Matching of a multimodule plasma opening switch to a liner load
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MA DYNAMICS
Matching of a Multimodule Plasma Opening Switch to a Liner Load G. I. Dolgachev, D. D. Maslennikov, A. G. Ushakov, A. S. Fedotkin, and I. A. Khodeev Russian Research Centre Kurchatov Institute, pl. Kurchatova 1, Moscow, 123182 Russia Received January 25, 2007; in final form, March 22, 2007
Abstract—One of the key problems of the Baikal project, intended to create a superpower pulsed generator for ICF experiments, is that of matching a multimodule plasma opening switch (POS) to a liner load. An intermediate inductance or a separating discharger is proposed to be used as a matching element between the POS and the load. An analysis is made of the effect of both versions of the matching system on the synchronization of the POS modules and the energy transfer from the inductive storage to the load. Methods for optimizing the matching element are examined. It is shown that the POS modules can be synchronized and the inductive storage energy can be efficiently transferred to a low-impedance load. A multigap vacuum discharger with a point anode and plane cathode is to be used as a separating discharger. Such an electrode system make it possible to concentrate the electric field at the point anode and to substantially enhance the electric strength of the interelectrode gap. Results are presented from experimental studies of vacuum breakdown in such an electrode system with a gap length of about 1 mm. PACS numbers: 52.59.Mv, 52.75.Kq, 84.70.+p DOI: 10.1134/S1063780X07100042
1. INTRODUCTION In the Baikal program, intended to create a superpower pulsed generator for ICF experiments, a plasma opening switch (POS) is planned to be used as an output power sharpener [1]. To increase the commutated current and output voltage, it is proposed to use a multimodule erosion POS with an external magnetic field produced by an independent source [2]. The use of a liner as a load at the output of the multimodule POS implies that such a POS should be matched to the load. The low initial impedance of the liner leads to the shortcircuiting of the POS, because even a slight increase in the POS resistance is accompanied by the switching of the current to the load. The result is that, because of the redistribution of the current between the POS modules, the process of their synchronization terminates, no energy goes into ion acceleration (i.e., into plasma erosion), and the POS becomes closed again, thereby disconnecting the load from the inductive energy storage. An analysis of the experimental data [3] on the synchronization of two parallel modules, each connected to its own load (Fig. 1), shows that the scatter in the operation times of the POS modules (see Fig. 2) is ∆t ~ Zc/Zl,
For the same reason, the energy from the inductive storage cannot be transferred to the liner: even at a very low voltage at the POS, the current is switched to the liner, whose initial impedance is nearly zero. After this, no energy is deposited in the POS and, therefore, the process of plasma erosion and creation of a magnetically insulated vacuum gap
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