Development of key components and technologies for a high repetition rate and high-power excimer laser

Key components and technologies have been developed for an ultrahigh repetition rate XeCl excimer laser of 5 kHz to be used for industrial applications. A compact axial blower having a revolution rate of up to 10 000 min −1 and a maximum pressure of 16.2 kPa in air was made with a canned magnetic coupler to circulate a laser gas at a flow velocity of over 150 m/s in a discharge region. Materials constituting a laser chamber were tested to prevent discharge instability by gas contamination to enable long time operation. The dominant cause of the instability was investigated by a simple simulation. For a preionization, a novel sealed-off x-ray tube was developed to compare the suitability in a high repetition rate operation with that of conventional UV preionization. The gas due to the shock and acoustic waves generated by discharge pulses was measured to design the damper, which enabled the suppression of the gas turbulence by around a tenth. To simplify cumbersome laser maintenance, a new power supply provided by a novel fast switching semiconductor device was evaluated by operating the laser. The experimental laser apparatus integrating these key components and technologies was operated to confirm the practical availability for high repetition of up to 5 kHz. Many kinds of basic experiments have been performed to increase repetition rate, average power, and reliability. Though these experimental results have not yet been integrated and performed simultaneously, we have achieved operation up to an average output power of 0.56 kW at 5 kHz. Based on the results and empirical knowledge, the prospect for a practical high repetition rate excimer laser was discussed.