固定调谐器对散裂中子源DTL电场稳定性的影响  

Influence of slug tuners on the field stabilization tuning of CSNS DTL

作　　者：瞿培华[1,2] 刘华昌 李阿红[1,2] 彭军 陈强[1,2] 吴小磊 李波[1,2] 樊梦旭 王云[1,2] 巩克云 QU Peihua;LIU Huachang;LI Ahong;PENG Jun;CHEN Qiang;WU Xiaolei;LI Bo;FAN Mengxu;WANG Yun;GONG Keyun(Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Spallation Neutron Source Center,Dongguan 523803,China)

机构地区：[1]中国科学院高能物理研究所,北京100049 [2]散裂中子源科学中心,东莞523803

出　　处：《核技术》2019年第12期28-35,共8页Nuclear Techniques

基　　金：国家自然科学基金(No.11105166);中国科学院青年创新促进会(No.201511)资助~~

摘　　要：中国散裂中子源(Chinese Spallation Neutron Source,CSNS)漂移管直线加速器(Drift Tube Linac,DTL)分为4个物理腔,于2015年12月正式投入运行。在DTL腔体低功率测量过程中,除DTL-1外,DTL-2、DTL-3和DTL-4工作频率均偏低,需要补偿的量超出了固定调谐器的调谐范围。原因发现是固定调谐器插入腔内过深,谐振腔模式发生耦合,腔体的双周期链被破坏,轴向电场稳定性不达标。利用CST(Computer Simulation Technology)软件计算轴向电场稳定性特性,给出耦合杆分组规律,加快了调谐效率。DTL-2所有固定调谐器达到行程极限,将两个可动调谐器在50 mm内长基础上向内延伸10 mm,工作频率达标;DTL-3和DTL-4在耦合杆上增加相同尺寸调谐环补偿频率。改进后的低功率测量结果表明:电场平整度达到±2%以内,稳定性调谐至±150%/MHz以内,温度25°C时谐频率调整至323.9 MHz±10 kHz,均满足工程使用要求。[Background]The Chinese spallation neutron source(CSNS)drift tube linac(DTL)accelerator has been put into operation since December 2015.During the low power measurement of the DTL cavity,except for DTL-1,the operating frequencies of DTL-2,DTL-3 and DTL-4 were all lower than the design value,and the frequency to be compensated exceeds the tuning range of the slug tuners.It was found that the insertion of the slug tuners was too deep and cavity modes were coupled,which destroyed the double-period chain of the cavity.[Purpose]This study aims to change the DTL structure to make field stability meet the engineering requirements.[Methods]The computer simulation technology microwave studio(CST MS)was used to calculate the stability characteristics of the axial electric field,and the grouping rule of the post couplers(PCs)was given,which accelerated the tuning efficiency.The internal length of DTL-2 slug tuners reached the adjustment limitation,hence two movable tuners were changed from 50 mm to 60 mm to make the working frequency satisfy design requirements.The tuning rings were added to the PCs of DTL-3 and DTL-4 cavity to increase the frequency.[Results]Experimental results show that the field flatness was within±2%,the stability was tuned to within±150%/MHz,and the resonant frequency was adjusted to 323.9 MHz±10 kHz at 25°C.[Conclusions]With structure adjustment for DTL,measurement results meet the engineering requirements.

关 键 词：固定调谐器 电场稳定性调谐 谐振频率 双周期链 耦合杆调谐环 

分 类 号：TL53[核科学技术—核技术及应用]