High-resolution mass separation between helium and deuterium with conventional quadrupole mass spectrometer by using varied ionization energy

Abstract

A new effective and reliable method is developed to monitor deuterium and helium by a conventional quadrupole mass spectrometer RGA200. The measurement of atomic mass unit (AMU) = 4 is obtained at the ionization energies set of 40 eV and 70 eV instead of 25 eV and 70 eV on RGA200. By this method, not only the minimum deuterium pressure lower limit is widened to ∼10−7 Pa, but also the detection ratio of deuterium to helium is extended to 1–100%. Likewise, it is applied to helium measurement. The calculation error of deuterium mainly depends on the ratio of deuterium to the sum of deuterium and helium. Most of the deuterium calculation errors are modified in the range of 2%–16%. The errors of the calculation results are within the acceptable range of the experiments in the EAST tokamak. It has been successfully applied in EAST 2019 campaign, during helium discharge cleaning process. It provides a viable method which can achieve high-resolution mass separation between helium and deuterium by RGA200 using varied ionization energy.