Diagnosis of plasma in high current laser ion source

Plasma characteristics are key parameters of ion source. The characteristics of plasma in high current laser ion source are diagnosed by optic emission spectroscopy and an ICCD camera. The plasma is produced by a quadruplicated frequency Nd: YAG laser irradiating Cu target. The laser energy density is about 108 W/cm2, and the duration time is 15 ns. The plasma expansion progress is captured by the ICCD camera, which shows the expansion velocity is about 1 cm/s. Meantime the plasma emission spectra are measured by a spectrograph, which are mostly Cu Ⅰ spectra from Cu atoms and some weakly Cu Ⅱ spectra from Cu+ ions. Electron temperatures are got by Boltzmann plot and they are about 1 eV. Electron densities are got by Stark broadening and they are about 1016 cm-3.