IPAC2013 - List of Authors (Weiland, T.)

Paper	Title	Page
MOPWO001	Moment Method Beam Dynamics Code Development: Extended for Radio Frequency Quadrupole Simulations	879
	T. Roggen, H. De Gersem, B. Masschaele KU Leuven, Kortrijk, Belgium W. Ackermann, S. Franke, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This research is funded by grant “KUL 3E100118” “Electromagnetic Field Simulation for Future Particle Accelerators”, project FP7-Euratom No. 269565 and the Belgian Nuclear Research Centre (SCK•CEN). A Radio Frequency Quadrupole (RFQ) enables acceleration of a continuous low-velocity hadron beam, combining velocity independent electric focusing and adiabatic bunching, resulting in high-current compact bunches with nearly 100% capture and transmission efficiency. With virtually no post-construction tuning capabilities, an RFQ design phase requires all transient parameters (machining tolerances, thermo-mechanical deformation factors). This allows the determination of acceptable tolerances on input and output beam characteristics, of major importance in beam availability and beam trip prevention, and makes fast beam dynamics simulation codes incorporating RFQs indispensable. This article presents the implementation and validation of an RFQ beam line element into V-Code, a moment method beam dynamics simulation code. V-Code time integrates the Vlasov equation for an initial particle distribution represented by a discrete set of characteristic moments, accounting for all exerting internal and external forces. V-Code delivers highly accurate beam dynamics results with precision and efficiency advantages in terms of average or rms beam dimensions, projected emittances or total energy.

MOPWO006	Eigenmode Computation for the GSI SIS18 Ferrite Cavity	894
	K. Klopfer, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Supported by GSI At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007	Numerical Calculation of Electromagnetic Fields in Acceleration Cavities Under Precise Consideration of Coupler Structures	897
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H12RD5 The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

TUPWA008	Computation of Wakefields for an In-vacuum Undulator at PETRA III	1736
	E. Gjonaj, L. Lünzer, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany R. Wanzenberg DESY, Hamburg, Germany
	Funding: Work supported by DESY, Hamburg, Germany At DESY the installation of an in-vacuum undulator at the synchrotron radiation facility PETRA III is under consideration. The moveable magnet array of the undulator is installed inside the vacuum chamber to achieve shorter wavelength synchrotron radiation. A thin metal foil covers the magnet structure to mitigate resistive wall wakefields. Moveable tapered transitions connect the magnet structure and the adjacent vacuum duct to reduce the geometric wakefields. Nevertheless these moveable tapered transitions contribute significantly to the impedance budget of PETRA III. The computer codes MAFIA, CST-Studio and PBCI have been used to calculate the longitudinal and transverse wakefields. The results for the loss and kick parameters are presented and compared to the corresponding parameters for a standard undulator section.

Paper

Title

Page

Moment Method Beam Dynamics Code Development: Extended for Radio Frequency Quadrupole Simulations

879

T. Roggen, H. De Gersem, B. Masschaele
KU Leuven, Kortrijk, Belgium
W. Ackermann, S. Franke, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This research is funded by grant “KUL 3E100118” “Electromagnetic Field Simulation for Future Particle Accelerators”, project FP7-Euratom No. 269565 and the Belgian Nuclear Research Centre (SCK•CEN).
A Radio Frequency Quadrupole (RFQ) enables acceleration of a continuous low-velocity hadron beam, combining velocity independent electric focusing and adiabatic bunching, resulting in high-current compact bunches with nearly 100% capture and transmission efficiency. With virtually no post-construction tuning capabilities, an RFQ design phase requires all transient parameters (machining tolerances, thermo-mechanical deformation factors). This allows the determination of acceptable tolerances on input and output beam characteristics, of major importance in beam availability and beam trip prevention, and makes fast beam dynamics simulation codes incorporating RFQs indispensable. This article presents the implementation and validation of an RFQ beam line element into V-Code, a moment method beam dynamics simulation code. V-Code time integrates the Vlasov equation for an initial particle distribution represented by a discrete set of characteristic moments, accounting for all exerting internal and external forces. V-Code delivers highly accurate beam dynamics results with precision and efficiency advantages in terms of average or rms beam dimensions, projected emittances or total energy.

MOPWO006

Eigenmode Computation for the GSI SIS18 Ferrite Cavity

894

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

Funding: Supported by GSI
At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt the heavy-ion synchrotron SIS18 is operated to further accelerate stable nuclei of elements with different atomic numbers. Two ferrite-loaded cavity resonators are installed within this ring. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing speed. To this end, dedicated biased ferrite-ring cores are installed inside the cavities for a broad frequency tuning. By properly choosing a suited bias current, the differential permeability of the ferrite material is modified, which finally enables to adjust the eigenfrequency of the resonator system. Consequently, the actual resonance frequency strongly depends on the magnetic properties of the ferrites. The goal of the current study is to numerically determine the lowest eigensolutions of the GSI SIS18 ferrite-loaded cavity. For this purpose, a new solver based on the Finite Integration Technique has been developed.

MOPWO007

Numerical Calculation of Electromagnetic Fields in Acceleration Cavities Under Precise Consideration of Coupler Structures

897

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

Funding: Work supported by BMBF under contract 05H12RD5
The acceleration with superconducting radio frequency cavities requires dedicated couplers to transfer energy from the radio frequency source to the beam. Simultaneously, higher order mode couplers are installed to effectively suppress parasitic modes. Therefore, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver to calculate the eigenmodes in the lossy acceleration structure is available. This eigenmode solver is based on complex-valued finite element analysis and utilizes basis functions up to the second order on curved tetrahedral elements to enable the high precision elliptical cavity simulations. The eigenmode solver has been applied to the TESLA 1.3 GHz accelerating cavity to determine the resonance frequency, the quality factor and the corresponding field distribution for all 192 eigenmodes up to the 5th dipole passband (3.12 GHz).

TUPWA008

Computation of Wakefields for an In-vacuum Undulator at PETRA III

1736

E. Gjonaj, L. Lünzer, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
R. Wanzenberg
DESY, Hamburg, Germany

Funding: Work supported by DESY, Hamburg, Germany
At DESY the installation of an in-vacuum undulator at the synchrotron radiation facility PETRA III is under consideration. The moveable magnet array of the undulator is installed inside the vacuum chamber to achieve shorter wavelength synchrotron radiation. A thin metal foil covers the magnet structure to mitigate resistive wall wakefields. Moveable tapered transitions connect the magnet structure and the adjacent vacuum duct to reduce the geometric wakefields. Nevertheless these moveable tapered transitions contribute significantly to the impedance budget of PETRA III. The computer codes MAFIA, CST-Studio and PBCI have been used to calculate the longitudinal and transverse wakefields. The results for the loss and kick parameters are presented and compared to the corresponding parameters for a standard undulator section.