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TEMPERATURE PLASMA

Nonsputtering Impulse Magnetron Discharge G. V. Khodachenko, D. V. Mozgrin, I. K. Fetisov, and T. V. Stepanova National Research Nuclear University Moscow Engineering Physics Institute, Kashirskoe sh. 31, Moscow, 115409 Russia Received December 9, 2010; in final form, April 28, 2011

Abstract—Experiments with quasisteady highcurrent discharges in crossed E × B fields in various gases (Ar, N2, H2, and SF6) and gas mixtures (Ar/SF6 and Ar/O2) at pressures from 10–3 to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of stable lowvoltage dis charge that does not transform into an arc. This type of discharge came to be known as a highcurrent diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experi mental studies of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasmaforming gas) of a highcurrent lowpressure diffuse discharge in crossed E × B fields. DOI: 10.1134/S1063780X1112004X

1. INTRODUCTION Wide engineering applications of magnetron sys tems for material sputtering have stimulated investiga tions of relatively lowpower steadystate discharges in crossed electric and magnetic fields. The properties of this type of magnetron discharge have been studied sufficiently well. At the same time, the properties of discharges operating in the parameter range corre sponding to the transition from a magnetron discharge with an ascending current–voltage characteristic to an arc discharge still remain poorly studied. Reliable experimental and theoretical data that would allow one to determine the limiting operating modes of a magnetron discharge in which most technological devices operate are lacking. Experiments with high power impulse discharges are limited by short pulse durations caused by the onset of instabilities and trans formation of the discharge into an arc [1, 2]. Studies of ionization relaxation in noble gases and comparison of the time of the gas response to a high voltage pulse with the characteristic times of instability development indicate that there can exist quasisteady discharges in a magnetic field that do not pass into a constricted mode at fairly high currents that usually correspond to the arc region of the current–voltage characteristic of such discharges. The operation of highpower discharges with a homogeneous plasma structure is limited by the onset of different types of instabilities resulting in the con striction of the discharge and its transition to the arc mode. The onset of thermal instability requires that the discharge operate in a pulsed or a quasisteady mode with a pulse duration shorter than the character istic time of gas heating in the discharge gap. From the standpoint of research and technological purposes, a quasisteady mode is preferable because of the

expected stability of the discharge and plasma param eters during the entire discharge pulse. The high