ICAP2012 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOADI1	High Precision Cavity Simulations	cavity, impedance, simulation, resonance	43
	W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DESY, Hamburg The design and optimization of particle accelerator components are fundamentally based on beam dynamics simulations. The knowledge of the interaction of moving charged particles with the surrounding materials and fields enables to optimize individual devices and consequently to take the best advantage of the entire machine. Among the essential accelerator components are radio-frequency cavities which are utilized for acceleration as well as for beam diagnostics. In these applications, precise beam dynamics simulations urgently require high-precision data of the electromagnetic fields. Numerical simulations based on Maxwell’s equations have to represent the resulting fields on an acceptable level of quality even with limited amount of degrees of freedom. On the other hand, the particle beam itself gives rise to the excitation of undesired modes which have to be extracted from the cavities. In the current work, some of the challenges faced in high precision cavity simulations are summarized. Based on high-performance eigenvalue calculations, important features like "low-noise" field evaluations or port-mode boundary approximations to enable traveling-wave transport are addressed.
	Slides MOADI1 [4.234 MB]

WEP14	Design of SRF Cavities with Cell Profiles Based on Bezier Splines	cavity, HOM, linac, SRF	167
	B. Riemann, T. Weis DELTA, Dortmund, Germany A. Neumann HZB, Berlin, Germany
	Funding: This work is funded by BMBF under contract 05K10PEA. Elliptical cavities have been a standard in SRF linac technology for 30 years. In this work, we present a novel approach [1] using Bezier spline profile curves. By using different degrees of spline curves, the number of free parameters can be varied to suit a given problem (endcell tuning, basecell figures of merit), thus leading to a high flexibility of the spline approach. As a realistic example, a cubic spline SRF multicell cavity geometry is calculated and the figures of merit are optimized for the operational mode. We also present an outline for HOM endcell optimization that can be realized using available 2D solvers. [1] B. Riemann et al., "SRF multicell cavity design using cubic and higher order spline cavity profiles", T 80.9, Verhandlungen DPG Göttingen 2012

WESCI2	Numerical Calculation of Beam Coupling Impedances in the Frequency Domain using FIT	impedance, kicker, space-charge, simulation	193
	U. Niedermayer, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany
	The transverse impedance of kicker magnets is considered to be one of the main beam instability sources in the projected SIS-100 at FAIR and also in the SPS at CERN. The longitudinal impedance can contribute to the heat load, which is especially a concern in the cold sections of SIS-100 and LHC. In the high frequency range, commercially available time domain codes like CST Particle Studio® serve to calculate the impedance but they become inapplicable at medium and low frequencies which become more important for larger size synchrotrons. We present the ongoing work of developing a Finite Integration (FIT) solver in frequency domain which is based on the Parallel and Extensible Toolkit for Scientific computing (PETSc) framework in C++. Pre- and post-processing are done in MATLAB®. Infinite beam pipe boundary conditions are used. The code is applied to an inductive insert used to compensate the longitudinal space charge impedance in low energy machines. Another application focuses on the impedance contribution of a ferrite kicker with inductively coupled pulse forming network (PFN) and frequency dependent complex material permeability.
	Slides WESCI2 [3.468 MB]

THSCC3	On Accelerator Driven Subcritical Reactor Power Gain	neutron, target, proton, feedback	259
	A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia
	The accelerator driven system (ADS) with subcritical reactor is considered. Such systems demonstrate high safety, due to the fact, that the reactor operates at sub-critical level. The problem of the reactor power rate maximiztion on fixed values of effective multiplication factor and the external neutron supply (neutron generating target) intensity is studied. In this paper the main attention is paid to the reactor core optimization. Some ways of ADS power rate gain and optimized reactor core parameters are proposed.
	Slides THSCC3 [1.857 MB]

FRAAC2	Arbitrary High-Order Discontinuous Galerkin Method for Electromagnetic Field Problems	electromagnetic-fields, higher-order-mode, cavity, simulation	275
	K. Papke, C.R. Bahls, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K10HRC For the design and optimization of Higher-Order-Mode Coupler, used in RF accelerator structures, numerical computations of electromagnetic fields as well as scattering parameter are essential. These computations can be carried out in time domain. In this work the implementation and investigation of a time integration scheme, using the Arbitrary high-order DERivatives (ADER) approach, applied on the Discontinuous Galerkin finite-element method (DG-FEM) is demonstrated for solving 3-D electromagnetic problems in time domain. This scheme combines the advantage of high accuracy with the possibility of an efficient implementation as local time stepping scheme, which reduces the calculation time for special applications considerable. It is implemented in NUDG++, a framework written in C++ that deals with the DG-FEM for spatial discretization of the Maxwell equations. Accuracy and performance is analyzed by a suitable benchmark. Nodal Unstructured Discontinuous Galerkin in C++
	Slides FRAAC2 [6.767 MB]

