IPAC2015 - List of Authors (Wang, G.)

Paper	Title	Page
MOPJE062	Testing Aspects of Advanced Coherent Electron Cooling Technique	445
	V. Litvinenko, Y.C. Jing, I. Pinayev, G. Wang BNL, Upton, Long Island, New York, USA D.F. Ratner SLAC, Menlo Park, California, USA V. Samulyak SBU, Stony Brook, USA
	An advanced version of the coherent-electron cooling based on the microbunching instability was proposed in . This approach promised to significantly increase the bandwidth of the system and, therefore, significantly shorter cooling time in high energy hadron colliders. In this paper we present our plans of simulating and testing the key aspects of this proposed technique using the set-up of the coherent-electron-cooling proof-of-principle experiment at BNL. D.F. Ratner, Phys. Rev. Lett. 111, 084802 (2013)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE062
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MOPMN015	Simulation of Beam-Induced Plasma for the Mitigation of Beam-Beam Effects	734
	J. Ma, V. Samulyak, K. Yu SBU, Stony Brook, USA V. Litvinenko, V. Samulyak, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA V. Samulyak SUNY SB, Stony Brook, New York, USA
	One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN015
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TUPWI060	RHIC Polarized Proton-Proton Operation at 100 GeV in Run 15	2384
	V. Schoefer, E.C. Aschenauer, G. Atoian, M. Blaskiewicz, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, X. Gu, T. Hayes, H. Huang, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, S.M. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA
	The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI060
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WEAB1	Compensating Tune Spread Induced by Space Charge in Bunched Beams	2450
	V. Litvinenko Stony Brook University, Stony Brook, USA G. Wang BNL, Upton, Long Island, New York, USA
	The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Several schemes were proposed to compensate for space charge effects in a coasting (e.g., continuous) hadron beam, and some have been tested. Using an appropriate transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But none of these methods address the issue of compensating space-charge induced tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present several practical examples of such a system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAB1
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THPF144	Analysis of FEL-based CeC Amplification at High Gain Limit	4063
	G. Wang, Y.C. Jing, V. Litvinenko BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. An analysis of CeC amplifier based on 1D FEL theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution . At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter . In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution *** and investigate how longitudinal space charge and electrons’ energy spread affect the FEL amplification process. * G. Wang, PhD Thesis, SUNY Stony Brook, 2008. G. Stupakov, M.S. Zolotorev, Comment on “Coherent Electron Cooling”, PRL 110 (2013) 269503. * E.L. Saldin, E.A. Schneidmiller, M.V. Yurkov, The Physics of Free Electron Lasers, 1999.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF144
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Paper

Title

Page

Testing Aspects of Advanced Coherent Electron Cooling Technique

445

V. Litvinenko, Y.C. Jing, I. Pinayev, G. Wang
BNL, Upton, Long Island, New York, USA
D.F. Ratner
SLAC, Menlo Park, California, USA
V. Samulyak
SBU, Stony Brook, USA

An advanced version of the coherent-electron cooling based on the microbunching instability was proposed in *. This approach promised to significantly increase the bandwidth of the system and, therefore, significantly shorter cooling time in high energy hadron colliders. In this paper we present our plans of simulating and testing the key aspects of this proposed technique using the set-up of the coherent-electron-cooling proof-of-principle experiment at BNL.
* D.F. Ratner, Phys. Rev. Lett. 111, 084802 (2013)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE062

Export •

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

MOPMN015

Simulation of Beam-Induced Plasma for the Mitigation of Beam-Beam Effects

734

J. Ma, V. Samulyak, K. Yu
SBU, Stony Brook, USA
V. Litvinenko, V. Samulyak, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
V. Samulyak
SUNY SB, Stony Brook, New York, USA

One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN015

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

TUPWI060

RHIC Polarized Proton-Proton Operation at 100 GeV in Run 15

2384

V. Schoefer, E.C. Aschenauer, G. Atoian, M. Blaskiewicz, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, X. Gu, T. Hayes, H. Huang, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, S.M. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA

The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI060

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WEAB1

Compensating Tune Spread Induced by Space Charge in Bunched Beams

2450

V. Litvinenko
Stony Brook University, Stony Brook, USA
G. Wang
BNL, Upton, Long Island, New York, USA

The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Several schemes were proposed to compensate for space charge effects in a coasting (e.g., continuous) hadron beam, and some have been tested. Using an appropriate transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But none of these methods address the issue of compensating space-charge induced tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present several practical examples of such a system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAB1

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

THPF144

Analysis of FEL-based CeC Amplification at High Gain Limit

4063

G. Wang, Y.C. Jing, V. Litvinenko
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An analysis of CeC amplifier based on 1D FEL theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution *. At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter **. In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution * *** and investigate how longitudinal space charge and electrons’ energy spread affect the FEL amplification process.
* G. Wang, PhD Thesis, SUNY Stony Brook, 2008.
** G. Stupakov, M.S. Zolotorev, Comment on “Coherent Electron Cooling”, PRL 110 (2013) 269503.
*** E.L. Saldin, E.A. Schneidmiller, M.V. Yurkov, The Physics of Free Electron Lasers, 1999.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF144

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