Electron Cooling
Paper Title Page
MOXAUD01
 Performance of the 2 MeV Electron Cooler at COSY  
 
  • V. Kamerdzhiev, A.J. Halama, R. Stassen, H. Stockhorst
    FZJ, Jülich, Germany
  • M.I. Bryzgunov, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov
    BINP SB RAS, Novosibirsk, Russia
  • T. Katayama
    Nihon University, Narashino, Chiba, Japan
  
  The 2 MeV electron cooler is operated in the COSY ring since 2013. So far electron beam energy up to 1.5 MeV was demonstrated. Dedicated electron cooling studies with proton beams up to 1.66 GeV kinetic energy and electron beam current up to 0.9 A were carried out. A reduction of proton beam emittance by one order of magnitude within a few hundred seconds was observed. Overview of HV and electron beam commissioning activities is presented. Electron cooling results are discussed.  
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MOXAUD02 Experimental Observation of Longitudinal Electron Cooling of DC and Bunched Proton Beam at 2425 MeV/c at COSY 10
 
  • V.B. Reva, M.I. Bryzgunov, V.V. Parkhomchuk
    BINP SB RAS, Novosibirsk, Russia
  • V. Kamerdzhiev, T. Katayama, R. Stassen, H. Stockhorst
    FZJ, Jülich, Germany
  
  The 2 MeV electron cooling system for COSY-Julich started operation in 2013 years. The cooling process was observed in the wide energy range of the electron beam from 100 keV to 908 keV. Vertical, horizontal and longitudinal cooling was tested at bunched and continuous beams. The cooler was operated with electron current up to 0.9 A. This report deals with the description of the experimental observation of longitudinal electron cooling of DC and bunched proton beam at 2425 MeV/c at COSY.  
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MOXAUD03
 Low Energy RHIC Electron Cooling (LEReC) Project  
 
  • A.V. Fedotov
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the U.S. Department of Energy.
An electron cooler is presently under construction to improve the luminosity of the Relativistic Heavy Ion Collider (RHIC) for heavy ion beam energies below 10 GeV/nucleon. Required electron beam and its acceleration (up to 2 MeV in Phase-I and up to 5 MeV in Phase-II) are provided by the photoemission electron gun and the RF linear accelerator. As a result, cooling will be accomplished by using bunched electron beams produced by high-brightness high-current electron linear accelerator. In addition, this will be the first electron cooling applied directly in a collider. In this presentation we describe accelerator physics requirements, design considerations and parameters, as well as associated challenges of such a low-energy RHIC electron cooler (LEReC).
*Presented for the LEReC team. 		 
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MOXAUD04
 The ELENA Electron Cooler  
 
  • L.V. Jørgensen, P. Belochitskii, G. Tranquille
    CERN, Geneva, Switzerland
  
  The ELENA project (Extra Low ENergy Antiprtons) at CERN is nearing completion. One of the crucial components of the this new decelerator ring will be the associated electron cooler. With a final antiproton energy in ELENA of 100 keV the electron cooler will be working at a very low electron energy of just 55 eV. We will present the design consideratiosn andproduction status of the cooler.  
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MOPF02 The Green Energy Turbine as Turbo Generator for Powering the HV-Solenoids at a Relativistic Electron Cooler 29
 
  • A. Hofmann, K. Aulenbacher, M.W. Bruker, J. Dietrich, T. Weilbach
    HIM, Mainz, Germany
  • V.V. Parkhomchuk, V.B. Reva
    BINP SB RAS, Novosibirsk, Russia
  
