Phasing beams with different dispersions and application to the petawatt-class beamline at the National Ignition Facility

In order to achieve the highest intensities possible with the short-pulse Advanced Radiographic Capability beamline at the National Ignition Facility (NIF), it will be necessary to phase the individual ARC apertures. This is made especially challenging because the design of ARC results in two laser beams with different dispersions sharing the same NIF aperture. The extent to which two beams with different dispersions can be phased with each other has been an open question. This paper presents results of an analysis showing that the different dispersion values that will be encountered by the shared-aperture beams will not preclude the phasing of the two beams. We also highlight a situation in which dispersion mismatch will prevent good phasing between apertures, and discuss the limits to which higher-order dispersion values may differ before the beams begin to dephase.