【作者】 代志勇； 张开志； 章文卫； 谢宇彤；

【Author】 DAI Zhi-Yong ZHANG Kai-Zhi ZHANG Wen-Wei XIE Yu-Tong (Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang 621900,China)

【机构】 中国工程物理研究院流体物理研究所；

【摘要】 "神龙一号"加速器在束流调试初期出现了严重的BBU,该BBU是由偏心束流通过多功能腔时激励的TM₁₁₀模引起的.分别以解析分析、数值计算和实验测量等方法对多功能腔的高频特性进行分析.几种方法得到的TM₁₁₀模频率与实验结果吻合,而横向耦合阻抗则有倍数之差,但都证明多功能腔在TM₁₁₀模式下的横向耦合阻抗过大,是激励BBU的最主要的因素.为此,设计了对多功能腔其他功能不产生影响的可以轴向伸缩的网罩,用来屏蔽多功能腔间隙.使用网罩后效果非常显著,实验结果表明,BBU受到抑制,束流脉冲中的高频振荡消失.更多还原

【Abstract】 BBU（Beam breakup）instability once appeared in the early stage of"Dragon-Ⅰ"LIA,which was excited by TM₁₁₀ mode stimulated when the eccentric beam passed through the multi-functional cavity（MFC）.The radio frequency characteristics of MFC were analyzed with three methods such as analytic calculation,numerical computation,and measurement.The frequency of the TM₁₁₀ mode from these methods agreed with the experimental results,while the transverse coupling impedance was different from the experimental results by some times.The main BBU exciter was the big transverse coupling impedance of the MFC which could be concluded.A grid was designed to shield the gap of the MFC.The experiments show that the BBU was compressed and the high frequency oscillation disappeared.更多还原