  One challenge in the development of a relativistic electron cooler is the powering of components, e.g. HV-solenoids, which sit on different potentials within a high voltage vessel and need a floating power supply. Within a design study, BINP SB RAS Novosibirsk has proposed two possibilities to build a power supply in a modular way. The first proposal is to use two cascade transformers per module. One cascade transformer powers 22 small HV-solenoids; the second one should generate the acceleration/deceleration voltage. The cascade transformers are fed by a turbo generator, which is powered by a gas under high pressure which is generated outside of the vessel. The second possibility is to use two big HV-solenoids per module. In this proposal, the HV-solenoids are powered directly by a turbo generator. For both concepts, a suitable turbo generator is essential. A potential candidate for the turbo generator could be the Green Energy Turbine (GET) from the company DEPRAG, which works with dry air and delivers a power of 5 kW. At the Helmholtz-Institut Mainz two GETS are tested. After an introduction, we present our experience with the GET and give an overview of the further road map.  
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MOPF03 Electron Lenses and Cooling for the Fermilab Integrable Optics Test Accelerator 32
 
  • G. Stancari, A.V. Burov, V.A. Lebedev, S. Nagaitsev, E. Prebys, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Recently, the study of integrable Hamiltonian systems has led to nonlinear accelerator lattices with one or two transverse invariants and wide stable tune spreads. These lattices may drastically improve the performance of high-intensity machines, providing Landau damping to protect the beam from instabilities, while preserving dynamic aperture. The Integrable Optics Test Accelerator (IOTA) is being built at Fermilab to study these concepts with 150-MeV pencil electron beams (single-particle dynamics) and 2.5-MeV protons (dynamics with self fields). One way to obtain a nonlinear integrable lattice is by using the fields generated by a magnetically confined electron beam (electron lens) overlapping with the circulating beam. The required parameters are similar to the ones of existing devices. In addition, the electron lens will be used in cooling mode to control the brightness of the proton beam and to measure transverse profiles through recombination. More generally, it is of great interest to investigate whether nonlinear integrable optics allows electron coolers to exceed limitations set by both coherent or incoherent instabilities excited by space charge. 		 
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MOPF06 Quantification of the Electron Plasma in TItan's Cooler Penning Trap 39
 
  • B.A. Kootte, B. Barquest, U. Chowdhury, J. Even, M. Good, A.A. Kwiatkowski, D. Lascar, K.G. Leach, A. Lennarz, D.A. Short
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • M. Alanssari
    Universität Muenster, Physikalisches Institut, Muenster, Germany
  • C. Andreoiu
    SFU, Burnaby, BC, Canada
  • J. Bale, J. Dilling, A. Finlay, A.A. Gallant, E. Leistenschneider
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • D. Frekers
    Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
  • G. Gwinner
    University of Manitoba, Manitoba, Canada
  • R. Klawitter
    Heidelberg University, Physics Institute, Heidelberg, Germany
  • T.T. Li
    UW/Physics, Waterloo, Ontario, Canada
  • A.J. Mayer
    University of Calgary, NW Calgary, Alberta, Canada
  • R. Schupp
    MPI, Muenchen, Germany
  
  Funding: Funded by Natural Sciences and Engineering Research Council of Canada (NSERC)
Modern rare isotope facilities provide beams of shortlived radionuclides primarily for studies in the field of nuclear structure, nuclear astrophysics, and low energy particle physics. At these facilities, many activities such as re-acceleration, improvement of resolving power, and precision experimental measurements require charge breeding of ions. However, the charge breeding process can increase the energy spread of an ion bunch, adversely affecting the experiment. A Cooler Penning Trap (CPET) is being developed to address such an energy spread by means of sympathetic electron cooling of the Highly Charged Ion bunches to . 1 eV/q. Recent work has focused on developing a strategy to effectively detect the trapped electron plasma without obstructing the passage of ions through the beamline. The first offline tests demonstrate the ability to trap and detect more than 108 electrons. This was achieved by using a novel wire mesh detector as a diagnostic tool for the electrons.
* E.M. Burbidge et al, Rev Mod Phys, 29 547 (1957)
** V.V. Simon et al, Phys Rev C, 85 064308 (2012)
*** Z. Ke et al, Hyp Int, 173 103 (2006)
**** U. Chowdhury et al, AIP Conf Proc, 1640 120 (2015) 		 
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MOPF08 Secondary Electron Measurements at the HIM Electron Cooler Test Set-Up 48
 
