Takashi Sakugawa

Pulsed streamer discharge characteristics of ozone production in dry air

Experimental investigation of HV short pulsed streamer discharges in dry air-fed ozonizers under various operating conditions are reported. Ozone concentration, energy input and ozone production yield (efficiency) were measured at various voltages (14 to 37 kV), pulse repetition rates (25 to 400 pulses per second, pps), flow rates (1.5 to 3.0 1/min) and different gap spacings (10 to 20 mm) at a pressure of 1.01/spl times/10/sup 5/ Pa in dry air. A spiral copper wire (1 mm in diameter) made to a cylindrical configuration (18 to 38 mm in diameter) in a concentric coaxial electrode system of various dimensions was employed. A magnetic pulse compressor provided the HV and current pulses. Higher voltage and higher repetition rates yielded higher concentrations of ozone at a fixed air flow rate. The present investigation was extended to assess the performance of this pulsed ozone generator using dry air under desired conditions of high concentration and high yield of ozone for industrial applications.

High power KrF excimer laser with a solid state switch for microlithography

New KrF excimer laser for microlithography KLES-G7 with a new simple solid state pulsed power circuit (SPC) is developed. This SPC has several advantages such as less maintenance cost and the higher reliability. The laser realizes 7.5W with 0.8 bandwidth, 600 Hz, 10mJ. The performance and the stability of the laser is demonstrated. The maintenance interval of the SPC is more than 10 X 109 pulse. The KLES-G7 reduces 20 percent of the photon cost compared with the old model. It will accelerate the mass production of after 64Mbit DRAM.

All-solid-state excitation circuit using saturable transformer for excimer laser excitation

To reduce the load on switching devices, a new type of all-solid-state excitation circuit has been successfully developed, where only one GTO thyristor is utilized in the switching device and a saturable transformer is used as the magnetic pulse compressor. We have used a saturable transformer with a winding ratio of 1:7. The initial pulse of 5.5 kV, 1.7 kA, 1.0 kA/microsecond(s) was transferred to the output pulse of 32.7 kV, 8.7 kA, 282 kA/ns. Employing this circuit for XeCl-excimer laser, we have succeeded in lasing the output energy of approximately 30 mJ/pulse.