Luminescence of atoms and ions of aluminum in pulse-periodic nanosecond discharge initiated by runaway electrons in nitrogen
D.V. Beloplotov, V.F. Tarasenko, M.I. Lomaev
High Current Electronics Institute of the Siberian Branch of the RAS, 634055, Tomsk, 4, Academichesky ave.
Keywords: наносекундный импульсно-периодический разряд, азот, неоднородное распределение электрического поля, алюминий, струи паров металла, цветные мини-струи, nanosecond pulse-periodic discharge, nitrogen, non-uniform electric field distribution, aluminum, metal vapor jets, colored mini jets
Abstract
Spectral and amplitude-temporal characteristics of plasma of a pulse-periodic nanosecond discharge initiated by runaway electrons in nitrogen in a pressure range 30-760 torr are investigated. Voltage pulses (U = 13 kV, FWHM is 10 ns, front duration is 4 ns, negative polarity, f = 60 Hz) applied to a cathode made of aluminum. The cathode had a cone form. Diameter of cone base, apex angle, and corner radius of cone apex were 6 mm, 30°, and 0.2 mm, respectively. A flat anode was located at distances of 2 and 6 mm from the cathode apex. Waveforms of voltage pulses, discharge current, radiation intensity, and spectra of discharge plasma were registered. At an interelectrode distance of 2 mm, colored jets of metal vapor were observed near the cathode apex throughout the pressure range. Size of jets was about 1 mm. Intense lines of atoms (Al I) and ions (Al II) of aluminum with wavelengths of 394.4; 396.15 nm and 622.62; 623.17; 704.21; 705.66; 706.36 nm were registered, respectively. Luminescence duration (> 2 ms) of the both was larger than the discharge current duration (~ 1 ms).
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