  • M.W. Bruker, K. Aulenbacher, J. Dietrich, A. Hofmann, T. Weilbach
    HIM, Mainz, Germany
  
  The planned advances in electron cooling technology aimed at improving the operation of future hadron storage rings include an increase in electron beam current and acceleration voltage. A test set-up has been built at Helmholtz-Insitut Mainz (HIM) to optimize the recuperation efficiency of such high-current beams in energy recovery operation, requiring a thorough understanding of their interaction with external electric and magnetic fields, such as those found in a Wien velocity filter. Beam diagnostics are carried out using a BPM and current-sensing scraper electrodes. At present, the set-up can be successfully operated at U=17 kV, I=600 mA, showing a relative secondary electron current of about 2·10-4. We present the current state of the project and its objectives for the foreseeable future.  
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MOPF12 N-body Code to Demonstrate Electron Cooling 59
 
  • S. Abeyratne, B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
  • B. Erdelyi
    ANL, Argonne, USA
  
  In the Electron Ion Collider (EIC), the collision between the electron beam and the proton, or heavy ion, beam results in emittance growth of the proton beam. Electron cooling, where an electron beam and the proton beam co-propagate, is the desired cooling method to cool or mitigate the emittance growth of the proton beam. The pre-booster, the larger booster, and the collider ring in EIC are the major components that require electron cooling. To study the cooling effect, we previously proposed Particles' High order Adaptive Dynamics (PHAD) code that uses the Fast Multiple Method (FMM) to calculate the Coulomb interactions among charged particles. We further used the Strang splitting technique to improve the code's efficiency and used Picard iteration-based novel integrators to maintain very high accuracy. In this paper we explain how this code is used to treat relativistic particle collisions. We are able calculate the transverse emittances of protons and electrons in the cooling section while still maintaining high accuracy. This presentation will be an update on progress with the parallelization of the code and the current status of production runs.  
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MOPF13 Taper and Tuner Scheme of a Multi-Frequency Cavity for the Fast Kicker Resonator in MEIC Electron Circular Cooler Ring 63
 
  • Y.L. Huang
    IMP/CAS, Lanzhou, People's Republic of China
  • R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
  
  An ultra-fast harmonic kicker consisted of normal conducting resonators with high transverse shunt impedance thus less RF power consumption was designed for the proposed Medium energy Electron Ion Collider (MEIC). In the prototype design, four quarter wave resonator (QWR) based deflecting cavities are used to generate ten cosine harmonic waveforms, the electron bunches passing through these cavities will experience an integral effect of all the harmonic fields, thus every 10th bunch in a continues bunch train of 10th harmonic bunch frequency will be kicked while all the other bunches un-kicked. Ten harmonic waves are distributed in the four cavities with the proportion of 5:3:1:1. For the multi-frequency cavities, a great challenge is to tune each harmonic to be exact frequency. In this paper, the taper and tuning scheme for the 5-modes cavity is presented. Five taper points in the inner conductor are chosen to make the five frequencies to be odd harmonics. Five stub tuners on the outer conductor are used to tune every harmonic back to its target frequency from the manufacturing errors.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. 		 
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MOPF14
 MEIC Electron Cooler Architecture and Beam Simulations  
 
  • F.E. Hannon
    JLab, Newport News, Virginia, USA
  
  A discussion of the complexities in meeting the MEIC electron cooling beam specifications is presented. Simulations of various schemes are shown to evaluate the best architecture.  
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TUXAUD02 Project of Electron Cooler for NICA 82
 
  • I.N. Meshkov, E.V. Ahmanova, A.G. Kobets, O. Orlov, V.I. Shokin, A.A. Sidorin, S. Yakovenko
    JINR, Dubna, Moscow Region, Russia
  • M.N. Kokurkin, N.Yu. Lysov
    Allrussian Electrotechnical Institute, Moskow, Russia
  
