prove that the protocol is secure in terms of the user security and the database security.

  1. Adaptive wavelets and relativistic magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Hirschmann, Eric; Neilsen, David; Anderson, Matthe; Debuhr, Jackson; Zhang, Bo

    2016-03-01

    We present a method for integrating the relativistic magnetohydrodynamics equations using iterated interpolating wavelets. Such provide an adaptive implementation for simulations in multidimensions. A measure of the local approximation error for the solution is provided by the wavelet coefficients. They place collocation points in locations naturally adapted to the flow while providing expected conservation. We present demanding 1D and 2D tests includingthe Kelvin-Helmholtz instability and the Rayleigh-Taylor instability. Finally, we consider an outgoing blast wave that models a GRB outflow.

  2. Arbitrarily Long Relativistic Bit Commitment

    NASA Astrophysics Data System (ADS)

    Chakraborty, Kaushik; Chailloux, André; Leverrier, Anthony

    2015-12-01

    We consider the recent relativistic bit commitment protocol introduced by Lunghi et al. [Phys. Rev. Lett. 115, 030502 (2015)] and present a new security analysis against classical attacks. In particular, while the initial complexity of the protocol scales double exponentially with the commitment time, our analysis shows that the correct dependence is only linear. This has dramatic implications in terms of implementation: in particular, the commitment time can easily be made arbitrarily long, by only requiring both parties to communicate classically and perform efficient classical computation.

  3. Relativistic electrons associated with solar flares.

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1972-01-01

    Solar flares which produce relativistic electrons generally occur within sunspot groups which are active in the emission of meter type I noise storms. It is suggested that relativistic electrons in solar flares are accelerated from the keV-energy electrons responsible for the type I noise storms. The relationship between flare developments and the ejection of keV-electrons is briefly considered.

  4. Comparative SEU sensitivities to relativistic heavy ions

    SciTech Connect

    Koga, R.; Crain, S.H.; Crain, W.R.; Crawford, K.B.; Hansel, S.J.

    1998-12-01

    SEU sensitivity of microcircuits to relativistic heavy ions is compared to that measured with low-energy ions of comparable LET values. Multiple junction charge collection in a complex circuit seems to mask the effect of varying charge generations due to different iron track structures. Heavy ions at sub-relativistic speeds may generate nuclear fragments, sometimes resulting in SEUs.

  5. Einstein Never Approved of Relativistic Mass

    ERIC Educational Resources Information Center

    Hecht, Eugene

    2009-01-01

    During much of the 20th century it was widely believed that one of the significant insights of special relativity was "relativistic mass." Today there are two schools on that issue: the traditional view that embraces speed-dependent "relativistic mass," and the more modern position that rejects it, maintaining that there is only one mass and it's…

  6. Representation of relativistic quantities by trigonometric functions

    NASA Astrophysics Data System (ADS)

    Majerník, V.

    1986-06-01

    A ``space-time angle'' φ is defined by setting v=c(sin φ). This leads to a form of Lorentz transformations which uses simple real trigonometric functions and yields a graphic correlation of important relativistic quantities for particles and for corresponding de Broglie waves. A number of relativistic relationships is obtained by the use of common trigonometric identities and formulas.

  7. Compton Effect with Non-Relativistic Kinematics

    ERIC Educational Resources Information Center

    Shivalingaswamy, T.; Kagali, B. A.

    2011-01-01

    In deducing the change of wavelength of x-rays scattered by atomic electrons, one normally makes use of relativistic kinematics for electrons. However, recoiling energies of the electrons are of the order of a few keV which is less than 0.2% of their rest energies. Hence the authors may ask whether relativistic formulae are really necessary. In…

  8. Nonlinear, relativistic Langmuir waves in astrophysical magnetospheres

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.

    1987-01-01

    Large amplitude, electrostatic plasma waves are relevant to physical processes occurring in the astrophysical magnetospheres wherein charged particles are accelerated to relativistic energies by strong waves emitted by pulsars, quasars, or radio galaxies. The nonlinear, relativistic theory of traveling Langmuir waves in a cold plasma is reviewed. The cases of streaming electron plasma, electronic plasma, and two-streams are discussed.

  9. Lattice Boltzmann equation for relativistic quantum mechanics.

    PubMed

    Succi, Sauro

    2002-03-15

    Relativistic versions of the quantum lattice Boltzmann equation are discussed. It is shown that the inclusion of nonlinear interactions requires the standard collision operator to be replaced by a pair of dynamic fields coupling to the relativistic wave function in a way which can be described by a multicomponent complex lattice Boltzmann equation. PMID:16210189

  10. Non-relativistic scale anomalies

    NASA Astrophysics Data System (ADS)

    Arav, Igal; Chapman, Shira; Oz, Yaron

    2016-06-01

    We extend the cohomological analysis in arXiv:1410.5831 of anisotropic Lifshitz scale anomalies. We consider non-relativistic theories with a dynamical critical exponent z = 2 with or without non-relativistic boosts and a particle number symmetry. We distinguish between cases depending on whether the time direction does or does not induce a foliation structure. We analyse both 1 + 1 and 2 + 1 spacetime dimensions. In 1 + 1 dimensions we find no scale anomalies with Galilean boost symmetries. The anomalies in 2 + 1 dimensions with Galilean boosts and a foliation structure are all B-type and are identical to the Lifshitz case in the purely spatial sector. With Galilean boosts and without a foliation structure we find also an A-type scale anomaly. There is an infinite ladder of B-type anomalies in the absence of a foliation structure with or without Galilean boosts. We discuss the relation between the existence of a foliation structure and the causality of the field theory.

  11. 3-D Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Nishikaw, K.-I.; Frank, J.; Christodoulou, D. M.; Koide, S.; Sakai, J.-I.; Sol, H.; Mutel, R. L.

