IPAC2016 - Classification: 05 Beam Dynamics and Electromagnetic Fields / D08 High Intensity in Linear Accelerators

Paper	Title	Page
MOPOR032	Using of the MENT Method for Reconstruction of 2D Particle Distributions in IFMIF Accelerators	668
	P.A.P. Nghiem, N. Chauvin, L. Ducrot, M. Valette CEA/DSM/IRFU, France
	Beam particles are characterized by their coordinates in real spaces or phase spaces that are at least two-dimensional. It is often necessary to reconstruct such a 2D-distribution from the knowledge of only its projections on some axes, either for making use of tomography measurement results or for setting up an input beam for transport simulations. In this article, the use of the MENT (Maximum Entropy) reconstruction method is reported for the IFMIF accelerators where high intensity beam distributions are far from Gaussian ones.
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MOPOR033	Simulations of Dark Current from the BERLinPro Booster Module	671
	M. McAteer, M. Abo-Bakr, B.C. Kuske, A. Neumann HZB, Berlin, Germany
	Funding: Work supported by the German Bundesministerium f\"ur Bildung und Forschung, Land Berlin and grants of Helmholtz Association Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented.
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MOPOR034	Numerical Space-Charge Compensation Studies and Comparison of Different Models	674
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner IAP, Frankfurt am Main, Germany
	The design of many Low-Energy Beam Transport sections relies on the presence of space-charge compensation by particles of opposing charge. To improve understanding of the processes involved in the built-up and steady-state, simulations using the Particle-in-Cell code bender were made. We will present the influence of various system parameters on the results. Furthermore, the electron velocity distribution was found to be approximately thermal. The spatial distribution can then be found by solving the Poisson-Boltzmann equation. Such a model for the electron distribution was implemented in a 2D PIC code and applied to typical beam transport situations. We will present results in comparison to the 3D simulations.
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MOPOR035	Space Charge Neutralization Studies with H⁻ Beam in Low Energy Beam Transport Test Stand	677
	S. Artikova Private Address, Tsukuba, Japan K. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan T. Shibata, A. Takagi KEK, Tokai, Ibaraki, Japan
	J-PARC is intensity-upgraded up to pulse current of 50 mA of H⁻ beam. Two-solenoid based LEBT test stand is being built to support the operation of J-PARC linac. It imitates the actual LEBT of linac, yet contains the diagnostics chamber composed of horizontal and vertical beam emittance-meters and Faraday-cup for the current measurement. Vacuum composition of LEBT is predominantly H2 gas. The pressure inside the LEBT can be varied by the differential pumps allowing us to study the beam phase space evolution under space charge effects. The measurements of the beam phase space emittance were made as a function of the residual gas pressure. This paper presents the results and discussion on beam space charge neutralization and its effect on the beam phase space emittance.
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MOPOR037	Beam Halo Measurements using Vibrating Wire at the KOMAC	680
SUPSS057	use link to see paper's listing under its alternate paper code
	D. Choe, M. Chung, S.Y. Kim UNIST, Ulsan, Republic of Korea S.G. Arutunian, A.V. Margaryan ANSL, Yerevan, Armenia E.G. Lazareva YSU, Yerevan, Armenia
	In high-intensity particle accelerators, due to the fact that preventing beam loss plays a crucial role in con-ducting any experiments, it is important to measure and control the beam halo. Fortunately, it is feasible nowadays to measure the beam halo region thanks to the development of several sensitive beam scanning methods, including the vibrating wire technique. Since the vibrating wire is exceptionally sensitive to the heat deposition by the beam particles, it can be used to scanning the beam profile. This study will be concentrated on the precise beam profile measurement using the vibrating wire at the Korea Multi-Purpose Accelerator Complex (KOMAC) facility. First, we describe the best condition to construct beam profile measurement experiment. Finally, we present the results of the beam halo measurements performed with 20 MeV proton beam at the KOMAC facility
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MOPOR038	Implications of Resonantly Driven Higher Order Modes on the ESS Beam	683
	A. Farricker, R.M. Jones, N.Y. Joshi UMAN, Manchester, United Kingdom S. Molloy ESS, Lund, Sweden