  The problems of development of high energy electron coolers are discussed on the basis of the existing experience. Necessities of electron cooling application to NICA collider are considered and the project parameters of the electron cooler at NICA collider are presented. Electron cooler of the NICA Collider is under design and development of its elements at JINR. It will provide the formation of an intense ion beam and maintain it in the electron energy range of 0.5'2.5 MeV. To achieve the required energy of the electrons all the elements of the Cooler are placed in the tanks filled with sulfur hexafluoride (SF6) gas under pressure of 6 atm. For testing the Cooler elements the test bench «Recuperator» is used and upgraded. The results of testing of the prototypes of the Cooler elements and the present stage of the technical design of the Cooler are described in this paper.  
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TUXAUD03
 ERL Cooling Ring Concepts for the MEIC  
 
  • S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, F. Marhauser, R.A. Rimmer, C. Tennant, H. Wang, H. Zhang, Y. Zhang
    JLab, Newport News, Virginia, USA
  
  Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150
The MEIC design at Jefferson Lab will collide electrons in a storage ring with ions in a separate ring. In order to enhance the luminosity, the ions must be cooled in a cooling channel. The required current and charge necessary to cool the ions is on the order of 200 mA and 420 pC at an electron energy as high as 55 MeV. This is too high for a DC accelerator such as a pelletron and so the electron beam must be provided by an Energy Recovery Linac (ERL). This presentation will discuss two options for such an ERL and show some early results of modeling and simulation for these designs. At least at the highest energy, the beam quality seems to be good enough to provide a reasonable cooling rate for the ions. 		 
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TUXAUD04
 Conceptual Design of the HIAF Electron Cooling System  
 
  • L.J. Mao, W.P. Chai, J. Li, P. Li, X.M. Ma, G.D. Shen, L.N. Sheng, M.T. Tang, J.W. Xia, T.L. Yan, J.C. Yang, X.D. Yang, D.Y. Yin, Y.J. Yuan, H. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  
  A new accelerator complex HIAF is under design at IMP Lanzhou to provide intense primary and radioactive ion beams for nuclear physics, atomic physics and applied researches. The key parts of HIAF are the booster ring which is used to accumulated heavy ions and the spectrometer ring which can be used as platform for nuclear and atomic physics experiments. A magnetized electron cooling device is supposed to be used in the booster ring for decreasing the transverse emittance of injected beams. Meanwhile, a magnetized electron cooling device together with a ultra-low temperature electron target are also considered to be equipped in the spectrometer ring. In this paper, the conceptual design and main parameters of the electron cooling devices are presented, and the instabilities of cooled high intensity heavy-ion beams are discussed preliminarily.  
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TUYAUD01
 Overview of Development of High Current Electron Sources for ERL Based Bunched Beam Electron Cooling  
 
  • M. Poelker
    JLab, Newport News, Virginia, USA
  
  New initiatives at Jefferson Lab require photoguns operating at 350 kV bias voltage. These initiatives include the construction of a test beamline to study high bunch-charge magnetized beams needed for cooling proton beams at electron-ion colliders. Worldwide, a number of groups have made great progress developing photoguns operating at 350 kV and higher. This contribution describes Jefferson Lab's efforts to build such a gun, but with an inverted-insulator geometry. The inverted-insulator geometry offers advantages over gun designs that employ large cylindrical insulators, but it introduces at least one new challenge, namely, how to reliably apply voltage to the cathode electrode via a high voltage cable without breakdown, which sometimes leads to puncture and catastrophic failure of the insulator. In addition, this contribution describes recent studies devoted to improving our understanding of field emission, and methods to eliminate it. The talk will conclude with a brief discussion of perceived advantages/disadvantages of different high current electron gun options, which could serve as starting-point road map aimed at identifying necessary future R&D.  
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TUYAUD02
 High Current ERL Technology  
 
