IPAC2022 - Classification: MC5: Beam Dynamics and EM Fields / D03: Calculations of EM fields

Paper	Title	Page
MOPOTK018	Parallelization of Radia Magnetostatics Code	481
SUSPMF067	use link to see paper's listing under its alternate paper code
	A. Banerjee SBU, Stony Brook, New York, USA J. Chavanne, G. Le Bec ESRF, Grenoble, France O.V. Chubar BNL, Upton, New York, USA J.P. Edelen, C.C. Hall, B. Nash RadiaSoft LLC, Boulder, Colorado, USA
	Funding: Work supported by the US DOE BES SBIR grant No. DE-SC0018556. Radia 3D magnetostatics code has been used for the design of insertion devices for light sources over more than two decades. The code uses the magnetization integral approach that is efficient for solving permanent magnet and hybrid magnet structures. The initial version of the Radia code was sequential, its core written in C++ and interface in the Mathematica language. This paper describes a new Python-interfaced parallel version of Radia and its applications. The parallelization of the code was implemented on C++ level, following a hybrid approach. Semi-analytical calculations of interaction matrix elements and resultant magnetic fields were parallelized using the Message Passing Interface, whereas the parallelization of the "relaxation" procedure (solving for magnetizations in volumes created by subdivision) was executed using a shared memory method based on C++ multithreading. The parallel performance results are encouraging, particularly for magnetic field calculation post relaxation where a ~600 speedup with respect to sequential execution was obtained. The new parallel Radia version facilitates designs of insertion devices and lattice magnets for novel particle accelerators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK018
About •	Received ※ 20 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOTK059	Implementation of the Vico-Greengard-Ferrando Poisson Solver in Synergia2	600
	C.S. Park KUS, Sejong, Republic of Korea
	Computation of space charge fields in accelerator simulations is one of the most challenging tasks. The algorithm proposed by Hockney and Eastwood is the fastest method for numerically solving Poisson equations with open boundaries and has been implemented in various accelerator simulation codes. Recently, Vico-Greengard-Ferrando proposed a new hybrid fast algorithm for computing volume potentials. The new algorithm is promising higher accuracy and faster error convergence than that of Hockney-Eastwood. This study presents the implementation of the Vico-Greengard-Ferrando solver in Synergia and shows a comparison of results with these Poisson solvers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK059
About •	Received ※ 10 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 29 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOTK060	An Induction-Type Septum Magnet for the EIC Complex	603
	N. Tsoupas, D. Holmes, C. Liu, I. Marneris, C. Montag, V. Ptitsyn, V.H. Ranjbar, J.E. Tuozzolo BNL, Upton, New York, USA B. Bhandari Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The electron Ion Collider (eIC) project* has been approved by the Department of Energy to be built at the site of Brookhaven National Laboratory (BNL). Part of the eIC accelerator complex and more specifically the Rapid Cycling Syncrotron (RCS) which accelerates the electron beam up to 18 GeV and the electron Storage Ring (eSR) which stores the electron beam bunces for collisions with the hadrons, will be built inside the tunnel of the Relativistic Heavy Ion Collider (RHIC). This paper provides information on the electromagnetic design of the septa magnets which will be employed to inject and extract the beam to and from the two synchrotrons used for the acceleration and storage of the electron beam bunches. The type of the septum is of induction type made o laminated iron and it is similar to the one described in ref.[3] The electromagnetic study is performed by the use of the transient module of the OPERA computer code. https://ww.bnl.gov/eic/ A. Zhuravlev, et al. PIPAC2013, Shanghai, China * https://www.3ds.com/products-services/simulia/products/opera/
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK060
About •	Received ※ 05 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 21 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOTK062	Numerical Calibration of the Bead-Pull Setup for Beam Coupling Impedance Evaluation	607
	D.M.F. El Dali, E. Métral, C. Zannini CERN, Meyrin, Switzerland G. De Michele, S. Fanella AVO-ADAM, Meyrin, Switzerland
	The bead-pull method is a commonly used electromagnetic field measurement technique exploited to tune a radiofrequency cavity to achieve design specifications. The frequency of a resonant cavity is perturbed by inserting a metallic or dielectric bead. For a given electromagnetic field, the amplitude of the perturbation depends only on the geometry of the perturbing object. Therefore, the calibration of the bead can be done in different resonant structures without loss of generality. In this paper, a method to perform an accurate calibration of the bead with electromagnetic simulations is proposed. Compared to the common practice of measuring a reference cavity, the flexibility given by the simulation method to study different bead shapes and sizes could be advantageous to optimize the measurement setup. A calibrated bead-pull setup allows to quantify the electric field and, therefore, the shunt impedance of the resonant modes of the cavity. As experimental benchmark, the beam coupling impedance measured with the calibrated bead-pull setup is compared with electromagnetic simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK062
About •	Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 20 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOTK065	Minimising Transverse Multipoles in Accelerating RF Cavities via Azimuthally Modulated Designs	610
SUSPMF066	use link to see paper's listing under its alternate paper code
	L.M. Wroe JAI, Oxford, United Kingdom R. Apsimon Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M. Dosanjh CERN, Meyrin, Switzerland S.L. Sheehy The University of Melbourne, Melbourne, Victoria, Australia
	In this paper, we build upon previous work of designing RF structures that support modes with tailored multipolar fields by applying the concept to negate the transverse multipoles in accelerating RF cavities caused by the incorporation of waveguide slots and tuning deformations. We outline a systematic method for designing structures that minimise these transverse multipoles and present analysis of simulations of two different minimisation designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK065
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 06 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOMS050	Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide	757
	S.N. Galyamin Saint Petersburg State University, Saint Petersburg, Russia S. Baturin ITMO University, Saint Petersburg, Russia
	Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper* where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated. * D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018). ** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050
About •	Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOPOTK018

