The need for enhanced performance of high-power RF vacuum electron devices has led to the investigation of multiple-beam, sheet beam, and annular beam configurations. A key issue with such devices is the magnetic field shaping required producing high-power, laminar beams. Field shaping is difficult when Pierce-type gun geometries are employed. The development of high current density cathodes makes the necessary beam power achievable without compression. Such cathodes can operate within a uniform magnetic field yielding advantages for both single and distributed-beam RF devices. However, the quality of the resulting beams presents problems. A project to optimize beam quality in zero-convergence electron guns was undertaken by Calabazas Creek Research, Inc. (CCR) and North Carolina State University (NCSU). The surprising result was that high-quality electron beams can be generated in uniform magnetic fields using convex (dome)-shaped cathodes. The underlying physics involves perturbation of the beam cyclotron motion by a nonadiabatic radial electric field impulse. This article examines this physical mechanism and extends the initial result to additional diode and beam geometries.

中文翻译：

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均匀磁场中来自凸阴极的零压缩层流电子束


对增强高功率射频真空电子器件性能的需求导致了对多束、片束和环形束配置的研究。此类设备的一个关键问题是产生高功率层流束所需的磁场整形。当采用皮尔斯型喷枪几何形状时，场整形很困难。高电流密度阴极的发展使得无需压缩即可实现必要的束功率。这种阴极可以在均匀磁场内工作，为单束和分布式射频器件带来优势。然而，所得光束的质量存在问题。 Calabazas Creek Research, Inc. (CCR) 和北卡罗来纳州立大学 (NCSU) 开展了一个优化零会聚电子枪束质量的项目。令人惊讶的结果是，使用凸（圆顶）形阴极可以在均匀磁场中产生高质量电子束。基础物理学涉及非绝热径向电场脉冲对束流回旋加速器运动的扰动。本文研究了这种物理机制，并将初步结果扩展到其他二极管和光束几何形状。