Modeling Ion Extraction from First Toroidal Electron-Cyclotron-Resonance Ion Source

该项目将使用计算建模来测试粒子加速器的新型离子源的可行性，粒子加速器是科学界最普遍的工具之一，其用途从基础研究到癌症治疗，材料科学和纳米纤维的应用。 世界上有几个粒子加速器将离子加速到非常高的速度，接近光速。例如，欧洲核子研究中心的大型强子对撞机加速了铅离子;布鲁克海文的相对论重离子对撞机碰撞了金离子，以重建和研究大爆炸后最初10微秒的物理学。 所有这些都需要离子源。它们还要求离子具有高电荷，即从尽可能多的电子中剥离。每单位时间需要很多离子。这里提出的新概念建立在一种称为电子回旋共振离子源的离子源的基础上，但在核聚变实验的启发下采用了新的甜甜圈形状的几何形状。 在本项目中调查的这样的来源将比目前可用的来源具有大大改善的特征。多年来，已经尝试增加电子回旋共振离子源（ECRIS）等离子体的密度、温度和约束时间，从而产生更高电荷的离子。在聚变等离子体中，为了增加聚变反应性，有一种推动力，即增加几乎相同数量的“三重产物”。受此类比的启发，本项目将数值探索环形约束的离子源相关性，并将其与线性ECRIS范例（磁镜与六极场相结合）进行比较。乍一看，环形几何形状非常有吸引力。它更好地利用了磁场，其中环形ECRIS可以被加热并被限制在相同的磁场中。另一方面，离子提取将不像来自线性ECRIS那样直接。本项目将通过比较静磁、静电和基于漂移的提取技术，在数值上解决这方面的问题。研究的第二个方面是如何在线性和环形ECRIS中比较传输和约束：虽然从聚变研究中已知H，D和T的热离子比线性的更好地约束在环形装置中，但对于重物质的冷碰撞离子，这并不能保证。这两个问题将通过数值跟踪几个“测试离子”的轨道，通过辛积分器，并通过让这些离子进行碰撞-根据分布函数-与彼此和离子和电子从背景等离子体来解决。

This project will use computational modeling to test the feasibility of a novel source of ions for particle accelerators, one of the most ubiquitous tools within the scientific community, with uses ranging from fundamental research to applications to cancer therapy, materials science, and nanofabrication. Several particle accelerators worldwide accelerate ions to very high velocities, approaching the speed of light. For example, the Large Hadron Collider at CERN accelerates ions of lead; the Relativistic Heavy Ion Collider at Brookhaven collided ions of gold to recreate and study the physics of the first 10 microseconds after the Big Bang. All require a source of ions. They also require the ions to have high charge, that is, to be stripped from as many electrons as possible. And they require many ions per unit time. The new concept proposed here builds on a type of ion source called an Electron Cyclotron Resonance Ion Source, but in a new doughnut-shaped geometry inspired by nuclear fusion experiments. Such a source, investigated within this project, would have greatly improved characteristics over those presently available. There have been attempts over the years to increase the density, temperature and confinement-time of Electron Cyclotron Resonance Ion Source (ECRIS) plasmas, resulting in ions of higher charge. In fusion plasmas there is a push to increase the 'triple product' of nearly the same quantities for the sake of increasing the fusion reactivity. Inspired by this analogy, this project will numerically explore the ion-source-relevance of toroidal confinement, and compare it with the linear ECRIS paradigm, a magnetic mirror combined with an hexapolar field. At a first glance, the toroidal geometry is highly attractive. It makes a better use of the magnetic field, where toroidal ECRIS could be heated and confined at the same field. On the other hand, ion extraction will not be as straightforward as from a linear ECRIS. This project will numerically address this aspect by comparing magnetostatic, electrostatic and drift-based extraction techniques. The second aspect to investigate is how transport and confinement compare in a linear and a toroidal ECRIS: while hot ions of H, D and T are well-known from fusion research to be better confined in toroidal devices than linear ones, the same is not guaranteed for cold collisional ions of heavy species. Both problems will be addressed by numerically tracing the orbits of several "test ions", by means of symplectic integrators, and by letting these ions undergo collisions - according to a distribution function - with each other and with ions and electrons from the background plasma.