单粒子微束辐照装置的束流光学计算

Beam optics simulation for the single-ion microbeam facility at Fudan University

利用束流光学计算程序TRANSPORT和TURTLE对基于2×3MV串列静电加速器的单粒子微束细胞精确照射装置的束流传输光学进行了一阶近似计算,得到了包括束流包络、束流相图、束斑大小及束流发散程度的相关数据。计算结果表明,对于能量1.5MeV,经2mm×2mm狭缝入射且初始发散角x'～y'≤3mrad的典型质子束流,通过优化光学元件的参数,在束线末端可获得束径x<0.2cm,y<0.3cm,发散角x'<4.8mrad,y'<6.5mrad的准平行束流,达到了微准直器获取单粒子微束所需的束流品质。计算结果为束线系统优化和束流调试工作提供了必要的参考依据。

A first-order simulation is performed on beam optics of the Fudan single-ion microbeam facility, which is designed to irradiate individual living cells at highly localized spatial region with accurately controlled dose. A typical proton beam of 1.5 MeV for routine experiments is simulated. The results of the transporting beam envelope and the beam profile, the phase space and the divergence angles at the end of the beam line show good status （x〈0.2 cm, y〈0.3 cm; x^2〈4.8 mrad, y^2〈6.5 mrad ） for extracting a collimated microbeam. Concerning the possible influences of space charge effects, 1.5 MeV protons with a beam current up to 7 mA （far higher than common value） is also calculated, the beam size at the end of the beam line can still be focused within 0.6 cm in diameter, with the divergence angles below 6.5 mrad. The results are still good enough for the requirements of a collimated microbeam throueh the carfillarv collimator.