Generation of high power, high frequency radiation using high brightness pseudospark-sourced relativistic electron beams

其主要目的是研究在任何已知类型的电子束源中，产生同时具有最高电流密度和亮度的电子束脉冲的伪火花放电。在建造和运行了第一个基于伪火花放电的相干辐射源之后，我们最近测量了亮度为10[11]到10[12]am[-2]rad[-2]的高电流密度(1.5kAcm[-2])电子束，拟议的方案旨在增强我们对伪火花放电的物理理解，因为这种等离子体阴极的尺寸减小，并首次产生和传输具有异常电流密度和束流质量的小直径(毫米和亚毫米)电子脉冲。从数百GHz到太赫兹频率范围内的自由电子辐射源可以产生的功率受到以下事实的限制：随着频率的增加，相互作用的直径必须减小，以防止脉泽变得过模，从而损失输出辐射的时间和空间相干性。相互作用区尺寸的减小使得使用传统阴极聚焦并通过高频脉泽的小尺寸相互作用区形成高电流密度、高质量的电子束变得越来越困难(如果不是不可能的话)。我们的目的是结合三个领先的大学研究小组在以下领域的集体知识和专业知识：1)伪火花物理，2)毫米波源的计算模型和太赫兹组件的设计，3)先进的毫米波制造技术，研究使用伪火花源电子束脉冲通过速调管(200 GHz)和反向波(390 GHz至1 THz)不稳定性产生高功率、高频相干电磁辐射。

The principle aim is the investigation of the pseudospark discharge resulting in the generation of electron beam pulses with the highest simultaneous current density and brightness of any known type of electron beam source. Having constructed and operated the first coherent radiation source based on a pseudospark discharge, we have recently measured a high current density (1.5kAcm [-2]) electron beam of brightness 10[11] to 10[12] Am[-2]rad[-2], the proposed programme aims to enhance our understanding of the physics the pseudospark discharge as the size of this plasma cathode is reduced and to produce and transport for the first time small (mm and sub-mm) diameter electron pulses of exceptionally current density and beam quality. The power that can be generated from free electron radiation sources in the hundreds of GHz to THz frequency range has been limited by the fact that as the frequency is increased, the diameter of the interaction has to be reduced in order to prevent the maser becoming overmoded resulting in a loss of the temporal and spatial coherence of the output radiation. The reduction in the size of the interaction region makes it increasingly difficult (if not impossible) using conventional cathodes to focus and form high current density, high quality electron beams through the small size interaction region of a high frequency maser. It is our intention to combine the collective knowledge and expertise of three leading university research groups in the fields of 1) pseudospark physics, 2) computational modelling of millimetre wave sources and design of THz components and 3) advanced millimetre wave manufacturing technologies, to investigate the use of pseudospark sourced electron beam pulses to generate high power, high frequency coherent electromagnetic radiation via the klystron (200GHz) and backward wave (390GHz up to 1THz) instability.