Flat-beam transforms (FBTs) provide a technique for controlling the emittance partitioning between the beam's two transverse dimensions. To date, nearly all FBT studies have been in regimes where the beam's own space-charge effects can be ignored, such as in applications with high-brightness electron linacs where the transform occurs at high, relativistic, energies. Additionally, FBTs may provide a revolutionary path to high power generation at high frequencies in vacuum electron devices where the beam emittance is currently becoming a limiting factor, which is the focus of this paper. Electron beams in vacuum electron devices operate both at a much lower energy and a much higher current than in accelerators and the beam's space charge forces can no longer be ignored. Here we analyze the effects of space-charge in FBTs and show there are both linear and nonlinear forces and effects. The linear effects can be compensated by retuning the FBT and by adding additional quadrupole elements. The nonlinear effects lead to an ultimate dilution of the lower recovered emittance and will lead to an eventual power limitation for high-frequency traveling-wave tubes and other vacuum electron devices.
Three-Dimensional Analysis of Wakefields Generated by Flat Electron Beams in Planar Dielectric-Loaded Structures
穿过电介质内衬波导的电子聚束产生$\check{C}$ erenkov辐射，该辐射可导致适于加速后续聚束的高峰值轴向电场。在亚毫米尺寸的结构中，取决于合适的电子聚束参数的实现，可以获得超过千兆伏每米的轴向场。一个有前途的配置包括使用平面电介质结构驱动的平面电子聚束。本文对平面介质结构中平板电子束产生的尾流场进行了三维分析，从而推广了文献[A]的工作。Tremaine，J. Rosenzweig，and P. Schoessow，Phys. Rev. E 56，No. 6，7204（1997）]。我们特别提供了封闭形式的表达式的正常频率和场振幅的激发模式和基准这些分析结果与有限差分时域粒子在细胞的数值模拟。最后，我们实现了一个半解析算法到一个流行的粒子跟踪程序，从而使开始到结束的高保真度建模的直线加速器的基础上介质内衬平面波导。
Searches for electroweak states at future plasma wakefield colliders
Massachusetts Institute of Technology（麻省理工学院）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of California, Berkeley（加州大学伯克利分校）；SISSA International School for Advanced Studies（国际高等研究院）；Stanford University（斯坦福大学）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）
