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

本项目的目的是为快速储存离子束开发一种新的三维激光冷却方案。项目实施期间取得的主要成果有：1。用跟踪码“SAD”和分子动力学码“SOLID”进行了数值模拟，证明了采用共振耦合方法可以将激光纵向冷却力扩展到光束运动的横向自由度。设计并制作了低功率耦合射频腔模型。结果表明，适合束流结晶的存储环晶格必须满足以下两个条件：(a)每个晶格周期内，电子加速器振荡的相进小于127度；(b)束流能量小于环的跃迁能量。只要满足上述条件，就可以利用谐振耦合方法产生超冷光束。研究了光束内加热速率与聚焦场误差大小的关系。已经得出结论，为了使结晶束稳定，需要锥形的冷却力。为了产生锥形光，提出了一种使用多个激光器的可能的冷却方案，并通过分子动力学模拟验证了其有效性。

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.