HB2018 - List of Keywords (focusing)

Paper	Title	Other Keywords	Page
TUP1WA02	Fixed Field Accelerators and Space Charge Modeling	space-charge, resonance, acceleration, synchrotron	158
	A. Adelmann PSI, Villigen PSI, Switzerland C.T. Rogers STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The efforts of the Fixed Field Accelerators FFA (formerly known as FFAG accelerators) community to address the high intensity challenge are reviewed. Starting from analytic estimates and linear models for space charge computation, the current possibilities of precise 3D models for start to end modeling are discussed.
	Slides TUP1WA02 [9.488 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP1WA02
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP1WA03	IBS Near Transition Crossing in NICA Collider	collider, optics, emittance, lattice	252
	S.A. Kostromin, A.O. Sidorin JINR, Dubna, Moscow Region, Russia I.V. Gorelyshev JINR/VBLHEP, Dubna, Moscow region, Russia V.A. Lebedev Fermilab, Batavia, Illinois, USA A.O. Sidorin Saint Petersburg State University, Saint Petersburg, Russia
	Intrabeam scattering (IBS) of charged particles in a particle beam results in an exchange of energy between different degrees of freedom. That results in an increase of average energy of particles in the beam frame and an increase of the 3D-emittance. The paper considers calculations of beam emittance growth rates for different options of NICA collider and IBS effects in close vicinity of the transition.
	Slides WEP1WA03 [1.774 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP1WA03
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THA1WD01	Experience and Perspective of FFAG Accelerator	acceleration, proton, cavity, resonance	342
	Y. Mori Kyoto University, Research Reactor Institute, Osaka, Japan
	Funding: This work was funded by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan) This talk is about operational challenge and perspective of Fixed Field Alternating Gradient accelerators, including the recent studies on advanced FFAG for high intensity secondary particles.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THA1WD01
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THP2WB01	Revisiting the Longitudinal 90 Degree Limit for Superconducting Linear Accelerators	space-charge, lattice, emittance, resonance	369
	I. Hofmann GSI, Darmstadt, Germany I. Hofmann TEMF, TU Darmstadt, Darmstadt, Germany
	In the design of high-intensity linear accelerators one of the generally adopted criteria is not to exceed a zero-current phase advance per focusing period of 90 degrees in order to avoid the space charge driven envelope instability, or a coinciding fourth order space charge resonance. Recently it was claimed that in certain structures, predominantly applicable to super-conducting linac lattices - such a constraint is not always necessary in the longitudinal plane (I. Hofmann and O. Boine-Frankenheim, Phys. Rev. Lett. 118, 2017). This applies primarily to such focusing structures, where the transverse focusing period only induces a weak space charge dependent modulation in the longitudinal plane, and a different periodicity is applicable to the longitudinal plane. Hence the longitudinal 90 degree stopband is practically absent, and phase advances significantly above 90 degrees should be possible in such structures, with a corresponding additional design freedom. As a consequence, we suggest that the 90 degree rule should no longer be taken as standard criterion in the longitudinal plane of linac design.
	Slides THP2WB01 [5.179 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP2WB04	Longitudinal Dynamics of Low Energy Superconducting Linac	cavity, linac, acceleration, lattice	383
	Z. Li SCU, Chengdu, People's Republic of China
	Funding: funded by NSFC(11375122, 11511140277) The superconducting linac is composed of short independent cavities, and the cavity occupies only a small portion (1/4 to 1/6) of the machine compared with the normal conducting one. When phase advance per period is greater than 60 degrees, the smooth approximation is no longer valid and the longitudinal motion has to be described by time dependent system. With the help of Poincare map, the single particle nonlinear time dependent longitudinal motion is investigated. The study shows that when phase advance per period is less than 60 degrees, the system can be well described by smooth approximation, that means there is a clear boundary (separatrix) between stable and unstable area; when phase advance is greater than 60 degrees, the system shows a quite different dynamic structures and the phase acceptance is decreased significantly compared with the smooth approximation theory predicated, especially when phase advance per period is greater than 90 degrees. The results show that even for low current ma-chine, the zero current phase advance should be kept less than 90 degrees to make sure there is no particle loss because of the shrink of the longitudinal acceptance.
	Slides THP2WB04 [1.061 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP2WB05	Halo Formation of the High Intensity Beams in a Periodic Solenoidal Fields	space-charge, resonance, solenoid, lattice	387
	Y.L. Cheon, M. Chung UNIST, Ulsan, Republic of Korea
	Funding: This research was supported by the National Research Foundation of Korea (Grant No. NRF-2017M1A7A1A02016413). Transport of intense beams over long distances can be restricted by space-charge fields which force the trajectories of charged particles to deviate from the stable regions of propagation. The space-charge fields can be calculated from the density distribution of the beam particles, and Poisson's equation. As the space-charge term is put in the equations of motion, it affects the envelope equations and betatron wave number of a charged particle in the beam. Also, with different initial conditions of the beam particles, there can be perturbations on the matched beam envelopes which can generate a resonant interaction between the beam core and test particles. Unlike for the K-V beam, for nonuniform density beams such as Gaussian beams in the periodic quadrupole or solenoidal focusing fields, there exists higher order terms and non-periodic solutions of beam particle oscillations, which can generate halo regions and chaotic motions during the beam propagation. In this study, we have investigated the higher order resonances and non-periodic solutions of the Gaussian beam in the solenoidal focusing fields to understand halo formation mechanisms of the intense beams.
	Slides THP2WB05 [2.295 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

TUP1WA02

Fixed Field Accelerators and Space Charge Modeling

space-charge, resonance, acceleration, synchrotron

158

A. Adelmann
PSI, Villigen PSI, Switzerland
C.T. Rogers
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The efforts of the Fixed Field Accelerators FFA (formerly known as FFAG accelerators) community to address the high intensity challenge are reviewed. Starting from analytic estimates and linear models for space charge computation, the current possibilities of precise 3D models for start to end modeling are discussed.

