Numerical and experimental investigation of 80K thermal shield assembly of 1^st Pre-Series Cryoline (PTCL) of ITER cryolines

The Pre-Series Cryoline (PTCL) is a representative segment of ITER torus & cryostat cryolines with the same cross-section (1:1) and roughly 1:5 scale in length. It was tested in ITER-India Cryogenic Laboratory, IPR, Gandhinagar to verify the thermal and mechanical performances. To evaluate the thermalization of 80K thermal shield installed in PTCL, the temperature of twenty critical locations was recorded during the PTCL test. Steady state measurement of PTCL test shows that the average temperature on a thermal shield was ~5K higher and the heat load at 80K was ~104Whigher than the estimated values by numerical analysis. The detailed investigation was performed to determine the possible causes of variance between estimated heat load and experimental heat load. The study result shows that transverse radiation is very critical for heat load at 80K.The revised heat load result obtained from numerical analysis considering transverse radiation with conduction (220.67W) differs only two percent from PTCL experimental heat load. Paper summarizes the PTCL experimental heat load at 80K and the effect of transverse radiation due to the bare surface of fixed supports, vacuum barriers, and sliding supports.