CAREER: Intermittency and Two-Fluid Transitions in Pulsed-Power-Driven Magnetized Turbulence

该奖项支持一项在实验室研究湍流等离子体物理学的研究计划。湍流存在于我们每天所经历的流体中。湍流的不可预测性限制了我们对从天气到航空旅行的一切预测能力。湍流也存在于等离子体中--高温的电离气体构成了可见宇宙的大部分。等离子体湍流在从黑洞吸积盘到星际介质等广泛的天体物理现象中扮演着重要的角色，在星际介质中，湍流产生的热量使有机分子得以形成，而有机分子是生命的基石。等离子体湍流也限制了未来潜在聚变能反应堆的性能。这项研究计划将开发一个在实验室产生湍流等离子体的新平台和测量等离子体湍流的新方法。该奖项还支持开发开放式等离子体实验室课程的实质性努力，其中包括设计、建造和测试实验室实验，这些实验可以很容易地被其他教师复制。如果成功，这一努力将通过将等离子体物理教学传播到更广泛的教育机构来加强美国STEM的劳动力。正如流体运动的漩涡形成流体动力学湍流一样，磁化等离子体湍流是由磁岛和电流片建立的，它们用于在不同空间尺度之间传递磁能。该项目将使用由麻省理工学院新的海雀发电机驱动的内爆碳线阵列Z-Pinch作为磁岛合并平台，以产生磁化等离子体湍流。这种磁化的等离子体湍流将处于一种以前未曾探索过的区域：持续的、高度碰撞的、驱动和耗散尺度之间的离子皮肤深度，能量在磁力、热能和动能之间大致等分。先进的诊断技术，如法拉第旋转成像、汤姆逊散射和成像折射测量，将被用于研究从层流到湍流等离子体的转变。诊断将用于描述离子表面深度上下的功率谱和间歇性结构的演变，以及外加或自生平均场在关联湍流结构中的作用。该奖项反映了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 research program to study the physics of a turbulent plasma in the laboratory. Turbulence exists in the fluids that we experience every day. The unpredictability of turbulence limits our forecasting ability for everything from weather to air travel. Turbulence also exists in plasmas - the hot, ionized gases that make up most of the visible Universe. Plasma turbulence plays an important role in a wide range of astrophysical phenomena, from black hole accretion disks to the interstellar medium, where the heating from turbulence enables the formation of organic molecules which are the building blocks of life. Plasma turbulence also limits the performance of potential future fusion energy reactors. This research program will develop a new platform for producing turbulent plasma in the laboratory and new methods for measuring plasma turbulence. The award also supports a substantial effort to develop an open-access plasma laboratory class, which includes designing, building, and testing laboratory experiments that can be easily reproduced by other instructors. If successful, this effort will strengthen the US STEM workforce by spreading plasma physics instruction to a broader range of educational institutions.Just as hydrodynamic turbulence is built from vortices of fluid motions, magnetized plasma turbulence is built from magnetic islands and current sheets, which serve to transfer the magnetic energy between different spatial scales. This project will use an imploding carbon wire-array Z-pinch, driven by the new PUFFIN generator at the Massachusetts Institute of Technology, as a magnetic island merging platform to generate magnetized plasma turbulence. This magnetized plasma turbulence will be in a previously unexplored regime: sustained, highly collisional, with an ion-skin depth between the driving and dissipative scales, and energy approximately equipartitioned between magnetic, thermal, and kinetic. Advanced diagnostics, such as Faraday rotation imaging, Thomson scattering, and imaging refractometry, will be used to study the transition from a laminar to a turbulent plasma. The diagnostics will serve to characterize the evolution of the power-spectrum and intermittent structures above and below the ion skin depth, and the role of an imposed or self-generated mean-field in correlating turbulent structures.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.