    1998-12-01

    We present 3-D numerical simulations of moderately hot, supersonic jets propagating initially along or obliquely to the field lines of a denser magnetized background medium with Lorentz factors of W=4.56 and evolving in a four-dimensional spacetime. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently in the simulations. This effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure. We also simulate jets with the more realistic initial conditions for injecting jets for helical mangetic field, perturbed density, velocity, and internal energy, which are supposed to be caused in the process of jet generation. Three possible explanations for the observed variability are (i) tidal disruption of a star falling into the black hole, (ii) instabilities in the relativistic accretion disk, and (iii) jet-related PRocesses. New results will be reported at the meeting.

  12. Relativistic Laser-Plasma Interactions

    SciTech Connect

    Skoric, Milos M.

    2009-11-10

    Ever since the much acclaimed paper of Akhiezer and Polovin plasma theorists have been attempting to comprehend complex dynamics related to the propagation of high and ultra-high intensity electromagnetic (EM) radiation through a plasma. This topic was successfully revisited a number of years later by Kaw and Dawson whose analysis threw more light on the propagation of coupled longitudinal-transverse waves of arbitrary intensity. The high phase velocity case was soon solved exactly by Max and Perkins, (early review). The problem of relativistic laser-plasma interactions is of particular interest concerning the fast ignition concept, relevant to contemporary laser inertial confinement fusion research. Moreover, the understanding of relativistic laser pulse evolution in a plasma is basic to many new applications, including optical-field-ionized x-ray lasers, plasma-based electron accelerator schemes, as well as, interpretation of some astrophysical phenomena, and references, therein). From a text given in two tutorial lectures, in a limited space, we mainly focus on an important paradigm of stimulated Raman scattering.

  13. Are relativistic jets monoparametric engines?

    NASA Astrophysics Data System (ADS)

    Georganopoulos, M.; Meyer, E. T.; Fossati, G.; Lister, M. L.

    We adopt as a working hypothesis that relativistic jets are essentially mono-parametric entities, and that their physical properties are a function of a single physical parameter, the same way the physical properties of main sequence stars are mainly a function of the star mass. We propose that the physical parameter is the jet kinetic power, and we use as a proxy for this quantity the low frequency extended radio luminosity (LFERL), an orientation insensitive quantity. We discuss the consequences of this hypothesis for the collective properties of relativistic jets and we show that a blazar sequence should spontaneously emerge on the peak frequency vs luminosity plot as the locus of those sources that are well aligned to the observer's line of sight. We also show that the sources of the same LFERL should form tracks that start from a location on the blazar sequence and move to lower luminosities and peak frequencies in a way that encodes information about the emitting plasma energetics and kinematics and velocity gradients, as well as about the inverse Compton (IC) emission seed photons. We are currently working on collecting the observations that will allow us to put this idea to the test.

  14. Relativistic Definition of Spin Operators

    NASA Astrophysics Data System (ADS)

    Ryder, Lewis H.

    2002-12-01

    Some years ago Mashhoon [1] made the highly interesting suggestion that there existed a coupling of spin with rotations, just as there exists such a coupling with orbital angular momentum, as seen in the Sagnac effect, for example. Spin being essentially a quantum phenomenon, the obvious place to look for this was by studying the Dirac equation, and Hehl and Ni, in such an investigation [2], indeed found a coupling term of just the type Mashhoon had envisaged. Part of their procedure, however, was to take the nonrelativistic limit, and this was done by performing appropriate Foldy-Wouthuysen (FW) transformations. In the nonrelativistic limit, it is well-known that the spin operators for Dirac particles are in essence the Pauli matrices; but it is also well-known, and indeed was part of the motivation for Foldy and Wouthuysen's paper, that for fully-fledged Dirac particles the (4×4 generalisation of the) Pauli matrices do not yield satisfactory spin operators, since spin defined in this way would not be conserved. The question therefore presented itself: is there a relativistic spin operator for Dirac particles, such that in the relativistic, as well as the nonrelativistic, régime a Mashhoon spin-rotation coupling exists?...

  15. Three-dimensional simulation analysis of the first sections of a standing-wave free-electron laser two-beam accelerator

    SciTech Connect

    Wang, Changbiao; Sessler, A.M.

    1993-05-01

    A 3-D, time-dependent code is used to simulate an array of standing-wave free-electron lasers (SWFELs) in the two-beam accelerator. It is shown that for an array of SWFELs with 9 cavities and a 100.6-ns, 0.5-kA, 7.98-MeV electron beam prebunched at 17.1 GHz, an averaged energy output of 14.7J/m can be obtained with a fluctuation of less than 11%.

  16. Relativistic fluids: fundamentals and recent developments

    NASA Astrophysics Data System (ADS)

    Sandoval-Villalbazo, A.; García-Perciante, A. L.

    2014-11-01

    Relativistic thermodynamics and kinetic theory have been subjects of intense research and debate recently. The topic has gained attention primarily due to its application in both astrophysical and experimental scenarios. In this talk I will review some of the challenges theorists have faced in search of a successful formalism capable of describing these systems and the alternatives proposed in order to avoid the well known instabilities and causality problems present in the first works on the subject published more than fifty years ago. Among these proposals I will focus on the first order in the gradients version of relativistic kinetic theory in order to describe special relativistic single component fluids in the presence of external forces. The main results obtained following this path will be shown including the relativistic expressions for dissipative fluxes and entropy production. Some consequences of relativistic modifications in the hydrodynamic equations will also be discussed. This work is supported by CONACyT through Grant CB2011/167563.

  17. Relativistic mixtures of charged and uncharged particles

    NASA Astrophysics Data System (ADS)

    Kremer, Gilberto M.

