BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
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 with the parallel VORPAL framework generate macro-particle distributions with subtle but important phase space correlations. 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 implemented an alternative approach based on particle-clone pairs**. Our approach allows for self-consistent treatment of shot noise and spontaneous radiation, with no need for quiet-start initialization of the FEL macro-particles' ponderomotive phase. We present results of comparing fully 3D amplifier modeling based on the particle-clone approach vs GENESIS simulations where distribution of bunching parameter was used as input. We also discuss enabling direct coupling of the VORPAL delta-f simulation output into 3D distributions of particle-clone pairs.
* 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** V.N. Litvinenko, "Macro-particle FEL model with self-consistent spontaneous radiation," unpublished (2002).
BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
JLAB, Newport News, Virginia, USA
BINP SB RAS, Novosibirsk, Russia
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.
BNL, Upton, Long Island, New York, USA
In Coherent Electron Cooling (CEC), it is essential to study the amplification of electron response to a single ion in the FEL process, in order to proper align the electron beam and the ion beam in the kicker to maximize the cooling effect. In this paper, we use Genesis to simulate the amplified electron beam response of single ion in FEL amplification process, which acts as 'Green function' of the FEL amplifier.
BNL, Upton, Long Island, New York, USA
* V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB
BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
The kink instability is one of the major beam dynamics issues of the linac-ring based electron ion collider. This head-tail type instability arises from the oscillation of the electron beam inside the opposing ion beam. It must be suppressed to achieve the desired luminosity. There are various ways to suppress the instability, such as tuning the chromaticity in the ion ring or by a dedicated feedback system of the electron beam position at IP, etc. However, each method has its own limitation. In this paper, we will discuss an alternative opportunity of suppressing the kink instability of the proposed eRHIC at BNL using the existing pickup-kicker system of the stochastic cooling system in RHIC.
BNL, Upton, Long Island, New York, USA
An Energy Recovery Linac (ERL) with a high peak electron bunch current is proposed for the Electron-Ion collider (eRHIC) project at the Brookhaven National Laboratory. The present design is based on the multi-pass electron beam transport in existing tunnel of the Relativistic Heavy Ion Collider (RHIC). As a result of a high peak current and a very long beam transport, consideration of various collective beam dynamics effects becomes important. Here we summarize effects of the coherent synchrotron radiation, resistive wall, accelerating cavities and wall roughness on the resulting energy spread and energy loss for several scenarios of the eRHIC project, including results for different electron distributions. A possible correction scheme of accumulated correlated energy spread is also presented.
BNL, Upton, Long Island, New York, USA
The thorough study of coherent electron cooling, the modern cooling technique capable to deal with accelerators operating in the range of few TeVs*, rises many interesting questions. One of them is a shielding dynamics of a hadron in an electron beam. Now this effect is computed analytically in an infinite beam approximation**. Many effects are drastically different in finite and infinite plasmas. Here we propose a method to compute the dynamical shielding effect in a finite cylindrical plasma - the realistic model of an electron beam in accelerators.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** G. Wang, M. Blaskiewicz, Phys. Rev. E 78, 026413 (2008).
Tech-X, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
Next generation electron-hadron colliders will require effective cooling of high-energy, high-intensity hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques*. The parallel VORPAL framework is used for 3D delta-f PIC simulations of anisotropic Debye shielding in a full longitudinal slice of the co-propagating electron beam, choosing parameters relevant to the proof-of-principle experiment under development at BNL. The transverse density conforms to an exponential Vlasov equilibrium for Gaussian velocities, with no longitudinal density variation. Comparison with 1D1V Vlasov/Poisson simulations shows good agreement in 1D. Parallel 3D simulations at NERSC show 3D effects for ions moving longitudinally and transversely. Simulation results are compared with the constant-density theory of Wang and Blaskiewicz**.
* V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** Wang and Blaskiewicz, Phys Rev E 78, 026413 (2008).
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Coherent Electron Cooling (CEC) based on FEL amplifier promises to be a very good way to cool protons and ions at high energies. A proof of principle experiment to demonstrate cooling at 40 GeV/u is under construction at BNL. One of possible sources to provide sufficient quality electron beam for this experiment is a SRF photoinjector. In this paper we discuss design and simulated performance of the photoinjector based on existing 112 MHz SRF gun and newly designed single-cavity SRF linac operating at 704 MHz.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Future electron-hadron collider eRHIC will consist of a six-pass 30-GeV electron ERL and one of RHIC storage rings operating with energy up to 250 GeV. The collider design extensively utilizes superconducting RF (SRF) technology in both electron and hadron parts. This paper describes various SRF systems, their requirements and parameters.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Tech-X, Boulder, Colorado, USA
