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SOVIET PHYSICS JETP A translation of the Zhurnal Eksperimental'noi i Teoreticheskoi Fiziki Editor in Chief-P. L. Kapitza; Associate Editors-M. A. Leontovich, E. M. Lifshitz, S. Yu. Luk'yanov; Editorial Board E. L. Andronikashvili, K. P. Belov, A. S. Borovik-Romanov (Editor, JETP Letters), V. P. Dzhelepov, N. V. Fedorenko, E. L. Feinberg, V. A. Fock, V. N. Gribov, R. V. Khokhlov, l. K. Kikoin, I. M. Lifshitz, S. Yu. Luk'yanov, A.M. Prokhorov, D. V. Shirkov, G. F. Zharkov(Secretary). Vol. 30, No.6, pp. 973-1224 (Russ. Orig. Vol. 57, No. 6, pp. 1801-2253) June 1970 FREE PLASMA FILAMENT IN A HIGH FREQUENCY FIELD AT HIGH PRESSURE* P. L. KAPITZA Physics Laboratory, U.S.S.R. Academy of Sciences Submitted August 8, 1969 Zh. Eksp. Teor. Fiz. 57, 1801-1866 (December, 1969) The main experimental results obtained in the course of an investigation of plasma in a filamentary high frequency discharge floating in the middle of a resonator are presented. An experimental ar rangement for obtaining a stable discharge is described; stabilization is obtained by rotation of the gas. The investigations are carried out primarily in an atmosphere of deuterium at a pressure of sev eral atmospheres. For an input power up to 20 kW the length of the discharge attains a value of 10 em. Spectrometric investigations and their theoretical interpretation lead to the conclusion that the dis charge consists of an internal cylindrical region filled with hot plasma at an electron temperature of the order of 106°K and of a cloud of partially ionized plasma (T = (7-6) x 103 °K) surrounding it. It is shown that the existence of such a high temperature is possible due to a temperature discontinuity at the plasma boundary; an explanation is proposed that this discontinuity arises as a result of a double layer at the boundary. The effective heating of the filament by HF current takes place due to the anom alous skin effect. Such an interpretation of plasma processes is experimentally confirmed by experiments on the ef fect on the discharge of a constant magnetic field (up to 25 kOe). A study is made of the ion tempera ture. The observed emission of neutrons is insufficient for the determination in terms of them of this temperature and cannot even be sufficiently reliably investigated in order to establish its thermonu clear nature. Other methods so far also do not give a reliable result for determining the ion tempera ture. The problem is considered as to how one could by means of magnetoacoustic oscillations and magnetic thermal insulation raise the ion temperature up to the level required for the production of a reliable thermonuclear reaction. Some preliminary experiments in this direction are described. The investigations reported here have been carried on for over ten years by the staff of the Physics Laboratory of the Academy of Sciences of the U.S.S.R. 1. INTRODUCTION heated and melted at one spot. This observation led to the thought that spherical lightning is a discharge which IN the course of development of high frequency (HF) is produced by HF radiation arising in storm clouds generators of high and continuous power we have con after ordinary lightning. Thus, a source of energy is structed in 1950 a planotron [[lJ, p. 115], which emit provided which is required to support luminosity of ted power of several kilowatts at a wavelength in the long duration accompanying ball lightning. This hypoth neighborhood of 10 em. When we passed this radiation esis was published in 1955.l2J Several years later after through a quartz sphere of 10 em diameter filled with we had constructed a more powerful generator of con helium at a pressure of 10 em of Hg a discharge was tinuous radiation which we have called a "nigotron [ [3, \ ignited in it which had a well defined boundary. The p. 7], we returned to the possibility of producing a free whole phenomenon was observed for several seconds HF discharge in helium. Indeed, in March of 1958 we since the walls of the quartz sphere became rapidly succeeded in obtaining in a spherical resonator, in which intense continuous oscillations of the H type oc 01 *Published by resolution of the Presidium of the U.S.S.R. Academy curred with a wavelength in the neighborhood of 19 em of Sciences, dated August 8, 1969. and which was filled with helium, a freely floating gas- 973 Copyright © by American Institute of Physics 1970