The S-DALINAC facility — Operational experience from the accelerator and the experimental installations☆

Abstract The superconducting cw-electron-accelerator S-DALINAC at Darmstadt became operational in January of 1991. It has been used extensively since then to deliver beam to the various experimental installations for nuclear and radiation physics associated with the accelerator. In order to fulfill the requirements of the experiments beam from the nA range up to 40 μA and at energies between 2.5 and 84 MeV could be provided in true cw operation. Energies above 100 MeV could be achieved in accelerator test runs. A special time structure of the electron beam was used for Free Electron Laser (FEL) physics. Spontaneous emission has been observed routinely. The principle of operation of the accelerator is sketched briefly while main emphasis is on specific problems of a superconducting recirculating electron accelerator and their solutions. The operating performance of the superconducting accelerator cavities like the gradients achieved and the amplitude and phase stability of the accelerating field in the presence of microphonic perturbations are discussed in detail including the influence of radiation pressure. For the two recirculating beamlines simple devices were developed to provide variable path lengths for the electron beam in order to optimize the reinjection phase for the successive acceleration in the linac.