Instability suppression by a gas jet in plasma focus devices
Abstract
The density of the filling gas in dense plasma foci is limited by the energy available for breakdown, and ionization of the neutral gas by the plasma sheath, during the rundown phase. On the other hand, it is desirable to increase the density of the plasma during the compression phase, when the current approaches its maximum, in order to improve the neutron yield. It has been shown both in samll [1] and large [2] plasma foci that, by the injection of a gas jet from the tip of the inner electrode, it is possible to decouple the compression phase from the breakdown and the rundown phases. Not only the neutron emission is significantly increased, but the uniformity of the discharges is also improved. Since the wide variability in the radiation of these kind of devices is strongly related to the m=0 instabilities during the compression phase, it has been speculated that the jet is able to suppress them. The purpose of this work is to study the conditions under which an axial jet could be able to suppress the instabilities in a compressional z-pinch. A magnetohydrodynamic approach is followed as a first approximation to the problem. [1] M. Milanese, R. Moroso y J. Pouzo, J.Phys.D: Applied Physics 31, 85 (1998). [2]H. Schmidt, M. Sadowski, L. Jakubowski, E. Skladnik-Sadowska, J. Stanislawski y A. Szydlowski, J. Tech. Phys. 38, 121 (1997).
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2002
- Bibcode:
- 2002APS..DPPBP1101H