• R. Eichhorn, A. Araz, U. Bonnes, F. Hug, M. Konrad, P. Nonn
  TU Darmstadt, Darmstadt
• G. Schreiber, W. Vinzenz
  GSI, Darmstadt
• R. Stassen
  FZJ, Jülich

During the redesign of the low level RF system for the S-DALINAC, a baseband approach was chosen. The RF signals from/ to the cavity are converted into the baseband via I/Q Modulators/ Demodulators. The advantage of this design was realized lateron, as adaption of other frequencies becomes rather easy. The system, originally designed for 3 GHz superconducting cavity in cw operation is currently modified to control a 324 MHz room temperature CH cavity in pulsed operation. We will report on the rf control system principle, the required modifications and first results.

• F. Hug, A. Araz, R. Eichhorn, N. Pietralla
  TU Darmstadt, Darmstadt

The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt/ Germany is a recirculating Linac with two recirculations. Currently acceleration in the Linac is done on crest of the acceleration field using the maximum of the field in every turn. The recirculation of the beam is done isochronous without any longitudinal dispersion. In this recirculation scheme the energy spread of the resulting beam is determined by the stability of the used RF system. In this work we will present a new non-isochronous recirculation scheme, which uses longitudinal dispersion in the recirculations and an acceleration on edge of the accelerating field as it is done in microtrons. We will present beam dynamic calculations which show the usability of this system even in a Linac with only two recirculations and first measurements of longitudinal dispersion using RF monitors.