Target engagement and survival

In collaboration with the Inertial Fusion Group at General Atomics, we perform research on direct-drive laser-IFE targets. Power plant targets are cryogenically cooled (below 20 K) capsules containing frozen DT. These targets must remain exquisitely symmetric until they are irradiated simulateneously by a number of intense lasers. We explore methods to track targets, steer lasers onto them, steer the targets themselves, and ensure survival during injection into a heated chamber.

Our research topics include:

Target engagement
Targets are injected at speeds of 50-400 m/s, and must be placed at chamber center with an accuracy of 5 mm at a repetition rate of 5-10 per second. We track these targets using optical metrology systems with accuracy better than 20 microns, and feed this information into fast steering mirrors to allow precise symmetric illumination of the target once it reaches the point of implosion.

Target steering
Direct drive targets are very light - typically just a few milligrams. By placing an electric charge on the target, electric fields can be used to steer the targets in flight. We are supporting General Atomics in the development of an electrostatic steering system coupled with our in-line target tracking technologies.

Target survival
Cryogenic direct-drive targets are very delicate. If the outer surface temperature changes by more than 1-2° K during transit through the chamber, then the target symmetry may degrade beyond the point where successful implosion will ensue. We explore the thermal, mechanical and phase-change behavior of direct-drive targets in order to establish the design window for successful injection.
 

Copyright © 2006 Regents of the University of California.
All rights reserved.

 
   
HAPL Research at UCSD
UCSD Center for Energy Research