Design and calibration of the volatiles ion trap analyzer for the Tianwen-2 Mission

As one of the scientific payloads of the Tianwen-2 Mission, the Volatiles Ion Trap Analyzer (VITA) of the Ejection Analyzer serves to detect the volatiles surrounding the main-belt comet 311P. Based on ion trap mass spectrometry, VITA is able to measure the chemical composition and concentration of volatiles. The crucial information obtained with VITA will facilitate the research on 311P including its formation and activity mechanism. To accomplish the challenging objectives of <italic>in-situ</italic> volatile analysis for 311P, VITA has a very compact design and extremely high sensitivity as well as the ability to operate in an automatic fashion. Calibration of the flight model results in a mass range of 1‒182 amu, a mass resolution better than 0.5 amu and a sensitivity of 1.1×10⁻⁴ ct/s/(1/cm³) for ²⁰Ne at <sc>5.8×10⁻¹⁰ Pa.</sc> The detectable volatiles and dynamic range fulfill performance requirements as well.