Parallelization of Radia Magnetostatics Code

481

SUSPMF067

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

A. Banerjee
SBU, Stony Brook, New York, USA
J. Chavanne, G. Le Bec
ESRF, Grenoble, France
O.V. Chubar
BNL, Upton, New York, USA
J.P. Edelen, C.C. Hall, B. Nash
RadiaSoft LLC, Boulder, Colorado, USA

Funding: Work supported by the US DOE BES SBIR grant No. DE-SC0018556.
Radia 3D magnetostatics code has been used for the design of insertion devices for light sources over more than two decades. The code uses the magnetization integral approach that is efficient for solving permanent magnet and hybrid magnet structures. The initial version of the Radia code was sequential, its core written in C++ and interface in the Mathematica language. This paper describes a new Python-interfaced parallel version of Radia and its applications. The parallelization of the code was implemented on C++ level, following a hybrid approach. Semi-analytical calculations of interaction matrix elements and resultant magnetic fields were parallelized using the Message Passing Interface, whereas the parallelization of the "relaxation" procedure (solving for magnetizations in volumes created by subdivision) was executed using a shared memory method based on C++ multithreading. The parallel performance results are encouraging, particularly for magnetic field calculation post relaxation where a ~600 speedup with respect to sequential execution was obtained. The new parallel Radia version facilitates designs of insertion devices and lattice magnets for novel particle accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK018

About •

Received ※ 20 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022

Cite •

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

MOPOTK059

Implementation of the Vico-Greengard-Ferrando Poisson Solver in Synergia2

600

C.S. Park
KUS, Sejong, Republic of Korea

Computation of space charge fields in accelerator simulations is one of the most challenging tasks. The algorithm proposed by Hockney and Eastwood is the fastest method for numerically solving Poisson equations with open boundaries and has been implemented in various accelerator simulation codes. Recently, Vico-Greengard-Ferrando proposed a new hybrid fast algorithm for computing volume potentials. The new algorithm is promising higher accuracy and faster error convergence than that of Hockney-Eastwood. This study presents the implementation of the Vico-Greengard-Ferrando solver in Synergia and shows a comparison of results with these Poisson solvers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK059

