AI 中文总结
该研究在RIKEN重离子直线加速器LEBT中引入含氟气体实现低能He2+束的空间电荷补偿，安装新型栅网式斩波器后成功稳定加速19.3 μA He2+束流，占空比达10%，对应连续波模式约193 μA，可支撑200 μA级束流加速。
AI 中文摘要
本研究通过在理化学研究所重离子直线加速器（RIKEN Heavy-Ion Linear Accelerator）的低能束流输运线（LEBT）中引入含氟气体，探究低能He2+束的空间电荷补偿（SCC）效果。引入SF6、C3F8和CHF3三种气体后，束流在LEBT中的传输效率均得到提升，其中SF6的提升效果最为显著；而引入Kr时，束流电流的提升幅度相对较小，效果弱于含氟气体。含氟气体的引入使斩波束流的上升时间延长至约10 ms，未使用预聚束器的实验证实，预聚束器是导致上升时间变慢的主要原因。此外，Kr与含氟气体之间上升时间的显著差异表明，两种情况下可能由不同的电荷载流子参与空间电荷补偿。基于上述结果，在射频四极直线加速器（RFQ）的上游紧邻处安装了新型栅网式束流斩波器，该配置可在LEBT中维持直流束流的同时，在RFQ前生成短束流脉冲，从而实现有效空间电荷补偿与快速束流电流上升。采用新型斩波器的加速实验中，19.3 μA的He2+束流成功且稳定地加速至放射性同位素产生束流线，占空比为10%，对应连续波模式下约193 μA的束流，证明该方法可有效实现200 μA级He2+束流的加速。
英文摘要
This study investigates the space-charge compensation (SCC) of a low-energy He2+ beam by introducing fluorine-containing gases into the low-energy beam transport line (LEBT) of the RIKEN Heavy-Ion Linear Accelerator. The introduction of SF6, C3F8, and CHF3 improved beam transmission through the LEBT, and the largest improvement was obtained using SF6. In contrast, the increase in the beam current with Kr was relatively small, and its effect was less pronounced than that of the fluorine-containing gases. The introduction of fluorine-containing gases increased the rise time of the chopped beam to approximately 10 ms. Experiments performed without the prebuncher confirmed that the prebuncher was largely responsible for this slow rise. Furthermore, the substantial difference in the rise time between Kr and the fluorine-containing gases suggests that different charge carriers may contribute to the SCC in these two cases. Based on the results, a new grid-type beam chopper was installed immediately upstream of the radio-frequency quadrupole linac (RFQ). This configuration allows short beam pulses to be generated immediately before the RFQ while maintaining a direct-current beam in the LEBT, thereby achieving both an effective SCC and a fast beam-current rise. In an acceleration test using the new chopper, a 19.3 micro A He2+ beam was successfully and stably accelerated to the radioisotope-production beamline at a duty factor of 10%. This corresponds to approximately 193 micro A in continuous-wave mode operation, demonstrating that the proposed method is effective for realizing the acceleration of a 200 micro A-class He2+ beam.
Comments7 pages, 7 figures. Corrected errors in the introduction: nuclear reaction and the number of cavities
