RadiaSoft LLC, Boulder, Colorado, USA
Relativistic magnetized electron cooling is one of the techniques explored for achieving the ion beam luminosity requirements of the presently designed electron-ion collider (EIC) facility at Brookhaven National Lab. Because the cooling system will have to operate in previously untested parameter regimes, accurate computation of magnetized dynamic friction is required at the design stage in order to obtain reliable estimates of the cooling time. At energies of interest to the EIC cooling system design, the beam-frame interaction time in the cooler becomes short compared to the plasma period, and some assumptions applicable to the physics of cooling at lower energies become invalid in this high-energy setting. We present and discuss the results of first-principles modeling the magnetized dynamic friction force in the strong-field, short-interaction-time regime, as well as a parametric longitudinal friction force model that we developed starting with a reduced ion-electron interaction potential. The model parameters are related in a simple way to the interaction time and the ion charge. We compare our simulation results to the predictions of previously developed theoretical models.
RadiaSoft LLC, Boulder, Colorado, USA
SLAC, Menlo Park, California, USA
Because the efficacy of conventional electron cooling falls off rapidly with energy, reaching the cooling times at collision energy targeted by the Electron-Ion Collider (EIC) design can be challenging. A possible solution is offered by cooling schemes that are based on fundamentally different techniques such as microbunched electron cooling (MBEC). Regular PIC simulations of MBEC in the parameter regime of the EIC cooling system would require a prohibitively large number of particles to resolve the evolution of the ion-imprinted phase space density modulation. We explored a solution to this problem by developing and implementing in the code Warp an approach based on two perturbative techniques, the beam-frame delta-f method and a variant of the distribution difference (DD) technique. To model the dynamics of the ion-seeded modulation in the MBEC chicanes, we developed an approach that combines the DD and quiet start techniques with analysis of correlations between the divergence of DD trajectories and their location within the e-beam. We have also prototyped in Warp the computation of the time-dependent 3D wakefield in the MBEC kicker.