About •

Received ※ 10 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 29 June 2022

Cite •

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

MOPOTK060

An Induction-Type Septum Magnet for the EIC Complex

603

N. Tsoupas, D. Holmes, C. Liu, I. Marneris, C. Montag, V. Ptitsyn, V.H. Ranjbar, J.E. Tuozzolo
BNL, Upton, New York, USA
B. Bhandari
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The electron Ion Collider (eIC) project* has been approved by the Department of Energy to be built at the site of Brookhaven National Laboratory (BNL). Part of the eIC accelerator complex and more specifically the Rapid Cycling Syncrotron (RCS) which accelerates the electron beam up to 18 GeV and the electron Storage Ring (eSR) which stores the electron beam bunces for collisions with the hadrons, will be built inside the tunnel of the Relativistic Heavy Ion Collider (RHIC)**. This paper provides information on the electromagnetic design of the septa magnets which will be employed to inject and extract the beam to and from the two synchrotrons used for the acceleration and storage of the electron beam bunches. The type of the septum is of induction type made o laminated iron and it is similar to the one described in ref.[3] The electromagnetic study is performed by the use of the transient module of the OPERA computer code***.
* https://ww.bnl.gov/eic/
** A. Zhuravlev, et al. PIPAC2013, Shanghai, China
*** https://www.3ds.com/products-services/simulia/products/opera/

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK060

About •

Received ※ 05 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 21 June 2022

Cite •

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

MOPOTK062

Numerical Calibration of the Bead-Pull Setup for Beam Coupling Impedance Evaluation

607

D.M.F. El Dali, E. Métral, C. Zannini
CERN, Meyrin, Switzerland
G. De Michele, S. Fanella
AVO-ADAM, Meyrin, Switzerland

The bead-pull method is a commonly used electromagnetic field measurement technique exploited to tune a radiofrequency cavity to achieve design specifications. The frequency of a resonant cavity is perturbed by inserting a metallic or dielectric bead. For a given electromagnetic field, the amplitude of the perturbation depends only on the geometry of the perturbing object. Therefore, the calibration of the bead can be done in different resonant structures without loss of generality. In this paper, a method to perform an accurate calibration of the bead with electromagnetic simulations is proposed. Compared to the common practice of measuring a reference cavity, the flexibility given by the simulation method to study different bead shapes and sizes could be advantageous to optimize the measurement setup. A calibrated bead-pull setup allows to quantify the electric field and, therefore, the shunt impedance of the resonant modes of the cavity. As experimental benchmark, the beam coupling impedance measured with the calibrated bead-pull setup is compared with electromagnetic simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK062

About •

Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 20 June 2022

Cite •

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

MOPOTK065

Minimising Transverse Multipoles in Accelerating RF Cavities via Azimuthally Modulated Designs

610

SUSPMF066

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

L.M. Wroe
JAI, Oxford, United Kingdom
R. Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M. Dosanjh
CERN, Meyrin, Switzerland
S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia

In this paper, we build upon previous work of designing RF structures that support modes with tailored multipolar fields by applying the concept to negate the transverse multipoles in accelerating RF cavities caused by the incorporation of waveguide slots and tuning deformations. We outline a systematic method for designing structures that minimise these transverse multipoles and present analysis of simulations of two different minimisation designs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK065

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 06 July 2022

Cite •

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

MOPOMS050

Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide

757

S.N. Galyamin
Saint Petersburg State University, Saint Petersburg, Russia
S. Baturin
ITMO University, Saint Petersburg, Russia

Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137).
Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation*. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper** where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated.
* D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018).
** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050

About •

Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022

Cite •

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