Presentation Information
[2E08]Numerical investigation of ionization characteristics in a quadrupole structure for sputter-ion pumps
*Akio Ogura1, Yamato Suzuki1, Souichi Katagiri1 (1. University of Tsukuba (Japan))
Stable operation of cold field emission guns requires extreme-high-vacuum conditions, where non-evaporable getter and sputter-ion pumps (SIPs) are used. Since SIP performance depends on gas ionization by confined electrons, we investigated whether a modified geometry can enhance ionization efficiency. A conventional cylindrical Penning cell and a quadrupole structure with identical cell volumes were compared using the charged-particle tracking code Simbuca. An ionization-scattering model was incorporated, and electron trajectories in nitrogen were simulated at 5 kV and 0.1 T. The quadrupole structure reduced the average interval between consecutive ionization events by about one order of magnitude. Ionization also occurred at higher electron kinetic energies, associated with the stronger radial potential gradient produced by the quadrupole electrodes. These results suggest that quadrupole electrode geometries may enhance ionization efficiency and SIP pumping performance.
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