Study on the E-beam pulse width scaling for a 25-kilojoule KrF amplifier

The KrF laser is being considered as an ICF driver candidate. Since this laser is not an energy storing system, the output energy of an amplifier is delivered over the entire pulse width of the excitation source. E-beam pumping is preferred for large energy systems. The e-beam pulse width is constrained to a few hundred nanoseconds by laser operation and pulsed power considerations. The target requires pulses of a few nanoseconds. Angular multiplexing of probe beams through the amplifier is a preferred scheme for bridging this difference in timing requirements. Progressively shorter target irradiation times may be obtained by using shorter pulse probe beams and by either increasing the number of angular multiplexed beams or by decreasing the e-beam pulse width. This report documents results of a study on the consequences of following the latter approach