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SRF2003 Show Abstract


Title Multipacting in the crab cavity
Type Poster cavity design / fabrication / treatment
Abstract For the Research and Development of the crab cavity for KEKB, we have fabricated two prototype cavities. The crab cavity is a beam-deflecting cavity excited with the 508 MHz, TM110-like mode. To extract unwanted parasitic modes, the cavity has a squashed cell shape and a coaxial coupler along the beam pipe. The prototype cavities were tested in a vertical cryostat with/without the coaxial coupler. We observed multipacting at the first RF excitation. To study this event in detail, we measured temperatures of the coupler and cavity during RF tests. Temperature measurement showed that multipacting occurred at the tip of coaxial coupler at low RF fields, and then along the coaxial line. These events were processed in an hour. We observed another type of temperature rise around the iris. Temperature rise began at low fields, continued to rise up to a surface peak field of 18 MV/m, and then, disappeared above 20 MV/m. The excitation mode of the crab cavity has a maximum magnetic field and zero electric field on the same iris position. Temperature rise near this region suggests the multipacting events. A model simulation shows a stable two-point multipacting can exist at this position. We will present temperature measurement results and discuss multipacting near the iris.

List of authors...

Principle author first.

Last (Family) Name First Name (Initials only) Affiliation or Organization (abbreviations if possible)
Morita Y KEK
Hara K KEK
Hosoyama K KEK
Kabe A KEK
Kojima Y KEK
Nakai H KEK
Nakanishi K GUAS
Rahman M GUAS



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