Cryostat Design and Analysis of the Superconducting Magnets for Jefferson Lab’s 11 Gev∕c Super High Momentum Spectrometer

Abstract

This paper describes the mechanical design and analysis of the cryostats for the two cos(2θ) quadrupoles and the cos(θ) dipole. All the magnets are currently being bid for commercial fabrication. The results of finite element analysis for the magnet cryostat helium vessels and outer vacuum chambers which investigate the mechanical integrity under maximum allowable internal working pressure, maximum allowable external working pressure, and cryogenic temperature are discussed. The allowable stress criterion is determined based on the allowable stress philosophy of the ASME codes. The computed cryogenic heat load of the magnets is compared with the allowable cryogenic consumption budget. The presented cool-down time of the magnets was studied under the conditions of a limited supply rate and a controlled temperature differential of 50 K in the magnets.

Design and Analysis of the Warm-to-Cold Suspension Links for Jefferson Lab’s 11 Gev∕c Super High Momentum Spectrometer

“…The warm-to-cold suspension links are one of the major heat load sources to liquid helium or liquid nitrogen [3]. Heat leak in the suspension links makes about 22% contribution to the total heat load to liquid helium and about 31% contribution to the total heat load to liquid nitrogen.…”

“…The suspension links shall be designed so that they will be able to support the weight of the coil and the helium vessel; the center of the coil will stay at the same position before and after cool-down; they will always remain in tension, and that no ice cubes will be generated at the top of the links. They must be slim so that that the total heat loads to liquid helium or liquid nitrogen will be below cryogenic consumption budgets [3]. Most importantly, their mechanical integrity must be maintained at various worst-case scenarios.…”

“…The Q23 and the Dipole superconducting magnets share numerous design and construction details [2,3]. They use the same cryo reservoir to supply helium, nitrogen, current leads, and electronic cables.…”

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

“…A new 11 GeV/c Super High Momentum Spectrometer (SHMS) has been planned for Jefferson Lab's experimental Hall C [1,2] as a part of 12 GeV Upgrade Project at Jefferson Lab. The SHMS consists of five large superconducting magnets: a small initial horizontal bend dipole (HB), three quadrupoles (Q1, Q2, Q3), and a 60 cm warm bore cosine type dipole (Dipole).…”

“…Major components of the cryogenic system, such as the cryogenic control reservoirs, and transfer lines will be discussed in this paper. The cryostats of the superconducting magnets have been presented in a previous paper [2], so it will not be investigated here.…”