One-point multipactor in crossed fields of rf cavities

Shemelin, Valery

doi:10.1103/physrevstab.16.102003

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…Prior studies on single surface multipactor instabilities mainly focused on superconducting accelerator designs at lower operating frequencies in L-band and S-band, and at lower gradients [21][22][23][24]. For a high gradient room temperature accelerator structure operating at 17 GHz, the operating regime is quite different.…”

Section: Introductionmentioning

confidence: 99%

Measurement of internal dark current in a 17 GHz accelerator structure with an elliptical sidewall

Shapiro

Temkin

2020

Phys. Rev. Accel. Beams

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A 17 GHz single cell, standing wave, copper accelerator structure with an axisymmetric elliptical central cell sidewall was tested for internal and downstream dark current as a function of gradient up to 93 MV=m. The elliptical sidewall was predicted to suppress the internal dark current and the lower order multipactor modes as compared with a previously tested structure having a straight sidewall. During the conditioning phase of the elliptical sidewall structure, strong internal dark current generated by an N ¼ 1 multipactor mode was observed at gradients in the 10 to 20 MV=m range. After conditioning with 2.2 × 10 5 pulses to 93 MV=m, the N ¼ 1 mode was completely suppressed and no multipactor resonances were observed. The internal dark current was reduced to a comparatively low level, much smaller than in the previously studied, straight sidewall structure, in good agreement with simulations. The energy spectrum of the electrons colliding with the sidewall was measured using an isolated side dark current monitor and a bias voltage. As the conditioning progressed, the electron energy spectrum showed an increase in the concentration of lower energy electrons, also in good agreement with simulations. Studies of internal dark current may help to understand the rf conditioning and ultimate performance of high gradient accelerator structures.

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Section: Introductionmentioning

confidence: 99%