High Power, Ultra-Long-Pulsed Gyrotron Backward Wave Oscillators.
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
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 14, 1995
- Accession Number
- ADA297731
Entities
People
- Ronald M. Gilgenbach
Organizations
- University of Michigan