| 摘要 |
Metal vapor, e.g., copper vapor, is expanded into a vacuum, its thermal energy being converted into translational, with consequent cooling. It passes between electrodes between which a short electrical discharge excites it to the upper laser state, from which it passes by lasing action to a metastable state initially relatively unpopulated because of low vapor temperature. The vapor velocity is such that the metastable atoms are replaced by a fresh supply of unexcited atoms before the next discharge, the used vapor being conveniently condensed upon a collector, although in operation in space this might be omitted.
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