Surface damage and thermal effects from transient thermonuclear radiation in inertial confinement fusion reactors

Abstract

A general model for transient deposition of thermonuclear radiation has been developed and applied to calculate the response of copper to a reference spectrum typical of laser fusion reactors. At 7 m from a 100 MJ pellet, temperature excursions of approximately 700°C above the ambient temperature are noted for both photons and ions, occurring 0.02 and 2 μs after the thermonuclear burn, respectively. Total displacement rates approach 100 dpa/s at the surface and 500 dpa/s at 1 μm into the copper. Filling the chamber with Ne at 0.5 Torr was found to be sufficient to reduce the temperature excursion in copper by 50% and the dpa rate at the front surface by 25%. The combination of surface temperature transients and ion bombardment was found to increase the sputtering yield by a factor of 4 over ambient temperature values indicating that previous calculations may have seriously underestimated the sputtering damage in laser fusion first walls.