    2014-01-01

    Mixtures of relativistic gases within the framework of Boltzmann equation are analyzed. Three systems are considered. The first one refers to a mixture of uncharged particles by using Grad's moment method, where the relativistic mixture is characterized by the moments of the distribution functions: particle four-flows, energy-momentum tensors, and third-order moment tensors. In the second Fick's law for a mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric are derived from an extension of Marle and McCormack model equations applied to a relativistic truncated Grad's distribution function, where it is shown the dependence of the diffusion coefficient on the gravitational potential. The third one consists in the derivation of the relativistic laws of Ohm and Fourier for a binary mixtures of electrons with protons and electrons with photons subjected to external electromagnetic fields and in presence of gravitational fields by using the Anderson and Witting model of the Boltzmann equation.

  18. Electron Correlation in 4-Component Relativistic Calculations

    NASA Technical Reports Server (NTRS)

    Visscher, Luuk; Arnold, James O. (Technical Monitor)

    1994-01-01

    The full 4-component Dirac-Coulomb equation can nowadays be used in molecular calculations, The first step in solving this relativistic many-electron equation usually consists of solving the closed or open-shell Diarc-Fock equations. Like in non-relativistic calculations the outcome does not account for the effects of electron correlation. This can in principle be remedied by developing relativistic variants of electron correlation methods like Configuration Interaction or Coupled Cluster. In this talk the differences and similarities of such relativistic approaches as compared to non-relativistic methods will be reviewed. Results of Configuration Interaction calculations on the PtH molecule and on the MeF(sub 6, sup 2-) (Me= Co, Rh, Ir) complexes will be presented to give an impression of the kind of results that currently can be obtained.

  19. Relativistic electron and ion dust charging currents

    SciTech Connect

    Tribeche, Mouloud; Boukhalfa, Soufiane

    2009-09-15

    A first theoretical attempt is made to present a relativistic generalization of the well-known orbit-limited motion theory. The appropriate relativistic (electron and ion) dust charging currents are derived. The nonlinear electrostatic potential is then expressed in terms of the variable dust charge and we take advantage of this new transcendental relation to investigate briefly the effects of relativistic charge carriers. As the relativistic character of the plasma increases, it becomes evident that certain negative values of the dust charge can never be achieved as increasingly larger values of the nonlinear potential are involved. The obtained formulas bring a possibility to build theories of nonlinear collective process in relativistic dusty plasmas.

  20. A New 100-GHz Band Two-Beam Sideband-Separating SIS Receiver for Z-Machine on the NRO 45-m Radio Telescope

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Kimura, K.; Nishimura, A.; Iwashita, H.; Miyazawa, C.; Sakai, T.; Iono, D.; Kohno, K.; Kawabe, R.; Kuno, N.; Ogawa, H.; Asayama, S.; Tamura, T.; Noguchi, T.

    2013-03-01

    We have developed a two-beam waveguide-type dual-polarization sideband-separating SIS receiver system in the 100-GHz band for z-machine on the 45-m radio telescope at the Nobeyama Radio Observatory. The receiver is intended for astronomical use in searching for highly redshifted spectral lines from galaxies of unknown redshift. This receiver has two beams, which have 45'' of beam separation and allow for observation with the switch in the on-on position. The receiver of each beam is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on a waveguide technique, and the receiver has four intermediate frequency bands of 4.0-8.0 GHz. Over the radio frequency range of 80-116 GHz, the single-sideband receiver noise temperature is lower than about 50 K, and the image rejection ratios are greater than 10 dB in most of the same frequency range. The new receiver system has been installed in the telescope, and we successfully observed a 12CO (J = 3-2) emission line toward a cloverleaf quasar at z = 2.56, which validates the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, is typically 150-300 K at a radio frequency of 97 GHz. We have begun a blind search of high-J CO toward high-z submillimeter galaxies.

  1. Relativistic effects in Lyman-α forest

    NASA Astrophysics Data System (ADS)

    Iršič, Vid; Di Dio, Enea; Viel, Matteo

    2016-02-01

    We present the calculation of the Lyman-alpha (Lyman-α) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range (z=2-5). Furthermore, we show a comprehensive application of our calculations to the Quasar-Lyman-α cross-correlation function. Our results indicate that the signal of relativistic effects are sizeable at Baryonic Acoustic Oscillation (BAO) scale mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross-correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considering cross-correlations between tracers with very different biases, and should be included in the data analysis of the current and future surveys. Moreover, the idea presented in this paper is highly complementary to other techniques and observables trying to isolate the effect of the relativistic corrections and thus test the validity of the theory of gravity beyond the Newtonian regime.

  2. Optics in the Relativistic Regime

    NASA Astrophysics Data System (ADS)

    Tajima, Toshiki

    2012-06-01

    Optics has extended the frontier of low energy physics. Here we present the progress in the opposite direction of relativistic intensity regime of optics. With intense and large energy laser, particles may be accelerated to high energies via laser wakefield acceleration (Tajima and Dawson, 1979) over a compact distance orders of magnitude shorter than the RF approach. We should be able to accelerate electrons (over 30m) and ions (over cm) toward TeV with an existing kJ laser. We can check Lorentz invariance in the ultrarelativistic regime. Further, laser allows us to explore the presence of weakly coupling fields such as Dark Matter and Dark Energy with an unprecedented sensitivity. We call this emerging capability as the Laser Particle Physics Paradigm (LP^3).

  3. 3-D Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Frank, J.; Koide, S.; Sakai, J.-I.; Christodoulou, D. M.; Sol, H.; Mutel, R. L.

    1998-12-01

    We present 3-D numerical simulations of moderately hot, supersonic jets propagating initially along or obliquely to the field lines of a denser magnetized background medium with Lorentz factors of W = 4.56 and evolving in a four-dimensional spacetime. The new results are understood as follows: Relativistic simulations have consistently shown that these jets are effectively heavy and so they do not suffer substantial momentum losses and are not decelerated as efficiently as their nonrelativistic counterparts. In addition, the ambient magnetic field, however strong, can be pushed aside with relative ease by the beam, provided that the degrees of freedom associated with all three spatial dimensions are followed self-consistently in the simulations. This effect is analogous to pushing Japanese ``noren'' or vertical Venetian blinds out of the way while the slats are allowed to bend in 3-D space rather than as a 2-D slab structure.

