Charge transfer pumping of the helium-nitrogen laser at atmospheric pressures in an electrical avalanche discharge

An atmospheric electrical avalanche (AEA) laser, stabilized by displacement current preionization, has been developed to support the study of the collisional pumping of the N+2, B→X, electronic transition by the kinetic step He+2+N2+He→N+2(B2Σu)+3He. With proper preionization, the AEA laser has been operated at a pulse repetition frequency (PRF) of 1–30 Hz in an avalanche mode at 100–200 A/cm2 and an E/p of 5 V/cm Torr. At pressures from 1 to 8 atm, an essentially uniform 30-cm3 volume containing a high concentration of He+2 has been produced. Resulting laser output pumped by the charge transfer reaction has exceeded 1 MW peak power at 427.8 nm in a 4-nsec pulse. Efficiency with respect to the instantaneous power conversion has exceeded 2%, and output pulse energies have exceeded 1% of the input pulse of energy dissipated in the laser tube.