Optical measurements of paired luminous rings in capacitive radio-frequency hydrogen discharges.
Optical measurements of paired luminous rings separated by a narrow dark gap have been conducted in capacitive radio-frequency (rf) hydrogen discharges. The lines of molecular H(2) are strongly excited at the ring emission compared with a weaker emission of the H(alpha) line. The number of ring pairs increases with gas pressure, and the outermost ring pairs near the electrodes start to appear earlier than the inner ones. Each ring emission is turning on and off with the applied rf frequency, i.e., the left-side (right-side) ring of a paired ring is on when the left-side (right-side) electrode is biased positively. The axial light intensity profile, which is time resolved with the applied rf frequency, indicates that the emission profiles are similar to those of dc glow discharges, and the luminous rings correspond to the standing striations at the positive column.
Sakawa
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Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603, Japan. g44210a@nucc.cc.nagoya-u.ac.jp
Hori
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M
Shoji
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Sato
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T