IPAC2017 - List of Authors (De Gersem, H.)

Paper	Title	Page
MOPAB037	Analytical and Numerical Performance Analysis of a Cryogenic Current Comparator	160
	N. Marsic, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany F. Kurian, M. Schwickert, T. Sieber GSI, Darmstadt, Germany
	Funding: This research is funded by the German Bundesministerium für Bildung und Forschung as the project BMBF-05P15RDRBB Ultra-Sensitive Strahlstrommessung für zukünftige Beschleunigeranlagen. Nowadays, cryogenic current comparators (CCCs) are among the most accurate devices for measuring extremely small electric currents. Probably the most interesting property of this equipment, is the excellent position independence of the current passing through it. This feature motivated the use of CCCs for beam instrumentation in particle accelerators. A typical CCC consists of a ferrite core, a pick-up coil, a superconducting quantum interference device, appropriate electronics and superconducting shielding consisting of a meander structure. This configuration offers a strong attenuation for all the magnetic field components, except for the azimuthal one. Thus, high precision measurements of extremely low beam currents are made possible. The damping performance of this device is analysed in this work. A 3D finite element (FE) analysis has been carried out and the computed results were compared to an analytical model. Furthermore, in order to reduce the computation time, a 2.5D FE model is also proposed and discussed. K. Grohmann et al., Field attenuation as the underlying principle of cryo-current comparators 2. Ring cavity elements, Cryogenics, vol. 16, no. 10, pp. 601-605, 1976.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB037
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MOPVA055	Upgrade of the Capture Section of the S-DALINAC Injector	993
SUSPSIK100	use link to see paper's listing under its alternate paper code
	D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This work is supported by the DFG through GRK 2128. In order to reduce the energy spread of the recirculated beam, the injector of the S-DALINAC needs to be optimized, because the non-isochronous recirculation cannot correct for errors originating from the injector linac. For the S-DALINAC, spatial restrictions suggest the use of SRF technology for the capture section. In this work, we consider various SRF cavities with an operating frequency of 3 GHz for a possible upgrade of the capture section of the S-DALINAC. The first results of the RF and beam dynamics simulations for the proposed options are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA055
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WEPIK064	Eigenvalue Calculations Based on the Finite Element Method With Physically Motivated Field Smoothing Using the Kirchhoff Integral	3074
	W. Ackermann, H. De Gersem, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	In current linear particle accelerators, the actual acceleration of the charged particles is realized with the help of the electric field strength within driven radio frequency resonators. The characterization and optimization of the applied resonating structures can be reliably performed based on numerical simulation techniques. Efficient numerical methods have been introduced in the last decades to determine the electromagnetic fields while special care has been put in the correct description of the geometry and the material distribution of the structures. Although the resonators are operated in a driven setup, one of the advantageous numerical strategies here is given by an eigendecomposition of the fields which is realized by the application of accurate eigenmode calculations together with suitable postprocessing steps. In particular, the extraction of representative field maps used for particle tracking for example requires an accurate numerical modeling of the field at any position inside the structure. In order to avoid numerically motivated discontinuities of the fields a proper smoothing algorithm based on the vector equivalents of the Kirchhoff integral is proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK064
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THOBA2	Coherent Synchrotron Radiation and Wake Fields With Discontinuous Galerkin Time Domain Methods	3649
	D. A. Bizzozero, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This work is supported by DESY, Hamburg. Coherent synchrotron radiation (CSR) is an essential issue in modern accelerators. We propose a new method to examine CSR in the time domain using an unstructured Discontinuous Galerkin (DG) method. The method uses a 2D spatial discretization in the longitudinal and transverse coordinates (Z,X) with a Fourier series decomposition in the transverse coordinate Y and computes the fields modally. Additionally, by alignment of mesh element interfaces along a source reference orbit, DG methods can naturally handle discontinuous or thin sources in the transverse X direction. We present an overview of the method, illustrate it by calculating wake potentials in a model problem, and in a bunch compressor.
	Slides THOBA2 [2.526 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOBA2
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Paper

