• L. Ge, K. Ko, Z. Li, C.-K. Ng
  SLAC, Menlo Park, California
• D. Li
  LBNL, Berkeley, California
• R. B. Palmer
  BNL, Upton, Long Island, New York

Funding: This work was supported by DOE contract No. DE-AC02-76SF00515 NERSC

The muon cooling cavity for Muon Collider works under strong external magnetic fields. It has been observed that this external magnetic field can enhance the multipacting activities and dark current heating. As part of a broad effort to optimize external magnetic field map and cavity shape for minimal dark current and multipacting, we use SLAC’s 3D parallel code Track3P to analyze the multipacting and dark current issues of the design. Track3P has been successfully used to predict multipacting phenomena in cavity and coupler designs. It provides unprecedented capabilities for simulating large-scale accelerator structure systems, including realistic 3D details and low turn-around times. In this paper, we present the comprehensive multipacting and dark current simulations for Muon Collider cavities.

• Z. Li, A.E. Candel, L. Ge, K. Ko, C.-K. Ng, G.L. Schussman
  SLAC, Menlo Park, California
• S. Döbert, M. Gerbaux, A. Grudiev, W. Wuensch
  CERN, Geneva
• T. Higo, S. Matsumoto, K. Yokoyama
  KEK, Ibaraki

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515 and used resources of NERSC supported by DOE Contract No. DE-AC02-05CH11231, and of NCCS supported by DOE Contract No. DE-AC05-00OR22725.

Normal conducting accelerator structures such as the X-Band NLC structures and the CLIC structures have been found to suffer damage due to RF breakdown and/or dark current when processed to high gradients. Improved understanding of these issues is desirable for the development of structure designs and processing techniques that improve the structure high gradient performance. While vigorous experimental efforts have been put forward to explore the gradient parameter space via high power testing, comprehensive numerical multipacting and dark current simulations would complement measurements by providing an effective probe for observing interior quantities. In this paper, we present studies of multipacting, dark current, and the associated surface heating in high gradient accelerator structures using the parallel finite element simulation code Track3P. Comparisons with the high power test of the CLIC accelerator structures will be presented.