P.E. Latham

University of Maryland, College Park

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W. Lawson

University of Maryland, College Park

V.L. Granatstein

University of Maryland, College Park

C. D. Striffler

University of Maryland, College Park

J.P. Calame

United States Naval Research Laboratory

B. Hogan

University of Maryland, College Park

M. Reiser

Geological Survey of Austria

B. Levush

United States Naval Research Laboratory

Gregory S. Nusinovich

University of Maryland, College Park

Thomas M. Antonsen

University of Maryland, College Park

W. Main

Accuray (United States)

Cooperative Institutions

University of Maryland, College Park

United States Naval Research Laboratory

University System of Maryland

Science Applications International Corporation (United States)

Calabazas Creek Research (United States)

University of California, Los Angeles

Niigata University

System Science Applications (United States)

National Tsing Hua University

Cornell University

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High power microwave sources for advanced accelerators

AIP conference proceedings (1992)

V. L. Granatstein P.E. Latham W. Lawson W. Main M. Reiser

The development of future linear colliders operating at ≳1 TeV center of mass energy will likely depend on the availability of microwave amplifiers which are both affordable and are capable of significantly surpassing the performance of klystrons in terms of power and frequency. One of the most promising concepts for the required amplifiers is the gyroklystron. This paper reviews the physical principles of the gyroklystron and contrasts its phase bunching behavior with that of a klystron. Experiments in a low power gyroklystron which have studied phase noise and penultimate cavity tuning are summarized. The stages in developing an X‐band gyroklystron resulting in the achievement of 29 MW, 1 μsec output pulses with 34% efficiency and 36 dB gain is recapitulated. Finally, plans are described for experiments which will extend gyroklystron performance to the ∼100 MW level at X‐band, and explore operation at a frequency of ∼20 GHz by operating the output cavity at the second harmonic of the electron cyclotron frequency.

Klystron

Harmonic

Center frequency

10.1063/1.42163

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Citations (4)

Design of a 80 kW, 700 MHz bandwidth W-band gyroklystron amplifier circuit

M. Blank B. Levush B.G. Danly P.E. Latham J.P. Calame

Summary form only given, as follows. A four cavity TE/sub 01/ mode gyroklystron amplifier has been designed as the driver for a W-band radar currently under development at NRL. The performance goals for the amplifier are 80-100 kW peak output power, 10 kW average power, and 600 MHz -3 dB bandwidth. A time dependent version of the non-linear code MAGYKL was developed to design the interaction circuit. The stagger tuning and cavity Qs were optimized through extensive theoretical studies to determine the tradeoffs between peak output power and bandwidth. A mechanical tolerance study was performed. The stability of the cavities and cutoff drift regions was also examined. The resulting circuit is predicted to achieve 80 kW peak output power and 20% efficiency with a 65 kV, 6 A electron beam with a velocity ratio of 1.5 and a perpendicular RMS velocity spread of 4.5%. Simulations indicate that the -3 dB bandwidth is 700 MHz. Details of the circuit and design studies are presented.

Klystron

Power bandwidth

10.1109/plasma.1997.604906

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A High Peak Power, X-Band Gyroklystron for Linear Accelerators

W. Lawson J.P. Calame V.L. Granatstein P.E. Latham G.S.Park

Klystron

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Optimum operation of gyrotwistrons

P.E. Latham

Relativistic gyrotwistrons,1 which can, in principle, achieve efficiencies in excess of 50%, arepromising sources for driving particle accelerators. The optimum operating point for these devicesrepresents a tradeoff between maximizing the available energy and minimizing the deleterious effectsof velocity spread. The former increases with Doppler upshift and pitch ratio, while the effects ofvelocity spread are made worse by both of these quantities. To quantify these ideas, we start withthe maximum single particle efficiency,2

Particle (ecology)

10.1117/12.2298633

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Gyrotwistrons as a source for future particle accelerators

High-Power Particle Beams, 1994 10th International Conference on (1994)