Title

Page

Analytical and Numerical Performance Analysis of a Cryogenic Current Comparator

160

N. Marsic, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany
F. Kurian, M. Schwickert, T. Sieber
GSI, Darmstadt, Germany

Funding: This research is funded by the German Bundesministerium für Bildung und Forschung as the project BMBF-05P15RDRBB Ultra-Sensitive Strahlstrommessung für zukünftige Beschleunigeranlagen.
Nowadays, cryogenic current comparators (CCCs) are among the most accurate devices for measuring extremely small electric currents. Probably the most interesting property of this equipment, is the excellent position independence of the current passing through it. This feature motivated the use of CCCs for beam instrumentation in particle accelerators. A typical CCC consists of a ferrite core, a pick-up coil, a superconducting quantum interference device, appropriate electronics and superconducting shielding consisting of a meander structure. This configuration offers a strong attenuation for all the magnetic field components, except for the azimuthal one. Thus, high precision measurements of extremely low beam currents are made possible. The damping performance of this device is analysed in this work. A 3D finite element (FE) analysis has been carried out and the computed results were compared to an analytical model*. Furthermore, in order to reduce the computation time, a 2.5D FE model is also proposed and discussed.
* K. Grohmann et al., Field attenuation as the underlying principle of
cryo-current comparators 2. Ring cavity elements, Cryogenics, vol. 16, no. 10, pp. 601-605, 1976.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPVA055

Upgrade of the Capture Section of the S-DALINAC Injector

993

SUSPSIK100

use link to see paper's listing under its alternate paper code

D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by the DFG through GRK 2128.
In order to reduce the energy spread of the recirculated beam, the injector of the S-DALINAC needs to be optimized, because the non-isochronous recirculation cannot correct for errors originating from the injector linac. For the S-DALINAC, spatial restrictions suggest the use of SRF technology for the capture section. In this work, we consider various SRF cavities with an operating frequency of 3 GHz for a possible upgrade of the capture section of the S-DALINAC. The first results of the RF and beam dynamics simulations for the proposed options are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK064

Eigenvalue Calculations Based on the Finite Element Method With Physically Motivated Field Smoothing Using the Kirchhoff Integral

3074

W. Ackermann, H. De Gersem, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

In current linear particle accelerators, the actual acceleration of the charged particles is realized with the help of the electric field strength within driven radio frequency resonators. The characterization and optimization of the applied resonating structures can be reliably performed based on numerical simulation techniques. Efficient numerical methods have been introduced in the last decades to determine the electromagnetic fields while special care has been put in the correct description of the geometry and the material distribution of the structures. Although the resonators are operated in a driven setup, one of the advantageous numerical strategies here is given by an eigendecomposition of the fields which is realized by the application of accurate eigenmode calculations together with suitable postprocessing steps. In particular, the extraction of representative field maps used for particle tracking for example requires an accurate numerical modeling of the field at any position inside the structure. In order to avoid numerically motivated discontinuities of the fields a proper smoothing algorithm based on the vector equivalents of the Kirchhoff integral is proposed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK064

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THOBA2

Coherent Synchrotron Radiation and Wake Fields With Discontinuous Galerkin Time Domain Methods

3649

D. A. Bizzozero, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by DESY, Hamburg.
Coherent synchrotron radiation (CSR) is an essential issue in modern accelerators. We propose a new method to examine CSR in the time domain using an unstructured Discontinuous Galerkin (DG) method. The method uses a 2D spatial discretization in the longitudinal and transverse coordinates (Z,X) with a Fourier series decomposition in the transverse coordinate Y and computes the fields modally. Additionally, by alignment of mesh element interfaces along a source reference orbit, DG methods can naturally handle discontinuous or thin sources in the transverse X direction. We present an overview of the method, illustrate it by calculating wake potentials in a model problem, and in a bunch compressor.

Slides THOBA2 [2.526 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOBA2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)