Studies of a Ring Discharge

Publisher Website
Google Scholar
Abstract
A driving e.m.f. of 890 cycles per second was employed to energize a ring discharge in mercury vapor in the pressure region near 2×10−4 mm. The ring was a secondary of one turn about a transformer core. E.m.f. per turn was usually near 5 volts. Probe measurements revealed a true electronic temperature with values ranging up to about 300,000°K at the peak of the wave of energization. Only 13 percent of the atoms were ionized at the maximum of the cycle of ionization. The highest electronic temperatures were not found at the lowest pressures. At a given e.m.f. the rate of build-up of the field of ions and the electronic temperature was lower at lower pressures. The energization reached a peak near the end of a half-cycle of the input voltage even though the current started at the zero of voltage. Stroboscopic and other spectral observations afforded qualitative confirmation of the probe measurements. Strong lines of Hg I-II-III together with faint lines of Hg IV were observed. The forbidden line 1S01−2P23 was definitely observed and the forbidden line 1S01−2P03 possibly observed, under conditions yielding the highest electronic temperatures but not otherwise. A probable rate of ion production in an electronic atmosphere of given density and temperature is calculated in accordance with accepted factors and found to be greatly in excess of that apparently prevailing in the present work. To explain the observed limitation upon degree of ionization, a hypothesis involving recombination of ion and electron with conservation of electrical energy is brought forward.