Author: Sauerland, D.
Paper Title Page
WEPFI007 Amplitude, Phase and Temperature Stabilization of the ELSA RF System 2717
  • D. Sauerland, W. Hillert, A. Roth, M. Schedler
    ELSA, Bonn, Germany
  • D. Teytelman
    Dimtel, San Jose, USA
  In the stretcher ring of the accelerator facility ELSA electrons are accelerated to a maximum energy of 3.2 GeV applying a fast energy ramp of up to 6 GeV/s. In order to be able to offer higher external beam currents one has to increase the current of the internal beam in ELSA accordingly. The beam current is limited due to excitation of multi bunch instabilities which are mainly caused by higher order modes of the two PETRA cavities used for particle acceleration in the stretcher ring. To control the resonance frequency of these modes, a variable bypass of the cavities' cooling system has been installed which allows a stabilization of their temperature. With this modification, it is possible to vary the temperature of the cavities between 26 °C and 65 °C and thus to shift the higher order modes by hundreds of kHz in frequency. Additionally, first operational studies with a prototype of a FPGA based LLRF system (Dimtel) have been performed which in future will be used to stabilize the amplitude and phase of the accelerating RF fields of the cavities.