Analysis of the FEL-RF interaction in recirculating energy-recovering linacs with an FEL
Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, phase oscillations and optical cavity detuning. These effects in turn cause changes in the laser output power through a time-varying FEL gain function. All three effects change the beam-induced voltage in the cavities and can lead to unstable variations of the accelerating field and output laser power. We have developed a model of the coupled system and solved it both analytically and numerically. It includes the beam-cavity interaction, low level RF feedback, and the electron-photon interaction. The latter includes the FEL gain function in terms of cavity detuning, energy offset, and is valid both in the small signal gain and in the saturated regimes. We have demonstrated that in the limit of small perturbations, the linear theory agrees with the numerical solutions and have performed numerical simulations for the IR FEL presently being commissioned at Jefferson Lab.
- 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:
- 796092
- Report Number(s):
- JLAB-ACT-99-11; DOE/ER/40150-2111; TRN: US0201445
- Journal Information:
- Nuclear Instruments and Methods in Physics Research A, Vol. 429; Other Information: contr. FEL 98 16-21 Aug 1998, Williamsburg, Virginia; PBD: 1 Jun 1999
- Country of Publication:
- United States
- Language:
- English
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