Since the introduction of the radio-frequency (rf) photoinjector electron source over thirty years ago, peak performance demands have dictated the use of high accelerating electric fields. With recent strong advances in obtainable field values, attendant increases in beam brightness are expected to be dramatic. In this article, we examine the implementation of very high gradient acceleration in a high frequency, cryogenic rf photoinjector. We discuss in detail the effects of introducing, through an optimized rf cavity shape, rich spatial harmonic content in the accelerating modes in this device. Higher spatial harmonics give useful, enhanced linear focusing effects, as well as potentially deleterious nonlinear transverse forces. They also serve to strongly increase the ratio of average accelerating field to peak surface field, thus aiding in managing power and dark current-related challenges. We investigate two scenarios which are aimed at unique exploitation of the capabilities of this source. First, we investigate the obtaining of extremely high six-dimensional brightness for advanced free-electron laser applications. We also examine the use of a magnetized photocathode in the device for producing unprecedented low asymmetric emittance, high-current electron beams that reach linear collider-compatible performance. As both of the scenarios demand an advanced, compact solenoid design, we describe a novel cryogenic solenoid system. With the high field rf and magnetostatic structures introduced, we analyze the collective beam dynamics in these systems through theory and multiparticle simulations, including a particular emphasis on granularity effects associated with microscopic Coulomb interactions.

中文翻译：

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多功能、高亮度、低温光注入电子源

自从三十多年前引入射频 (rf) 光注入器电子源以来，峰值性能要求决定了使用高加速电场。随着最近在可获得的场值方面的巨大进步，预计光束亮度的伴随增加将是戏剧性的。在本文中，我们研究了在高频低温射频光注射器中实现非常高的梯度加速。我们详细讨论了通过优化的射频腔形状在该设备的加速模式中引入丰富的空间谐波含量的影响。更高的空间谐波提供有用的、增强的线性聚焦效应，以及潜在有害的非线性横向力。它们还有助于大大增加平均加速场与峰值表面场的比率，从而有助于管理与电源和暗电流相关的挑战。我们调查了两种旨在独特利用此源功能的场景。首先，我们研究了为高级自由电子激光应用获得极高的六维亮度。我们还研究了在器件中使用磁化光电阴极来产生前所未有的低不对称发射率、高电流电子束，从而达到与线性对撞机兼容的性能。由于这两种情况都需要先进、紧凑的螺线管设计，因此我们描述了一种新型低温螺线管系统。随着高场射频和静磁结构的引入，我们通过理论和多粒子模拟分析了这些系统中的集体光束动力学，