Population inversions in C IV in a recombing theta-pinch plasma

Population inversions on the 5g-4f and 4f-3d transitions of C IV at 253.0 and 116.9 nm have been observed in the recombination phase of a theta-pinch plasma initially containing 14 mTorr of acetylene and 0.5 mTorr of hydrogen gas. Population ratios of 17:11:1 for the 5g, 4f, and 3d levels were deduced from measured absolute line intensities of the 5g-4f and 4f-3d, and 3d-2p transitions at 253.0, 116.9, and 38.4 nm. The resulting gain-length product for a single pass through the 23-cm-long plasma column, based on the measured Doppler-broadened linewidth, is 2.3% at 116.9 nm and 5.8% at 253.0 nm.