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Proceedings Paper

Intense Electron Beam Cyclotron Masers With Microsecond Pulselengths
Author(s): R. M. Gilgenbach; J. G. Wang; J. J. Choi; C. A. Outten; T. Spencer
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Paper Abstract

Experiments are underway to investigate the generation of MW to GW microwave power levels utilizing intense (1-10 kA), relativistic (0.4-1 MV), electron beams with pulselengths from 0.4 to 1 μs. Significant research issues concern the effects of beam voltage fluctuations and space charge on long-pulse microwave emission power and frequency stability. Two prototype masers have been developed utilizing a moderate energy pulseline generator with peak parameters: 0.4 MV, 1.2 kA, and 0.4 μs. Prototype I utilized a nonadiabatic step in the diode magnetic field to impart a large α (V⊥/V11≈1-2) to a relatively low transported current of 30-60A. With a uniform waveguide resonator this maser generated peak microwave power levels of 0.6 MW and pulselengths of 0.3 μs over 85% voltage droop. The emission frequency was close to the relativistic cyclotron frequency. The Prototype II maser employed an improved magnetic field profile which transported 500-1000 A of beam current, but at a lower value of α(0.2 - 0.3). A series of permanent magnet wiggler/kickers were used in preliminary tests. Power levels were achieved in the range of 2 MW in the X-band and at MW levels in the K-band. These emission frequencies apparently correspond to the CRM forward-wave and backward-wave interaction with the TE11n cavity modes. By lowering the magnetic field below a critical value the microwave emission was cut off. Design studies have been performed for a long-pulse MW-GW cyclotron maser on the MELBA accelerator with parameters: 0.8 - 1 MV, 1 - 10 kA, and 1 - 1.5 μs.

Paper Details

Date Published: 25 July 1989
PDF: 4 pages
Proc. SPIE 1061, Microwave and Particle Beam Sources and Directed Energy Concepts, (25 July 1989); doi: 10.1117/12.951801
Show Author Affiliations
R. M. Gilgenbach, The University of Michigan (United States)
J. G. Wang, The University of Michigan (United States)
J. J. Choi, The University of Michigan (United States)
C. A. Outten, The University of Michigan (United States)
T. Spencer, The University of Michigan (United States)


Published in SPIE Proceedings Vol. 1061:
Microwave and Particle Beam Sources and Directed Energy Concepts
Howard E. Brandt, Editor(s)

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