LINAC2012 - List of Keywords (space-charge)

Paper	Title	Other Keywords	Page
MO3A03	FRANZ – Accelerator Test Bench and Neutron Source	proton, neutron, rfq, ion	130
	O. Meusel, L.P. Chau, M. Heilmann, H. Podlech, U. Ratzinger, K. Volk, C. Wiesner IAP, Frankfurt am Main, Germany
	The challenge of existing and planned neutron sources is to provide highly brilliant ion beams with high reliability. The Frankfurt neutron source FRANZ is not only a neutron source but also a test bench for novel accelerator and diagnostic concepts for intense ion beams. The experiment consists of a compact linear accelerator test bench for the acceleration of an intense proton beam to 2 MeV producing the neutrons via the ⁷Li(p,n) reaction. The final beam intensity will be 200 mA, therefore the space charge and space charge compensation effects can be studied with high statistical relevance along the accelerator. The low energy beam transport LEBT is equipped with four solenoids matching the beam into the chopper system and into the RFQ-IH combination already under construction. The coupling of the RFQ accelerator stage and the IH drift tube cavity offers the possibility to use only one power amplifier as a driver for both of these resonators and reduces investment costs. The compact design of this low-β accelerator stage is optimized for high beam intensities to overcome the strong space charge forces expected in this accelerator test bench.

TUPB021	Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability	plasma, electron, impedance, linac	522
	D. Huang, Q. Gu SINAP, Shanghai, People's Republic of China K.Y. Ng Fermilab, Batavia, USA
	The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions. [1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008) [2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999) [3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

THPLB11	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	simulation, electron, emittance, focusing	834
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB055	Numerical Simulations of ProjectX/PXIE RFQ	rfq, linac, emittance, simulation	975
	J.-F. Ostiguy, A. Saini, N. Solyak Fermilab, Batavia, USA
	Funding: Fermi Research Alliance, LLC under DOE Contract No. De-AC02-07CH11359 Project-X is a proposed superconducting linac-based high intensity proton source at Fermilab. The machine first stages operate in CW mode from 2.1 to 3 GeV and a high bandwidth chopper is used to produce the required bunch patterns. A 162.5 MHz CW RFQ accelerates the beam from 30 keV to 2.1 MeV. A concern with CW operation is that losses either within the RFQ or in the dowstream modules should be well-understood and remain very low to ensure safe and/or reliable operation. In this contribution, we investigate the suitability of existing RFQ codes and model the PXIE RFQ (ProjectX test facility) designed constructed by LBNL to make useful predictions of loss patterns and phase space distribution.

THPB061	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	simulation, electron, emittance, focusing	978
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

Paper

Title

Other Keywords

Page

MO3A03

FRANZ – Accelerator Test Bench and Neutron Source

proton, neutron, rfq, ion

130

O. Meusel, L.P. Chau, M. Heilmann, H. Podlech, U. Ratzinger, K. Volk, C. Wiesner
IAP, Frankfurt am Main, Germany

The challenge of existing and planned neutron sources is to provide highly brilliant ion beams with high reliability. The Frankfurt neutron source FRANZ is not only a neutron source but also a test bench for novel accelerator and diagnostic concepts for intense ion beams. The experiment consists of a compact linear accelerator test bench for the acceleration of an intense proton beam to 2 MeV producing the neutrons via the ⁷Li(p,n) reaction. The final beam intensity will be 200 mA, therefore the space charge and space charge compensation effects can be studied with high statistical relevance along the accelerator. The low energy beam transport LEBT is equipped with four solenoids matching the beam into the chopper system and into the RFQ-IH combination already under construction. The coupling of the RFQ accelerator stage and the IH drift tube cavity offers the possibility to use only one power amplifier as a driver for both of these resonators and reduces investment costs. The compact design of this low-β accelerator stage is optimized for high beam intensities to overcome the strong space charge forces expected in this accelerator test bench.

TUPB021

Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability

plasma, electron, impedance, linac

522

D. Huang, Q. Gu
SINAP, Shanghai, People's Republic of China
K.Y. Ng
Fermilab, Batavia, USA

The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions.
[1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008)
[2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
[3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

THPLB11

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

simulation, electron, emittance, focusing

834

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB055

Numerical Simulations of ProjectX/PXIE RFQ

rfq, linac, emittance, simulation

975

J.-F. Ostiguy, A. Saini, N. Solyak
Fermilab, Batavia, USA

Funding: Fermi Research Alliance, LLC under DOE Contract No. De-AC02-07CH11359
Project-X is a proposed superconducting linac-based high intensity proton source at Fermilab. The machine first stages operate in CW mode from 2.1 to 3 GeV and a high bandwidth chopper is used to produce the required bunch patterns. A 162.5 MHz CW RFQ accelerates the beam from 30 keV to 2.1 MeV. A concern with CW operation is that losses either within the RFQ or in the dowstream modules should be well-understood and remain very low to ensure safe and/or reliable operation. In this contribution, we investigate the suitability of existing RFQ codes and model the PXIE RFQ (ProjectX test facility) designed constructed by LBNL to make useful predictions of loss patterns and phase space distribution.

THPB061

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

simulation, electron, emittance, focusing

978

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.