2011 Particle Accelerator Conference - List of Authors (Ge, L.)

Paper	Title	Page
TUP111	Multipactoring Observation, Simulation and Suppression on a Superconducting TE011 Cavity	1050
	H. Wang, G. Ciovati JLAB, Newport News, Virginia, USA L. Ge, Z. Li SLAC, Menlo Park, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and COMPASS of SciDAC No. A superconducting cavity of the same shape as used for the development of superconducting photo injectors has been built for the studies of high magnetic field induced Q slope due to the local heating. The multipactoring problem has been observed on the TE011 mode, 3.3GHz with magnetic field barriers. To understand and overcome this problem, 3D multipactoring simulations by Omega3P and Track3P have been done and found these to be one-point multipactors pulled out from the flat bottom surface by finite normal component of electric field. Asymmetric coupling ports on the side of the beam tube could have caused the distortion of the TE011 mode. The thermometry measurement later confirmed the predicted impact locations. A structure modification has been adopted based on the simulation prediction. More experimental results with the new geometry will allow further comparison with the 3D multipactoring simulations.

THP068	Multipacting Analysis for the Half-Wave Spoke Resonator Crab Cavity for LHC	2258
	Z. Li, L. Ge SLAC, Menlo Park, California, USA
	Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515 and was partially supported by the DOE through the US LHC Accelerator Research Program (LARP). A compact 400-MHz half-wave spoke resonator (HWSR) superconducting crab cavity is being developed for the LHC upgrade. The cavity shape and the LOM/HOM couplers for such a design have been optimized to meet the space and beam dynamics requirements, and satisfactory RF parameters have been obtained. As it is known that multipacting is an issue of concern in a superconducting cavity which may limit the achievable gradient. Thus it is important in the cavity RF design to eliminate the potential MP conditions to save time and cost of cavity development. In this paper, we present the multipacting analysis for the HWSR crab cavity using the Track3P code developed at SLAC, and to discuss means to mitigate potential multipacting barriers.

Paper

Title

Page

Multipactoring Observation, Simulation and Suppression on a Superconducting TE011 Cavity

1050

H. Wang, G. Ciovati
JLAB, Newport News, Virginia, USA
L. Ge, Z. Li
SLAC, Menlo Park, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and COMPASS of SciDAC No.
A superconducting cavity of the same shape as used for the development of superconducting photo injectors has been built for the studies of high magnetic field induced Q slope due to the local heating. The multipactoring problem has been observed on the TE011 mode, 3.3GHz with magnetic field barriers. To understand and overcome this problem, 3D multipactoring simulations by Omega3P and Track3P have been done and found these to be one-point multipactors pulled out from the flat bottom surface by finite normal component of electric field. Asymmetric coupling ports on the side of the beam tube could have caused the distortion of the TE011 mode. The thermometry measurement later confirmed the predicted impact locations. A structure modification has been adopted based on the simulation prediction. More experimental results with the new geometry will allow further comparison with the 3D multipactoring simulations.

THP068

Multipacting Analysis for the Half-Wave Spoke Resonator Crab Cavity for LHC

2258

Z. Li, L. Ge
SLAC, Menlo Park, California, USA

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515 and was partially supported by the DOE through the US LHC Accelerator Research Program (LARP).
A compact 400-MHz half-wave spoke resonator (HWSR) superconducting crab cavity is being developed for the LHC upgrade. The cavity shape and the LOM/HOM couplers for such a design have been optimized to meet the space and beam dynamics requirements, and satisfactory RF parameters have been obtained. As it is known that multipacting is an issue of concern in a superconducting cavity which may limit the achievable gradient. Thus it is important in the cavity RF design to eliminate the potential MP conditions to save time and cost of cavity development. In this paper, we present the multipacting analysis for the HWSR crab cavity using the Track3P code developed at SLAC, and to discuss means to mitigate potential multipacting barriers.