Kinetic Effects in Nonlinear Plasma Waves

该奖项支持一项实验、模拟和理论计划，内容涉及一种新型的大幅度等离子体波的不稳定性--自由相互作用的带电粒子气体中的波。这些研究将集中在以几乎恒定的波速传播的波中似乎主宰这种不稳定性的新颖的“动力学”效应，并对其进行表征。这种波在自然产生的等离子体和实验室等离子体中都普遍存在。新的不稳定性机制非常简单和普遍，因此适用于一系列场景，包括用于发电的空间等离子体和聚变等离子体。实验将在非中性等离子体上进行，使用具有广泛操作制度和诊断范围的电子陷阱和离子陷阱。这些系统的简单性使得理论和实验之间有了深入的理解和精确的比较，这对于复杂几何结构的准中性等离子体来说是很难做到的。其目的是验证该理论的适用性，并在需要的地方刺激新的理论。最近的分析发现，令人惊讶的是，标准流体理论不足以描述近声Trivel块-Gould[Tg]等离子体波的参数不稳定性。一种新的动力学不稳定性机制，包括一小部分被困在波谷中的等离子体，将被研究并应用于理解在Tg波和电声波中观察到的参数不稳定性。实验和模拟将被用来描述波浪作用下的颗粒分布，包括被捕获的颗粒，以便与理论进行直接比较。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 program of experiments, simulations, and theory on a new type of instability of large amplitude plasma waves - waves in a gas of freely interacting electrically charged particles. The studies will focus on and characterize novel 'kinetic' effects that appear to dominate this instability in waves that propagate with nearly constant wave speed. Such waves are ubiquitous in both naturally-occurring and laboratory plasmas. The new instability mechanism is quite simple and general, and therefore has application to a range of scenarios, including space plasmas and fusion plasmas for power generation.Experiments will be performed on non-neutral plasmas, utilizing an electron trap and an ion trap with a broad range of operating regimes and diagnostics. The simplicity of these systems allows a depth of understanding and a precision of comparison between theory and experiment which is rarely possible for quasi-neutral plasmas in complex geometry. The goal is to verify applicability of the theory, and to stimulate new theory where needed. Recent analysis has found that, surprisingly, standard fluid theory is inadequate to describe parametric instability for near-acoustic Trivelpiece-Gould [TG] plasma waves. A new kinetic instability mechanism, involving a small fraction of plasma that is trapped in the wave troughs, will be studied and applied to understand parametric instabilities observed both in TG waves and in electron-acoustic waves. Experiments and simulations will be used to characterize the particle distribution under the action of the wave, including trapped particles, for direct comparison to theory.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.