	The European Spallation Source (ESS) in Lund, Sweden, will be a facility for fundamental physics studies of atomic structure using a spallation source of unparalleled brightness. To achieve this end, a 2.86 ms long pulsed proton beam will be accelerated up to a final energy of 2 GeV using three suites of superconducting cavities. If a Higher Order Mode (HOM) lies on a harmonic of the bunch frequency the HOM will be resonantly driven. This will dilute the beam quality significantly. Errors in fabricating these cavities are inevitable, and this sets a tolerance on how close the HOM can be within a harmonic of the bunch frequency. The baseline design for ESS requires HOMs to be at least 5 MHz from a machine line. Here we provide details of several finite element electromagnetic simulations on the HOMS anticipated in these ESS cavities. We analyse their impact on the beam emittance using a drift-kick-drift model with the potential for relaxed tolerances.
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MOPOR042	Beam Dynamics Modeling of Drift-tube Linacs with CST Particle Studio	689
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	The CST Studio provides convenient tools for self-consistent 3D modeling of accelerators, even large ones. Here we demonstrate this approach for the LANSCE drift-tube linac (DTL) taken as an example. The RF fields in 3D models of full DTL tanks are calculated and tuned with MicroWave Studio (MWS). Beam dynamics in the DTL is modeled with Particle Studio for bunches and bunch trains with realistic initial beam distributions using the MWS-calculated RF fields and quadrupole magnetic fields. The output beam parameters and locations of particle losses are calculated and compared for different beam distributions. Our main emphasis is on the formation of low-energy tails (longitudinal halo) and their interaction with regular bunches. Such effects are usually not taken into account in standard multi-particle phase-space codes.
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MOPOY032	Beam Twiss Measurement With Ws Including Space Charge Effect	925
	Y.L. Zhao, H. Geng, C. Meng, F. Yan IHEP, Beijing, People's Republic of China
	Wire Scanners (WS) are used to measure beam profile and calculate the transverse Twiss parameters at the entrance of MEBT1 in the CADS injector I test stand. As to data process, the traditional method with transfer map doesn't consider the space charge effect. But, as we know, space charge effect can't be neglected for high intensity accelerators. In this paper, optimization algorithm is used in beam emittance measurement.
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THYA01	Advanced Concepts and Methods for Very High Intensity Linacs	3155
	P.A.P. Nghiem, N. Chauvin, D. Uriot CEA/DSM/IRFU, France M. Comunian INFN/LNL, Legnaro (PD), Italy C. Oliver CIEMAT, Madrid, Spain W. Simeoni IF-UFRGS, Porto Alegre, Brazil M. Valette CERN, Geneva, Switzerland
	For very high intensity linacs, both beam power and space charge should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an issue from the lowest energy, careful and exhaustive beam loss predictions have to be done. High space charge implies lattice compactness making the implementation of beam diagnostics very problematic, so a clear strategy for beam diagnostic has to be defined. Beam halo becomes no longer negligible, and it plays a significant role in the particle loss process. Therefore, beam optimization must take the halo into account and beam characterization must be able to describe the halo part in addition to the core one. This presentation discusses advanced concepts and methods for beam analysis, beam loss prediction, beam optimization, beam diagnostic and beam characterization especially dedicated to very high intensity accelerators.
	Slides THYA01 [6.177 MB]
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THOBA02	Space Charge Induced Collective Modes and Beam Halo in Periodic Channels	3165
	C. Li, Zh.C. Liu, Q. Qin, Y.L. Zhao IHEP, Beijing, People's Republic of China
	Funding: This work is supported by the Ministry of Science and Technology of China under Grant No. 2014CB845501. The collective mode instabilities of periodically focused high intensity beams based on the Vlasov-Poisson equation are investigated both analytically and numerically. It is found that the broadened collective stop bands resulting from space charge induced structure resonance in long periodic channels predict well the areas where the rms emittance growth accompanied with n-fold phase space structure (beam halo) would take place. We believe that the formed beam halo, which is depicted in action-angle frame, could be understood as a side-effect of the collective beam mode.
	Slides THOBA02 [4.704 MB]
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Paper

Title

Page

Using of the MENT Method for Reconstruction of 2D Particle Distributions in IFMIF Accelerators

668

P.A.P. Nghiem, N. Chauvin, L. Ducrot, M. Valette
CEA/DSM/IRFU, France

Beam particles are characterized by their coordinates in real spaces or phase spaces that are at least two-dimensional. It is often necessary to reconstruct such a 2D-distribution from the knowledge of only its projections on some axes, either for making use of tomography measurement results or for setting up an input beam for transport simulations. In this article, the use of the MENT (Maximum Entropy) reconstruction method is reported for the IFMIF accelerators where high intensity beam distributions are far from Gaussian ones.

