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.