The Development of an Ultra-Short-Wavelength RF Undulator

光源是一种加速器，它使电子围绕存储环循环，产生波长范围内非常强的光子束。光子是由同步辐射产生的，当电子由于轨迹方向的改变而加速时，就会产生同步辐射。通过将这些光子照射在待研究的样品上，可以推断这些样品材料的基本性质。使用不同波长的辐射（如x射线或紫外线）可以帮助阐明所研究样品在不同距离尺度上的材料特性。光源有许多应用，包括生物学、物理学、材料科学和国家安全。该提案旨在开发一种新技术来快速改变光源中电子的方向或波动。典型的光源使用静态磁铁，使电子束波动产生辐射。然而，以目前的技术，很难在不影响整体光束质量的情况下获得较短辐射波长和降低电子束能量操作所需的短波动周期。为了克服这些限制，PI将开发一种新的短周期电磁波动器，工作在毫米波，周期小于1毫米（mm）。这种类型的波动的标度定律预测孔径，通常是波动周期的三倍。这代表了光源波动器设计和实现的范式转变。由于射频（RF）波动器壁面的磁场非常低，因此预计波动器中心的磁场比任何可能的静态磁波动器都要高得多。设计目标是为周期小于1毫米的波动器提供约5特斯拉的场。该装置将具有快速动态强度和产生光的偏振控制的附加好处。该奖项将支持斯坦福大学的博士生和博士后学者的培训，使他们参与先进的射频/微波设计算法和仿真工具。这个项目有可能对许多基于光束的光源产生深远的影响。紧凑经济的自由电子激光器可以安装在许多大学和研究机构，随着射频波动器成为一种常见的工具，这一梦想将更接近现实。这也适用于为各种医疗和工业应用以及与国家安全有关的应用开发的光源。

Light sources are accelerators that circulate electrons around a storage ring, producing very intense beams of photons in a range of useful wavelengths. Photons are produced by synchrotron radiation, which is generated when electrons experience acceleration due to a change in the direction of their trajectory. By shining these photons on a sample to be studied, basic properties of these sample materials can be inferred. Using radiation of different wavelength (e.g, X-rays or ultraviolet) can help elucidate material properties at different distance scales in the samples being studied. Light sources have many applications, including in biology, physics, materials science, and national security. This proposal aims to develop a new technique to quickly change the direction, or undulate, electrons in a light source. Typically light sources use static magnets that undulate electron beams to generate radiation. However, with current technology it is difficult to obtain short undulator periods needed for shorter radiation wavelengths and reduced electron beam energy operation without compromising the overall beam quality. To overcome these limitations, the PI will develop a novel short-period electromagnetic undulator operating at millimeter-wave with a period of less than 1 millimeter (mm). The scaling laws for this type of undulator predict an aperture, typically, three times the undulator period. This represents a paradigm shift for the design and implementation of undulators for light sources. Because the surface field is very low at the walls of the Radio-Frequency (RF) undulator, the field at the center of the undulator is predicted to be much higher than anything possible with a static magnetic undulator. The design goal is to have an approximately 5 Tesla field for an undulator that has less than 1 mm period. This device will have the added benefit of fast dynamic strength and polarization control of the produced light.This award will support the training of PhD students and post-doctoral scholars at Stanford University, engaging them in advanced RF/microwave design algorithms and simulation tools. This project has the potential to have a profound impact on many beam-based light sources. Dreams of compact economical free electron lasers, which can be installed at many universities and research institutions, will become closer to reality as RF undulators become a common tool. This applies also to light sources developed for a variety of medical and industrial applications as well as applications related to national security.