Cryogenic system design of 11 GEV/C super high momentum spectrometer superconducting magnets at Jefferson Lab

Abstract

The design of the cryogenic system for the 11 GeV/c Super High Momentum Spectrometer (SHMS) is presented. A description of the cryogenic control reservoir and the cryogenic transfer line is given. Details of the cryogenic control reservoirs, cryogenic transfer lines, and pressure piping are summarized. Code compliance is ensured through following the requirements of the ASME Pressure Vessel Code and Pressure Piping Code. An elastic-plastic-analysis-based combined safety factor approach is proposed to meet the low stress requirement of ASME 2007 Section VIII, Division 2 so that Charpy V-notch (CVN) impact testing can be avoided through analysis. Material toughness requirements in ASME 2007 Section VIII, Division 2 are adopted as CVN impact testing rules of stainless steel 304 piping at 4.2 K and 77 K. A formula-based combined safety factor approach for pressure piping is also proposed to check whether the impact testing can be avoided due to low stress. Analysis and calculation have shown that no CVN impact testing of base metal and heat affected zones is required for the helium reservoir, nitrogen reservoir, and their relevant piping. Total heat loads to liquid helium and liquid nitrogen are studied also. The total heat load to LHe for SHMS is estimated to be 137 W, and the total load to LN2 is calculated to be 420 W.