RUI: Electron Beam Production for Optical-Scale Accelerators using Pyroelectric Crystal Arrays

这项实验研究项目旨在展示一种使用不寻常的材料-热释电晶体-制造微型电子粒子加速器的机制，热释电晶体在加热和冷却时会产生强大的电场。粒子加速器一直是物质基本性质科学研究的重要组成部分，但也是现代医学、国防应用和工业的关键工具。典型的加速器体积大，价格昂贵，但现在正在开发新型加速器，这种加速器有可能使用一种微小(毫米大小)的设备来提供电子束，这种设备可以廉价地建造在硅片上。然而，这些微加速器也需要新型的微型电子束源：注入的电子束应该大约1微米(百万分之一米)宽，但速度接近光速。这项研究项目旨在演示一种利用热释电晶体产生这种光束的机制。该项目将在一所小型文理学院进行，让本科生有机会直接参与尖端研究，并为培养下一代科学家做出贡献。这个项目的技术目标是演示一种新的注入器方案，能够产生适合于介质型微加速器使用的近相对论微米级电子束，并且作为一种小占地面积的束流和辐射源具有潜在的价值。由热释电晶体阵列提供的场使纳米发射器阵列能够进行场发射，然后将发射的光束加速到接近相对论的速度。热释电体的使用允许高加速场和输出能量，而不需要较大的外部电压。这一概念得到了迄今为止对铌酸锂晶体的实验测量的支持。该方法包括一个通过三晶阵列中心的狭窄真空通道，预计将产生数十mV/m的高度均匀的加速场，并将在其中插入一片亚毫米的碳纳米管。预计输出电流在纳安范围内，能量大于250keV。将对输出光束参数进行完整的测量，使人们能够更好地了解热释电加速器的物理和工程原理，并导致对适用于应用的注入器模块进行优化设计。该项目还将提供关于热释电材料的更完整的信息，包括最佳加热方式、内部和表面场及其响应的时间结构。

This experimental research project aims to demonstrate a mechanism for producing miniature electron particle accelerators using unusual materials: pyroelectric crystals, which create strong electric fields during heating and cooling. Particle accelerators have been an essential part of scientific research into the fundamental properties of matter, but are also critical tools in modern medicine, defense applications, and industry. Typical accelerators are large and costly, but new types of accelerators which have the potential to provide electron beams using a tiny (millimeter-sized) device that can be built cheaply on a silicon wafer are now being developed. However, these microaccelerators also require new kinds of miniature electron beam sources: the injected beam should be about 1 micrometer (a millionth of a meter) wide, but have a speed near that of light. This research project aims to demonstrate a mechanism for producing such a beam using pyroelectric crystals. This project will be carried out at a small liberal-arts college, giving undergraduate students the opportunity to participate directly in cutting-edge research and contributing to the training of the next generation of scientists. The project will also enable development of new teaching tools for undergraduate lab courses.The technical objectives of this project are to demonstrate a novel injector scheme, capable of producing near-relativistic micron-scale electron beams that are suitable for use with dielectric-based microaccelerators and also potentially valuable as a small-footprint beam and radiation source. Fields provided by an array of pyroelectric crystals enable field emission from an array of nanoemitters and then accelerate the emitted beam to near-relativistic velocities. The use of pyroelectrics allows high accelerating fields and output energies without the need for large external voltages. This concept is supported by experimental measurements to date on lithium niobate crystals. The approach involves a narrow vacuum channel through the center of a three-crystal array, which is predicted to produce highly uniform accelerating fields of tens of MV/m, and in which a submillimeter patch of carbon nanotubes will be inserted. Projected output current is in the nanoampere range, with energy greater than 250 keV. Complete measurement of output beam parameters will be performed, enabling improved understanding of the physics and engineering principles of the pyroelectric accelerator, and leading to an optimized design for an application-ready injector module. This project will also yield more complete information about pyroelectric materials, including optimal heating modalities, internal and surface fields, and the time structure of their response.