  • D. Kayran, I. Ben-Zvi, A.V. Fedotov, J. Kewisch, V. Litvinenko, V. Ptitsyn, B. Sheehy, E. Wang, W. Xu
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi, D. Kayran, 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.
High current ERL is essential for high energy electron coolers: magnetized, non-magnetized, coherent and other. SRF Linac with well dumped HOMs and high current low energy electron injector are required. At BNL the R&D high-current ERL is under commissioning. The key components of this ERL are: the highly damped 5-cell superconducting RF cavity and the high-current superconducting RF gun. The gun is equipped with multi-alkaline photocathode insertion system. Gun and Linac operating RF frequency is 703.59 MHz. Current laser operates at 10 MHz. The R&D ERL is designed to generate 350 mA of average current. The unique design of merger system allows operating at low injection energy while preserves emittance. The flexible returning loop optics allowed to study different aspects of stability operation. Recently 500 pC per bunch charge and 5mA current in short pulses has been demonstrated. Some aspects of BNL R&D ERL design and beam tests results will be discussed. After ERL commissioning in BLDG 912 the ERL will be relocated to RHIC IP2 to be used for LEReC. 		 
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TUYAUD03 Formation of Bunched Electron Beam at the Electron Cooler of CSRm 85
 
  • X.D. Yang, J. Li, X.M. Ma, L.J. Mao, M.T. Tang, T.L. Yan
    IMP/CAS, Lanzhou, People's Republic of China
  
  The motivation for formation of bunched electron beam at the electron cooler of CSRm is based on the three requirements. Firstly, the high energy electron cooling, especially, the ion beam with TeV energy, the bunched electron beam for cooling would be easier than the DC operating mode. Secondly, the electric field induced by the intensity modulated electron beam will be used for the suppression of instability developed in the high intensity ion beam after accumulation with the help of electron cooling, Thirdly, the electron beam was required to turn on and off in the different period of the atomic physics experiments. Some initial design and consideration were presented in this paper. And also the current situation and condition of CSRm electron cooler were described here. An off-line testbench will be established in the laboratory, and the test and the optimization will be explored in this experimentation. The validity of this system will be verified in the near future. The procedure of the modulation on the voltage of control electrode in the electron gun of the CSRm cooler was discussed. The scheme of off-line measurement was devised according to the progress.  
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TUYAUD04 Development of an Ultra Fast RF Kicker for an ERL-based Electron Cooler 89
 
  • A.V. Sy, A.J. Kimber, J. Musson
    JLab, Newport News, Virginia, USA
  
  The staged approach to electron cooling proposed for Jefferson Lab's Medium Energy Electron-Ion Collider (MEIC) utilizes bunched beam electron cooling with a single-pass energy recovery linac (ERL) for cooling in the ion collider ring. Possible luminosity upgrades make use of an ERL and full circulator ring and will require ultra-fast kickers that are beyond current technology. A novel approach to generating the necessary ultra fast (ns-level) RF kicking pulse involves the summation of specific subharmonics of the cooling electron bunch frequency; the resultant kicking pulse is then naturally constrained to have rise and fall times equal to the electron bunch frequency. The uniformity of such a pulse and its effects on the beam dynamics of the cooling electron bunch are discussed.  
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TUPF02 Development of the Electron Cooling Simulation Program for MEIC 101
 
  • H. Zhang, J. Chen, R. Li
    JLab, Newport News, Virginia, USA
  • H. Huang, L. Luo
    ODU, Norfolk, Virginia, USA
  
  Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177
In the medium energy electron ion collider (MEIC) project at Jefferson Lab, the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during collision at the collider ring. A DC cooler at the booster ring and a bunched beam cooler at the collider ring are proposed. To fulfil the requirements of the cooler design for MEIC, we are developing a new program, which allows us to simulate the following cooling scenarios: DC cooling to coasting ion beam, DC cooling to bunched ion beam, bunched cooling to bunched ion beam, and bunched cooling to coasting ion beam. The new program has been benchmarked with existing code in aspect of accuracy and efficiency. The new program will be adaptive to the modern multicore hardware. We will present our models and some simulation results. 		 
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TUPF08 High Efficiency Electron Collector for the High Voltage Electron Cooling System of COSY 112
 
