Crack Formation Inside Plasma-Facing Materials Irradiated by Pulsed Laser to Simulate Heat Load in Inertial Confinement Fusion System

Abstract

The first wall in an inertial confinement fusion (ICF) reactor is eroded by charged particles, neutrons, and X-rays as the nuclear fusion output within an extremely short period. Because damage to plasma-facing materials (PFMs) determines the lifetime of a nuclear fusion system, it is crucial to examine the internal state of PFMs. We irradiated a pulsed laser to simulate the heat load generated by the ICF output using tungsten as the wall material. No cracks were observed on the surface of the sample using an optical microscope, whereas cracks appeared near the surface inside the sample manufactured in the depth direction using a focused ion beam device. The observed cracks were formed in deeper locations than in previous studies. The cracks were generated owing to the temperature difference between the surface and the interior generated by the thermal load within an extremely short period.