Lithium plasma generation by resonant laser light

The ion source for inertial confinement fusion by lithium (Li) ion, must produce a pure Li beam at 5kA/cm/sup 2/ current density. In the Applied-B ion diode, the source plasma should be a mm thick pure Li/sup +/ layer and must have 10/sup 16/cm/sup -2/ surface density. To test a laser produced Li plasma as the ion source, surfaces coated with Li metal are irradiated by laser lights. A resonant 6708A dye laser is used to vaporize and ionize the Li layer. A Q-switched Ruby laser is also used for comparison. The Li layer is produced on a pyrex glass or a brass disk by the vacuum evaporation method. Its thickness is changed from 0.08μm to 0.22μm by controlling the evaporation condition. The diagnostics used in this experiment includes spectroscopy of the light emission of the plasma, double or triple probes, a biased ion collector (BIC) and a fast streak camera. The plasma parameters were measured as functions of the laser power density, the Li layer thickness, and time. Typical Li lines (6103, 4603A) had been observed by a 50cm spectrometer and the plasma density was estimated from the Stark-broadened lines. Obtained results were consistent with the ones estimated from the probe and BIC measurements. The gross behaviors of the plasma production process were also observed by the streak camera