Breakdown Mechanisms for Laser-induced Discharges in Super-high Pressure Gases


Book Description

The paper presents the results of validation experiments on the effects of laser induced breakdown of super-high pressure gases (7 to 2000 atmospheres). It was determined that the optical extension of the classical diffusion - controlled microwave breakdown theory correctly predicts a minimum in the electric field vs. pressure curve. The experiments identify electron impact as the responsible breakdown mechanism. (Author).







Breakdown mechanisms for laser-induced plasmas in super-high pressure gases


Book Description

Possible mechanisms responsible for laser-induced breakdown in super-high pressure gases are investigated both theoretically and experimentally. It is shown that the breakdown mechanism involves energy gain of free electrons by acceleration in the incident electromagnetic field while undergoing collisions with neutrals, and subsequent electron-impact ionization. This mechanism is described by classical microwave breakdown theory and favorably compares with the experimental measurements. Experimental breakdown threshold data in He, Ar, H2, and N2 was obtained over the pressure range 100-30,000 psi. Plasmas are produced in He, Ar, H2, and N2 over the pressure range 100-30,000 psi. The radiation from a giant-pulse ruby laser is focused within a pressure cell having three quartz windows and capable of withstanding 60,000 psi. Breakdown threshold data is taken for comparison with theory. Kerr cell photographs of the focal region provide time resolution of the macroscopic growth of the plasma. Two possible mechanisms are evaluated: multiquantum absorption and electron-impact ionization. The latter is analyzed both quantum mechanically by the inverse Bremsstrahlung theory and classically by microwave theory.




Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.













Electrical Breakdown and Discharges in Gases


Book Description

The Advanced Study Institute on Breakdown and Discharges in Gases was held in Les Arcs, France, June 28 to July 10, 1981. The object of the Institute was to provide a broad but compre hensive presentation of the various topics in the field of Gaseous electronics. To achieve this goal, a number of lectures, seminars, and panel discussions were scheduled. Each topic was developed by two tutorial and/or review lectures, and brought to the present state of the topic by seminars and panel discussions. The program of topics and speakers was selected with the assistance of the advisory committee composed of: J. A. Rees, European Coordinator, England; M. Goldman, French Coordinator, France; A. H. Guenther, USA; M. Kristiansen, USA; and A. V. Phelps, USA. The most memorable aspect of the Institute was the sustained high interest of the faculty and participants for the two week period. The daily schedule was demanding: five hours of lectures, two hours of seminars and one of discussion. These sessions were often extended because of presentation by the participants of im proptu seminars. The discussions were intense. Majestic }10nt Blanc provided the backdrop for the lecture hall, and these surroundings and the weather contributed to the overall positive mood. It was a wonderful occasion. The lectures and seminars have been collected into two volumes.