Abstract

One of the key requirements for inertial confinement fusion (IGF) is a highly uniform implosion of the spherical pellet. In directly driven ICF, this requires the spatial profile of the laser beam to be smooth and controllable within subnanosecond averaging times. This is especially true in the low-intensity prepulse (foot pulse), where the pellet has not yet developed the large blowoff plasma that could help smooth the spatial nonuniformities by thermal diffusion. In megajoule ICF laser designs, such as the National Ignition Facility (MF), a rapid and effective beamsmoothing technique is essential in the foot pulse if the facility is to be useful for direct-drive as well as hohlraum experiments.

© 1996 Optical Society of America