Thermal analysis and high heat flux testing of unidirectional carbon-carbon composite for infrared imaging diagnostic

Unidirectional carbon fiber-carbon matrix (CFC) composite tiles, which are proposed to be employed in thermal imaging diagnostic of powerful particle beams, have been designed, manufactured, and tested. The particle beam is intercepted by the tiles, which erodes the carbon surface producing debris, while a plasma forms in front of the tiles due to beam-gas interaction. Carbon fibers are aligned along the tile thickness to transfer the heat flux from the front to the rear surface with limited thermal pattern broadening thanks to the ten times higher thermal conductivity along the fibers. This feature of the tiles allows to detect thermal radiation at the tile rear surface by thermographic cameras, producing curves to be correlated to energy, intensity profile, and duration of the particle beam. Thermal patterns with spatial resolution of a few mm, time resolution up to 40 ms, and maximum temperature of 1300 C have been measured on CFC tiles exposed to accelerated hydrogen beam pulses with power densities up to 13 MW m-2 in thehigh heat flux test facility GLADIS. Multiphysics transient non-linear parametric finite-element models have been developed to simulate thermal transfer inside tiles, thermal patterns at surfaces, and thermal deformations of tiles by varying spatial distribution and peak value of the power density. Temperature gradients, hoop deformations around the heated region, location of failure region, and failure time have been analysed and discussed to recognise the tile behaviour during the high heat flux tests. Simulation models have been validated by comparing outputs to experimental measurements. Finally, model geometry and parameters have been changed to simulate the behaviour of the complete diagnostic to be used in the Source for the Production of Ions of Deuterium Extracted from a Radio-frequency pplasma (SPIDER) test bed of the ITER Neutral Beam Test Facility with expected power density up to 20 MW m-2.