  • M.I. Bryzgunov, A.V. Bubley, V.A. Chekavinskiy, I.A. Gusev, A.V. Ivanov, M.N. Kondaurov, V.M. Panasyuk, V.V. Parkhomchuk, D.N. Pureskin, A.A. Putmakov, V.B. Reva, D.V. Senkov, D.N. Skorobogatov
    BINP SB RAS, Novosibirsk, Russia
  • V.B. Reva
    NSU, Novosibirsk, Russia
  
  A high efficiency electron collector for the COSY high voltage electron cooling system was developed. The main feature of the collector is usage of special insertion (Wien filter) before the main collector, which deflects secondary electron flux to special secondary collector, preventing them fly to the electrostatic tube. In first tests of the collector in COSY cooler efficiency of recuperation better then 10-5 was reached. Before assembling of the cooler in Jülich upgrades of the collector and electron gun were made. After the upgrade efficiency better then 10-6 was reached. Design and testing results of the collector are described.  
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TUPF09 Decoupling and Matching of Electron Cooling Section in the MEIC Ion Collider Ring 116
 
  • G.H. Wei, F. Lin, V.S. Morozov, H. Zhang
    JLab, Newport News, Virginia, USA
  
  To get a luminosity level of 1033 cm-2 s-1 at all design points of the MEIC, small transverse emittance is necessary in the ion collider ring, which is achieved by an electron cooling. And for the electron cooling, two solenoids are used to create a cooling environment of temperature exchange between electron beam and ion beam. However, the solenoids can also cause coupling and matching problem for the optics of the MEIC ion ring lattice. Both of them will have influences on the IP section and other areas, especially for the beam size, Twiss parameters, and nonlinear effects. A symmetric and flexible method is used to deal with these problems. With this method, the electron cooling section is merged into the ion ring lattice elegantly.  
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TUPF10 Harmonic Stripline Kicker for MEIC Bunched Beam Cooler 120
 
  • J. Guo, H. Wang
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
In the current MEIC design, the ion collider ring needs to be cooled by a bunched electron beam of up to 200 mA 55 MeV, with the possibility to upgrade to 1.5 A. Although it's not impossible to design and build an ERL to provide such a beam, the technical risk and cost associated with such an ERL will be very high. An alternative is to recirculate the electron bunches in a ring for up to 25 turns until the bunch's quality is degraded, reducing the beam current in the ERL by a factor of 25. This scheme requires a pair of fast kickers that kick one in every 25 bunches. In this paper, we will analyze the electrodynamics of a harmonic stripline kicker for this application, and compare it to a harmonic resonator kicker. 		 
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TUPF11
 Progress in Experimental Demonstration of Cooling of Ions by a Bunched Electron Beam  
 
  • L.J. Mao, X.M. Ma, M.T. Tang, H. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  • A. Hutton, H. Wang, H. Zhang, Y. Zhang
    JLab, Newport News, Virginia, USA
  • V.V. Parkhomchuk, V.B. Reva
    BINP SB RAS, Novosibirsk, Russia
  
  Electron cooling is essential for achieving high luminosities for hadron colliders by enabling a reduction of emittance of hadron beams in storage rings. For several future projects such as low energy RHIC cooling program (LEReC) at BNL, a low energy electron-ion collider based on HIAF at IMP and a Medium energy Electron-Ion Collider (MEIC) at JLab, since the hadron beam energies are in a range from several GeV to 100 GeV, the required electron energy is up to 55 MeV. Such high energy electron beams can only be provided by a RF/SRF linac. As a result, the electron beam is highly bunched. Cooling of ions by a bunched electron beam has never been realized before, thus it becomes a critical R&D to these projects. Recently we proposed a proof-of-concept experiment to demonstrate cooling by a bunched electron beam utilizing an existing DC cooler at IMP. Here we present a progress report of this experiment. We briefly describe the experiment and show the design parameters. We then report hardware installation and results of the bench tests. We also summarize the results of the cooling simulation studies and discuss the required beam measurement capability.  
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TUPF12
 Single-Pass Simulations of Coherent and Conventional Electron Cooling Schemes  
 
