Abstract: The fuel cell system is provided which detects a freeze among specific components and portions thereof by evaluating various conditions upon starting operation of the fuel cell system. If a freeze is detected through those evaluations, the start of the system is prohibited in order to prevent some deterioration in the fuel cell system.

Abstract: The present invention intends to generate an electromagneticwave of wavelength in an EUV area repeatedly by irradiating laser beam in high frequency more than few kHz. For such purpose, a laser plasma EUV light source apparatus is comprised of a vacuum chamber, a target disposed in the vacuum chamber, a beam irradiate means for irradiating energy beam to the target, an input optical system for introducing energy beam to the target, an output optical system being communicated with the vacuum chamber for introducing electromagneticwave generated from the target, a shield device for protecting at least one of the input optical system and output optical system from spattering particle, and a wave length select device for selecting from electromagneticwave an electromagneticwave at wavelength in the EUV area. By such construction, generation of the debris can be restricted, and generated debris is shielded by the shield device 4.