IPAC2015 - List of Authors (Litvinenko, V.)

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)
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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.
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MOPMN027	Optimization of Dynamic Aperture for Hadron Lattices in eRHIC	757
	Y.C. Jing, V. Litvinenko, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The potential upgrade of the Relativistic Heavy Ion Collider (RHIC) to an electron ion collider (eRHIC) involves numerous extensive changes to the existing collider complex. The expected very high luminosity is planned to be achieved at eRHIC with the help of squeezing the beta function of the hadron ring at the IP to a few cm, causing a large rise of the natural chromaticities and thus bringing with it challenges for the beam long term stability (Dynamic aperture). We present our effort to expand the DA by carefully tuning the nonlinear magnets thus controlling the size of the footprints in tune space and all lower order resonance driving terms. We show a reasonably large DA through particle tracking over millions of turns of beam revolution.
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TUPMA048	Experimental and Simulational Result of Multipactors in 112 MHz QWR Injector	1938
	T. Xin Stony Brook University, Stony Brook, USA S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, I. Pinayev, J. Skaritka, Q. Wu, B. P. Xiao BNL, Upton, Long Island, New York, USA
	Funding: This work was carried out at Brookhaven Science Associates, LLC under Contracts No. DE-AC02-98CH10886 and at Stony Brook University under grant DE-SC0005713 with the U.S. DOE. The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were install and tested for the first time. During this experiment, we observed several multipacting barriers at varied gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.7 MV gun voltage under pulsed mode after several round of conditioning processes.
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TUPMA049	First Beam Commissioning at BNL ERL SRF Gun	1941
	W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, L.R. Hammons, T. Hayes, J.P. Jamilkowski, P. K. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, V. Litvinenko, L. Masi, G.T. McIntyre, K. Mernick, T.A. Miller, G. Narayan, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, F. Severino, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, J.E. Tuozzolo, E. Wang, D. Weiss, M. Wilinski, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn Stony Brook University, Stony Brook, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. The 704 MHz superconducting RF gun successfully generated the first photoemission beam on Nov. 17 2014. This paper will report the latest results of SRF beam commissioning, including the SRF cavity performance, cathode QE measurements, and beam parameter measurements. The beam commissioning setup is described in the paper as well.
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TUPTY047	ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC	2120
	D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.
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TUPWI050	Optics Correction for the Multi-pass FFAG ERL Machine eRHIC	2363
	C. Liu, S.J. Brooks, V. Litvinenko, M.G. Minty, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Gradient errors in the multi-pass Fixed Field Alternating Gradient (FFAG) Energy Recovery Linac (ERL) machine, eRHIC, distort the beam orbit and therefore cause emittance increase. The localization and correction of gradient errors are essential for an effective orbit correction and emittance preservation. In this report, the methodology and simulation of optics correction for the multi-pass FFAG ERL machine eRHIC will be presented. The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
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TUPWI051	Study of Orbit Correction for eRHIC FFAG Design	2366
	C. Liu, Y. Hao, V. Litvinenko, F. Méot, M.G. Minty, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The chromaticities in the eRHIC linear non-scaling Fixed Field Alternating Gradient (FFAG) lattice are very large. Therefore, particles will decohere in phase space given the presence of lattice errors. The decoherence causes a deviation of the orbit response which is the basis for orbit corrections. In this report we will present a study of the linearity of the orbit response in a lattice with large chromaticity, a comparison of the results of orbit corrections for several cases together with a conclusion that correcting the average orbit with a measured orbit response works as good as an orbit correction for on-momentum particles. The work was performed under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
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WEPWI049	Commissioning of the 112 MHz SRF Gun and 500 MHz Bunching Cavities for the CeC PoP Linac	3597
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, G. Narayan, P. Orfin, I. Pinayev, T. Rao, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, T. Xin Stony Brook University, Stony Brook, USA P.A. McIntosh, A.J. Moss, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase I a 112 MHz superconducting RF photoemission gun and two 500 MHz normal conducting bunching cavities were installed and commissioned. The paper describes the Phase I linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems.
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WEPWI051	Update on the CeC POP 704 MHz 5-Cell Cavity Cryomodule Design and Fabrication	3603
	J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, I. Pinayev, J. Skaritka, L. Snydstrup, R. Than, J.E. Tuozzolo, W. Xu BNL, Upton, Long Island, New York, USA S.M. Gerbick, M.P. Kelly, T. Reid ANL, Argonne, Illinois, USA T.L. Grimm, R. Jecks, J.A. Yancey Niowave, Inc., Lansing, Michigan, USA Y. Huang Fermilab, Batavia, Illinois, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system currently under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up to 22 MeV. Novel mechanical designs, including the helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for the CeC PoP experiment. .
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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.
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TUPWI043	Chromatic Effects in Long Periodic Transport Channels	2342
	V. Litvinenko Stony Brook University, Stony Brook, USA Y. Hao, Y.C. Jing BNL, Upton, Long Island, New York, USA
	Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels
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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.
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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)

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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.

