Population Inversions in C IV in a Recombining Theta-Pinch Plasma.

Population inversions on the 4f - 3d and 5g - 4f transitions of C IV at 116.9 and 253.0 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, 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 and 5.8% at 253.0 nm.