Experiments on toroidal inductively coupled alternating-current gas discharges
The discharges studied were sustained at pressures roughly between one tenth of a torr and some tens of torrs. After breakdown was obtained at low pressure, additional gas was let in from a reservoir. The energy was inductively coupled into the electrodeless discharge by means of an iron core transformer of which the toroidal plasma column was the secondary winding. The power dissipated in the plasma was between 80 and 260 kW and was delivered by a motor-generator system at a frequency of 8 kHz for times up to 2 sec. The matching of the impedance of the generator and that of the plasma transformer was obtained by means of an autotransformer and capacitors. A toroidal magnetic field of 0.5 T maximum can be supplied in a short pulse. Five difference gases (hydrogen, deuterium, helium, argon, and nitrogen) were used. The pressure range in which the discharges were sustained is specified and the dynamic current-voltage characteristics are given for different pressures. Some typical streak pictures with simultaneously obtained recordings of the time behavior of the discharge current and of the loop voltage are presented for the initial phase (at low pressure) of the discharge. The shape and position of fully developed discharges at various pressures are discussed on the basis of photographic observations. The temperature of hydrogen plasmas is derived both from the electrical conductivity and from the emission of line radiation. The values of the temperature obtained in these ways differ in magnitude and in time behavior. A possible explanation of the discrepancy can be obtained in terms of expansion and contraction of electron density and temperature profiles during a period of the discharge current. This picture is confirmed by microwave measurements.
- Research Organization:
- Stichting voor Fundamenteel Onderzoek der Materie, Jutphaas (Netherlands). Instituut voor Plasma-Fysica
- OSTI ID:
- 7106240
- Report Number(s):
- N-77-13844
- Resource Relation:
- Other Information: Thesis. Submitted to Utrecht State Univ. Sponsored in part by Neth. Organ. For Pure Sci. Res. (Zwo) and Euratom
- Country of Publication:
- United States
- Language:
- English
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