Cyclotrons2019 - Table of Session: WEB (FFA Concepts, Beam Dynamics and Simulations)

Paper	Title	Page
WEB01	Status of FFAs (Modelling and Existing/planned Machines)	266
	J.-B. Lagrange, D.J. Kelliher, S. Machida, C.R. Prior, C.T. Rogers STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Since their rebirth two decades ago, great progress has been made in Fixed Field alternating gradient Accelerator (FFA) design, with different optical concepts and technological developments. Several machines have been built, and others are planned. The talk will review the recent progress around the world.
	Slides WEB01 [7.965 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB01
About •	paper received ※ 15 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020
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WEB02	Surrogate Models for Particle Accelerators
	A. Adelmann PSI, Villigen PSI, Switzerland
	Precise accelerator simulations are powerful tools in the design and optimization of exiting and new charged particle accelerators. We all know from experience, the computational burden of precise simulations often limits their use in practice. This becomes a real hurdle when requiring real time computation. I will demonstrate two techniques, based on Polynomial Chaos Expansion [1] and Deep Neural Networks [2] that hints a path forward, towards precise real time computing. The examples will be based on linear accelerators and cyclotrons. [1] A. Adelmann, "On Nonintrusive Uncertainty Quantification and Surrogate Model Construction in Particle Accelerator Modeling", SIAM/ASA J. Uncertainty Quantification, 7(2), 383-416 (2019) https://epubs.siam.org/doi/abs/10.1137/16M1061928 [2] A. Edelen, A. Adelmann, N. Neveu, Y. Huber, M. Frey, "Machine Learning to Enable Orders of Magnitude Speedup in Mult-Objective Optimization of Particle Accelerator Systems", https://arxiv.org/abs/1903.07759
	Slides WEB02 [3.099 MB]
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WEB03	Factors Influencing the Vortex Effect in High-Intensity Cyclotrons	270
	C. Baumgarten PSI, Villigen PSI, Switzerland
	We discuss factors that have potential influence on the space charge induced vortex motion of particles within high intensity bunches (curling of bunches, Gordon 1969) in isochronous cyclotrons. The influence of the phase slip due to deviations from strict isochronism determines if the bunches of a specific turn are above, below or at "transition", and hence whether stable vortex motion of the bunches is possible at all. Secondly there are possible longitudinal and transverse effects of rf acceleration, the former depending on the bunch phase ("bunching" or "debunching"), the latter depending on the gradient of the accelerating voltage. High accelerating voltages in the first turns call the applicability of adiabatic approximations and analytic methods into question. The influence of the rf acceleration is expected to be significant only at low beam energy, i.e. should have small or even negligible effect beyond the central region of compact machines.
	Slides WEB03 [1.145 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB03
About •	paper received ※ 16 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB04	BDSIM Simulation of the Complete Radionuclide Production Beam Line from Beam Splitter to Target Station at the PSI Cyclotron Facility	275
	H. Zhang, R. Eichler, J. Grillenberger, W. Hirzel, S. Joray, D.C. Kiselev, J.M. Schippers, J. Snuverink, R. Sobbia, A. Sommerhalder, Z. Talip, N.P. van der Meulen PSI, Villigen PSI, Switzerland L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom L.J. Nevay JAI, Egham, Surrey, United Kingdom
	The beam line for radionuclide production on the PSI Cyclotron Facility starts with an electrostatic beam splitter, which peels protons of a few tens of microampere from a beam around two milliampere. The peeled beam is then guided onto a target station for routine production of a variety of radionuclides [1]. Beam Delivery Simulation (BDSIM), a Geant4 based simulation tool, enables the simulation of not only beam transportation through optics elements like dipoles and quadrupoles, but also particle passage through components like collimator and degrader [2-3]. Furthermore, BDSIM facilitates user built elements with accompanying electromagnetic field, which is essential for the modeling of the first element of the beam line, the electrostatic beam splitter. With a model including all elements from beam splitter to target, BDSIM simulation delivers a better specification of the beam along the complete line, for example, beam profile, beam transmission, energy spectrum, as well as power deposit, which is of importance not only for present operation but also for further development. REFERENCES [1] M. Olivo and H. W. Reist, Proc. EPAC’88, Rome, Italy, June 1988, pp. 1300-1302. [2] www.pp.rhul.ac.uk/bdsim [3] S. Agostinelli, et al, Nucl. Instr. Meth. Phys. Res. A(3) 250-303.
	Slides WEB04 [4.761 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB04
About •	paper received ※ 13 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB05	Beam dynamics and preliminary design of the RFQ Direct Injection Project
	D. Winklehner MIT, Cambridge, Massachusetts, USA
	Injecting beam into a compact cyclotron from an external ion source usually requires a low energy beam transport line (LEBT) with several beam shaping elements (magnets and a buncher), the transfer through the cyclotron axial bore hole, and finally, bending the beam into the median plane using a spiral inflector. In the RFQ Direct Injection Project we are combining LEBT, buncher, and axial transfer within one element, the RFQ (Radio Frequency Quadrupole), which is inserted axially into the cyclotron yoke. This is a very compact solution that offers an excellent bunching efficiency. To accommodate the small diameter that is available in the axial bore hole together with a low RF frequency of 32.8 MHz, a split-coaxial RFQ type was chosen. Longitudinal and transverse de-bunching are mitigated by an internal re-bunching cell, and an external electrostatic quadrupole, respectively. The preliminary design phase of this project has been concluded and the RFQ is currently under construction at Bevatech GmbH in Germany. Here, we present the beam dynamics simulations, showing the feasibility of the system, and the preliminary design of the RFQ and test cyclotron with central region.
	Slides WEB05 [6.177 MB]
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Paper

Title

Page

Status of FFAs (Modelling and Existing/planned Machines)

266

J.-B. Lagrange, D.J. Kelliher, S. Machida, C.R. Prior, C.T. Rogers
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Since their rebirth two decades ago, great progress has been made in Fixed Field alternating gradient Accelerator (FFA) design, with different optical concepts and technological developments. Several machines have been built, and others are planned. The talk will review the recent progress around the world.

