Experimental demonstration of dark current mitigation by an over-inserted plug in a normal conducting very-high-frequency gun
The room temperature continuous wave (cw) very-high-frequency (VHF) gun is one of the candidates for the electron gun of the high-repetition-rate free-electron lasers (FELs). The VHF gun operates with a cathode gradient of ∼20 MV/m and an accelerating voltage of ∼750 kV. The gun dark current emiss...
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| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2025-04-01
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| Series: | Physical Review Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevAccelBeams.28.043401 |
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| Summary: | The room temperature continuous wave (cw) very-high-frequency (VHF) gun is one of the candidates for the electron gun of the high-repetition-rate free-electron lasers (FELs). The VHF gun operates with a cathode gradient of ∼20 MV/m and an accelerating voltage of ∼750 kV. The gun dark current emission leads to beam loss along the FEL machine, therefore, it is a critical parameter for the performance of the cw gun. In this paper, we present a systematic study of the dark current reduction of the VHF gun, including cathode region optimizations, dark current tracking simulations, and measurements. Over-inserted cathode plugs were tested in two VHF guns of different acceleration gap sizes, and both demonstrated significant dark current reduction ratios of more than two orders of magnitude. |
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| ISSN: | 2469-9888 |