An Experimental Method for Measuring the Response of a Target to the Thermal Environment of the Fusion Reaction Chamber

An experiment has been designed to measure what happens to the ice layer inside an inertial fusion energy (IFE) target when it is injected into a reactor. This experiment uses a stationary planar, deuterium (D
₂
) ice target equipped with several diagnostics and directs a flux of high-temperature, high-velocity xenon (Xe) atoms (and/or D ions) at the surface. This mimics the effect of a cryogenic target moving at high velocity (up to 400 m/s) into a low-pressure, high-temperature furnace. The change in ice temperature and the extent of melting will be measured for different heat loads. The condensation rate of xenon on the target surface is measured to determine the sticking and accommodation coefficients of xenon on the target, critical parameters for assessing the temperature profile around the target. The high-temperature gas flux (2000+degC at the target) simulates the heat flux inside the fusion chamber (10 to 20times10
³
W/m
²
) at a flow rate of 7.8times10
^-4
g/min. The properties of the beam were experimentally characterized in terms of its temperature distribution, beam divergence, and energy flux at the target. Reflection high-energy electron diffraction (RHEED) monitors the growth of the Xe film on the target's surface, giving an estimate of the heat of condensation from the Xe atoms. A different method, based on a platinum (Pt) sensor placed inside the D
₂
target, detects the ice/liquid fraction contacting it and provides an estimation of the total heat flux through the target