Discharge device for pulsed laser

Abstract

In a preionization discharge circuit when a switch SW is turned on, an electric current i from a constant current source flows through a loop of a coil L en electrode A and the switch SW When it is assumed that an inductance of the coil L is L (H) and the current i flowing through the coil L is I (A), energy EL of (1/2)·L·I{circumflex over ( )}2 is accumulated in the coil Meanwhile, in a preionization discharge control section a preionization discharge timing signal (namely, a corona emission timing signal) Ydt is output to the switch SW after lapse of a time ty (=Tds−tyd) after a pulse oscillation synchronizing signal TRL is received so that preionization discharge is caused earlier by a preset time tyd than the preionization discharge timing signal Ydt. When the switch SW is switched from on to off according to the corona emission timing signal Ydt, the energy EL accumulated in the coil L is abruptly supplied to the electrode A of the preionization electrode Then, an electric field is produced between the electrode A and an electrode plate C and, when the electric field of the preionization electrode rises to a predetermined preionization start electric field, a corona discharge is produced in a tube B as a dielectric of the preionization electrode to flow an electric current i and a main discharge gap is preionized before the main discharge is caused by main discharge electrodes and