PAC2013 - List of Authors (Zhang, H.)

Paper	Title	Page
MOPBA11	Space Charge Simulation in COSY Using Fast Multipole Method	195
	P. Snopok Illinois Institute of Technology, Chicago, IL, USA M. Berz, B.T. Loseth, K. Makino MSU, East Lansing, Michigan, USA H. Zhang JLAB, Newport News, Virginia, USA
	A method is presented that allows the computation of space charge effects of arbitrary and large distributions of particles in an efficient and accurate way based on a variant of the Fast Multipole Method (FMM). It relies on an automatic multigrid-based decomposition of charges in near and far regions and the use of high-order differential algebra methods to obtain decompositions of far fields that lead to an error that scales with a high power of the order. Given an ensemble of N particles, the method allows the computation of the self-fields of all particles on each other with a computational expense that scales as O(N). Furthermore, the method allows the computation of all high-order multipoles of the space charge fields that are necessary for the computation of high-order transfer maps and all resulting aberrations. Space charge effects are crucial in modeling the latter stages of the six-dimensional (6D) cooling channel for the Muon Collider. FMM has been implemented in COSY Infinity, and the results of applying it to simulating the 6D cooling channel for the Muon Collider are presented.

TUPHO02	Single Pass Electron Cooling Simulations for MEIC	583
	G.I. Bell, I.V. Pogorelov, B.T. Schwartz Tech-X, Boulder, Colorado, USA H. Zhang, Y. Zhang JLAB, Newport News, Virginia, USA
	Funding: This work is supported by the US DOE Office of Science, Office of Nuclear Physics, grant numbers DE-SC0009508 and DE-SC0000835. Resources of NERSC were used under contract No. DE-AC02-05CH11231. Cooling of medium energy protons is critical for the proposed Jefferson Lab Medium Energy Ion Collider (MEIC). We present simulations of electron cooling of protons up to 60 GeV. In the beam frame in which the proton and electrons are co-propagating, their motion is non-relativistic. We use a binary collision model which treats the cooling process as the sum of a large number of two-body collisions which are calculated exactly. This model can treat even very close collisions between an electron and ion with high accuracy. We also calculate dynamical friction using a delta-f PIC model. The code VSim (formerly Vorpal) is used to perform the simulations. We compare the friction rates with that obtained by a 3D integral over electron velocities which is used by BETACOOL.

TUPHO04	MEIC Electron Cooling Simulation Using Betacool	586
	H. Zhang, Y. Zhang JLAB, Newport News, Virginia, USA
	Funding: * Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357. Electron cooling of ion beams is the most critical R&D issue in Jefferson Lab's MEIC design. In the ion collider ring, a bunched electron beam driven by an energy-recovery SRF linac assisted by a circulate ring will be employed to cool protons or ions with energies up to 100 GeV/u, a parameter regime that electron cooling has never been applied. It is essential to understand how efficient the electron cooling is, particularly in the high energy range, to confirm the feasibility of the design. Electron cooling is also important in LEIC design although the ion energy is 25 GeV/u, lower than MEIC. In this paper, we will present first results of the simulation studies of electron cooling processes in the collider ring of both MEIC and LEIC using BETACOOL code.

Paper

Title

Page

Space Charge Simulation in COSY Using Fast Multipole Method

195

P. Snopok
Illinois Institute of Technology, Chicago, IL, USA
M. Berz, B.T. Loseth, K. Makino
MSU, East Lansing, Michigan, USA
H. Zhang
JLAB, Newport News, Virginia, USA

A method is presented that allows the computation of space charge effects of arbitrary and large distributions of particles in an efficient and accurate way based on a variant of the Fast Multipole Method (FMM). It relies on an automatic multigrid-based decomposition of charges in near and far regions and the use of high-order differential algebra methods to obtain decompositions of far fields that lead to an error that scales with a high power of the order. Given an ensemble of N particles, the method allows the computation of the self-fields of all particles on each other with a computational expense that scales as O(N). Furthermore, the method allows the computation of all high-order multipoles of the space charge fields that are necessary for the computation of high-order transfer maps and all resulting aberrations. Space charge effects are crucial in modeling the latter stages of the six-dimensional (6D) cooling channel for the Muon Collider. FMM has been implemented in COSY Infinity, and the results of applying it to simulating the 6D cooling channel for the Muon Collider are presented.

TUPHO02

Single Pass Electron Cooling Simulations for MEIC

583

G.I. Bell, I.V. Pogorelov, B.T. Schwartz
Tech-X, Boulder, Colorado, USA
H. Zhang, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: This work is supported by the US DOE Office of Science, Office of Nuclear Physics, grant numbers DE-SC0009508 and DE-SC0000835. Resources of NERSC were used under contract No. DE-AC02-05CH11231.
Cooling of medium energy protons is critical for the proposed Jefferson Lab Medium Energy Ion Collider (MEIC). We present simulations of electron cooling of protons up to 60 GeV. In the beam frame in which the proton and electrons are co-propagating, their motion is non-relativistic. We use a binary collision model which treats the cooling process as the sum of a large number of two-body collisions which are calculated exactly. This model can treat even very close collisions between an electron and ion with high accuracy. We also calculate dynamical friction using a delta-f PIC model. The code VSim (formerly Vorpal) is used to perform the simulations. We compare the friction rates with that obtained by a 3D integral over electron velocities which is used by BETACOOL.

TUPHO04

MEIC Electron Cooling Simulation Using Betacool

586

H. Zhang, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: * Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357.
Electron cooling of ion beams is the most critical R&D issue in Jefferson Lab's MEIC design. In the ion collider ring, a bunched electron beam driven by an energy-recovery SRF linac assisted by a circulate ring will be employed to cool protons or ions with energies up to 100 GeV/u, a parameter regime that electron cooling has never been applied. It is essential to understand how efficient the electron cooling is, particularly in the high energy range, to confirm the feasibility of the design. Electron cooling is also important in LEIC design although the ion energy is 25 GeV/u, lower than MEIC. In this paper, we will present first results of the simulation studies of electron cooling processes in the collider ring of both MEIC and LEIC using BETACOOL code.