Characteristics of laser action and excitation of levels in an Se-He discharge

High-frequency transverse discharges in mixtures of He and molecular Se vapors (Se2, Se4, and Se6) were studied experimentally. It is found that, in the quasi-continuous mode of operation, emission from molecular Se prevailed at the onset of the pulse, but emission from atomic Se prevailed at the termination of the pulse. Dissociation of the molecules led to a delay in laser oscillation. When the discharge was excited by short (3 microsec) RF pulses, emission from Se and laser oscillation occurred at a pulse repetition frequency exceeding 4 kHz. This was due to the accumulation of Se atoms in the discharge with high repetition frequencies.