Abstract

Laser fusion requires a high degree of uniformity of drive to achieve the high-density compressions required for sustaining a thermonuclear burn. Indirect drive uses hohlraum targets to absorb the laser energy and convert it to x rays which drive the target.¹ An alternative approach, direct drive, implodes the target by irradiating it directly with laser light from a large number of overlapping beams. Compression and heating of the fuel are obtained by depositing energy on the surface of a fuel-containing capsule causing surface material to be ablated and driving the remainder of the target inward like a spherical rocket to ignition-critical implosion velocities of > 10⁷ cm/sec. For success, a high degree of spherical convergence of the fuel is required, placing severe constraints on uniformity of energy deposition on the target surface. The level of nonuniformity in deposition that can be tolerated depends on the details of individual target designs.

© 1983 Optical Society of America