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Proceedings Paper

Computational and experimental progress on laser-activated gas avalanche switches for broadband, high-power electromagnetic pulse generation
Author(s): David J. Mayhall; Jick H. Yee; Francesco Villa
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Paper Abstract

The gas avalanche switch a high-voltage picosecond-speed switch has been proposed. The basic switch consists of pulse-charged electrodes immersed in a high-pressure (7800 atm) gas. An avalanche discharge is induced in the gas between the electrodes by ionization from a picosecond-scale laser pulse. The avalanching electrons move toward the anode causing the applied voltage to collapse in picoseconds. This voltage collapse if rapid enough generates electromagnetic waves. A two-dimensional (2D) finite difference computer code solves Maxwell''s equations for transverse magnetic modes for rectilinear electrodes between parallel plate conductors along with electron conservation equations for continuity momentum and energy. Collision frequencies for ionization and momentum and energy transfer to neutral molecules are assumed to scale linearly with neutral pressure. Electrode charging and laser-driven electron deposition are assumed to be instantaneous. Code calculations are done for a pulse generator geometry consisting of an 0. 7 mm wide by 0. 8 mm high beveled rectangular center electrode between grounded parallel plates at 2 mm spacing in air. In one operational mode a uniform distribution of initial electrons is induced in the gap between the center electrode and the lower plate. With the center electrode at 227 kV positive and 15 atm pressure voltage pulses of 24 1 kV 2 Ps rise times 8 ps full widths at half maximum (FWHM) 30 ps durations and 24 GHz 3 dB bandwidths are induced at the ends

Paper Details

Date Published: 1 March 1991
PDF: 14 pages
Proc. SPIE 1378, Optically Activated Switching, (1 March 1991); doi: 10.1117/12.25045
Show Author Affiliations
David J. Mayhall, Lawrence Livermore National Lab. (United States)
Jick H. Yee, Lawrence Livermore National Lab. (United States)
Francesco Villa, Stanford Linear Accelerator Ctr. (United States)

Published in SPIE Proceedings Vol. 1378:
Optically Activated Switching
Fred J. Zutavern, Editor(s)

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