Optimization of a Ne/Ar/Kr/F2gas mixture with respect to maximum KrF laser output has been performed. As an excitation source a transverse electron beam with a pulse length of 10 ns was used. The laser output obtained with a typical Ne/Ar/Kr/F2mixture containing mainly Ne was found to increase linearly with Ne partial pressure. At a pressure of 14 bar the laser output energy exceeds the one achieved with an optimized Ar/Kr/F2mixture by a factor of 4.5.