  • I.V. Pogorelov, G.I. Bell
    Tech-X, Boulder, Colorado, USA
  • D.L. Bruhwiler
    RadiaSoft LLC, Boulder, Colorado, USA
  • V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the U.S DOE Office of Science, Office of Nuclear Physics. Simulations used the resources of NERSC, a U.S. DOE research facility.
Relativistic electron cooling is a key technology for achieving high luminosity required by the next generation of electron-ion and hadron-hadron colliders. We present a selection of computational techniques developed over the past several years for modeling the cooling physics on the ‘‘microscopic" timescales, i.e., during a single traversal of the cooling system. We will discuss modeling of the coherent electron cooling (CeC) scheme and its variants, and also the computation of the dynamical friction force responsible for conventional electron cooling. Modeling CeC requires a coupling between delta-f-PIC simulation of the modulator, customized simulations of the FEL amplifier, and electrostatic PIC simulations of the kicker subsections of the CeC cooler. Improved algorithms for computing the dynamical friction in single-pass frictional cooling simulations allow to control noise and correctly account for the statistics of rare but strong small-impact-parameter electron-ion collisions. We will present and briefly discuss the results of our simulations for the parameters of the CeC Proof-of-Principle Experiment at RHIC and the proposed MEIC CCR. 		 
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TUPF13
 Microbunching Instability in Recirculation Arcs  
 
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • S.V. Benson, D. Douglas, R. Li, C. Tennant, C.-Y. Tsai
    JLab, Newport News, Virginia, USA
  
  Microbunching instability is one of the most challenging issues in the design of the transport lines for recirculating or energy recovery linac machines. We have developed a linear Vlasov solver to incorporate relevant collective effects, including coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) impedances, for a general linear beamline analysis. With application of this code to two specially designed recirculation arcs * and a circulating cooler ring design of MEIC at Jefferson Lab **, the resultant microbunching gain functions are presented. Some underlying physics with inclusion of these collective effects are discussed. We expect that the analysis can help illustrate the microbunching gain evolution and its spectral response, and further improve the advanced beamline designs.
* D. Douglas et al., http://arxiv.org/abs/1403.2318
** MEIC Design Summary, http://arxiv.org/abs/1504.07961
 
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WEWAUD01
 Recent Progress in the Coherent Electron Cooling Experiment  
 
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • V. Litvinenko
    BNL, Upton, Long Island, New York, USA
  
  In this talk I will present progress in theoretical, simulation and experimental aspects of Coherent electron Cooling. I will present current status of the accelerator and other system under construction at RHIC for demonstration experiment.  
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WEWAUD02
 Matched Electron Cooling  
 
  • Y.S. Derbenev
    JLab, Newport News, Virginia, USA
  
  Electron cooling of an ion beam is considered in a ring with coupled optics matched with the solenoid of a cooling section. Betatron motion of ions is then represented as a superposition of the two independent circular modes of the two uncorrelated uncoupled canonical emittances, similar to the drift and cyclotron modes of an electron beam in a solenoid. Then cooling of the ion cyclotron mode is not limited by the ion space charge. Cooling of the drift mode is attained by use of dispersion of both beams introduced to the solenoid section. Ion optics organized in this way allows one to drastically diminish the space charge impact on the 4D emittance at beam stacking in a booster and cooling in a collider ring, thus enhancing the cooling rate. Equilibrium due to the IBS is estimated. We also evaluate the gain in luminosity by means of a round to flat beam transformation around the Interaction Point.
*Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. 		 
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WEXAUD01
 Single-pass Simulation Studies of High Energy Electron Cooling – Review and Future Directions  
 