  4. Invisibility cloaks in relativistic motion

    NASA Astrophysics Data System (ADS)

    Halimeh, Jad C.; Thompson, Robert T.; Wegener, Martin

    2016-01-01

    We consider an ideal invisibility cloak which is illuminated by monochromatic light and which moves in vacuum at constant relativistic velocity with respect to the common inertial frame of light source and observer. We show that, in general, the moving cloak becomes detectable by image distortions and by generating a broad frequency spectrum of the scattered light. However, for many special combinations of incident light frequency, wave vector of light, and cloak velocity, ideal cloaking remains possible. It becomes nonreciprocal though. This means that light rays emitted by the light source arrive at the observer as though they have traveled through vacuum, but they take completely different paths after being retroreflected at the observer position.

  5. Relativistic recoil and the railgun

    NASA Astrophysics Data System (ADS)

    Allen, J. E.; Jones, T. V.

    1990-01-01

    Calculations are presented that refute recent statements (e.g., Graneau, 1987) made to the effect that the operation of a railgun cannot be explained in terms of classical relativistic electrodynamics. It is demonstrated that, on the contrary, there is no difficulty in using the concept of electromagnetic momentum to calculate the electromagnetic forces that propel the projectile in a railgun. The error made by other authors was to suppose that classical electrodynamics demand that a large amount of momentum be associated with the electromagnetic field at some previous time. The projectile can acquire much more momentum than that associated with the incident wave, because the electromagnetic waves are reflected both at the projectile end and at the breech end of the railgun.

  6. Landau damping in relativistic plasmas

    NASA Astrophysics Data System (ADS)

    Young, Brent

    2016-02-01

    We examine the phenomenon of Landau damping in relativistic plasmas via a study of the relativistic Vlasov-Poisson (rVP) system on the torus for initial data sufficiently close to a spatially uniform steady state. We find that if the steady state is regular enough (essentially in a Gevrey class of degree in a specified range) and if the deviation of the initial data from this steady state is small enough in a certain norm, the evolution of the system is such that its spatial density approaches a uniform constant value quasi-exponentially fast (i.e., like exp ( - C |" separators=" t | ν ¯ ) for ν ¯ ∈ ( 0 , 1 ) ). We take as a priori assumptions that solutions launched by such initial data exist for all times (by no means guaranteed with rVP, but a reasonable assumption since we are close to a spatially uniform state) and that the various norms in question are continuous in time (which should be a consequence of an abstract version of the Cauchy-Kovalevskaya theorem). In addition, we must assume a kind of "reverse Poincaré inequality" on the Fourier transform of the solution. In spirit, this assumption amounts to the requirement that there exists 0 < ϰ < 1 so that the mass in the annulus ϰ ≤ |" separators=" v | < 1 for the solution launched by the initial data is uniformly small for all t. Typical velocity bounds for solutions to rVP launched by small initial data (at least on ℝ6) imply this bound. We note that none of our results require spherical symmetry (a crucial assumption for many current results on rVP).

  7. Localization scheme for relativistic spinors

    NASA Astrophysics Data System (ADS)

    Ciupka, J.; Hanrath, M.; Dolg, M.

    2011-12-01

    A new method to determine localized complex-valued one-electron functions in the occupied space is presented. The approach allows the calculation of localized orbitals regardless of their structure and of the entries in the spinor coefficient matrix, i.e., one-, two-, and four-component Kramers-restricted or unrestricted one-electron functions with real or complex expansion coefficients. The method is applicable to localization schemes that maximize (or minimize) a functional of the occupied spinors and that use a localization operator for which a matrix representation is available. The approach relies on the approximate joint diagonalization (AJD) of several Hermitian (symmetric) matrices which is utilized in electronic signal processing. The use of AJD in this approach has the advantage that it allows a reformulation of the localization criterion on an iterative 2 × 2 pair rotating basis in an analytical closed form which has not yet been described in the literature for multi-component (complex-valued) spinors. For the one-component case, the approach delivers the same Foster-Boys or Pipek-Mezey localized orbitals that one obtains from standard quantum chemical software, whereas in the multi-component case complex-valued spinors satisfying the selected localization criterion are obtained. These localized spinors allow the formulation of local correlation methods in a multi-component relativistic framework, which was not yet available. As an example, several heavy and super-heavy element systems are calculated using a Kramers-restricted self-consistent field and relativistic two-component pseudopotentials in order to investigate the effect of spin-orbit coupling on localization.

  8. Relativistic Theory of Few Body Systems

    SciTech Connect

    Franz Gross

    2002-11-01

    Very significant advances have been made in the relativistic theory of few body systems since I visited Peter Sauer and his group in Hannover in 1983. This talk provides an opportunity to review the progress in this field since then. Different methods for the relativistic calculation of few nucleon systems are briefly described. As an example, seven relativistic calculations of the deuteron elastic structure functions, A, B, and T{sub 20}, are compared. The covariant SPECTATOR {copyright} theory, among the more successful and complete of these methods, is described in more detail.

  9. Momentum relaxation of a relativistic Brownian particle.

    PubMed

    Felderhof, B U

    2012-12-01

    The momentum relaxation of a relativistic Brownian particle immersed in a fluid is studied on the basis of the Fokker-Planck equation for the relativistic Ornstein-Uhlenbeck process. An analytical expression is derived for the short-time relaxation rate. The relaxation spectrum has both discrete and continuum components. It is shown that the Fokker-Planck equation under consideration is closely related to the Schrödinger equation for the hydrogen atom. Hence it follows that there is an infinite number of discrete states. The momentum autocorrelation function is calculated numerically for a strongly relativistic particle. PMID:23367889

  10. Relativistic scattered wave calculations on UF6

    NASA Technical Reports Server (NTRS)

    Case, D. A.; Yang, C. Y.