Paper

Title

Other Keywords

Page

MOADI1

High Precision Cavity Simulations

cavity, impedance, simulation, resonance

43

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

Funding: Work supported by DESY, Hamburg
The design and optimization of particle accelerator components are fundamentally based on beam dynamics simulations. The knowledge of the interaction of moving charged particles with the surrounding materials and fields enables to optimize individual devices and consequently to take the best advantage of the entire machine. Among the essential accelerator components are radio-frequency cavities which are utilized for acceleration as well as for beam diagnostics. In these applications, precise beam dynamics simulations urgently require high-precision data of the electromagnetic fields. Numerical simulations based on Maxwell’s equations have to represent the resulting fields on an acceptable level of quality even with limited amount of degrees of freedom. On the other hand, the particle beam itself gives rise to the excitation of undesired modes which have to be extracted from the cavities. In the current work, some of the challenges faced in high precision cavity simulations are summarized. Based on high-performance eigenvalue calculations, important features like "low-noise" field evaluations or port-mode boundary approximations to enable traveling-wave transport are addressed.

Slides MOADI1 [4.234 MB]

WEP14

Design of SRF Cavities with Cell Profiles Based on Bezier Splines

cavity, HOM, linac, SRF

167

B. Riemann, T. Weis
DELTA, Dortmund, Germany
A. Neumann
HZB, Berlin, Germany

Funding: This work is funded by BMBF under contract 05K10PEA.
Elliptical cavities have been a standard in SRF linac technology for 30 years. In this work, we present a novel approach [1] using Bezier spline profile curves. By using different degrees of spline curves, the number of free parameters can be varied to suit a given problem (endcell tuning, basecell figures of merit), thus leading to a high flexibility of the spline approach. As a realistic example, a cubic spline SRF multicell cavity geometry is calculated and the figures of merit are optimized for the operational mode. We also present an outline for HOM endcell optimization that can be realized using available 2D solvers.
[1] B. Riemann et al., "SRF multicell cavity design using cubic and higher order spline cavity profiles", T 80.9, Verhandlungen DPG Göttingen 2012

WESCI2

Numerical Calculation of Beam Coupling Impedances in the Frequency Domain using FIT

impedance, kicker, space-charge, simulation

193

U. Niedermayer, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany

The transverse impedance of kicker magnets is considered to be one of the main beam instability sources in the projected SIS-100 at FAIR and also in the SPS at CERN. The longitudinal impedance can contribute to the heat load, which is especially a concern in the cold sections of SIS-100 and LHC. In the high frequency range, commercially available time domain codes like CST Particle Studio® serve to calculate the impedance but they become inapplicable at medium and low frequencies which become more important for larger size synchrotrons. We present the ongoing work of developing a Finite Integration (FIT) solver in frequency domain which is based on the Parallel and Extensible Toolkit for Scientific computing (PETSc) framework in C++. Pre- and post-processing are done in MATLAB®. Infinite beam pipe boundary conditions are used. The code is applied to an inductive insert used to compensate the longitudinal space charge impedance in low energy machines. Another application focuses on the impedance contribution of a ferrite kicker with inductively coupled pulse forming network (PFN) and frequency dependent complex material permeability.

Slides WESCI2 [3.468 MB]

THSCC3

On Accelerator Driven Subcritical Reactor Power Gain

neutron, target, proton, feedback

259

A.G. Golovkina, I.V. Kudinovich, D.A. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia

The accelerator driven system (ADS) with subcritical reactor is considered. Such systems demonstrate high safety, due to the fact, that the reactor operates at sub-critical level. The problem of the reactor power rate maximiztion on fixed values of effective multiplication factor and the external neutron supply (neutron generating target) intensity is studied. In this paper the main attention is paid to the reactor core optimization. Some ways of ADS power rate gain and optimized reactor core parameters are proposed.

Slides THSCC3 [1.857 MB]

FRAAC2

Arbitrary High-Order Discontinuous Galerkin Method for Electromagnetic Field Problems

electromagnetic-fields, higher-order-mode, cavity, simulation

275

K. Papke, C.R. Bahls, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K10HRC
For the design and optimization of Higher-Order-Mode Coupler, used in RF accelerator structures, numerical computations of electromagnetic fields as well as scattering parameter are essential. These computations can be carried out in time domain. In this work the implementation and investigation of a time integration scheme, using the Arbitrary high-order DERivatives (ADER) approach, applied on the Discontinuous Galerkin finite-element method (DG-FEM) is demonstrated for solving 3-D electromagnetic problems in time domain. This scheme combines the advantage of high accuracy with the possibility of an efficient implementation as local time stepping scheme, which reduces the calculation time for special applications considerable. It is implemented in NUDG++*, a framework written in C++ that deals with the DG-FEM for spatial discretization of the Maxwell equations. Accuracy and performance is analyzed by a suitable benchmark.
* Nodal Unstructured Discontinuous Galerkin in C++

Slides FRAAC2 [6.767 MB]