  • D.L. Bruhwiler
    RadiaSoft LLC, Boulder, Colorado, USA
  
  Funding: Preparation of this report was supported by RadiaSoft LLC. Much of the work discussed here was supported by the US Department of Energy, Office of Science, Office of Nuclear Physics.
We review computational work on single-pass dynamics for relativistic hadrons in electron cooling systems relevant to high-luminosity electron-hadron colliders *. We identify parameter regimes where binary collisions must be correctly treated and where they can be neglected. The mathematically correct derivation of non-magnetized dynamical friction is presented, showing how the modified Pareto distribution of impact parameters can lead to incorrect interpretation of numerical results. We discuss important aspects of dynamical friction in magnetized electron cooling that require additional study.
* D.L. Bruhwiler, 'Simulating single-pass dynamics for relativistic electron cooling,' ICFA Beam Dynamics Newsletter 65, Eds. Y. Zhang and W. Chou (2014). 		 
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WEXAUD02 Emittance Growth From Modulated Focusing and Bunched Beam Electron Cooling 132
 
  • M. Blaskiewicz, J. Kewisch, C. Montag
    BNL, Upton, Long Island, New York, USA
  
  The Low Energy electron Cooling (LEReC) project at Brookhaven employs an energy recovery linac to supply electrons in the 1.6 to 5 MeV range. Along with cooling the stored ion beam these bunches create a coherent space charge field which can cause emittance growth. This process is investigated both analytically and via simulation.  
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WEXAUD04 Electron Cooling at GSI and FAIR – Status and Latest Activities 136
 
  • J. Roßbach, C. Dimopoulou, M. Steck
    GSI, Darmstadt, Germany
  
  The status, function and operation parameters of the existing and future electron coolers at GSI and FAIR are presented. We report on the progress of the ongoing recommissioning of the former CRYRING storage ring with its electron cooler at GSI. First systematic results on the cooling of a 400 MeV proton beam during the last ESR beamtime are discussed. Motivated by the demands of the experiments on high stability, precise monitoring and even absolute determination of the velocity of the electrons i.e. the velocity of the electron- cooled ion beams, high precision measurements on the electron cooler voltage at the ESR were carried out towards the refurbishment of the main high-voltage supply of the cooler. Similar concepts are underway for the CRYRING cooler high-voltage system.  
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THWCR01
 Exploring New Techniques for Operation and Diagnostics of Relativistic Electron Coolers  
 
  • K. Aulenbacher
    HIM, Mainz, Germany
  
  The Helmholtzinstitut Mainz (HIM) performs test experiments related to a possible improvement of high energy electron coolers. Results and activities concerning non-invasive beam diagnostics and beam control under large operational currents will be presented. Further, progress of our project to use turbogenerators as a means for potential free power generation in high energy electron coolers is presented.  
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FRXAUD02 Lepta - the Facility for Fundamental and Applied Research 179
 
  • A.G. Kobets, E.V. Ahmanova, P. Horodek, I.N. Meshkov, O. Orlov, A.A. Sidorin
    JINR, Dubna, Moscow Region, Russia
  • M.K. Eseev
    NAFU, Arkhangelsk, Russia
  
  The project of the Low Energy Positron Toroidal Accumulator (LEPTA) is under development at JINR. The LEPTA facility is a small positron storage ring equipped with the electron cooling system. The project positron energy is of 2 ' 10 keV. The main goal of the facility is to generate an intense flux of positronium atoms ' the bound state of electron and positron. Storage ring of LEPTA facility was commissioned in September 2004 and is under development up to now. The positron injector has been constructed in 2005 / 2010, and beam transfer channel ' in 2011. By the end of August 2011 the experiments on injection into the ring of electrons and positrons stored in the trap were carried out. In 2012 - 2015, the LEPTA trap optimization and new experiments on accumulation of electrons and positrons in the trap has been performed. Furthermore new cooler for positrons source has been designed and manufactured, its assembling is in progress. The recent results are presented here.  
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