A nitrogen ion laser pumped by charge transfer

The first nitrogen ion laser pumped by charge transfer from ${\mathrm{He}}_2^{+}$ is reported in this work. Intense laser emission in the violet at 427 nm has been observed and found to have a linewidth less than 0.3 nm. The pumping ion, ${\mathrm{He}}_2^{+}$ , was produced by discharge of a fast‐pulsed electron beam gun, APEX‐1, into 7 atm 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. Under these conditions, the efficiency of the emission of 427‐nm laser radiation was found to be 1.9% relative to the energy lost by the electron beam in the radiating volume.