Evolution of an excimer laser gas mix

摘要

Abstract: The work described in this paper forms part of the Eureka EU213 HiPulse excimer laser project to build an excimer laser with an average power greater than 1 kW, and a pulse repetition rate up to 5 kHz. Because of the very large volume of gas needed in such a laser, and the rising costs of rare gases such as xenon, a sophisticated gas processor system is needed which is capable of recycling the rare gas component of the gas mix indefinitely. If the laser head needs to be opened up for some reason, the laser gas needs to be pumped out and stored in a suitable vessel. When the laser is running, a variety of contaminants are generated by various chemical reactions going on inside the laser head; the exact contaminants depend on the materials from which the head is made. As part of the design of a laser gas processor, the authors are investigating the changes in gas constituents as the laser is running, using a quadruple mass spectrometer connected to a computer. The mass spectrometer samples the laser gas through a special capillary and porous plug arrangement which maintains the necessary pressure difference between the laser gas at 2-5 bar and the analyzer head at microbar pressure levels.!