ICAP2012 - List of Keywords (factory)

Paper	Title	Other Keywords	Page
MOADC2	Implementational Aspects of Eigenmode Computation Based on Perturbation Theory	cavity, simulation, electromagnetic-fields	48
	K. Brackebusch, 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 contracts 05H09HR5 and 05K10HRC. Geometry perturbations affect the eigenmodes of a resonant cavity and thereby can improve but also impair the performance characteristics of the cavity. To investigate the effects of both, intentional and inevitable geometry variations parameter studies are to be undertaken. Using common eigenmode solvers involves to perform a full eigenmode computation for each variation step, even if the geometry is only slightly altered. Therefore, such investigations tend to be computationally extensive and inefficient. Yet, the computational effort for parameter studies may be significantly reduced by using perturbative computation methods. Knowing a set of initial eigenmodes of the unperturbed geometry these allow for the expansion of the eigenmodes of the perturbed geometry in terms of the unperturbed modes. In this paper, we study the complexity of a numerical implementation of perturbative methods. An essential aspect is the computation and analysis of the unperturbed modes since the number and order of these modes determine the accuracy of the results.
	Slides MOADC2 [2.431 MB]

TUADI1	Storage Ring EDM Simulation: Methods and Results	simulation, lattice, storage-ring, proton	99
	Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin FZJ, Jülich, Germany S.N. Andrianov, A.N. Ivanov St. Petersburg State University, St. Petersburg, Russia M. Berz, K. Makino MSU, East Lansing, Michigan, USA
	The idea of Electric Dipole Moment search using the electrostatic storage ring with polarized beam is based on accumulation of additional tiny spin rotation, about one-billionth of radians per second, occurred only in the presence of EDM. This method can be realized under condition of the long-time spin coherency ~1000 seconds. During this time each particle performs about 109 turns in ring moving on different trajectories. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start playing a crucial role. To design such a ring the computer simulation is necessary taking into account all factors affecting the spin. We used COSY-Infinity and integrating program with symplectic Runge-Kutta methods in composition with analytic methods. We developed a new lattice based on the alternating spin rotating. As a result, we can achieve the SCT of ~5000 seconds. The difficulties of these studies are still in the fact that the aberrations growth is observed in the scale of 109 turns and few million particles. For this simulation we use a supercomputer with parallel computing process.
	Slides TUADI1 [0.951 MB]

WEP07	Traveling Poles Elimination Scheme and Calculations of External Quality Factors of HOMs in SC Cavities	cavity, simulation, HOM, linac	152
	T. Galek, T. Flisgen, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Neumann HZB, Berlin, Germany B. Riemann DELTA, Dortmund, Germany
	Funding: Funded by EU FP7 Research Infrastructure Grant No. 227579 and funding approved by German Federal Ministry of Research & Education, Project: 05K10HRC The main scope of this work is the automation of the extraction procedure of the external quality factors Qext of Higher Order Modes (HOMs) in Superconducting (SC) radio frequency cavities []. The HOMs are generated by charged particle beams traveling at the speed of light through SC cavity. The HOMs decay very slowly, depending on localization inside the structure and cell-to-cell coupling, and may influence succeeding charged particle bunches. Thus it is important, at the SC cavity design optimization stage, to calculate the Qext of HOMs. The Traveling Poles Elimination (TPE) scheme has been used on scattering parameters spectra to obtain external quality factors. The combination of Coupled S-Parameter Calculations (CSC) method and vector fitting procedure allows us to study very complicated structures in much better details and almost automated extraction of HOMs' Qext factors. The results are also reasserted by careful eigenmode analysis of the SC cavity. The S-Parameter and eigenmode simulations were performed using CST Microwave Studio. Axel Neumann et al., "Status of the HOM Calculations for the BERLinPro Main Linac Cavity", FRAAC3 (this conference)

THACI1	Lumped Equivalent Models of Complex RF Structures	HOM, impedance, RF-structure, scattering	245
	T. Flisgen, J. Heller, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: partly funded by EU FP7 Research Infrastructure Grant No. 227579 The prediction of RF properties of complex accelerating structures is an important issue in computational accelerator physics. This paper describes the derivation of state space equations for complex structures based on real eigenmodes of sections of the decomposed complex structure. The state space equations enable the calculation of system responses due to port excitations by means of standard ordinary differential equation solvers. Therefore, the state space equations are referred to as lumped equivalent models of such complex RF structures. Besides fast computation of system responses, the equivalent models enable the calculation of secondary quantities such as external quality factors. The present contribution discusses theoretical aspects and illustrates an application example.
	Slides THACI1 [1.538 MB]

