Research and implementation of the adaptive control method for emission current of electron ionization ion source

The electron ionization (EI) ion source has been widely used in the development of the mass spectrometer, and the stability of emission current of EI ion source directly affects important performance such as the sensitivity of the mass spectrometer. Realizing the stable control of emission current is the key to ensuring the accurate measurement of the mass spectrometer. However, the stability of the emission current is easily affected by factors such as filament resistance and pressure of the mass spectrometer chamber. For adaptive control of emission current, two adaptive control methods based on negative feedback operational amplifier and fuzzy logic system (FLS) are proposed and applied to the self-developed quadrupole mass spectrometer (QMS). Further, three emission current control experiments when the QMS is powered on, works stably, and the pressure changes are designed to verify the effectiveness of the adaptive control method proposed. Experimental results show that the two adaptive control methods in this paper are compared to the open-loop control method of stabilizing the output of the heating power supply have faster control response rate, longer stable control time, and better adaptive control ability.