A Versatile High-Power Laser System for High Spatial Resolution Nanosecond Plasma Diagnostic in Electron-Beam Driven HPM Sources.
Final technical rept. 1 Aug 96-31 Dec 98,
NEW MEXICO UNIV ALBUQUERQUE DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
Pagination or Media Count:
The purpose of the acquired instrumentation was to perform high spatial resolution and nanosecond time resolution plasma diagnostics in intense electron beam-driven high power microwave HPM sources to better understand the pulse shortening problem. We have thus performed the first laser interferometry measurement inside a high power backward wave oscillator or any other intense beam-driven HPM source for that matter during the course of microwave generation reported in the literature. Line-integrated electron densities between 9 x 10exp 15 and 2 x 10exp 16sq cm for microwave powers between 20 and 120 MW have been measured. The two main sources of the measured electron density are postulated to be 1 plasma generated from the cutoff neck due to beam scrape off and, 2 material removed and ionized from the slow wave structure walls during microwave generation. A catastrophic microwave discharge results in termination of subsequent microwave generation. Novel modifications to the inlet of the slow wave structure in intense beam-driven backward wave oscillators are suggested as a result of this research.
- Lasers and Masers
- Plasma Physics and Magnetohydrodynamics