04 Hadron Accelerators
A11 Beam Cooling
Paper Title Page
MOZGBF3 40 Years of Electron Cooling at CERN 69
 
  • G. Tranquille
    CERN, Geneva, Switzerland
 
  For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.  
slides icon Slides MOZGBF3 [14.902 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF3  
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TUPAF039 Electron Cooling Simulation and Experimental Benchmarks at LEIR 776
 
  • A. Latina, H. Bartosik, N. Biancacci, R. Corsini, D. Gamba, S. Hirlaender, A. Huschauer
    CERN, Geneva, Switzerland
 
  A fast and accurate simulation of Electron Cooling has recently been implemented in the tracking code RF-Track. The implementation, which is based on a "hybrid kinetic" model, enables the simulation of a large variety of realistic scenarios, including imperfections such as gradients in the electron density, misalignments of electrons / ions / solenoidal fields, both in the static and in the dynamic regimes. Benchmarks of the simulations against measurements performed at LEIR, using Lead and Xenon ions, are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF039  
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TUPAF056 The CERN-ELENA Electron Cooler Magnetic System 842
 
  • G. Tranquille, L.V. Jørgensen
    CERN, Geneva, Switzerland
  • D. Luckin, R.J. Warner
    Tesla Engineering Limited, West-Sussex, United Kingdom
 
  Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF056  
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TUPAF078 Recent Results of HESR Original Stochastic Cooling Tanks at COSY 913
 
  • R. Stassen, B. Breitkreutz, N. Shurkhno
    FZJ, Jülich, Germany
 
  The High Energy Storage Ring (HESR) of the FAIR project at GSI Darmstadt will be very important for different scientific programs due to the modularized start version of FAIR. Stochastic cooling together with barrier bucket operation will be the key component to fulfill the requirements of the different experiments. First pickup and first kicker of the HESR stochastic cooling system have been installed into the COSY accelerator at FZJ Jülich. COSY is well suited to test the performance of the HESR stochastic cooling hardware at different energies and variable particle numbers. The novel dedicated HESR-structures were already successfully tested at the Nuclotron in Dubna for longitudinal cooling and during a beam time 2017 for transverse cooling at COSY. The results of the last stochastic cooling beam time will be presented as well as the first use of GaN based amplifiers in a stochastic cooling system. The HESR needs fast transmission-lines between PU and KI. Beside air-filled coax-lines, optical hollow fiber-lines are very attractive. First results with such a hollow fiber used for the transverse signal path will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF078  
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TUPAL068 The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring 1171
 
  • G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068  
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TUPAL069 Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam 1174
 
  • Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, H. Wang, S. Wang, H. Zhang
    JLab, Newport News, Virginia, USA
  • J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed*. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals.
* L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069  
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TUPAL072 Dispersive Electron Cooling for JLEIC 1178
 
  • H. Zhang, Y.S. Derbenev, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
JLEIC is the electron ion collider under design at Jefferson Lab, which will provide a luminosity up to 1034 cm-2s−1. To reach the high luminosity, short ion and electron bunches with high charge density colliding in high frequency are proposed in JLEIC design. The high charge density of the ion beam leads to strong intrabeam scattering effect, which enlarges the ion beam emittance and ruins the luminosity if not mitigated. Magnetized electron cooling is implemented to overcome the intrabeam scattering effect and to reduce or maintain the ion beam emittance. In this paper, we discuss the redistribution of the cooling effects in the longitudinal and the transverse directions by introducing the dispersion of the ion beam in the cooling section. When the charge density of the cooling electron beam varies, the dispersion of the ion beam leads to an increase of the transverse cooling rate and a reduction of the longitudinal cooling rate, while the total decrement of the Courant-Snyder invariant of the ion beam increases. Both theoretical analysis and numerical calculation are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL072  
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