Ion emittance growth due to focusing modulation from slipping electron bunch

Wang, G.¹ 

[1] Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

关键词: ELECTRON COOLING;    IONS;    MHZ RANGE;    FOCUSING;    BROOKHAVEN RHIC;    RF SYSTEMS;    MODULATION;    SPACE CHARGE;    OPERATION;    TUNING;    VARIATIONS;    BEAM EMITTANCE;    BEAM BUNCHING;    MEV RANGE 01-10 Relativistic Heavy Ion Collider;   

DOI  :  10.2172/1172092
RP-ID  :  BNL--107540-2015-IR
RP-ID  :  BNL--C-A/AP/536
PID  :  OSTI ID: 1172092
Others  :  R&D Project: KBCH139
Others  :  Other: KB0202011
Others  :  TRN: US1500139

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

Low energy RHIC operation has to be operated at an energy ranging from ?? = 4.1 to ?? = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunch from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons??? space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.