Mechanism of Electron Emission Produced by a Giant-Pulse Laser

A spinning-prism $Q$-switched ruby laser, with a peak power output of 2 MW, has been employed to produce single pulses of electron emission about 100 nanoseconds long. Pulses of the order of hundreds of mA/${\mathrm{cm}}^2$ were emitted from well-cleaned tungsten, thoriated tungsten, and platinum targets in a hydrogen atmosphere at 3×${10}^{-8\mathrm{}}$ Torr. The mechanisms for production of the electrons were investigated. No component attributable to multiphoton or other nonlinear processes was identified. The amplitudes and shapes of the electron pulses agree with calculated values based on the assumption that all the electron emission is produced by conventional thermal effects.