MRI: Development of the PHAse Space MeAsurements (PHASMA) Experiment

在了解外层空间自然发生的现象方面面临的挑战之一是，在整个有关区域进行科学测量是多么困难。另一个挑战是，大自然很少会善意地一遍又一遍地产生完全相同的事件，这样科学家就可以区分他们测量结果中的随机波动和由感兴趣的现象引起的随机波动。特别令人感兴趣的空间现象是那些在地球周围的空间环境中发挥重要作用并可能影响人类在空间的基础设施的现象，例如卫星、载人航天器等，以及地球上的技术系统，例如电网、全球定位系统和长途无线电通信。该项目涉及建造一个实验室设施，能够产生与太空中发生的等离子体现象类似的现象。等离子体是炽热的气体，电子会从原子中剥离。由此产生的带电粒子集合对电场和磁场都有反应，就像太空中的等离子体一样。这个特殊的设备将研究当磁场湮没时，当等离子体湍流时，或当等离子体移动速度快于音速时，等离子体中的离子和电子是如何被加热和加速的。该设施将雇用西弗吉尼亚州各地的等离子体物理研究人员组成的财团。这项工作的更广泛影响还将包括在实验和理论等离子体物理协同结合的研究环境中培养研究生和本科生，并通过参与尖端研究活动吸引高质量的本科生进入物理学。虽然实验室实验与其他研究空间物理的方法之间存在很强的协同性，但目前世界上还没有直接测量等离子体体积中三维离子和电子分布函数的空间相关实验。根据该奖项将开发的仪器名为相空间测量(PHASMA)实验，其特点是用于离子测量的激光诱导荧光诊断，用于电子速度分布函数测量的汤姆逊散射诊断，以及用于湍流测量的微波散射系统。航天器的测量已经发展到了速度分布函数测量正在导致对广泛的空间等离子体现象的范式改变的洞察的地步。在实验室中直接测量速度分布函数的能力将补充和提高在空间进行的直接测量的价值。PHASMA实验将使磁重联、无碰撞冲击和等离子体湍流中的粒子加速和等离子体加热的研究成为可能。实验设施研究团队包括在粒子诊断测量方面具有独特优势和在动力学建模方面具有专业知识的成员，使该团队非常适合研究这些主题。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。

One of the challenges in understanding naturally occurring phenomena in outer space is how difficult it is to perform scientific measurements throughout the region of interest. Another challenge is that nature is rarely kind enough to produce the exact same event over and over again so that scientists can distinguish random fluctuations in their measurements from those that result from the phenomena of interest. The phenomena in space of particular interest are those that play important roles in the space environment around the Earth and which can impact human infrastructure in space, e.g., satellites, manned space vehicles, etc., and technological systems on Earth, e.g., power grids, global positioning systems (GPS), and long distance radio communication. This project involves the construction of a laboratory facility capable of producing plasma phenomena like those that occur in space. Plasmas are gasses so hot that the electrons are stripped away from their atoms. The resulting collection of charged particles responds to both electric and magnetic fields, just like plasmas in space. This particular facility will investigate how the ions and electrons in plasmas are heated and accelerated when magnetic fields annihilate, when the plasma is turbulent, or when the plasma moves faster than the speed of sound. The facility will engage a consortium of plasma physics researchers throughout West Virginia. The broader impacts of this work will also include the training of graduate and undergraduate students in a research environment that synergistically combines experimental and theoretical plasma physics and attracts high quality undergraduates into physics through involvement in cutting-edge research activities.While there is a strong synergy between laboratory experiments and other approaches to studying space physics, there are currently no space-relevant experiments in the world making direct measurements of three-dimensional ion and electron distribution functions in a plasma volume. The instrument to be developed under this award, called the PHAse Space MeAsurements (PHASMA) experiment, features laser induced fluorescence diagnostics for ion measurements, Thomson scattering diagnostics for electron velocity distribution function measurements, and a microwave scattering system for turbulence measurements. Spacecraft measurements have advanced to the point where velocity distribution function measurements are leading to paradigm-changing insights about a broad spectrum of space plasma phenomena. The ability to directly measure velocity distribution functions in the lab will complement and enhance the value of the direct measurements made in space. The PHASMA experiment will enable studies of particle acceleration and plasma heating in magnetic reconnection, collisionless shocks, and plasma turbulence. The experimental facility research team includes members with unique strengths in particle diagnostic measurements and expertise in kinetic modeling -- making the team ideally suited to investigate these topics.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.