TUIOC  —  Electron cooling   (13-Sep-11   15:30—16:50)

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TUIOC01 High Energy Electron Cooling for an Electron-ion Collider  
 
  • Y. S. Derbenev
    JLAB, Newport News, Virginia
  
  Realization of high luminoity (up to 1035/cm2.s) polarized beams an Electron-Ion Collider designed for frontiers in Nuclear Physics at Jefferso Laboratory requires use of ERL-based electron beam of about 75 MeV energy range at average current 2-3 A electron beam circulating in a ring during about 100 revolutions. In the presented CW operated beam switching scheme based on use of a low energy pulsed beam-kicker, the average current in ERL does not exceed 30 mA at bunch repetition rate 15 MHz (while 1.5 GHz at 3A in the cooler ring). The cooling scheme is implementing 3 stages (cooling at injection enrgy, cooling after acceleration - takes about 10 min in both cases, and continuous cooling in the collider mode to maintain high luminosity). The synchronization, tolerances, space charge and other issues will be discussed.  
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TUIOC02 Simulations of the Modulator, FEL Amplifier and Kicker for Coherent Electron Cooling of 40 GeV/n Au+79  
 
  • D. L. Bruhwiler, G. I. Bell, K. Paul, I. V. Pogorelov, B. T. Schwartz
    Tech-X, Boulder, Colorado
  • Y. Hao, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York
  • S. Reiche
    PSI, Villigen
  
  Increasing the luminosity of hadron beams in particle accelerators is critical for the advancement of nuclear and particle physics. Coherent electron cooling (CeC) promises to cool relativistic hadron beams significantly faster than alternative methods.* We present simulations of 40 GeV/n Au+79 ions for a single pass through a CeC system, which consists of a modulator, a free-electron laser (FEL) amplifier and a kicker. In the modulator, the electron beam copropagates with the ion beam, which perturbs the electron beam density and velocity via anisotropic Debye shielding. Self-amplified spontaneous emission lasing in the FEL both amplifies and imparts wavelength-scale modulation on the electron beam perturbations. The modulated electric fields appropriately accelerate or decelerate the copropagating ions in the kicker. In analogy with stochastic cooling, these field strengths are crucial for estimating the effective drag force on the hadrons and, hence, the expected cooling time. The inherently 3D particle and field dynamics is modeled with the parallel VORPAL framework (modulator and kicker) and with GENESIS (amplifier), with careful coupling between codes. Physical parameters are taken from the CeC proof-of-principle experiment that is being designed at BNL.

* Litvinenko & Derbenev, "Coherent Electron Cooling," PRL (2009).

 
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