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MOPMN027

Optimization of Dynamic Aperture for Hadron Lattices in eRHIC

757

Y.C. Jing, V. Litvinenko, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The potential upgrade of the Relativistic Heavy Ion Collider (RHIC) to an electron ion collider (eRHIC) involves numerous extensive changes to the existing collider complex. The expected very high luminosity is planned to be achieved at eRHIC with the help of squeezing the beta function of the hadron ring at the IP to a few cm, causing a large rise of the natural chromaticities and thus bringing with it challenges for the beam long term stability (Dynamic aperture). We present our effort to expand the DA by carefully tuning the nonlinear magnets thus controlling the size of the footprints in tune space and all lower order resonance driving terms. We show a reasonably large DA through particle tracking over millions of turns of beam revolution.

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TUPMA048

Experimental and Simulational Result of Multipactors in 112 MHz QWR Injector

1938

T. Xin
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, I. Pinayev, J. Skaritka, Q. Wu, B. P. Xiao
BNL, Upton, Long Island, New York, USA

Funding: This work was carried out at Brookhaven Science Associates, LLC under Contracts No. DE-AC02-98CH10886 and at Stony Brook University under grant DE-SC0005713 with the U.S. DOE.
The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were install and tested for the first time. During this experiment, we observed several multipacting barriers at varied gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.7 MV gun voltage under pulsed mode after several round of conditioning processes.

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TUPMA049

First Beam Commissioning at BNL ERL SRF Gun

1941

W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, L.R. Hammons, T. Hayes, J.P. Jamilkowski, P. K. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, V. Litvinenko, L. Masi, G.T. McIntyre, K. Mernick, T.A. Miller, G. Narayan, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, F. Severino, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, J.E. Tuozzolo, E. Wang, D. Weiss, M. Wilinski, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn
Stony Brook University, Stony Brook, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The 704 MHz superconducting RF gun successfully generated the first photoemission beam on Nov. 17 2014. This paper will report the latest results of SRF beam commissioning, including the SRF cavity performance, cathode QE measurements, and beam parameter measurements. The beam commissioning setup is described in the paper as well.

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TUPTY047

ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC

2120

D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.
The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.

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TUPWI050

Optics Correction for the Multi-pass FFAG ERL Machine eRHIC

2363

C. Liu, S.J. Brooks, V. Litvinenko, M.G. Minty, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Gradient errors in the multi-pass Fixed Field Alternating Gradient (FFAG) Energy Recovery Linac (ERL) machine, eRHIC, distort the beam orbit and therefore cause emittance increase. The localization and correction of gradient errors are essential for an effective orbit correction and emittance preservation. In this report, the methodology and simulation of optics correction for the multi-pass FFAG ERL machine eRHIC will be presented.
The work was performed under Contract No. DE-AC02-98CH10886
with the U.S. Department of Energy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI050

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TUPWI051

Study of Orbit Correction for eRHIC FFAG Design

2366

C. Liu, Y. Hao, V. Litvinenko, F. Méot, M.G. Minty, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The chromaticities in the eRHIC linear non-scaling Fixed Field Alternating Gradient (FFAG) lattice are very large. Therefore, particles will decohere in phase space given the presence of lattice errors. The decoherence causes a deviation of the orbit response which is the basis for orbit corrections. In this report we will present a study of the linearity of the orbit response in a lattice with large chromaticity, a comparison of the results of orbit corrections for several cases together with a conclusion that correcting the average orbit with a measured orbit response works as good as an orbit correction for on-momentum particles.
The work was performed under Contract No. DE-AC02-98CH10886
with the U.S. Department of Energy.

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WEPWI049

Commissioning of the 112 MHz SRF Gun and 500 MHz Bunching Cavities for the CeC PoP Linac

3597

S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, G. Narayan, P. Orfin, I. Pinayev, T. Rao, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, T. Xin
Stony Brook University, Stony Brook, USA
P.A. McIntosh, A.J. Moss, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase I a 112 MHz superconducting RF photoemission gun and two 500 MHz normal conducting bunching cavities were installed and commissioned. The paper describes the Phase I linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI049

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WEPWI051

Update on the CeC POP 704 MHz 5-Cell Cavity Cryomodule Design and Fabrication

3603

J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, I. Pinayev, J. Skaritka, L. Snydstrup, R. Than, J.E. Tuozzolo, W. Xu
BNL, Upton, Long Island, New York, USA
S.M. Gerbick, M.P. Kelly, T. Reid
ANL, Argonne, Illinois, USA
T.L. Grimm, R. Jecks, J.A. Yancey
Niowave, Inc., Lansing, Michigan, USA
Y. Huang
Fermilab, Batavia, Illinois, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system currently under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up to 22 MeV. Novel mechanical designs, including the helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for the CeC PoP experiment.
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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.

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TUPWI043

Chromatic Effects in Long Periodic Transport Channels

2342

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

Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels

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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.

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