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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 prov...

A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assisted gate-triggered thyristor (MAGT) was incorporated with a single stage magnetic pulse compression circuit (MPC). The MAGT was specially designed to directly replace thyratrons in a power supply for a high repetition rate laser. Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retaining a high blocking voltage and to extremely reduce the transient turn-on power losses, enduring a higher peak current. A maximum peak current density of 32 kA/cm2 and a current density risetime rate di/dt of 142 kA/(cm2×μs) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV–300 A at a repetition rate of 5 kHz, which, coupled with the MPC, was equivalent to the capability of a high power thyratron. A high repe...

We developed an all solid state exciter composed of a semiconductor switch with MAGTs (MOS Assisted Gate-triggered Thyristors) and a single-stage MPC (Magnetic Pulse Compression circuit) for high repetition rate XeCl excimer laser. Thirty two (32) MAGTs connected in series were used as the semiconductor switch for a 25kV-900A-0.6μs pulse generation. For MPC, cobalt-based amorphous alloy treated by annealing was selected as core materials for the purpose of reducing magnetic losses.The continuous operation with an average laser power of 43W at 3kHz was verified with this exciter. The efficiency of the switch of 75% was obtained at 3kHz operation. The experimental results verify that replacing thyratrons with the all solid state exciter is possible.

For pulsed power systems such as lasers and accelerators, semiconductor switches with their longer service life have actively been developed as replacements for thyratrons. The MOS-driven thyristors are suitable for pulsed power applications because they have high-power handling and fast turn-on capabilities. The MOS-assisted gate-triggered thyristor (MAGT), designed especially for pulsed power, is a promising candidate in this field. This paper presents the results of an investigation into the performance of MAGTs. Using a pulse-forming network (PEN), the pulse-switching characteristics and the dynamic resistance characteristics during the current flow are investigated. A maximum current density of 21.8 kA/cm2 and di/dt of 106 kA/μs/cm2 with 1550-V anode voltage on a single-shot basis were obtained. Furthermore, a life test with 109 shots at a high repetition rate showed no degradation in the observed characteristics. Based on these experimental results, a carrier flow model of MAGT during turn-on process is proposed and the turn-on mechanism is considered.