One meter KrF laser system

This interim report covers research directed towards efficient high power UV/visible lasers. The key issues being addressed are: (1) e-beam and e-beam controlled discharge excitation, (2) laser kinetics and modeling, (3) discharge stability and enhancement, (4) laser medium gain, adsorption and energy extraction and (5) intrinsic laser efficiency and scaling. Using e-beam controlled discharge pumping of a one meter KrF laser, 75 joules of laser output were obtained with 10% intrinsic efficiency at a specific energy of 10 J/liter. The use of an externally applied magnetic field to guide the e-beam is shown to effectively prevent e-beam steering by the discharge current and thus allow this excitation technique to be scaled to large laser apertures and very large single pulse energies. For efficient discharge pumping spatial e-beam energy deposition uniformity is shown to be important and methods of improving the deposition uniformity are proposed. Using pure e-beam excitation of XeF, a laser output of 36 joules was obtained with 2.6% intrinsic efficiency at a specific energy of 8 J/liter. Processes limiting XeF laser efficiency are identified and remedies proposed.