Abstract: High temperature plasma raw material is added drop-wise, for example, and evaporated by irradiation with a laser beam. The laser beam passes through a discharge area between a pair of electrodes and irradiates the high temperature plasma raw material. Pulsed power is applied to the space between the electrodes in such a way that discharge current reaches a specified threshold value at a time when at least part of the evaporated material reaches the discharge channel. As a result, discharge starts between the electrodes, plasma is heated and excited and then EUV radiation is generated. The EUV radiation thus generated passes through a foil trap, is collected by EUV radiation collector optics and then extracted. The irradiation of the laser beam allows setting of the space density of the high temperature plasma raw material to a specified distribution and defining of the position of a discharge channel.

Abstract: High temperature plasma raw material (21) is gasified by irradiation with a first energy beam (23). When the gasified raw material reaches the discharge region, pulsed power is applied between the electrodes (11, 12) and a second energy beam (24) irradiates. In this manner, the plasma is heated and excited and an EUV emission occurs. The emitted EUV emission is collected and extracted by EUV collector optics. Because of irradiation by the first and second energy beams (23, 24), a special distribution of high temperature plasma raw material density can be set to a specified distribution and demarcation of the position of the discharge channel can be set. Moreover, it is possible to lengthen pulses of extreme ultraviolet emission by supplying raw material gas of which the ion density in the discharge path is nearly the same as the ion density under EUV radiation emission conditions.