IPAC2014 - List of Authors (Markovik, A.)

Paper	Title	Page
MOPME019	Study of a Fast Convolution Method for Solving the Space Charge Fields of Charged Particle Bunches	418
	D. Zheng, A. Markoviḱ, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	The kernel of beam dynamics simulations using the particle-in-cell (PIC) model is the solution of Poisson's equation for the electric potential. A very common way to solve Poisson's equation is to use the convolution of charge density and Green's function, the so-called Green's function method. Additionally, the integrated Green's function method* is being used in order to achieve a higher accuracy. For both methods, the convolutions are done using fast Fourier transform based on the convolution theorem. However, the construction of the integrated Green's function and the further convolution is still very time-consuming. The computation can be accelerated without loosing precision if the calculation of Green’s function values is limited to that part of the computational domain with non-zero grid charge density. In this paper we present a general numerical study of these Green's function methods for computing the potential of different bunches: The results can also be used in other simulation codes to improve efficiency. * J. Qiang, S. Lidia, R. D. Ryne, and C. Limborg-Deprey, “A Three-Dimensional Quasi-Static Model for High Brightness Beam Dynamics simulation,” Phys. Rev. ST Accel. Beams, vol 9, 044204 (2006).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME019
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TUPRI016	First Studies on Ion Effects in the Accelerator ELSA	1585
	D. Sauerland, W. Hillert, M.T. Switka ELSA, Bonn, Germany A. Markoviḱ, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Meseck HZB, Berlin, Germany
	Funding: BMBF (Federal Ministry of Education and Research) In the ELSA stretcher ring electrons are accelerated by a fast energy ramp of 6 GeV/s to a beam energy of 3.2 GeV. The high energetic electrons ionize the residual gas molecules in the beam pipe by collisions or synchrotron radiation. The generated ions in turn accumulate inside the beam potential, causing several undesired effects such as tune shifts and beam instabilities. These effects are studied experimentally at ELSA using its full diagnostic capabilities. Both tune shifts due to beam neutralization and transversal beam-ion instabilities can be determined from the beam spectrum. Additionally the beam's transfer function can be measured using a broadband transversal kicker. In the stretcher ring at a beam energy of 1.2 GeV, a periodic beam blow-up was detected in the horizontal plane. Additional measurements of the transversal beam spectrum and ns-time resolution observations with a streak camera identified this blow-up as a coherent dipole oscillation of the beam. This horizontal instability is presumably caused by trapped ions, as there is a strong correlation with the high voltage-bias of the clearing electrodes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI016
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TUPRI046	Dynamics of Ion Distributions in Beam Guiding Magnets	1668
	A. Markoviḱ, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany W. Hillert, D. Sauerland ELSA, Bonn, Germany A. Meseck HZB, Berlin, Germany
	Funding: Supported by the German Federal Ministry of Education and Research (BMBF) under contract number 05K13HRC. Ions generated by synchrotron radiation and collisions of the beam with the rest gas in the vacuum chamber could be a limiting factor for the operation of electron storage rings and Energy Recovery Linacs (ERL). In order to develop beam instability mitigation strategies, a deeper understanding of the ion-cloud behaviour is needed. Numerical simulations of the interaction between electron beams and parasitic ions verified with dedicated measurements can help to acquire that knowledge. This paper presents results of detailed simulations of the interaction in quadrupole magnets and drift sections of the Electron Stretcher Accelerator ELSA in Bonn. The focus is on the evaluation of the dynamics of different ion species and their characteristic distribution in quadrupole magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI046
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Paper

Title

Page

Study of a Fast Convolution Method for Solving the Space Charge Fields of Charged Particle Bunches

418

D. Zheng, A. Markoviḱ, G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

The kernel of beam dynamics simulations using the particle-in-cell (PIC) model is the solution of Poisson's equation for the electric potential. A very common way to solve Poisson's equation is to use the convolution of charge density and Green's function, the so-called Green's function method. Additionally, the integrated Green's function method* is being used in order to achieve a higher accuracy. For both methods, the convolutions are done using fast Fourier transform based on the convolution theorem. However, the construction of the integrated Green's function and the further convolution is still very time-consuming. The computation can be accelerated without loosing precision if the calculation of Green’s function values is limited to that part of the computational domain with non-zero grid charge density. In this paper we present a general numerical study of these Green's function methods for computing the potential of different bunches: The results can also be used in other simulation codes to improve efficiency.
* J. Qiang, S. Lidia, R. D. Ryne, and C. Limborg-Deprey, “A Three-Dimensional Quasi-Static Model for High Brightness Beam Dynamics simulation,” Phys. Rev. ST Accel. Beams, vol 9, 044204 (2006).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME019

Export •

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

TUPRI016

First Studies on Ion Effects in the Accelerator ELSA

1585

D. Sauerland, W. Hillert, M.T. Switka
ELSA, Bonn, Germany
A. Markoviḱ, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Meseck
HZB, Berlin, Germany

Funding: BMBF (Federal Ministry of Education and Research)
In the ELSA stretcher ring electrons are accelerated by a fast energy ramp of 6 GeV/s to a beam energy of 3.2 GeV. The high energetic electrons ionize the residual gas molecules in the beam pipe by collisions or synchrotron radiation. The generated ions in turn accumulate inside the beam potential, causing several undesired effects such as tune shifts and beam instabilities. These effects are studied experimentally at ELSA using its full diagnostic capabilities. Both tune shifts due to beam neutralization and transversal beam-ion instabilities can be determined from the beam spectrum. Additionally the beam's transfer function can be measured using a broadband transversal kicker. In the stretcher ring at a beam energy of 1.2 GeV, a periodic beam blow-up was detected in the horizontal plane. Additional measurements of the transversal beam spectrum and ns-time resolution observations with a streak camera identified this blow-up as a coherent dipole oscillation of the beam. This horizontal instability is presumably caused by trapped ions, as there is a strong correlation with the high voltage-bias of the clearing electrodes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI016

Export •

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

TUPRI046

Dynamics of Ion Distributions in Beam Guiding Magnets

1668

A. Markoviḱ, G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
W. Hillert, D. Sauerland
ELSA, Bonn, Germany
A. Meseck
HZB, Berlin, Germany

Funding: Supported by the German Federal Ministry of Education and Research (BMBF) under contract number 05K13HRC.
Ions generated by synchrotron radiation and collisions of the beam with the rest gas in the vacuum chamber could be a limiting factor for the operation of electron storage rings and Energy Recovery Linacs (ERL). In order to develop beam instability mitigation strategies, a deeper understanding of the ion-cloud behaviour is needed. Numerical simulations of the interaction between electron beams and parasitic ions verified with dedicated measurements can help to acquire that knowledge. This paper presents results of detailed simulations of the interaction in quadrupole magnets and drift sections of the Electron Stretcher Accelerator ELSA in Bonn. The focus is on the evaluation of the dynamics of different ion species and their characteristic distribution in quadrupole magnets.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI046

Export •

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