Slides WEB01 [7.965 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB01

About •

paper received ※ 15 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020

Export •

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

WEB02

Surrogate Models for Particle Accelerators

A. Adelmann
PSI, Villigen PSI, Switzerland

Precise accelerator simulations are powerful tools in the design and optimization of exiting and new charged particle accelerators. We all know from experience, the computational burden of precise simulations often limits their use in practice. This becomes a real hurdle when requiring real time computation. I will demonstrate two techniques, based on Polynomial Chaos Expansion [1] and Deep Neural Networks [2] that hints a path forward, towards precise real time computing. The examples will be based on linear accelerators and cyclotrons.
[1] A. Adelmann, "On Nonintrusive Uncertainty Quantification and Surrogate Model Construction in Particle Accelerator Modeling", SIAM/ASA J. Uncertainty Quantification, 7(2), 383-416 (2019) https://epubs.siam.org/doi/abs/10.1137/16M1061928
[2] A. Edelen, A. Adelmann, N. Neveu, Y. Huber, M. Frey, "Machine Learning to Enable Orders of Magnitude Speedup in Mult-Objective Optimization of Particle Accelerator Systems", https://arxiv.org/abs/1903.07759

Slides WEB02 [3.099 MB]

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

WEB03

Factors Influencing the Vortex Effect in High-Intensity Cyclotrons

270

C. Baumgarten
PSI, Villigen PSI, Switzerland

We discuss factors that have potential influence on the space charge induced vortex motion of particles within high intensity bunches (curling of bunches, Gordon 1969) in isochronous cyclotrons. The influence of the phase slip due to deviations from strict isochronism determines if the bunches of a specific turn are above, below or at "transition", and hence whether stable vortex motion of the bunches is possible at all. Secondly there are possible longitudinal and transverse effects of rf acceleration, the former depending on the bunch phase ("bunching" or "debunching"), the latter depending on the gradient of the accelerating voltage. High accelerating voltages in the first turns call the applicability of adiabatic approximations and analytic methods into question. The influence of the rf acceleration is expected to be significant only at low beam energy, i.e. should have small or even negligible effect beyond the central region of compact machines.

Slides WEB03 [1.145 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB03

About •

paper received ※ 16 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020

Export •

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

WEB04

BDSIM Simulation of the Complete Radionuclide Production Beam Line from Beam Splitter to Target Station at the PSI Cyclotron Facility

275

H. Zhang, R. Eichler, J. Grillenberger, W. Hirzel, S. Joray, D.C. Kiselev, J.M. Schippers, J. Snuverink, R. Sobbia, A. Sommerhalder, Z. Talip, N.P. van der Meulen
PSI, Villigen PSI, Switzerland
L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
L.J. Nevay
JAI, Egham, Surrey, United Kingdom

The beam line for radionuclide production on the PSI Cyclotron Facility starts with an electrostatic beam splitter, which peels protons of a few tens of microampere from a beam around two milliampere. The peeled beam is then guided onto a target station for routine production of a variety of radionuclides [1]. Beam Delivery Simulation (BDSIM), a Geant4 based simulation tool, enables the simulation of not only beam transportation through optics elements like dipoles and quadrupoles, but also particle passage through components like collimator and degrader [2-3]. Furthermore, BDSIM facilitates user built elements with accompanying electromagnetic field, which is essential for the modeling of the first element of the beam line, the electrostatic beam splitter. With a model including all elements from beam splitter to target, BDSIM simulation delivers a better specification of the beam along the complete line, for example, beam profile, beam transmission, energy spectrum, as well as power deposit, which is of importance not only for present operation but also for further development.
REFERENCES
[1] M. Olivo and H. W. Reist, Proc. EPAC’88, Rome, Italy, June 1988, pp. 1300-1302.
[2] www.pp.rhul.ac.uk/bdsim
[3] S. Agostinelli, et al, Nucl. Instr. Meth. Phys. Res. A(3) 250-303.

Slides WEB04 [4.761 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-Cyclotrons2019-WEB04

About •

paper received ※ 13 September 2019 paper accepted ※ 26 September 2019 issue date ※ 20 June 2020

Export •

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

WEB05

Beam dynamics and preliminary design of the RFQ Direct Injection Project

D. Winklehner
MIT, Cambridge, Massachusetts, USA

Injecting beam into a compact cyclotron from an external ion source usually requires a low energy beam transport line (LEBT) with several beam shaping elements (magnets and a buncher), the transfer through the cyclotron axial bore hole, and finally, bending the beam into the median plane using a spiral inflector. In the RFQ Direct Injection Project we are combining LEBT, buncher, and axial transfer within one element, the RFQ (Radio Frequency Quadrupole), which is inserted axially into the cyclotron yoke. This is a very compact solution that offers an excellent bunching efficiency. To accommodate the small diameter that is available in the axial bore hole together with a low RF frequency of 32.8 MHz, a split-coaxial RFQ type was chosen. Longitudinal and transverse de-bunching are mitigated by an internal re-bunching cell, and an external electrostatic quadrupole, respectively. The preliminary design phase of this project has been concluded and the RFQ is currently under construction at Bevatech GmbH in Germany. Here, we present the beam dynamics simulations, showing the feasibility of the system, and the preliminary design of the RFQ and test cyclotron with central region.

Slides WEB05 [6.177 MB]

Export •

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