Miniature Magnetic Devices-based Chip-scale Panofksy Quadrupoles for Focusing Electron Beams

该项目将研究一种新型的微型磁性装置，它可以聚焦电子束，类似于透镜聚焦光线的方式。 磁场对于聚焦电子束是非常有效的，但目前的磁铁体积庞大且昂贵。这项拟议中的工作旨在创造一种新的磁聚焦设备，其体积至少比现有的同类设备小一百倍。控制电子束具有广泛的应用。 它们用于世界上最强大的显微镜，自由电子激光器，可以研究单个原子的运动。 这些激光显微镜可以提供对原子和分子的基本行为的洞察，这些行为可以对日常生活产生影响，例如发现新药。此外，电子束也用于治疗癌症，电子束疗法的好处是它可以比放射疗法更精确地靶向。小型化的磁聚焦装置不仅可以更广泛地使用这些电子束作为激光显微镜，还可以将电子束放入以前无法进入的地方，例如癌症治疗的导管。在这项工作中将研究的基本问题是这些设备的小型化的限制（即，这些磁体能被制造得多小同时仍然有效地聚焦电子束）。 为了应对小型化的挑战，必须追求与当前最先进技术完全不同的新设计。这些设备的制造将需要结合微芯片制造商目前使用的方法和专门为此工作开发的定制方法。 大学的学生将能够在少数设施中进行以前仅限于光束线科学家的动手实验。拟议的活动将包括作为“圣莫尼卡学院/加州大学洛杉矶分校”暑期学者研究计划的教师带头人，开发关于磁性器件的高中课程，每年撰写一篇关于科学和工程领域女性的文章。为了提供更多细节，拟议的研究将创造一种新型的微型电磁四极聚焦电子束。电子束在许多应用领域产生了深远的影响，从世界上最精确的显微镜到癌症的靶向消融。直到最近，所有这些应用都依赖于大型、昂贵的实验室设备来产生和加速电子束。例如，允许以前所未有的时间（飞秒）和空间（埃）分辨率成像的存储环和线性相干光源通常位于千米级的设施中。最新的进展使厘米级的芯片加速器有可能将电子束加速到相对论速度，与在更大规模的设施中的速度相当。虽然这些结果很有希望，但仍然存在一个关键障碍：目前还没有芯片级的方法可以聚焦这些下一代加速器产生的光束。受不对称四极杆的启发，利用磁场梯度将电子束聚焦在矩形孔径中，这项工作提出了设计，制造和表征一类新的微型矩形四极杆。然而，大型矩形四极杆不能简单地直接小型化。必须开发新的设计以适应特别是小规模制造的制造约束，并且必须开发新的制造方法以在中尺度尺寸范围内构建器件，该中尺度尺寸范围福尔斯在微制造和标准制造可以舒适地操作的区域之间。所提出的设备将提供20倍的聚焦梯度，并适合于比当前最先进的矩形四极杆小七个数量级的体积。如果成功，这将是有史以来第一次使用芯片级设备聚焦相对论电子束的演示。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The project will investigate a new class of miniature magnetic devices that can focus beams of electrons, similar to the way that lenses focus light. Magnetic fields are highly effective for focusing beams of electrons, but current magnets are bulky and expensive. The proposed work aspires to create a new class of magnetic focusing devices that are at least one hundred times smaller than their existing counterparts. Steering electron beams has a broad range of applications. They are used in the world's most powerful microscopes, free electron lasers, which can study the motion of individual atoms. These laser microscopes can provide insight into the fundamental behavior of atoms and molecules, which can have impact in everyday life, such as discovery of new drugs. Additionally, electron beams are also used in treating cancer, with electron beam therapy having the benefit that it can be targeted much more precisely than radiation therapy. Miniaturizing magnetic focusing devices would not only allow broader access to these electron beams for use as laser microscopes, it would also allow electron beams to be put into places previously inaccessible, such as catheters for cancer therapy. The fundamental issues that will be studied in this work are the limits of miniaturization of these devices (i.e., how small can these magnets be made while still effectively focusing electron beams). To address the challenge of miniaturization, new designs, fundamentally different from the current state-of-the-art, must be pursued. Fabrication of these devices will require a combination of methods currently used by microchip manufacturers with custom methods developed especially for this work. Students at universities will be able to perform hands-on experiments that were previously limited to beamline scientists at a handful of facilities. The proposed activities will include being a faculty lead for "Santa Monica College/UCLA" Summer Scholar Research Program, development of high-school curriculum on magnetic devices, writing one article per year covering women in science and engineering.To provide more detail, the proposed research will create a new class of microfabricated electromagnet quadrupoles for focusing electron beams. Electron beams have made profound impacts in many application areas, ranging from the world's most precise microscopes to targeted ablation of cancer. Until recently, all these applications relied on large, expensive pieces of laboratory equipment to generate and accelerate electron beams. For example, storage rings and linear coherent light sources that allow for imaging with unprecedented temporal (femtosecond) and spatial (Angstrom) resolution are often housed in facilities on the scale of kilometers. Recent advances have enabled centimeter-scale accelerators on-chip with the potential to accelerate electron beams to relativistic velocities, comparable to those at kilometer-scale facilities. While these results are promising, there remains a critical barrier: there is currently no chip-scale method that can focus the beams produced by these next-generation accelerators. Inspired by asymmetric quadrupoles, which use magnetic field gradients to focus electron beams in a rectangular aperture, this work proposes to design, fabricate, and characterize a new class of miniature rectangular quadrupoles. However, the large-scale rectangular quadrupoles cannot simply be directly miniaturized. New designs must be developed to adapt to the fabrication constraints particular to small scale fabrication, and new fabrication methods must be developed to build devices at a mesoscale size range that falls between the regions where microfabrication and standard fabrication can comfortably operate. The proposed devices will provide 20 times greater focusing gradient and fit in a volume seven orders of magnitude smaller than the current state-of-the-art rectangular quadrupoles. If successful, this will be the first-ever focusing demonstration of a relativistic electron beam using a chip-scale device.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.