Scaling of the helium-nitrogen charge transfer laser

Abstract

The scaling to high powers of the nitrogen ion laser pumped by charge transfer from He⁺₂ is reported. Intense emission has been found from three laser lines at 3914, 4278, and 4709 Å upon discharge of a fast‐pulsed electron beam gun, APEX‐1, into several atmospheres of a mixture of helium and nitrogen. Excitation current densities were 1.4 kA/cm² at 1 MV over a 1×10‐cm transverse geometry. The efficiency of the 4278‐Å laser emission was found to be proportional to the total pressure raised to the 1.2 power. Outputs of 36 mJ have been obtained from the 16‐cm³ working volume at 30‐atm pressure and a peak efficiency of 1.6% relative to the energy lost by the electron beam in this radiating volume has been achieved.