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Schwartz, B. T.

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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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TUCOC01 Simulations of an FEL Amplifier for Coherent Electron Cooling  
 
  • I. V. Pogorelov, D. L. Bruhwiler, B. T. Schwartz
    Tech-X, Boulder, Colorado
  • Y. Hao, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York
  • S. Reiche
    PSI, Villigen
 
  Next-generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques*. Particle-in-cell (PIC) simulations of a CeC modulator, performed with the VORPAL framework, generate macro-particle distributions with subtle but important phase space correlations. It is essential to couple these macro-particles into a 3D simulation code for the free-electron laser (FEL) amplifier, while retaining all details of the 6D phase space coordinates. We will present and discuss our recent results of modeling the FEL amplifier stage of the CeC process, including work on generating a 3D distribution of bunching parameters for GENESIS and an alternative approach for self-consistent treatment of shot noise and spontaneous radiation**, with no need to reorder the FEL macro-particles uniformly in the ponderomotive phase.

* V. N. Litvinenko and Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009)
** V. N. Litvinenko, "Macro-particle FEL model with self-consistent spontaneous radiation" (2002), unpublished

 
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