Paper

Title

Other Keywords

Page

MOADC2

Implementational Aspects of Eigenmode Computation Based on Perturbation Theory

cavity, simulation, electromagnetic-fields

48

K. Brackebusch, 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 contracts 05H09HR5 and 05K10HRC.
Geometry perturbations affect the eigenmodes of a resonant cavity and thereby can improve but also impair the performance characteristics of the cavity. To investigate the effects of both, intentional and inevitable geometry variations parameter studies are to be undertaken. Using common eigenmode solvers involves to perform a full eigenmode computation for each variation step, even if the geometry is only slightly altered. Therefore, such investigations tend to be computationally extensive and inefficient. Yet, the computational effort for parameter studies may be significantly reduced by using perturbative computation methods. Knowing a set of initial eigenmodes of the unperturbed geometry these allow for the expansion of the eigenmodes of the perturbed geometry in terms of the unperturbed modes. In this paper, we study the complexity of a numerical implementation of perturbative methods. An essential aspect is the computation and analysis of the unperturbed modes since the number and order of these modes determine the accuracy of the results.

Slides MOADC2 [2.431 MB]

TUADI1

Storage Ring EDM Simulation: Methods and Results

simulation, lattice, storage-ring, proton

99

Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin
FZJ, Jülich, Germany
S.N. Andrianov, A.N. Ivanov
St. Petersburg State University, St. Petersburg, Russia
M. Berz, K. Makino
MSU, East Lansing, Michigan, USA

The idea of Electric Dipole Moment search using the electrostatic storage ring with polarized beam is based on accumulation of additional tiny spin rotation, about one-billionth of radians per second, occurred only in the presence of EDM. This method can be realized under condition of the long-time spin coherency ~1000 seconds. During this time each particle performs about 109 turns in ring moving on different trajectories. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start playing a crucial role. To design such a ring the computer simulation is necessary taking into account all factors affecting the spin. We used COSY-Infinity and integrating program with symplectic Runge-Kutta methods in composition with analytic methods. We developed a new lattice based on the alternating spin rotating. As a result, we can achieve the SCT of ~5000 seconds. The difficulties of these studies are still in the fact that the aberrations growth is observed in the scale of 109 turns and few million particles. For this simulation we use a supercomputer with parallel computing process.

Slides TUADI1 [0.951 MB]

WEP07

Traveling Poles Elimination Scheme and Calculations of External Quality Factors of HOMs in SC Cavities

cavity, simulation, HOM, linac

152

T. Galek, T. Flisgen, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Neumann
HZB, Berlin, Germany
B. Riemann
DELTA, Dortmund, Germany

Funding: Funded by EU FP7 Research Infrastructure Grant No. 227579 and funding approved by German Federal Ministry of Research & Education, Project: 05K10HRC
The main scope of this work is the automation of the extraction procedure of the external quality factors Qext of Higher Order Modes (HOMs) in Superconducting (SC) radio frequency cavities [*]. The HOMs are generated by charged particle beams traveling at the speed of light through SC cavity. The HOMs decay very slowly, depending on localization inside the structure and cell-to-cell coupling, and may influence succeeding charged particle bunches. Thus it is important, at the SC cavity design optimization stage, to calculate the Qext of HOMs. The Traveling Poles Elimination (TPE) scheme has been used on scattering parameters spectra to obtain external quality factors. The combination of Coupled S-Parameter Calculations (CSC) method and vector fitting procedure allows us to study very complicated structures in much better details and almost automated extraction of HOMs' Qext factors. The results are also reasserted by careful eigenmode analysis of the SC cavity. The S-Parameter and eigenmode simulations were performed using CST Microwave Studio.
*Axel Neumann et al., "Status of the HOM Calculations for the BERLinPro Main Linac Cavity", FRAAC3 (this conference)

THACI1

Lumped Equivalent Models of Complex RF Structures

HOM, impedance, RF-structure, scattering

245

T. Flisgen, J. Heller, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: partly funded by EU FP7 Research Infrastructure Grant No. 227579
The prediction of RF properties of complex accelerating structures is an important issue in computational accelerator physics. This paper describes the derivation of state space equations for complex structures based on real eigenmodes of sections of the decomposed complex structure. The state space equations enable the calculation of system responses due to port excitations by means of standard ordinary differential equation solvers. Therefore, the state space equations are referred to as lumped equivalent models of such complex RF structures. Besides fast computation of system responses, the equivalent models enable the calculation of secondary quantities such as external quality factors. The present contribution discusses theoretical aspects and illustrates an application example.

Slides THACI1 [1.538 MB]