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Accelerator Seminar


"Investigations on Critical Higher Order Modes in CEBAF Upgrade Cavities"

Frank Marhauser,
SRF Institute, Jefferson Lab




We recently have reported on the necessity to thoroughly characterize the Higher Order Mode (HOM) damping performance of cavities including a review of cavity design, prototyping and operational experience, problems encountered and measures taken towards a reliable CW cavity cryomodule concept for the CEBAF 12 GeV upgrade. Whereas for trapped cavity modes - resonating below the cavity beam tube cutoff - experimental conditions could be established resembling the final 12 GeV cryomodule environment, BBU-critical high frequency modes have been identified above the cutoff frequency with propagating fields interacting differently and sensitively on variable boundary conditions not representative for the final design.


Therefore a thorough experimental Higher Order Mode (HOM) survey has been carried out recently for a string of eight seven-cell SRF cavities at 2 Kelvin to investigate the damping efficiency of cavities fully equipped and installed in a realistic cryomodule configuration. Results and their consequences for the 12 GeV upgrade cryomodules are presented.


Thursday, August 27, 2009

3:30 p.m. - 4:30 p.m.
CEBAF Center, Room L102/104

Talk Slides: (Slides)

Dr. Alex Bogacz or Anne-Marie Valente.