Experimental Study of Ion Species Separation in Multi-Component Plasma Shocks

经常在空气中观察到的冲击波也会出现在高温气体中，在高温气体中，电子从离子中释放出来，形成等离子体。该项目将通过实验研究等离子体喷流与停滞等离子体的碰撞产生的冲击波。当等离子体由不同电荷和质量的物质组成时，冲击波中等离子体性质的快速变化可能导致这些物质的分离，从而使激波结构进一步复杂化。了解这些情景中存在的物理现象对于进一步了解天体物理现象，包括第二类超新星爆炸，以及在惯性约束聚变实验中发生的内爆物理，具有重要意义。这个项目将收集详细的实验数据，描述高速多组分等离子体喷流与停滞等离子体之间的碰撞，在这个实验中，冲击波的厚度被预测到足够大，以便诊断仪器很容易观察到。这个项目的目的是在一个参数空间中实验识别多组分等离子体中的冲击，在这个参数空间中，有可能解决离子激波层的结构。多组分碰撞等离子体喷流与停滞等离子体的相互作用将在这样一个区域中进行研究，其中平均自由程小到足以使喷流相互作用发生碰撞，而大到足以尝试诊断数百个平均自由程上的激波结构。该项目的范围将是确定在这些相互作用期间形成的激波，并调查参数空间，以确认所观测到的激波是否存在于多离子物种等离子体中。线性等离子体-电枢轨道炮将发射一系列多离子组分的等离子体射流。第一股喷流在障碍物上停滞后不久，第二股喷流将以足以在等离子体中产生冲击波的速度与停滞的等离子体相遇。将使用一套诊断方法来捕获指示单个等离子体物种存在的数据。将采用的诊断方法包括(I)高空间分辨率测量光谱学，以定位激波前沿离子物种的发射；(Ii)多弦干涉法，它将与光谱学结合使用，以推断激波和非激波区域的电荷状态和电子温度。这项研究所寻求的实验观测有可能揭示由于离子物种的碰撞扩散而导致的前所未有的激波结构。这可以增进对天体物理现象和惯性聚变等离子体物理学的理解。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。

Shock waves, frequently observed in air, also occur in high temperature gases where electrons have been liberated from ions, forming a plasma. This project will experimentally study shock waves by colliding plasma jets with stagnant plasma. When the plasma is composed of species of differing electric charge and mass, the rapid change in plasma properties across the shock wave can cause separation of these species, further complicating the shock structure. Understanding the physics present in these scenarios is important to furthering the understanding of astrophysical phenomena, including Type II supernova explosions, as well as the physics of implosions that occur in inertial-confinement fusion experiments. This project will collect detailed experimental data characterizing collisions between high-velocity multi-species plasma jets and stagnant plasma in an experiment where shock thickness is predicted to be large enough to be readily observable by diagnostic instruments.This project aims to experimentally identify shocks in multi-component plasmas in a parameter space where it is possible to resolve the structure of the ion shock layer. Interactions of collisional multi-species plasma jets with stagnated plasma will be studied in a regime where the mean-free-path is small enough for the jet interaction to be collisional yet large enough to attempt diagnosis of the shock structure over a few hundred mean-free-paths. The scope of the project will be to identify shocks formed during these interactions and investigate the parameter space to confirm whether the observed shocks are present in multi-ion-species plasmas. A series of multi-ion-species plasma jets will be emitted by a linear plasma-armature railgun. Shortly after the first jet stagnates against a barrier, the second jet will encounter the stagnant plasma at velocities sufficient to drive a shock in the plasma. A suite of diagnostics will be used to capture data indicating the presence of individual plasma species. The diagnostics that will be employed include (i) high spatial resolution survey spectroscopy to locate emission from ion species at the shock front and (ii) multi-chord interferometry which will be used in conjunction with spectroscopy to infer charge state and electron temperature in the shocked and unshocked regions. The experimental observations sought by this research have the potential to shed light on never-before-observed shock structures caused by collisional diffusion of ion species. This could enhance understanding of astrophysical phenomena and the physics of inertial fusion plasmas.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.