Introduction to Helium Leak Detection Techniques for Cryogenic Systems

Abstract

Many welding processes are performed to construct cryogenic system. Leak-tight for the cryogenic system is required at low temperature environment. Helium leak detection techniques are commonly used to find leak for the cryogenic system. The helium leak detection techniques for spraying, sniffing and pressurizing techniques are introduced. High vacuum is also necessary to use helium leak detector. So, types of fluid flow, effective temperature, conductance and pumping speed are introduced for vacuum pumping. Leak test procedure is shown for pipe welding, cryomodule and low temperature test. Cryogenic seals which include copper gasket, helicoflex gasket and indium are investigated.

Preparations of QWR superconducting cavities for beam commissioning

“…In the fourth case, the warm section pressure goes up and then down, which causes increased cavity vacuum pressure. Gas shows molecular flow in this low pressure range [10]. Gases mainly collide with the cavity wall and beam tubes.…”

Low Temperature Test of HWR Cryomodule

“…It is important to get high pumping speed at the target pressure. When the conductance of vacuum system is considered, the pressure is expressed as [9] (6)…”

“…Helium leak detection consists of spraying test, sniffing test and pressurizing test [9]. The spraying test is follows: Test body is being pumped with leak detector.…”

“…The effective temperature was defined for non-uniform temperature distribution [6][7][8]. Helium leak detection techniques were introduced to construct cryogenic systems [9]. Molecular gas flow through a tube was investigated [10,11] and vacuum test of cavity was performed with liquid nitrogen [12].…”

Vacuum Test of Cavity with Liquid Nitrogen

“…Molecular gas flow through a tube was investigated [4,5] and dynamic of capillary rise was studied [6]. Ultrahigh vacuum technology was developed for a large accelerator [7] and helium leak detection techniques were introduced for cryogenic system [8]. The effective temperature for non-uniform temperature distribution was studied [9,10].…”