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Simulation Study of the Beam Loading Effects During the Bunch Merging in HIAF-BRing
Fucheng CAI, Jiancheng YANG, Jiawen XIA, Dayu YIN, Jie LIU, Guodong SHEN, Geng WANG, Shuang RUAN, Liping YAO, Xiaoqiang CHEN
2020, 37(2): 180-185. doi: 10.11804/NuclPhysRev.37.2019058  Published:2020-07-15
Keywords: HIAF-BRing, wake field, beam loading effect, bunch merging, potential well distortion
In the booster ring (BRing) of the High Intensity heavy-ion Accelerator Facility (HIAF), the multi-bunch should be merged into single bunch after the acceleration. To study the influence of the beam loading effects during the bunch merging, the simulations of particle tracking with 238U35+ beam are carried out. According to the simulation results, during the bunching merging, the beam loading effects can result in the growth of the momentum spread and the bunch length as well as the oscillation of the bunch length and the bunch center. The potential well distortion induced by the wake voltage and wake field coupling during the bunch merging are the reasons why the bunch center oscillates and the emittance of the beam grows. To reduce the influence of the beam loading effects, the multi-harmonic feed-forward system is employed to compensate the wake voltage. With the feed-forward system, the beam loading effects can be compensated during the bunching merging. The feed-forward system is able to guarantee the high quality of the beam for extraction in the BRing. The frequency range to be covered and the largest wake voltage to be compensated by the feed-forward system are determined according to the simulation results.
Design and Simulation of EicC Beam Cooling Scheme
Fu MA, Lijun MAO, He ZHAO, Jie LIU, Guodong SHEN, Jiancheng YANG
2023, 40(1): 36-44. doi: 10.11804/NuclPhysRev.40.2022029  Published:2023-03-20
Keywords: electron cooling, bunched beam cooling, intrabeam scattering, luminosity, collider
The study of the internal structure of nucleons is an important frontier of current theoretical and experimental research. The high-energy scattering experiments are ideal tools for exploring the structure of nucleons. A Polarized Electron Ion Collider(EicC) is proposed based on High Intensity heavy-ion Accelerator Facility(HIAF) by Institute of Modern Physics, Chinese Academy of Sciences. EicC will provide polarized electron and proton beams with a center-of-mass energy of $15 \sim 20$ GeV. The luminosity is up to $2\times10^{33}\ {{\rm{cm}}^{-2}{\rm{s}}^{-1}}$. Effective cooling of the ion beams is needed to achieve the luminosity goal. Due to the characteristics of large initial emittance, high energy and high intensity of ion beam, EicC adopts a two-stage beam cooling scheme. First, a conventional DC electron cooler is used to significantly reduce the ion beam emittance in the Booster ring(BRing). Secondly, a high-energy bunched cooling system based on an energy recovery linear(ERL) is used to suppress the emittance growth of ion beam during the collision in the collider ring(pRing). In this paper, taking the proton beam as an example, the effects of the electron beam size, temperature, magnetic field and lattice function on the cooling rate and cooling process in the EicC beam cooling device are simulated and investigated, and finally the beam cooling parameters that meet the luminosity requirements are obtained.
EicC Collider Lattice Design
Ruiru WANG, Jiancheng YANG, Guodong SHEN, Geng WANG
2020, 37(1): 40-45. doi: 10.11804/NuclPhysRev.37.2019048  Published:2020-03-01
Keywords: EicC, collider, lattice design, chromaticity compensation, dynamic aperture
Electron Ion Collider in China (EicC), a new plan proposed by Institute of Modern Physics, Chinese Academy of Science to upgrade the HIAF facility, is mainly designed for studying sea quark, gluon and valence quark. The Center Mass Energy of the EicC is near 20 GeV. In order to maintain polarizability of proton bunched beams, the pRing (proton Ring) is designed to have the octave shape layout, while the racetrack layout is adopted by the eRing (electron Ring) to make full use of the tunnel space. For pRing, the proton center energy is 20 GeV, the horizontal and vertical rms emittance is 300 and 180 nm·rad respectively, and the β function at collider point is 0.08 and 0.04 m in the horizontal and vertical plane. For eRing, the electron beam center energy is 3.5 GeV, the rms emittance in transversal plane is 60 nm·rad, and the β function at collider point is optimized to be 0.4 and 0.12 m in horizontal and vertical direction respectively. As a result, the designed luminosity can achieve 2×1033 cm–2s–1. Furthermore, the influence of chromaticity compensation scheme on the Dynamic Aperture (DA), including the compensation patterns, the beta function and the phase advance in the collision points, is also studied. Accordingly, chromaticity compensation scheme is finalized as compensating by arc and short straight sextupoles, the DA of the pRing (>8σ) and the eRing (>20σ) can meet the design requirement of the beam size larger than 6σ.