Design Study of a Coupling RF Cavity for Three-Dimensional Laser Cooling

本项目的目的是开发一种新的用于快存储离子束的三维激光冷却方案。项目期间取得的主要成果如下：1.利用跟踪程序SAD和分子动力学程序SOLID，利用共振耦合方法，数值证明了纵向激光冷却力可以扩展到光束运动的横向自由度。设计并制作了低功耗的耦合射频腔模型。结果表明，适合于束流晶化的存储环晶格必须满足以下两个条件：(A)。每个晶格周期的倍他电子管振荡的相位提前小于127度，以及(B)。束流能量小于光环的跃迁能量。只要满足上述条件，就有可能通过共振耦合方法产生超冷梁。研究了束内加热速率与聚焦场误差量之间的关系。得出的结论是，为了稳定晶束，需要一个锥形的冷却力。为了产生锥形光，提出了一种可能的多激光器冷却方案，并用分子动力学模拟验证了该方案的有效性。

The purpose of this project is to develop a novel three-dimensional laser cooling scheme for fast stored ion beams. The main results obtained during the term of the project are :1. It has been numerically demonstrated, with the tracking code "SAD" and molecular dynamics code "SOLID", that longitudinal laser cooling force can be extended to the transverse degrees of freedom of beam motion by employing the resonant coupling method.2. A low-power model of coupling RF cavity was designed and fabricated.3. It has been shown that the storage-ring lattice suitable for beam crystallization must satisfy the following two conditions : (a). the phase advance of betatron oscillation per lattice period is below about 127 degrees, and (b). the beam energy is less than the transition energy of the ring.4. Provided that the above-mentioned conditions are fulfilled, it is possible to produce an ultra-cold beam by means of the resonant coupling method.5. The relation between intra-beam heating rate and the amount of focusing field errors was studied.6. It has been concluded that, in order to stabilize a crystalline beam, a tapered cooling force is necessary.7. In order to generate a tapered light, a possible cooling scheme using multiple lasers has been proposed, and its validity was tested with molecular dynamics simulations.