Optical spectroscopy of plasma in high power microwave pulse shortening experiments driven by a microsecond electron beam
- Univ. of Michigan, Ann Arbor, MI (United States)
- Air Force Research Lab., Kirtland AFB, NM (United States)
Spectroscopic measurements have been performed to characterize the undesired plasma in a multi-megawatt coaxial gyrotron and a rectangular-cross-section (RCS) gyrotron. These gyrotrons are driven by the Michigan Electron Long Beam Accelerator (MELBA) at parameters: V = {minus}800 kV, I{sub tube} = 0.3 kA, and pulselengths of 0.5--1 {micro}s. Pulse shortening typically limits the highest ({approximately}10 MW) microwave power pulselength to 100--200 ns. Potential explanations of pulse shortening are being investigated, particularly plasma production inside the cavity and at the e-beam collector. The source of this plasma is believed to be due to water vapor absorbed on surfaces which is ejected, dissociated, and ionized by electron beam impact. Plasma H-{alpha} line radiation has been characterized in both time-integrated and temporally-resolved measurements and correlated with microwave power and microwave cutoff. Measurements from a residual gas analyzer (RGA) will be used to support this interpretation. Experiments involving RF plasma cleaning of the coaxial cavity are planned.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 343597
- Report Number(s):
- CONF-980601-; TRN: IM9921%%60
- Resource Relation:
- Conference: 25. international conference on plasma science, Raleigh, NC (United States), 1-4 Jun 1998; Other Information: PBD: 1998; Related Information: Is Part Of IEEE conference record -- Abstracts. 1998 IEEE international conference on plasma science; PB: 343 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Optical spectroscopy of plasma in high power microwave pulse shortening experiments driven by a {mu}s e-beam
Experiments and diagnostics of multi-MW, large orbit, axis-encircling, coaxial gyrotron oscillator