    1980-01-01

    Self-consistent Dirac-Slater multiple scattering calculations are presented for UF6. The results are compared critically to other relativistic calculations, showing that the results of all molecular orbital calculations are in qualitative agreement, as measured by energy levels, population analyses, and spin-orbit splittings. A detailed comparison is made to the relativistic X alpha(RX alpha) method of Wood and Boring, which also uses multiple scattering theory, but incorporates relativistic effects in a more approximate fashion. For the most part, the RX alpha results are in agreement with the present results.

  11. Forced Turbulence in Relativistic Conformal Fluids

    NASA Astrophysics Data System (ADS)

    Westernacher-Schneider, John Ryan; Green, Stephen; Lehner, Luis; Canon, Kipp; Oz, Yaron

    2015-04-01

    Given the renewed interest arising both from AdS/CFT and astrophysics, we revisit the phenomenon of relativistic turbulence. We build on some recent work which extends known non-relativistic results in turbulence to the case of relativistic (and thus compressible) fluids. In particular, we derive the scaling behaviour of two-point correlation functions in 2+1 dimensions--holographically dual to 3+1 dimensional gravity. Turbulence in 2+1 dimensions also approximates several astrophysical situations, such as thin accretion disks around black holes. We perform numerical simulations of forced steady-state turbulence to verify our derived correlation functions.

  12. Relativistic corrections to the triton binding energy

    SciTech Connect

    Sammarruca, F.; Xu, D.P.; Machleidt, R. )

    1992-11-01

    The influence of relativity on the triton binding energy is investigated. The relativistic three-dimensional version of the Bethe-Salpeter equation proposed by Blankenbecler and Sugar (BbS) is used. Relativistic (nonseparable) one-boson-exchange potentials (constructed in the BbS framework) are employed for the two-nucleon interaction. In a 34-channel Faddeev calculation, it is found that relativistic effects increase the triton binding energy by about 0.2 MeV. Including charge dependence (besides relativity), the final triton binding energy predictions are 8.33 and 8.16 MeV for the Bonn A and B potentials, respectively.

  13. Relativistic quantum mechanics and relativistic entanglement in the rest-frame instant form of dynamics

    SciTech Connect

    Alba, David; Crater, Horace W.; Lusanna, Luca

    2011-06-15

    A new formulation of relativistic quantum mechanics is proposed in the framework of the rest-frame instant form of dynamics, where the world-lines of the particles are parametrized in terms of the Fokker-Pryce center of inertia and of Wigner-covariant relative 3-coordinates inside the instantaneous Wigner 3-spaces, and where there is a decoupled (non-covariant and non-local) canonical relativistic center of mass. This approach: (a) allows us to make a consistent quantization in every inertial frame; (b) leads to a description of both bound and scattering states; (c) offers new insights on the relativistic localization problem; (d) leads to a non-relativistic limit with a Hamilton-Jacobi treatment of the Newton center of mass; (e) clarifies non-local aspects (spatial non-separability) of relativistic entanglement connected with Lorentz signature and not present in its non-relativistic treatment.

  14. Relativistic Effects in Two Photon Decay of 0-+ Quarkonium

    NASA Astrophysics Data System (ADS)

    Zhou, H. Q.; Zou, B. S.

    Relativistic effects in two photon decay of 0-+ quarkonium are investigated with a relativistic phenomenological approach. Comparing with the non-relativistic approximation, the relativistic phenomenological approach gives corrections coming from three sources: qbar q relative momentum distribution, qbar q relative energy distribution and description of quark spinors in the meson. These relativistic effects are studied in detail for cbar c and sbar s systems.

  15. Relativistic Electron-Electron Bremsstrahlung in Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Jia; Kawai, Norio; Kawamura, Takaichi; Maegauchi, Tetsuo; Narumi, Hajime

    1982-05-01

    Transition matrices and differential cross sections for electron-electron bremsstrahlung in relativistic energy region are calculated by the lowest-order perturbation theory of quantum electrodynamics. The bremsstrahlung spectra and emission rates are evaluated for relativistic Maxwellian plasma. The results are discussed in comparison with those obtained by non-relativistic and extreme-relativistic approximations and it is noted that the relativistic effect becomes appreciable above the order of 10 keV for the electron temperature.

  16. Coherent states for the relativistic harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Aldaya, Victor; Guerrero, J.

    1995-01-01

    Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.

  17. Relativistic plasma astrophysics with intense lasers

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Yasuhiro; Chu, Hsu-Hsin; Hau, Lin-Ni; Chen, Shih-Hung; Liu, Yao-Li; Hsieh, Chia-Ying; Sakawa, Youichi; Hideaki, Takabe; Wang, Jyhpyng

    2015-12-01

    Recent progresses of laser technologies enable us to investigate space and astrophysical phenomena in laboratories. In space plasmas the local observations by spacecrafts provide us the microscopic information of the plasma and electric/magnetic fields, however, it is difficult to obtain the global structures of the phenomena. In astrophysical plasmas, in contrast, global images provide us the macroscopic information, although there is no local observation and thus no microscopic information. Laboratory experiments on space and astrophysical phenomena provide us the local and global information simultaneously. We have investigated so far mostly non-relativistic phenomena in the universe with long laser pulses. Now we extend our research from non-relativistic to relativistic regime with an ultra intense laser, the 100 TW laser facility at National Central University. We introduce our facility and model relativistic phenomena in laboratory, focusing on the magnetic field generation and the magnetic reconnection in the universe.