Slides TUP1WA02 [9.488 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP1WA02

Export •

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

WEP1WA03

IBS Near Transition Crossing in NICA Collider

collider, optics, emittance, lattice

252

S.A. Kostromin, A.O. Sidorin
JINR, Dubna, Moscow Region, Russia
I.V. Gorelyshev
JINR/VBLHEP, Dubna, Moscow region, Russia
V.A. Lebedev
Fermilab, Batavia, Illinois, USA
A.O. Sidorin
Saint Petersburg State University, Saint Petersburg, Russia

Intrabeam scattering (IBS) of charged particles in a particle beam results in an exchange of energy between different degrees of freedom. That results in an increase of average energy of particles in the beam frame and an increase of the 3D-emittance. The paper considers calculations of beam emittance growth rates for different options of NICA collider and IBS effects in close vicinity of the transition.

Slides WEP1WA03 [1.774 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP1WA03

Export •

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

THA1WD01

Experience and Perspective of FFAG Accelerator

acceleration, proton, cavity, resonance

342

Y. Mori
Kyoto University, Research Reactor Institute, Osaka, Japan

Funding: This work was funded by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan)
This talk is about operational challenge and perspective of Fixed Field Alternating Gradient accelerators, including the recent studies on advanced FFAG for high intensity secondary particles.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THA1WD01

Export •

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

THP2WB01

Revisiting the Longitudinal 90 Degree Limit for Superconducting Linear Accelerators

space-charge, lattice, emittance, resonance

369

I. Hofmann
GSI, Darmstadt, Germany
I. Hofmann
TEMF, TU Darmstadt, Darmstadt, Germany

In the design of high-intensity linear accelerators one of the generally adopted criteria is not to exceed a zero-current phase advance per focusing period of 90 degrees in order to avoid the space charge driven envelope instability, or a coinciding fourth order space charge resonance. Recently it was claimed that in certain structures, predominantly applicable to super-conducting linac lattices - such a constraint is not always necessary in the longitudinal plane (I. Hofmann and O. Boine-Frankenheim, Phys. Rev. Lett. 118, 2017). This applies primarily to such focusing structures, where the transverse focusing period only induces a weak space charge dependent modulation in the longitudinal plane, and a different periodicity is applicable to the longitudinal plane. Hence the longitudinal 90 degree stopband is practically absent, and phase advances significantly above 90 degrees should be possible in such structures, with a corresponding additional design freedom. As a consequence, we suggest that the 90 degree rule should no longer be taken as standard criterion in the longitudinal plane of linac design.

Slides THP2WB01 [5.179 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB01

Export •

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

THP2WB04

Longitudinal Dynamics of Low Energy Superconducting Linac

cavity, linac, acceleration, lattice

383

Z. Li
SCU, Chengdu, People's Republic of China

Funding: funded by NSFC(11375122, 11511140277)
The superconducting linac is composed of short independent cavities, and the cavity occupies only a small portion (1/4 to 1/6) of the machine compared with the normal conducting one. When phase advance per period is greater than 60 degrees, the smooth approximation is no longer valid and the longitudinal motion has to be described by time dependent system. With the help of Poincare map, the single particle nonlinear time dependent longitudinal motion is investigated. The study shows that when phase advance per period is less than 60 degrees, the system can be well described by smooth approximation, that means there is a clear boundary (separatrix) between stable and unstable area; when phase advance is greater than 60 degrees, the system shows a quite different dynamic structures and the phase acceptance is decreased significantly compared with the smooth approximation theory predicated, especially when phase advance per period is greater than 90 degrees. The results show that even for low current ma-chine, the zero current phase advance should be kept less than 90 degrees to make sure there is no particle loss because of the shrink of the longitudinal acceptance.

Slides THP2WB04 [1.061 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB04

Export •

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

THP2WB05

Halo Formation of the High Intensity Beams in a Periodic Solenoidal Fields

space-charge, resonance, solenoid, lattice

387

Y.L. Cheon, M. Chung
UNIST, Ulsan, Republic of Korea

Funding: This research was supported by the National Research Foundation of Korea (Grant No. NRF-2017M1A7A1A02016413).
Transport of intense beams over long distances can be restricted by space-charge fields which force the trajectories of charged particles to deviate from the stable regions of propagation. The space-charge fields can be calculated from the density distribution of the beam particles, and Poisson's equation. As the space-charge term is put in the equations of motion, it affects the envelope equations and betatron wave number of a charged particle in the beam. Also, with different initial conditions of the beam particles, there can be perturbations on the matched beam envelopes which can generate a resonant interaction between the beam core and test particles. Unlike for the K-V beam, for nonuniform density beams such as Gaussian beams in the periodic quadrupole or solenoidal focusing fields, there exists higher order terms and non-periodic solutions of beam particle oscillations, which can generate halo regions and chaotic motions during the beam propagation. In this study, we have investigated the higher order resonances and non-periodic solutions of the Gaussian beam in the solenoidal focusing fields to understand halo formation mechanisms of the intense beams.

Slides THP2WB05 [2.295 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB05

Export •

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