Experimental investigation of an optimum configuration for a high-voltage photoemission gun for operation at ≥500kV experimental investigation of an optimum ... Nobuyuki Nishimori et al.

Nobuyuki Nishimori, Ryoji Nagai, Shunya Matsuba, Ryoichi Hajima, Masahiro Yamamoto, Yosuke Honda, Tsukasa Miyajima, Hokuto Iijima, Masao Kuriki, Makoto Kuwahara

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    We demonstrated the generation of a 500-keV electron beam from a high dc voltage photoemission gun for an energy recovery linac light source [N. Nishimori et al., Appl. Phys. Lett. 102, 234103 (2013)]. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in the dc gun. One is field emission generated from a central stem electrode. We employed a segmented insulator to protect the ceramic insulator surface from the field emission. The other is microdischarge at an anode electrode or a vacuum chamber, which is triggered by microparticle transfer or field emission from a cathode electrode. An experimental investigation revealed that a larger acceleration gap, optimized mainly to reduce the surface electric field of the anode electrode, suppresses the microdischarge events that accompany gas desorption. It was also found that nonevaporable getter pumps placed around the acceleration gap greatly help to suppress those microdischarge events. The applied voltage as a function of the total gas desorption is shown to be a good measure for finding the optimum dc gun configuration.

    Original languageEnglish
    Article number053401
    JournalPhysical Review Special Topics - Accelerators and Beams
    Volume17
    Issue number5
    DOIs
    Publication statusPublished - 2014 May 19

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics
    • Physics and Astronomy (miscellaneous)
    • Surfaces and Interfaces

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