A high efficiency relativistic uniform backward wave oscillator
Conference
·
OSTI ID:51769
- Univ. of New Mexico, Albuquerque, NM (United States)
- Sandia National Labs., Albuquerque, NM (United States)
A recent numerical calculation predicts efficiencies of 25--30% for uniform BWOs over a wider range of beam parameters than for nonuniform BWOs. This new model includes the interaction between the electron beam and the reflected forward traveling wave. For efficient BWO operation, it is important that the backward traveling wave and the reflected forward traveling wave are properly matched at the cutoff neck and the adiabatic transition into the output waveguide. A uniform BWO based on the principles described in the above model was investigated using the Sinus-6 relativistic electron beam accelerator. Cathode voltages from 400 kV to 650 kV and beam currents from 2.5 kA to 5 kA were obtained by varying the pressure in the Sinus-6 spark gap switch. The RF pulse was 10 ns long at 9.6 GHz. A peak power of 250 MW was measured in the far field with a corresponding efficiency of 20%. At higher beam parameters significant air breakdown was observed in front of the 15 cm diameter conical horn aperture. The TM{sub 01} mode pattern was observed and photographed in the plasma formed by the air breakdown. A mode converter was used to convert the TM{sub 01} mode into a TE{sub 11} mode with the corresponding air breakdown pattern observed. A standing wave was created by placing a metal mirror 1.5 meter from the aperture. PIC code simulations of this BWO were made with KARAT and TWOQUICK. Power and frequency measurements are compared with the experiment.
- OSTI ID:
- 51769
- Report Number(s):
- CONF-940604--; ISBN 0-7803-2006-9
- Country of Publication:
- United States
- Language:
- English
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