Wuppertal 2015 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 6: SC Resonators

AKBP 6.3: Talk

Tuesday, March 10, 2015, 14:15–14:30, BZ.08.06 (HS 1)

A Method for Quality Factor Measurements of the S-DALINAC Superconducting Cavities* — •Ruben Grewe, Christoph Burandt, Florian Hug, Thorsten Kürzeder, and Norbert Pietralla — Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany

The S-DALINAC is a recirculating superconducting linear electron accelerator designed for beam energies of up to 130 MeV. For acceleration it uses 20-cell niobium cavities that are operated at 2 K. While operational experience showed that the design electric field gradient of 5 MV/m can be reached and exceeded, it was found that the quality factor is more than two times worse than the design value of 3·10⁹. This results in more power being dissipated into the liquid helium bath which limits the electric field gradient for cw operation. For the assessment of q-factor improvements and for monitoring of q-factor variance over time, an in-situ method is needed. A phase-locked loop is used to make in-situ decay time measurements of the cavities. The presented method makes use of the extended adjusting capabilities of the S-DALINAC rf-input couplers to reach sufficiently low uncertainties of Δ Q₀/Q₀ < 10 %.

* Work supported by DFG through SFB 634