Export •

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

MOPOR033

Simulations of Dark Current from the BERLinPro Booster Module

671

M. McAteer, M. Abo-Bakr, B.C. Kuske, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by the German Bundesministerium f\"ur Bildung und Forschung, Land Berlin and grants of Helmholtz Association
Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of BERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using Astra to track the propagation of emitted electrons from the surfaces of the cavities to examine the effects of dark current in the BERLinPro injector. Results of these simulations, including optimization of the layout to reduce propagation of electrons to the cathode and an estimation of power from dark current deposited throughout the injector, are presented.

Export •

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

MOPOR034

Numerical Space-Charge Compensation Studies and Comparison of Different Models

674

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
IAP, Frankfurt am Main, Germany

The design of many Low-Energy Beam Transport sections relies on the presence of space-charge compensation by particles of opposing charge. To improve understanding of the processes involved in the built-up and steady-state, simulations using the Particle-in-Cell code bender were made. We will present the influence of various system parameters on the results. Furthermore, the electron velocity distribution was found to be approximately thermal. The spatial distribution can then be found by solving the Poisson-Boltzmann equation. Such a model for the electron distribution was implemented in a 2D PIC code and applied to typical beam transport situations. We will present results in comparison to the 3D simulations.

Export •

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

MOPOR035

Space Charge Neutralization Studies with H⁻ Beam in Low Energy Beam Transport Test Stand

677

S. Artikova
Private Address, Tsukuba, Japan
K. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Shibata, A. Takagi
KEK, Tokai, Ibaraki, Japan

J-PARC is intensity-upgraded up to pulse current of 50 mA of H⁻ beam. Two-solenoid based LEBT test stand is being built to support the operation of J-PARC linac. It imitates the actual LEBT of linac, yet contains the diagnostics chamber composed of horizontal and vertical beam emittance-meters and Faraday-cup for the current measurement. Vacuum composition of LEBT is predominantly H2 gas. The pressure inside the LEBT can be varied by the differential pumps allowing us to study the beam phase space evolution under space charge effects. The measurements of the beam phase space emittance were made as a function of the residual gas pressure. This paper presents the results and discussion on beam space charge neutralization and its effect on the beam phase space emittance.

Export •

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

MOPOR037

Beam Halo Measurements using Vibrating Wire at the KOMAC

680

SUPSS057

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

D. Choe, M. Chung, S.Y. Kim
UNIST, Ulsan, Republic of Korea
S.G. Arutunian, A.V. Margaryan
ANSL, Yerevan, Armenia
E.G. Lazareva
YSU, Yerevan, Armenia

In high-intensity particle accelerators, due to the fact that preventing beam loss plays a crucial role in con-ducting any experiments, it is important to measure and control the beam halo. Fortunately, it is feasible nowadays to measure the beam halo region thanks to the development of several sensitive beam scanning methods, including the vibrating wire technique. Since the vibrating wire is exceptionally sensitive to the heat deposition by the beam particles, it can be used to scanning the beam profile. This study will be concentrated on the precise beam profile measurement using the vibrating wire at the Korea Multi-Purpose Accelerator Complex (KOMAC) facility. First, we describe the best condition to construct beam profile measurement experiment. Finally, we present the results of the beam halo measurements performed with 20 MeV proton beam at the KOMAC facility