P.E. Latham W. Lawson V. Irwin B. Hogan Gregory S. Nusinovich

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Design of wide-band gyro-twystrons for high power millimeter wave radar applications

M. Blank P.E. Latham B. Levush B.G. Danly

Summary form only given. The Naval Research Laboratory is currently investigating gyro-twystrons as high-power, wideband sources for millimeter wave radars. For many radar applications, the gyro-twystron configuration represents a suitable compromise between the high power, narrow band gyro-klystron and the lower power, broadband gyro-TWT. A non-linear simulation code was used to design two gyro-twystrons, the first in Ka-band and the second in W-band. For the Ka-band device, the interaction between the TE/sub 01/ mode and a 65 kV, 7 A electron beam with /spl alpha/=1.3 was studied. The rms perpendicular electron velocity spread was assumed to be 4.5%. The simulation results indicate that an output power of 123 kW, corresponding to an efficiency of 27%, can be achieved. The 3 dB instantaneous bandwidth, which extends from 34.6 GHz to 36.2 GHz, is 4.5%. Next, the non-linear code was used to design a W-Band gyro-twystron. The interaction mode was, once again, the TE/sub 01/. A 65 kV, 4 A beam with /spl alpha/=1.3 and an RMS perpendicular velocity spread of 4.5% was used. The simulations show that 34 kW output power, corresponding to 13% efficiency, can be realized with a 3 dB instantaneous bandwidth of 4.3% (91 GHz to 95 GHz). The theoretical bandwidths were obtained assuming a frequency independent bunching parameter.

Klystron

Extremely high frequency

W band

Wideband

Ka band

X band

10.1109/plasma.1996.551520

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Experimental design of a 30 MW, 10 GHz gyroklystron

International Electron Devices Meeting (1986)

W. Lawson J.P. Calame V. L. Granatstein Heidi Heikkinen P.E. Latham

The design of a 30 MW peak power, X-band gyroklystron is presented. Emphasis is placed on the modulator, electron gun, and microwave circuit technology. An improved circuit code that uses realistic cold cavity field profiles is discussed. A conversion efficiency of ∼ 37% from the 500 kV 160 A beam to the TE 01 ^o mode with a gain of ∼ 57 dB is predicted.

Klystron

Emphasis (telecommunications)

10.1109/iedm.1986.191184

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Citations (1)

Linear analysis of a free-electron laser coupled to betatron oscillations

Physics of Fluids B Plasma Physics (1989)

P.E. Latham

The dispersion relation is derived for the interaction of a sheet beam propagating between parallel plates in a planar wiggler magnetic field. Instead of the usual free electron laser (FEL) mode, one is considered in which the radiation field is perpendicular to the quiver velocity and couples either to betatron or plasma oscillations. In the cold beam limit, coupling to betatron oscillations leads to an absolute instability. This mode competes with the conventional FEL and can disrupt the beam unless suppressed. The effects of energy spread are investigated, and a critical energy spread is found that suppresses the instability. For ultrarelativistic beams, this energy spread is an exponentially decreasing function of the beam energy. For moderately relativistic high current beams, it is proportional to the square root of the beam current. In this regime, there is a limit to the current that can propagate stably in the FEL circuit. Coupling to plasma oscillations also leads to an instability. However, the instability associated with this mode can be made convective with a suitable choice of parameters, and thus is not particularly dangerous to the conventional FEL. It is, however, interesting because the dispersion relation is characteristic of a second harmonic FEL, even though the wiggler is planar.

Betatron

Wiggler

Dispersion relation

Free-electron laser

Oscillation (cell signaling)

10.1063/1.859073

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Citations (2)

Simple modelling of relativistic gyroklystrons

O. Dumbrajs Gregory S. Nusinovich P.E. Latham

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Theory of relativistic cyclotron masers

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics (1995)

Gregory S. Nusinovich P.E. Latham O. Dumbrajs

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).

Cyclotron resonance

Electron cyclotron resonance

Ion cyclotron resonance

10.1103/physreve.52.998

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Citations (20)