Analyses and design of additional thermal shields for MITICA Cryopumps

Following requests from IO Vacuum Group and F4E in June 2015, a thermal shield to protect the Cryopumps edges facing the Beam Source has been studied, analyzed and preliminarily designed. The function of the thermal shield is to intercept and dump deflected ions and electrons, to limit the local heat loads applied to the Cryopump edges facing the Beam Source. This is necessary to guarantee the correct performances of both Cryopump and MITICA Cryogenic Plant , avoiding excessive overheating of 80 K thermal shields and cryogenic circuits. P ossible design solution s, numerical models, analyses and results are presented in this report. The final design of additional thermal shields connected to the Vacuum Vessel shall be further developed, but the interfaces of thermal shields with Beam Line Vessel (BLV) lateral walls have been fully defined in this report, to allow proper design changes and manufacturing of BLV , presently under procurement . This document also includes the results of further thermal analyses with different assumptions , according to requests from M. Dremel (IO) on 9 th March 2016. This version of the document (release 3) reports all the results , with complete presentation of temperature contours and temperature vs time diagrams.