  18. Hot relativistic winds and the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Fujimura, F. S.; Kennel, C. F.

    1981-01-01

    Efforts to formulate a self-consistent model of pulsar magnetospheres which links the particle source near the pulsar to the outflowing relativistic wind and couples the wind to the surrounding nebula are reviewed. The use of a relativistic MHD wind is recommended to account for global photon emission and the invisibility of the method of plasma transport. Consideration of a magnetic monopole relativistic wind due to an axially symmetric aligned rotator is combined with calculations of the initial velocity of the wind to show that the flow velocity in such a model will never exceed Mach 1. Extending the solution to the case of a hot relativistic wind at supersonic speeds is noted to yield results consistent with observations of the Crab Nebula

  19. Electromagnetic processes in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Bertulani, C. A.; Baur, G.

    1986-10-01

    Electromagnetic effects in relativistic heavy ion collisions with impact parameter larger than the sum of the nuclear radii are studied using the virtual photon method. With increasing value of the relativistic parameter γ the hardness of the virtual photon spectrum increases. This leads to interesting new effects which will also have to be considered in the design of future relativistic heavy ion machines and experiments. The excitation of high-lying giant E1 and E2 multipole resonances is calculated as well as electromagnetic pion production. Coulomb bremsstrahlung is calculated and compared to the bremsstrahlung emitted in the more violent central nuclear collisions. K-shell ionization and electron-positron pair production is studied. The latter process has a very large cross section for heavy ions and contributes significantly to the stopping power of relativistic heavy ions in a dense medium.

  20. Quantum probability assignment limited by relativistic causality.

    PubMed

    Han, Yeong Deok; Choi, Taeseung

    2016-01-01

    Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717

  1. Pseudospectral approach to relativistic molecular theory.

    PubMed

    Nakajima, Takahito; Hirao, Kimihiko

    2004-08-22

    The efficient relativistic Dirac-Hartree-Fock (DHF) and Dirac-Kohn-Sham (DKS) methods are proposed by an application of the pseudospectral (PS) approach. The present PS-DHF/DKS method is a relativistic extension of the PS-HF/KS method of Friesner, though we aim at higher numerical accuracy by elimination of superfluous arbitrariness. The relativistic PS-DHF/DKS method is implemented into our REL4D programs. Several PS applications to molecular systems show that the relativistic PS-DHF/DKS approach is more efficient than the traditional approach without a loss of accuracy. The present PS-DKS method successfully assigns and predicts the photoelectron spectra of hexacarbonyl complexes of tungsten and seaborgium theoretically. PMID:15303907

  2. Relativistic Thomson Scatter from Factor Calculation

    Energy Science and Technology Software Center (ESTSC)

    2009-11-01

    The purpose of this program is calculate the fully relativistic Thomson scatter from factor in unmagnetized plasmas. Such calculations are compared to experimental diagnoses of plasmas at such facilities as the Jupiter laser facility here a LLNL.

  3. Quantum probability assignment limited by relativistic causality

    PubMed Central

    Han, Yeong Deok; Choi, Taeseung

    2016-01-01

    Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717

  4. Relativistic projection and boost of solitons

    SciTech Connect

    Wilets, L.

    1991-12-31

    This report discusses the following topics on the relativistic projection and boost of solitons: The center of mass problem; momentum eigenstates; variation after projection; and the nucleon as a composite. (LSP).

  5. Relativistic projection and boost of solitons

    SciTech Connect

    Wilets, L.

    1991-01-01

    This report discusses the following topics on the relativistic projection and boost of solitons: The center of mass problem; momentum eigenstates; variation after projection; and the nucleon as a composite. (LSP).

  6. A 100 kV, 60 A solid state 4 kHz switching modulator for high power klystron driving

    NASA Astrophysics Data System (ADS)

    Cortázar, O. D.; Ganuza, D.; De La Fuente, J. M.; Zulaika, M.; Pérez, A.; Anderson, D. E.

    2013-05-01

    A solid state high power modulator capable of delivering 120 kV and 60 A developed in collaboration with the JEMA Corporation, ESS Bilbao, and the SNS (ORNL) for driving high power klystrons is presented. Pulses with less than 10 μs risetime and flatness under 0.1% are obtained with programmable frequency pulses between 2 and 50 Hz. Eight solid state switches combined with custom air-insulated high voltage transformers working at a switching frequency of 4 kHz produce high quality pulses by phase shifting the transformer drives. Each relative high frequency stage pumps a double stage high voltage Marx generator that supplies the output pulse shape and frequency. This merged topology between a Marx generator and direct modulator takes advantage of the strengths of both approaches. Low energy storage in the output stages assures safe operation in case of a load arc discharge. Real time voltage correction during the pulse is also provided to compensate for the droop inherent with the use of low energy storage in the output stages. Data at full power with a dummy resistive load are presented.

  7. A 100 kV, 60 A solid state 4 kHz switching modulator for high power klystron driving.

    PubMed

    Cortázar, O D; Ganuza, D; De La Fuente, J M; Zulaika, M; Pérez, A; Anderson, D E

    2013-05-01

    A solid state high power modulator capable of delivering 120 kV and 60 A developed in collaboration with the JEMA Corporation, ESS Bilbao, and the SNS (ORNL) for driving high power klystrons is presented. Pulses with less than 10 μs risetime and flatness under 0.1% are obtained with programmable frequency pulses between 2 and 50 Hz. Eight solid state switches combined with custom air-insulated high voltage transformers working at a switching frequency of 4 kHz produce high quality pulses by phase shifting the transformer drives. Each relative high frequency stage pumps a double stage high voltage Marx generator that supplies the output pulse shape and frequency. This merged topology between a Marx generator and direct modulator takes advantage of the strengths of both approaches. Low energy storage in the output stages assures safe operation in case of a load arc discharge. Real time voltage correction during the pulse is also provided to compensate for the droop inherent with the use of low energy storage in the output stages. Data at full power with a dummy resistive load are presented. PMID:23742574

  8. Relativistic particle acceleration in plerions

    NASA Technical Reports Server (NTRS)

