Commissioning of a 20 K helium refrigeration system for NASA-JSC Chamber-A

Abstract

Abstract.A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL's Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (23 metric tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the design, project execution and commissioning results.

Commissioning and operational results of helium refrigeration system at JLab for the 12GeV upgrade

“…Similar successful results for implementation of this process on the NASA-JSC 20-K refrigeration system used for the James Webb project have been presented [10]. Additionally, this process is being used for the MSU-FRIB project [11,12] and is anticipated to be used in other projects like LCLS-II.…”

Modifications to JLab 12 GeV Refrigerator and Wide Range Mix Mode Performance Testing Results

“…These test results and other accomplished elsewhere [15] have demonstrated the robustness and effectiveness of the Floating -Pressure process. The advances gained at JLab over the past 15 years in the design of cryogenic systems have culminated in the 12 GeV cryogenic system.…”

“…There is still great opportunity for advancement as there are many areas needing further work and development. The FRIB project at MSU and the LCLS-II project at SLAC are directly benefiting from the advances accomplished previously [15] and from the 12 GeV cryogenic system. It is extremely fortunate for highly schedule driven projects like LCLS-II that the time, money and effort was expended to develop the 12 GeV cryogenic system.…”

Application of JLab 12GeV helium refrigeration system for the FRIB accelerator at MSU

“…The FRIB total load exergy requirement is expected to be of the same order or smaller than the 12 GeV cryogenic system. Based on JLab studies of 2-K process options [4] and experience with systems having a similar design philosophy [5,6], it was decided to change the process from partial cold compression, as indirectly requested in the specifications, to complete cold compression similar to the JLab and SNS operating systems.…”