The concept of dielectric-laser acceleration (DLA) provides the highest gradients among breakdown-limited (nonplasma) particle accelerators and thus the potential of miniaturization. The implementation of a fully scalable electron accelerator on a microchip by twodimensional alternating phase focusing (APF), which relies on homogeneous laser fields and external magnetic focusing in the third direction, was recently proposed. In this Letter, we generalize the APF for DLA scheme to 3D, such that stable beam transport and acceleration is attained without any external equipment, while the structures can still be fabricated by entirely twodimensional lithographic techniques. In the new scheme, we obtain signifcantly higher accelerating gradients at given incident laser field by additionally exploiting the new horizontal edge. This enables ultra-low injection energies of about 2.5 keV (beta = 0.1) and bulky high voltage equipment as used in previous DLA experiments can be omitted. DLAs have applications in ultrafast time-resolved electron microscopy and -diffraction. Our fndings are crucial for the miniaturization of the entire setup and pave the way towards integration of DLAs in optical fiber driven endoscopes, e.g., for medical purposes.
基于超冷原子的电子源最近已被提出作为在现代粒子加速器中广泛使用的常规光注入器或电子枪的替代物。基于超冷原子的电子源的优点在于从等离子体（由超冷原子的近阈值光电离产生）提取的电子具有非常低的温度，即低至几十开尔文。这些电子的提取具有产生非常低的发射率电子聚束的潜力。这些特性对于下一代粒子加速器至关重要，包括自由电子激光、等离子体加速器和未来的直线对撞机。该源也有许多潜在的直接应用，包括超快电子衍射（UED）和电子显微镜，由于其固有的高相干性。本文讨论了超冷电子束产生的基本机理，介绍了我们研制的超冷低发射度电子源。该源是基于一种新的交流磁光阱（AC-MOT）。对所提出的提取系统的详细模拟表明，对于1 pC的聚束电荷，可获得0.35 mm mrad的束流发射度，其中聚束长度为3 mm，能量扩展为1%。
Design of a Storage Ring based on a Fixed Field Alternating Gradient Configuration with an Internal Target for Heavy-Ion Beams with Stochastic Charge State Conversions
Institute for Integrated Radiation and Nuclear Science, Kyoto University（京都大学辐射核科学综合研究所）；Advanced Science Research Center, Japan Atomic Energy Agency（日本原子能研究机构先进科学研究中心）
