• R. Grill, H. Kestler, L.S. Sigl, H. Traxler
  Plansee Metall GmbH, Reutte

Nb-RRR sheet material is one of the key components of super conducting linear particle accelerator projects (e.g. XFEL, ILC). The high quality requirements led to sophisticated quality systems in the manufacturing line. A major aspect is the development of non-destructive inspection methods for the detection of surface defects, delaminations, and inclusions. Up to now the standard inspection technologies for quality assurance of Nb-RRR sheet material are based on electromagnetic techniques, e.g. SQUID and eddy current. For these methods the detection limit is in the range of 0.1 mm. Ultrasonic microscopy (USM) in the frequency range of 1 GHz is a well established and economic technique for non-destructive surface inspection. For volume inspection of sheet material ultrasonic frequencies of 50 to 100 MHz are applied. For Nb-RRR sheets with typical thickness of 2.8 mm a detection limit of 0.1 mm is expected. First results of USM on Nb-RRR sheet material are presented.

• S.A. Belomestnykh, V.D. Shemelin
  CLASSE, Ithaca, New York

Funding: Work is supported by the National Science Foundation grant PHY 0131508
Multipactor in beam-pipe transitions of superconducting rf cavities can be explained using rf potential well theory*. In this paper we present simulation results supporting this explanation for both rf cavities and transmission lines.

*S. Belomestnykh and V. Shemelin, "Multipacting-free Transitions between Cavities and Beam-pipes," submitted to Nuclear Instruments and Methods in Physics Research A.