Abstract: ITER will first achieve the controlled thermonuclear fusion reactor, which is comparable to the future practical fusion scale world-widely, to solve many physical and engineering problems involving in the fusion engineering. As one of the core components of the International Thermonuclear Fusion Experimental Reactor ITER, the key issue in the manufacturing process is the sealing performance of weld. The common leak detection method for sealing performance of weld is helium mass spectrometry vacuum pressure leak detection. This paper mainly introduces the optimization analysis and detection steps of the helium mass spectrometry pressure vacuum leak detection in coil leakage detection. The auxiliary mechanical pump is added to the connecting unit in the gas chamber of helium mass spectrometry pressure leak detection method, in order to avoid the excessive influence of the background signal due to the leakage of the connecting flange under vacuum conditions. This method improves the sensitivity and accuracy of the measurement data, reduced the chance of misjudgment, and expands the application range of helium mass spectrometry pressure vacuum leak detection method.

Key words: helium gas, vacuum leak rate, vacuum pressure leak, helium mass spectrometer leak detector