    Arons, Jonathan; Tavani, Marco

    1994-01-01

    We discuss recent research on the structure and particle acceleration properties of relativistic shock waves in which the magnetic field is transverse to the flow direction in the upstream medium, and whose composition is either pure electrons and positrons or primarily electrons and positrons with an admixture of heavy ions. Particle-in-cell simulation techniques as well as analytic theory have been used to show that such shocks in pure pair plasmas are fully thermalized -- the downstream particle spectra are relativistic Maxwellians at the temperature expected from the jump conditions. On the other hand, shocks containing heavy ions which are a minority constituent by number but which carry most of the energy density in the upstream medium do put approximately 20% of the flow energy into a nonthermal population of pairs downstream, whose distribution in energy space is N(E) varies as E(exp -2), where N(E)dE is the number of particles with energy between E and E+dE. The mechanism of thermalization and particle acceleration is found to be synchrotron maser activity in the shock front, stimulated by the quasi-coherent gyration of the whole particle population as the plasma flowing into the shock reflects from the magnetic field in the shock front. The synchrotron maser modes radiated by the heavy ions are absorbed by the pairs at their (relativistic) cyclotron frequencies, allowing the maximum energy achievable by the pairs to be gamma(sub +/-)m(sub +/-)c squared = m(sub i)c squared gamma(sub 1)/Z(sub i), where gamma(sub 1) is the Lorentz factor of the upstream flow and Z(sub i) is the atomic number of the ions. The shock's spatial structure is shown to contain a series of 'overshoots' in the magnetic field, regions where the gyrating heavy ions compress the magnetic field to levels in excess of the eventual downstream value. This shock model is applied to an interpretation of the structure of the inner regions of the Crab Nebula, in particular to the 'wisps

  9. Relativistic positioning systems: Numerical simulations

    NASA Astrophysics Data System (ADS)

    Puchades Colmenero, Neus

    The position of users located on the Earth's surface or near it may be found with the classic positioning systems (CPS). Certain information broadcast by satellites of global navigation systems, as GPS and GALILEO, may be used for positioning. The CPS are based on the Newtonian formalism, although relativistic post-Newtonian corrections are done when they are necessary. This thesis contributes to the development of a different positioning approach, which is fully relativistic from the beginning. In the relativistic positioning systems (RPS), the space-time position of any user (ship, spacecraft, and so on) can be calculated with the help of four satellites, which broadcast their proper times by means of codified electromagnetic signals. In this thesis, we have simulated satellite 4-tuples of the GPS and GALILEO constellations. If a user receives the signals from four satellites simultaneously, the emission proper times read -after decoding- are the user "emission coordinates". In order to find the user "positioning coordinates", in an appropriate almost inertial reference system, there are two possibilities: (a) the explicit relation between positioning and emission coordinates (broadcast by the satellites) is analytically found or (b) numerical codes are designed to calculate the positioning coordinates from the emission ones. Method (a) is only viable in simple ideal cases, whereas (b) allows us to consider realistic situations. In this thesis, we have designed numerical codes with the essential aim of studying two appropriate RPS, which may be generalized. Sometimes, there are two real users placed in different positions, which receive the same proper times from the same satellites; then, we say that there is bifurcation, and additional data are needed to choose the real user position. In this thesis, bifurcation is studied in detail. We have analyzed in depth two RPS models; in both, it is considered that the satellites move in the Schwarzschild's space

  10. Relativistic diffusive motion in random electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2011-08-01

    We show that the relativistic dynamics in a Gaussian random electromagnetic field can be approximated by the relativistic diffusion of Schay and Dudley. Lorentz invariant dynamics in the proper time leads to the diffusion in the proper time. The dynamics in the laboratory time gives the diffusive transport equation corresponding to the Jüttner equilibrium at the inverse temperature β-1 = mc2. The diffusion constant is expressed by the field strength correlation function (Kubo's formula).

  11. On the convexity of relativistic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Ibáñez, José M.; Cordero-Carrión, Isabel; Martí, José M.; Miralles, Juan A.

    2013-03-01

    The relativistic hydrodynamic system of equations for a perfect fluid obeying a causal equation of state is hyperbolic (Anile 1989 Relativistic Fluids and Magneto-Fluids (Cambridge: Cambridge University Press)). In this report, we derive the conditions for this system to be convex in terms of the fundamental derivative of the equation of state (Menikoff and Plohr1989 Rev. Mod. Phys. 61 75). The classical limit is recovered. Communicated by L Rezzolla

  12. Modulational instabilities in relativistic pair plasmas

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.

    2016-05-01

    We study the modulational instability of an intense photon beam in a relativistic pair plasma. We use the wave-kinetic description of the photon field and relativistic fluid equations for electrons and positrons. This allows us to consider the influence of the photon spectral distribution and photon recoil effects on the instability threshold and growth rates. The case of very low frequencies modulations, well below plasma frequency, is compared to that of high-frequency modulations corresponding to the plasmon decay instability.

  13. Recording of relativistic particles in thin scintillators

    SciTech Connect

    Tolstukhin, I A.; Somov, Alexander S.; Somov, S. V.; Bolozdynya, A. I.

    2014-11-01

    Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment.

  14. Relativistic particle beams for interstellar propulsion

    NASA Astrophysics Data System (ADS)

    Nordley, Gerald D.

    1993-04-01

    The concept of pellet-stream propulsion proposed by Singer (1980) is extended to particle beams and relativistic velocities. A simple relativistic mission study is presented, and it is shown how certain technological developments might enhance the concept. In particular, considerations discussed include beam drivers; beam cooling, steering, and focusing; beam driven mission mechanics; and the radiation problem. The energy issues are also briefly considered.

  15. A soft X-ray free electron laser (FEL) using a two-beam elliptical pill-box wake-field cavity

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Chen, K. W.

