(DURIP 96) High Resolution Diagnostics for Plasma in High Power Microwave Sources
Abstract
The gyrotron microwave source is driven by the Michigan Electron Long Beam Accelerator (MELBA) which operates at -0.8 MV, 1-10 kA, and 0.5-1.5 microsecond pulselength. The correlation was measured between optical spectroscopic emission versus microwave power and pulselength. It was found that the optical emission from hydrogen H-alpha radiation was correlated with microwave power and inversely related to microwave pulselength. The physical mechanism is related to plasma accreted from water vapor on the inside of the microwave cavity and collector. This water is ablated and dissociated to release hydrogen. (A continuing AFOSR/MURI program is exploring techniques to remove water from surfaces by RF plasma processing.) The microwave network analyzer was utilized to obtain cold tests of microwave structures in a rectangular-cross-section gyrotron and a coaxial gyrotron. The primary cold-cavity modes were measured and agreed very well with the results of heterodyned high power microwave signals analyzed by time-frequency analysis. Frequency chirping and mode hopping due to voltage fluctuations were observed as other possible causes of pulse shortening.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1998
- Accession Number
- ADA353654
Entities
People
- Ronald M. Gilgenbach
Organizations
- University of Michigan