Abstract: An optical waveguide is formed using a gas-enclosed vessel that has an internal space in which a polyvalent ionizable gas is enclosed, a laser beam irradiation unit, and a discharge circuit that causes a pulse current to flow in the gas-enclosed vessel at an initial current value. The pulse current is increased from the initial current value to a subsequent current value greater than the initial current value, and a polyvalent ionization channel is formed in the internal space, while increasing the pulse current, by irradiating the internal space in the plasma state with a trigger laser beam generated by the pulse laser beam irradiation device. The polyvalent ionization channel expands by an inverse pinch effect after the internal space is irradiated with the trigger laser beam due to a concentration of the pulse current in the internal space.

Abstract: An optical waveguide is formed using a gas-enclosed vessel that has an internal space in which a polyvalent ionizable gas is enclosed, a laser beam irradiation unit, and a discharge circuit that causes a pulse current to flow in the gas-enclosed vessel at an initial current value. The pulse current is increased from the initial current value to a subsequent current value greater than the initial current value, and a polyvalent ionization channel is formed in the internal space, while increasing the pulse current, by irradiating the internal space in the plasma state with a trigger laser beam generated by the pulse laser beam irradiation device. The polyvalent ionization channel expands by an inverse pinch effect after the internal space is irradiated with the trigger laser beam due to a concentration of the pulse current in the internal space.

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: To achieve pulse-stretched EUV radiation without putting a large heat load on electrodes or requiring sophisticated control, a pulsed power is supplied between a first electrode and a second electrode provided inside a chamber to form a narrow discharge channel therebetween. A laser beam from a laser source irradiates high temperature plasma material to form low temperature plasma gas having an ion density of approximately 1017 to 1020 cm?3 which is supplied to a narrow discharge channel formed between the electrodes. Electric discharge acts on the low temperature plasma gas to raise the electron temperature, resulting in high temperature plasma. As a result, EUV radiation is produced. Since the low temperature plasma gas is continuously supplied to the discharge channel, the pinch effect or confining effect of its self-magnetic field is repeated, resulting in the continuation of EUV radiation.

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.