Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.     

谈谈普朗克常数

 普朗克常数是现代物理学中最重要的物理常数之一,它成为区分宏观客体和微观客体的界限。普朗克常数的发现,在物理学的发展史上具有划时代的意义,它第一次表明了辐射能量的不连续性,这是现代物理学中富有革命性的事件。由于它的发现,物理学进入了一个全新的时代,这个理论物理学的新概念导致了量子理论的建立。普朗克常数发现前经典物理面临的困难19世纪末20世纪初,物理学的各分支已相当成熟,建立起了系统的理论,在应用中发挥越来越大的作用。但是,在和实验进一步对比的过程中,也出现了一些经典物理的范畴内无法解决的困难。黑体辐射19世纪末,人们用经典物理学解释黑体辐射实验时,出现了著名的所谓“紫外灾难”。     

Theoretical Design of a 104MHz Ladder Type IH-RFQ Accelerator

Beam dynamics and rf designs of a 104 MHz ladder type IH-RFQ （L-IH-RFQ） accelerator are finished at Peking University for the acceleration of 14C＋ from 40 keV to 500 keV. As a specific feature, the output beam energy spread is as low as 0.6% achieved with the internal discrete bunching method, which makes potential applications of RFQ feasible, such as accelerator mass spectrometry and ion implantation. Tolerances of the beam dynamics design are studied by means of changing the input beam parameters, and the results are quite satisfying. On the other hand, the L-IH-RFQ structure is employed, taking advantage of its mechanical stability and the absence of inter-electrode voltage asymmetry. Radio-frequency properties are studied and optimized for reducing power loss with Microwave Studio （MWS）. Tuning of the field flatness and frequency is investigated in principle.     

Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of ¹⁴C⁺ in the framework of RFQ based ¹⁴C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. ¹⁴C⁺ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.     

束团压缩用踢波器的模型腔

 为了提高中子产额,法兰克福强中子源采用Mobley型束团压缩器来增强打靶时质子流的密度,其入口处由射频踢波器实现微脉冲的偏转,踢波器由一对电偏转板和串联电感线圈组成谐振腔体。考虑到高频下寄生电容效应、导体腔壁对线圈电感的影响以及涡流效应对线圈交流电阻的影响,对一台模型腔的射频特性进行了理论预测。对腔体内电磁场分布进行了数值模拟,并利用电容微扰法进行了冷模测量。针对谐振频率、品质因数和并联分路阻抗等参数,分析比较了理论计算、数值模拟及冷模测量的结果,总结得出射频踢波器的有效设计方法。     

在WBEPM理论中受扰里德堡能级研究

在最弱受约束电子势模型理论下,研究了外来微扰能级对里德堡能级系列的影响,给出了确定外来微扰能级位置的方法.依此计算了钡原子6snp(n≥15).P1和6snd(n≥9)3D3两个里德堡能级系列的量子数亏损和能级.计算结果和实验值的绝对误差在1 cm-1以内,达到了较高的精度.