ICF delivers the energy of a laser (or ion beam) not
directly to the fuel capsule, but rather to an enclosure, or hohlraum,
in which it is thermalized.This
thermal radiation is typically characterized by temperatures of 2 to 3
million K, so it is primarily X-rays.
Images of a gold hohlraum used at the NOVA laser at Livermore (far left).The
picture on the right was
taken in X-rays and shows the
laser hotspots on the interior of the hohlraum radiating through the hohlraum walls.