Cryogenic upgrade of the low heat load liquid helium cryostat used to house the Cryogenic Current Comparator in the Antiproton Decelerator at CERN

Cryogenic Engineering Conference 2017

材料科学;物理学

Lees, A.^1 ; Koettig, T.^1 ; Fernandes, M.^1 ; Tan, J.^1

CERN, Accelerator Technology Department, Geneva 23

CH-1211, Switzerland^1

关键词: Antiproton decelerator;    Ceramic insulators;    Cooling power;    Cryogenic current comparator;    Liquid helium cryostats;    Pulse tube cryocoolers;    Thermal Performance;    Titanium support;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/278/1/012193/pdf
DOI  :  10.1088/1757-899X/278/1/012193

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

The Cryogenic Current Comparator (CCC) and its purpose built cryostat were installed in the low-energy Antiproton Decelerator (AD) at CERN in 2015. A pulse-tube cryocooler recondenses evaporated helium to liquid at 4.2 K filling the helium vessel of the cryostat at an equivalent cooling power of 0.69 W. To reduce the transmission of vibration to the highly sensitive CCC, the titanium support systems of the cryostat were optimized to be as stiff as possible while limiting the transmission of heat to the liquid helium vessel. During operation the liquid helium level in the cryostat was seen to reduce, indicating that heat load was higher than intended. To verify the reason for this additional heat load and improve the cryogenic performance of the cryostat, an upgrade was undertaken during the 2016 technical stop of the AD. This article presents the studies undertaken to understand the thermal performance of the cryostat and details the improvements made to reduce heat load on the liquid helium vessel. Also discussed are the procedures used to reduce the diffusion of helium to the vacuum space through ceramic insulators. Finally the upgraded cryogenic performance of the cryostat is presented.