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Indexed by:期刊论文

Date of Publication:2019-08-01

Journal:VACUUM

Included Journals:SCIE、EI

Volume:166

Page Number:114-122

ISSN No.:0042-207X

Key Words:DC discharge; Oxide cathode; Secondary electron emission; Gas pressure; Oxide layer structure

Abstract:In present study, DC discharge with high secondary electron emission (SEE) oxide cathodes (NiO/Ni and MgO/NiO/Ni cathode) is characterized with a significant increase in discharge current compared to the one with normal Ni cathode at different gas pressures from 400 to 700 torr. The increase multiple value of the discharge current decreases as the gas pressure increases, which can be related to a relative weakened ion-induced SEE process at high gas pressure. The NiO intermediate layer plays an important role in a sandwich MgO/NiO/Ni cathode for DC discharge, which may be due to the fact that its high resistance favors field-enhanced SEE process. Regardless of the gas pressure, the structural characteristics (thickness and roughness) of oxide layer have an effect on the enhancement of the discharge current, which can be attributed to field-enhanced SEE process. Additionally, the increase in the number of needle electrodes is conducive to the increase of discharge current with oxide cathode, which is related to an increase in the discharge area on the cathode surface according to the discharge images.