Computer Code Prediction of Picosecond Voltage Switching and TEM Wave Generation in Air Gas Avalanche Switches
LAWRENCE LIVERMORE NATIONAL LAB CA
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The realization of efficient, reliable picosecond closing switches will make possible high gradient 1- 3 GeV linacs with pulsed accelerating electrode structures. Recently a promising candidate for picosecond, high voltage switching, the gas avalanche switch, has been proposed. The medium in this switch is high pressure 10-800 atm gas. An avalanche discharge is initiated between pulse-charged high voltage electrodes by multiphoton ionization from a picosecond order laser pulse. The laser-initiated electrons avalanche toward the anode, causing the applied voltage to collapse in picoseconds, long before the hot current channel formation of a conventional spark gap. Several versions of the gas avalanche switch may be conceived. A parallel plate capacitor version consists of a high pressure gas confined between two parallel metal plates. An analysis of the formation or voltage delay and voltage collapse times for this geometry has been done by Villa and Cassell by numerical integration of a zero-dimensional OD electric circuit equation, which includes a resistively limited charge feed. This analysis predicts voltage collapse times of the order of several picoseconds for N2 and air and 1 psec or less for Ar.
- Electrical and Electronic Equipment