Generation of A High-Density, Axially Homogeneous Helicon Plasma for the AWAKE Wakefield Accelerator Project

该奖项支持一项新方法的研究，该方法使用等离子体作为加速介质将粒子加速到非常高的能量。基本粒子加速到高能量需要产生高电场，这些粒子可以达到接近光速的速度。在这个项目中，等离子体——一种带电粒子的电离气体——被用来产生非常强的电场，可以将粒子加速到如此高的速度。制造这种具有正确特征的等离子体的技术是独一无二的，需要控制等离子体柱，使其在几百米内非常均匀。该项目旨在开发这项技术，并为欧洲核子研究中心（CERN）的一种新型粒子加速器的设计过程提供技术支持。该奖项支持研究生和本科生，包括合作学生前往CERN设施。计划中的粒子加速器产生等离子体需要利用被称为惠斯勒波的射频波。这种被称为螺旋等离子体生成的方法是在几十年前开发出来的，以非常高的效率产生等离子体。在本项目中，螺旋等离子体源技术作为下一代粒子加速器技术，可以应用于尾流场粒子加速。建立了先进的、基于激光的光谱方法来测量等离子体密度，并与最先进的波传播有限元模型和使用微波干涉仪和磁探头测量这些特性一起使用。这些努力为欧洲核子研究中心先进质子驱动等离子体尾流场加速实验（AWAKE）项目的等离子体源原型设计奠定了基础。AWAKE项目的轴向等离子体密度分布必须在0.25%以内均匀，这是该等离子体源达到的前所未有的目标。如果成功，等离子体源将使下一代线性加速器的长度减少20-30倍，因此可能对未来基于加速器的高能粒子物理研究的系统复杂性和成本产生重大影响。该奖项反映了美国国家科学基金会的法定使命，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。

This award supports a study of a novel method to accelerate particles to very high energies using plasma as the accelerating medium. Acceleration of elementary particles to high energies entails creating high electric fields in which these particles can reach velocities close to the speed of light. In this project, a plasma - an ionized gas of electrically charged particles - is used to create very strong electric fields that can accelerate particles to such high velocities. The technology to create this plasma with the right features is unique and involves controlling the plasma column to make it very uniform for several hundred meters. The project aims to develop this technology and provide it for the design process for a new type of particle accelerator at the European Organization for Nuclear Research, known as CERN. The award supports graduate and undergraduate students, including collaborative student travel to the CERN facility. The plasma generation for the planned particle accelerator entails utilizing radio-frequency waves known as Whistler waves. This approach, called helicon plasma generation, was developed several decades ago and is known to create plasma with very high efficiency. In this project, the helicon plasma source technology is qualified for application in wakefield particle acceleration as a next-generation particle accelerator technology. Advanced, laser-based spectroscopic methods to measure plasma density are established and used together with state-of-the-art finite element modeling of the wave propagation and measurements of these characteristics using a microwave interferometer and magnetic probes. These efforts establish the basis for the design of a plasma source prototype for the Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) project at CERN. The axial plasma density profile for the AWAKE project has to be homogeneous within 0.25%, an unprecedented goal to reach with this plasma source. If successful, the plasma source will reduce the length of next-generation linear accelerators by a factor of 20-30, and hence may have a major impact on system complexity and cost for future accelerator-based high energy particle physics studies.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.