Comparative simulation studies of multipacting in higher-order-mode couplers of superconducting rf cavities

Li, Y. M.; Liu, Kexin; Geng, Rongli

doi:10.1103/physrevstab.17.022002

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…Advanced Computational Electromagnetics 3D Parallel suite (ACE3P) is a 3D parallel finite element code for design and development of accelerating units which includes packages for various aspects of RF related problems such as electromagnetic (Omega3P), thermal and mechanical effects (TEM3P) [35]. Track3P is designated for multipacting and dark current simulations [36,37]. All of the calculations performed with ACE3P utilize massively parallel computers which allows for increased memory (problem size) and speed of the simulation [38].…”

Section: B Ace3pmentioning

confidence: 99%

Mitigation of multipacting in 113 MHz superconducting rf photoinjector

Petrushina

Litvinenko

Pinayev

et al. 2018

Phys. Rev. Accel. Beams

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Superconducting RF (SRF) photo-injectors are one of the most promising devices for generating continuous wave (CW) electron beams with record high brightness. Ultra-high vacuum of SRF guns provides for long lifetime of the high quantum efficiency (QE) photocathodes, while SRF technology provides for high accelerating gradients exceeding 10 MV/m. It is especially true for low frequency SRF guns where electrons are generated at photocathodes at the crest of accelerating voltage. Two main physics challenges of SRF guns are their compatibility with high QE photocathodes and multipacting. The first is related to a possibility of deposition of photocathode materials (such as Cs) on the walls of the SRF cavity, which can result in increased dark current via reduction of the bulk Nb work function and in enhancing of a secondary electron emission yield (SEY). SEY plays critical role in multipacting (e.g. an exponential growth of the multipactor discharge), which could both spoil the gun vacuum and speed up the deposition of the cathode material on the walls of the SRF cavity. In short, the multipactor behavior in superconducting accelerating units must be well understood for successful operation of an SRF photo-injector. In this paper we present our studies of 1.2 MV 113 MHz quarter-wave SRF photo-injector serving as a source of electron beam for the Coherent electron Cooling experiment (CeC) at BNL. During three years of operating our SRF gun we encountered a number of multipacting zones. We also observed that presence of CsK2Sb photocathode in the gun could create additional multipacting barriers. We had conducted a comprehensive numerical and experimental study of the multipactor discharge in our SRF gun. We had developed a process of crossing the multipacting barriers from zero to the operational voltage without affecting the lifetime of our photocathode and enhancing the strength of multipacting barriers. We found a good agreement between the results of simulations and our experimental data.

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Section: B Ace3pmentioning

confidence: 99%