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1993•Journal of Vacuum Science & Technology A Vacuum Surfaces and FilmsRequires access

Refrigerator-cooled bakeable-type cryopump at 3 K for extremely high vacuum

Yutaka Matsui, Hiroki Ohzora, Hiroyuki YAMAKAWA

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Abstract

A compact Joule–Thomson (JT) cooling system was adopted to a new type of cryopump which has three cryopanels. The refrigerator system is composed of a JT loop directly connected to the cryopanels and a Gifford–McMahon (GM) refrigerator for precooling. The cryopanels were cooled to the temperatures of 3, 20, and 80 K with circulating cold helium from the closed JT loop. We made an evaluation test of cooling and pumping capabilities and proved its potential capability for the production of extremely high vacuum. Connecting a test dome made of stainless steel to the pump, the volume has been evacuated to extremely low pressure less than 1×10−10 Pa in 11 h after vacuum bakeout.

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What this paper is about

A compact Joule–Thomson (JT) cooling system was adopted to a new type of cryopump which has three cryopanels. The refrigerator system is composed of a JT loop directly connected to the cryopanels and a Gifford–McMahon (GM) refrigerator for precooling. The cryopanels were cooled to the temperatures of 3, 20, and 80 K with circulating cold helium from the closed JT loop. We made an evaluation test of cooling and pumping capabilities and proved its potential capability for the production of extremely high vacuum. Connecting a test dome made of stainless steel to the pump, the volume has been evacuated to extremely low pressure less than 1×10−10 Pa in 11 h after vacuum bakeout.

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Available abstract

A compact Joule–Thomson (JT) cooling system was adopted to a new type of cryopump which has three cryopanels. The refrigerator system is composed of a JT loop directly connected to the cryopanels and a Gifford–McMahon (GM) refrigerator for precooling. The cryopanels were cooled to the temperatures of 3, 20, and 80 K with circulating cold helium from the closed JT loop. We made an evaluation test of cooling and pumping capabilities and proved its potential capability for the production of extremely high vacuum. Connecting a test dome made of stainless steel to the pump, the volume has been evacuated to extremely low pressure less than 1×10−10 Pa in 11 h after vacuum bakeout.

Key concepts: Cryopump, Refrigerator car, Materials science, Nuclear engineering, Ultra-high vacuum, Helium, Joule–Thomson effect, Liquid helium

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