Fusion News: Laser Focus World- Assessing Progress Laser Fusion
The recent new results from the National Ignition, published in the February issue of Nature, is a sign of progress and has provided the facilities with the knowledge to control fusion implosions. As reported by the Laser Focus World in the article, “Assessing Progress on Laser Fusion:”
That’s a definite sign of progress. So is the increasing fraction of the fusion energy that comes from self-heating rather than from fuel compression, which dominates at lower yields. But NIF was built to demonstrate ignition of a fusion reaction, defined as generating more fusion energy than the 1.8 MJ delivered to the fusion target (i.e., the hohlraum containing the D-T pellet). The new results improved fusion yield by an order of magnitude over earlier D-T experiments, but two orders of magnitude remain to match the 1.8 MJ in the input laser pulse.
The “high foot” tests crucially showed that pulse shaping can reduce instability of the fuel implosion, which has been a crucial problem. But the “high foot” pulses do not scale simply to drive fuel implosions to ignition. “Hohlraum physics is limiting our ability to use the full power capability” of NIF, the authors write in Nature, so they are exploring new strategies. Taming those problems to see a clear path to ignition would be a breakthrough.
