Accession Number : ADA297731

Title :   High Power, Ultra-Long-Pulsed Gyrotron Backward Wave Oscillators.

Descriptive Note : Final rept. 15 Jan 92-14 Jun 95,

Corporate Author : MICHIGAN UNIV ANN ARBOR INTENSE ENERGY BEAM INTERACTION LAB

Personal Author(s) : Gilgenbach, Ronald M.

PDF Url : ADA297731

Report Date : 14 JUN 1995

Pagination or Media Count : 22

Abstract : The objective of this research program was to explore tapering of interaction tubes and magnetic fields as techniques for enhancing the performance of high power microwave gyrotron-backward-wave- oscillators (gyro-BWOs). Experiments were performed on the Michigan Electron Long-Beam Accelerator, (MELBA), which operated with parameters: voltage=O.7-O.9 MV, diode current = 1-10 kA, injected current = 1-4 kA, and pulselengths of 0.5-i microsecond. Microwave emission frequency was in the range from 4.5-6 GHz. Experiments on the fundamental cyclotron wave showed peak microwave tube power up to 40-55 MW over shortened pulselengths (<100 ns). Longer pulse microwave emission was obtained at lower powers (multi-MW). The second harmonic gyro-BWO emission spectrum was also measured at MW power levels. The microwave spectral width was < 200 MHz (<3.7%) for uniform B field with uniform or tapered tubes. Widened spectra of 200-400 MHz (<7.4%) were measured for tapered magnetic fields with uniform or tapered tubes. Modeling was performed with the MAGIC code to guide the experiments. Results showed qualitative agreement between TE11 mode experiments and TE01 MAGIC Code simulations, regarding microwave power versus tapering direction and scaling. (KAR) P. 3

Descriptors :   *BACKWARD WAVE OSCILLATORS, HIGH POWER, SIMULATION, POWER LEVELS, EMISSION, MAGNETIC FIELDS, MICROWAVES, CODING, PEAK POWER, SPECTRA, PULSES, WIDTH, TAPER, MICROWAVE TUBES, MICROWAVE FREQUENCY, RADIOFREQUENCY POWER, CYCLOTRON WAVES.

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE