A method and apparatus is provided for stabilizing output beam parameters of a gas discharge laser by maintaining a molecular fluorine component of the laser gas mixture at a predetermined partial pressure using a gas supply unit and a processor. A rake thermocouple is provided that includes a plurality of probe tubes arranged parallel to one another, and each probe assembly is placed into an individual probe tube. In this example embodiment, the spring-loaded locking mechanism has a locked state where the spring-loaded locking mechanism engages with the base such that the position of the bracket is locked in place with respect to the position of the base. Each of the first signal and the second signal includes a combination of first data stored in a first track and second data stored in a second track. A corresponding portion of the map data is transferred from the solid-state media to a map cache coupled to the control processor, the transferred portion having a size equal to the adjusted map data pre-fetch size.