Export •

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

MOPOR038

Implications of Resonantly Driven Higher Order Modes on the ESS Beam

683

A. Farricker, R.M. Jones, N.Y. Joshi
UMAN, Manchester, United Kingdom
S. Molloy
ESS, Lund, Sweden

The European Spallation Source (ESS) in Lund, Sweden, will be a facility for fundamental physics studies of atomic structure using a spallation source of unparalleled brightness. To achieve this end, a 2.86 ms long pulsed proton beam will be accelerated up to a final energy of 2 GeV using three suites of superconducting cavities. If a Higher Order Mode (HOM) lies on a harmonic of the bunch frequency the HOM will be resonantly driven. This will dilute the beam quality significantly. Errors in fabricating these cavities are inevitable, and this sets a tolerance on how close the HOM can be within a harmonic of the bunch frequency. The baseline design for ESS requires HOMs to be at least 5 MHz from a machine line. Here we provide details of several finite element electromagnetic simulations on the HOMS anticipated in these ESS cavities. We analyse their impact on the beam emittance using a drift-kick-drift model with the potential for relaxed tolerances.

Export •

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

MOPOR042

Beam Dynamics Modeling of Drift-tube Linacs with CST Particle Studio

689

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

The CST Studio provides convenient tools for self-consistent 3D modeling of accelerators, even large ones. Here we demonstrate this approach for the LANSCE drift-tube linac (DTL) taken as an example. The RF fields in 3D models of full DTL tanks are calculated and tuned with MicroWave Studio (MWS). Beam dynamics in the DTL is modeled with Particle Studio for bunches and bunch trains with realistic initial beam distributions using the MWS-calculated RF fields and quadrupole magnetic fields. The output beam parameters and locations of particle losses are calculated and compared for different beam distributions. Our main emphasis is on the formation of low-energy tails (longitudinal halo) and their interaction with regular bunches. Such effects are usually not taken into account in standard multi-particle phase-space codes.

Export •

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

MOPOY032

Beam Twiss Measurement With Ws Including Space Charge Effect

925

Y.L. Zhao, H. Geng, C. Meng, F. Yan
IHEP, Beijing, People's Republic of China

Wire Scanners (WS) are used to measure beam profile and calculate the transverse Twiss parameters at the entrance of MEBT1 in the CADS injector I test stand. As to data process, the traditional method with transfer map doesn't consider the space charge effect. But, as we know, space charge effect can't be neglected for high intensity accelerators. In this paper, optimization algorithm is used in beam emittance measurement.

Export •

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

THYA01

Advanced Concepts and Methods for Very High Intensity Linacs

3155

P.A.P. Nghiem, N. Chauvin, D. Uriot
CEA/DSM/IRFU, France
M. Comunian
INFN/LNL, Legnaro (PD), Italy
C. Oliver
CIEMAT, Madrid, Spain
W. Simeoni
IF-UFRGS, Porto Alegre, Brazil
M. Valette
CERN, Geneva, Switzerland

For very high intensity linacs, both beam power and space charge should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an issue from the lowest energy, careful and exhaustive beam loss predictions have to be done. High space charge implies lattice compactness making the implementation of beam diagnostics very problematic, so a clear strategy for beam diagnostic has to be defined. Beam halo becomes no longer negligible, and it plays a significant role in the particle loss process. Therefore, beam optimization must take the halo into account and beam characterization must be able to describe the halo part in addition to the core one. This presentation discusses advanced concepts and methods for beam analysis, beam loss prediction, beam optimization, beam diagnostic and beam characterization especially dedicated to very high intensity accelerators.

Slides THYA01 [6.177 MB]

Export •

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

THOBA02

Space Charge Induced Collective Modes and Beam Halo in Periodic Channels

3165

C. Li, Zh.C. Liu, Q. Qin, Y.L. Zhao
IHEP, Beijing, People's Republic of China

Funding: This work is supported by the Ministry of Science and Technology of China under Grant No. 2014CB845501.
The collective mode instabilities of periodically focused high intensity beams based on the Vlasov-Poisson equation are investigated both analytically and numerically. It is found that the broadened collective stop bands resulting from space charge induced structure resonance in long periodic channels predict well the areas where the rms emittance growth accompanied with n-fold phase space structure (beam halo) would take place. We believe that the formed beam halo, which is depicted in action-angle frame, could be understood as a side-effect of the collective beam mode.

Slides THOBA02 [4.704 MB]

Export •

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