    1988-01-01

    Stimulated bremsstrahlung in an undulating electric field in the lasing beam direction (electric wiggler) was shown to be possible from the quantum-mechanical viewpoint. Herein, this possibility is scrutinized from the viewpoint of classical electrodynamics. It is found that if stimulated bremsstrahlung in a transverse undulating magnetic field (magnetic wiggler) occurs, stimulated bremsstrahlung in the electric wiggler must also occur. It is further shown that a free electron laser (FEL) using a magnetic wiggler to provide a catalyzer field for stimulated bremsstrahlung cannot serve as a practical FEL operating in the soft X-ray region from both theoretical and experimental viewpoints. On the other hand, it is demonstrated that the FEL using a traveling wake field in a two-beam elliptical pill-box cavity is well suited as a source of coherent radiation in the soft X-ray region.

  16. Evaluation of material parameters using contra-directional single incident beam two-beam coupling in Fe:LiNbO3

    NASA Astrophysics Data System (ADS)

    Saleh, M. A.; Evans, D. R.; Allen, A. S.; Bunning, T. J.; Guha, S.

    2002-03-01

    By fitting the experimental results to a theoretical analysis of two-beam coupling including diffraction effects [1], the photorefractive gain as well the dark current irradiance has been evaluated. Crystals with a transparent conductive coating were used to reduce grating writing instabilities; instabilities as well as multiple reflection effects were also eliminated by AR (anti-reflection) coating the crystal surfaces [2]. [1] G. Cook, D. C. Jones, C. J. Finnan, L. L. Taylor, T. W. Vere, and J. P. Duignan, Materials Research Society Symposium Proceedings 597 (2000) 263-274. [2] D. R. Evans, S. A. Basun, M. A. Saleh, T. P. Pottenger, G. Cook, T. J. Bunning, and S. Guha, "Elimination of Photorefractive Grating Writing Instabilities in Iron-doped Lithium Niobate," Submitted to IEEE J. Quantum Electronics. Dec. 2001.

  17. Two-beam interferometric encoding of photoluminescent gratings in LiF crystals by high-brightness tabletop soft x-ray laser

    SciTech Connect

    Tomassetti, G.; Ritucci, A.; Reale, A.; Arrizza, L.; Flora, F.; Montereali, R. M.; Faenov, A.; Pikuz, T.

    2004-11-01

    Two-beam interferometric encoding of periodic lines of permanent color centers in LiF has been obtained by use of an intense and high spatially coherent soft x-ray laser beam. A spatial resolution of the lines less than 1 {mu}m is demonstrated. We have used the 46.9 nm laser pulses (0.3 mJ, 1.7 ns at 0.2 Hz) produced in compact capillary discharges. Due to the low penetration depth of their radiation, their high brightness and spatial coherence, soft x-ray lasers can represent a powerful tool to encode integrated optical devices having low dimensionality and high spatial resolution inside optically transparent dielectrics, in extremely short exposure times.

  18. Entropy current for non-relativistic fluid

    NASA Astrophysics Data System (ADS)

    Banerjee, Nabamita; Dutta, Suvankar; Jain, Akash; Roychowdhury, Dibakar

    2014-08-01

    We study transport properties of a parity-odd, non-relativistic charged fluid in presence of background electric and magnetic fields. To obtain stress tensor and charged current for the non-relativistic system we start with the most generic relativistic fluid, living in one higher dimension and reduce the constituent equations along the light-cone direction. We also reduce the equation satisfied by the entropy current of the relativistic theory and obtain a consistent entropy current for the non-relativistic system (we call it "canonical form" of the entropy current). Demanding that the non-relativistic fluid satisfies the second law of thermodynamics we impose constraints on various first order transport coefficients. For parity even fluid, this is straight forward; it tells us positive definiteness of different transport coefficients like viscosity, thermal conductivity, electric conductivity etc. However for parity-odd fluid, canonical form of the entropy current fails to confirm the second law of thermodynamics. Therefore, we need to add two parity-odd vectors to the entropy current with arbitrary coefficients. Upon demanding the validity of second law, we see that one can fix these two coefficients exactly.

  19. The Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Fischer, Wolfram

    The Relativistic Heavy Ion Collider (RHIC), shown in Fig. 1, was build to study the interactions of quarks and gluons at high energies [Harrison, Ludlam and Ozaki (2003)]. The theory of Quantum Chromodynamics (QCD) describes these interactions. One of the main goals for the RHIC experiments was the creation and study of the Quark-Gluon Plasma (QGP), which was expected to be formed after the collision of heavy ions at a temperature of approximately 2 trillion kelvin (or equivalently an energy of 150 MeV). The QGP is the substance which existed only a few microseconds after the Big Bang. The QGP was anticipated to be weakly interacting like a gas but turned out to be strongly interacting and more like a liquid. Among its unusual properties is its extremely low viscosity [Auerbach and Schlomo (2009)], which makes the QGP the substance closest to a perfect liquid known to date. The QGP is opaque to moderate energy quarks and gluons leading to a phenomenon called jet quenching, where of a jet and its recoil jet only one is observable and the other suppressed after traversing and interacting with the QGP [Jacak and Müller (2012)]...

  20. Detonation waves in relativistic hydrodynamics

    SciTech Connect

    Cissoko, M. )

    1992-02-15

    This paper is concerned with an algebraic study of the equations of detonation waves in relativistic hydrodynamics taking into account the pressure and the energy of thermal radiation. A new approach to shock and detonation wavefronts is outlined. The fluid under consideration is assumed to be perfect (nonviscous and nonconducting) and to obey the following equation of state: {ital p}=({gamma}{minus}1){rho} where {ital p}, {rho}, and {gamma} are the pressure, the total energy density, and the adiabatic index, respectively. The solutions of the equations of detonation waves are reduced to the problem of finding physically acceptable roots of a quadratic polynomial {Pi}({ital X}) where {ital X} is the ratio {tau}/{tau}{sub 0} of dynamical volumes behind and ahead of the detonation wave. The existence and the locations of zeros of this polynomial allow it to be shown that if the equation of state of the burnt fluid is known then the variables characterizing the unburnt fluid obey well-defined physical relations.