IPAC2012 - List of Authors (Ackermann, W.)

Paper	Title	Page
MOPPC058	Eigenmode Computation for Ferrite-loaded Cavity Resonators	265
	K. Klopfer, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt is operating the heavy-ion synchrotron SIS18 for fundamental research. Within the ring two ferrite-loaded cavity resonators are installed. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing velocity. Within the resonator structures dedicated biased ferrite rings are installed. In the whole setup a properly chosen bias current is used to modify the differential permeability of the ferrite material which consequently enables to adjust the eigenfrequency of the resonator system. The goal of the current study is to numerically determine the lowest eigensolutions of accelerating ferrite-loaded cavities based on the Finite Integration Technique. Since the underlying eigenmodes depend on the differential permeability, the static magnetic field generated by the bias current has to be computed in a first step. The eigenmodes can then be determined with the help of a dedicated Jacobi-Davidson eigensolver. Particular emphasis is put on the implementation to enable high performance computations based on distributed memory machines.

MOPPC059	Various Approaches to Electromagnetic Field Simulations for RF Cavities	268
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H09RD5. The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.

Paper

Title

Page

Eigenmode Computation for Ferrite-loaded Cavity Resonators

265

K. Klopfer, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt is operating the heavy-ion synchrotron SIS18 for fundamental research. Within the ring two ferrite-loaded cavity resonators are installed. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing velocity. Within the resonator structures dedicated biased ferrite rings are installed. In the whole setup a properly chosen bias current is used to modify the differential permeability of the ferrite material which consequently enables to adjust the eigenfrequency of the resonator system. The goal of the current study is to numerically determine the lowest eigensolutions of accelerating ferrite-loaded cavities based on the Finite Integration Technique. Since the underlying eigenmodes depend on the differential permeability, the static magnetic field generated by the bias current has to be computed in a first step. The eigenmodes can then be determined with the help of a dedicated Jacobi-Davidson eigensolver. Particular emphasis is put on the implementation to enable high performance computations based on distributed memory machines.

MOPPC059

Various Approaches to Electromagnetic Field Simulations for RF Cavities

268

C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H09RD5.
The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.