Theory and computer simulation of a new type of plasma Cherenkov maser
Theory and computer simulation of a new experimental high-power microwave generator is presented. In this device, a circular waveguide is partially filled with a dense annular plasma. When an intense relativistic electron-beam pulse passes through the central vacuum region, microwaves are emitted with high efficiency (less than or equal to 20%). The plasma creates slow (i.e., v/sub ph/ < c) TM modes in the waveguide. The radiation mechanism is stimulated Cherenkov emission of these slow TM waves by the beam electrons. The linear theory is analyzed first. A dispersion relation and field-structure equations are derived for the azimuthally symmetric TM modes of this system. Numerical solutions demonstrate the existence of the slow TM waves without the beam, and confirm that some are unstable in the presence of the beam. To analyze the nonlinear theory, a new particle-simulation code was developed. This code is described in detail, and results of simulations of the experimental device are presented. In these simulations, the system initially evolves in good quantitative agreement with linear theory, while the nonlinear saturation amplitudes are consistent with experimentally observed efficiencies. Saturation of linear instability is shown to be due to trapping of the beam electrons, and the saturation amplitudes agree quite well with a simple trapping model
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 5215245
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
420300* -- Engineering-- Lasers-- (-1989)
AMPLIFIERS
BEAMS
CHERENKOV RADIATION
COMPUTERIZED SIMULATION
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRONIC EQUIPMENT
EMISSION
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EQUIPMENT
LEPTON BEAMS
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NONLINEAR PROBLEMS
OPERATION
PARTICLE BEAMS
RADIATIONS
RELATIVISTIC RANGE
SIMULATION
STIMULATED EMISSION
WAVEGUIDES