Simulation of an ionization gauge with carbon nanotube cathode using SIMION 3D

The carbon nanotube (CNT) cathode ionization gauge is simulated using SIMION 8.0 software. The results show that all movement electrons emitted from the heated filament electron source are restrained inside anode ionization guage. However, to the CNT cathode ionization gauge, a few escaped electrons cannot be collected by anode. These escaped electrons influence the effective electron path length (L_e), along with the sensitivity. Moreover, as the ratio between anode voltage and gate voltage increases, the L_e first increases, and then almost keeps constant. However, the sensitivity declines with the rising anode voltage, which is primarily attributed to the decrease of ionization proficiency. In order to improve the performance of CNT cathode ionization gauge, a suppressor electrode is set, which will help to decrease the electrons energy emitted from CNT cathode, and improve the ionization probability. The simulation results will be contributed to penetrate the operation mechanism of CNT cathode ionization gauge, and provide important academic guidance to develop the new-style extreme high vacuum ionization gauge with CNT cathode.