CERN Accelerating science

Article
Title	Pushing the Limits : RF Field Control at High Loaded Q
Author(s)	Liepe, Matthias ; Belomestnykh, Sergey ; Dobbins, John ; Hovater, Curt ; Kaplan, Roger ; Plawski, Tomasz ; Strohman, Charles R ; Stuhl, Benjamin K
Affiliation	(Cornell University, Ithaca, New York) ; (Jefferson Lab, Newport News, Virginia)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.2642
Subject category	Accelerators and Storage Rings
Abstract	The superconducting cavities in an Energy-Recovery-Linac will be operated with a high loaded Q of several 1E7, possible up to 1E8. Not only has no prior control system ever stabilized the RF field in a linac cavity with such high loaded Q, but also highest field stability in amplitude and phase is required at this high loaded Q. Because of a resulting bandwidth of the cavity of only a few Hz, this presents a significant challenge: the field in the cavity extremely sensitive to any perturbation of the cavity resonance frequency due to microphonics and Lorentz force detuning. To prove that the RF field in a high loaded Q cavity can be stabilized, and that Cornell's newly developed digital control system is able to achieve this, the system was connected to a high loaded Q cavity at the JLab IR-FEL. Excellent cw field stability - about 2&#183;10<sup><font size="-1">-4