High-repetition-rate operation of a segmented hollow-cathode Ne-Cu/sup +/ 249-nm laser

摘要

A segmented hollow-cathode Ne-Cu/sup +/ 249-nm laser is operated at a pulse repetition rate of 500 Hz and a pulse duration of 30 /spl mu/s. The laser pulse has a risetime of 5 /spl mu/s and is delayed by 5 /spl mu/s on the leading edge of the current pulse. The fast evolution of the laser pulse results from a higher gas temperature at the start of each discharge pulse, and consequently during the pulse, due to the higher mean cathode temperature required to transfer the discharge power from cathode to anode. The higher gas temperature results in a faster diffusion of the sputtered copper atoms into the negative glow and in an increased rate coefficient for charge transfer, both of which increase the pumping rate for the laser transition. An initial overshoot in the discharge voltage gives rise to a sharp initial peak in the laser pulse. A significant sharp peak in the laser pulse immediately at the end of the current pulse indicates that an enhanced laser pulse of duration 10 /spl mu/s at a pulse repetition rate of 1 kHz may be achieved by appropriately shortening the current pulse duration.