Axisymmetric electric discharge as a means for distant heating of gas media
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A DIAGNOSTICS
Axisymmetric Electric Discharge as a Means for Distant Heating of Gas Media É. M. Barkhudarova, T. S. Zhuravskayab, I. A. Kossyia, V. A. Levinb, V. V. Markovb, N. A. Popovc, N. M. Tarasovaa, S. M. Temchina, and M. I. Taktakishvilia a
Prokhorov Institute of General Physics, Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 Russia b Institute of Mechanics, Moscow State University, Moscow, Michurinskiі pr. 1, 119992 Russia cSkobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, 119992 Russia Received January 22, 2009
Abstract—Gasdynamic phenomena accompanying a ring electric discharge excited in atmosphericpres sure air have been studied experimentally and theoretically. It is shown experimentally that the discharge gen erates a toroidal (threedimensional) shock wave that converges toward the axis. A mathematical model describing the focusing of a toroidal shock wave is constructed. The measured characteristics of shock pro cesses accompanying the discharge agree well with results of calculations. This makes it possible to estimate the gas temperature that can be achieved in the convergent shock wave at a certain distance from the center of the ring discharge. PACS numbers: 52.50.Nr, 47.40.Nm DOI: 10.1134/S1063780X09110038
1. INTRODUCTION Electricdischarge devices for excitation of high current surface discharges (see [1−3]) can be used to produce dense plasma rings capable of affecting gas eous media on the discharge axis at distances on the order of the radius R of the plasma ring. Thus, in [2], generation of a plasma with an anomalously long life time in the axial region of a ring discharge under the action of UV discharge radiation was observed. In [3], it was shown that gasdynamic processes initiated by a plasma ring play a significant role in energy transfer from the plasma ring to gas regions adjacent to the axis. As was pointed out in [3, 4], the mechanism gov erning this process is generation of a toroidal (three dimensional) shock wave that converges toward the axis. Studies of convergent shock waves having a closed wave front are of considerable interest for fundamental gas dynamics [5]. The phenomenon of unbounded energy accumulation of a spherical/cylindrical shock wave as it approaches the center/axis was predicted by Guderley [6] (see also [7, 8]). The solutions found in those works are onedimensional and unstable against any nononedimensional perturbation [9, 10]. In this context, it was suggested in [11] that unbounded amplification of spherical and cylindrical waves is related to their degenerate onedimensional nature; it was also pointed to the importance of finding neces
sary and sufficient conditions for cumulative amplifi cation of threedimensional convergent shock waves. In [3, 4], it was demonstrated experimentally that it is not of crucial importance whether a convergent wave is onedimensional or nononedimensional. Shock waves investigated in [3, 4] had a ring (toroidal) geometry, i.e., were obviously nononedimensional. It
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