Higher-Order-Modes and beam breakup simulations in the Jefferson Lab FEL recirculating linac
Measurements were performed of the frequencies and external Q's of the first two Higher-Order Mode (HOM) dipole passbands in the eight superconducting cavities of the cryomodule used in the recirculating linac of the driver accelerator of Jefferson Lab's IR FEL. Anomalous high-Q resonances were found, which could lead to beam instabilities at currents close to the operating current of the machine. These results led to more detailed simulations of its beam breakup (BBU) behavior. The analysis indicates that a few modes are responsible for the relatively low value of 27 mA of the threshold current. A simple modification of the superconducting cavities could lead to an increase of the threshold current by an order of magnitude.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 754517
- Report Number(s):
- DOE/ER/40150-1355; JLAB-ACC-98-09; TRN: US0002213
- Resource Relation:
- Conference: 1998 Linear Accelerator Conference, Chicago, IL (US), 08/24/1998--08/24/1998; Other Information: PBD: 1 Aug 1998
- Country of Publication:
- United States
- Language:
- English
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