Experimental Investigation of Ion Heating Due to Magnetohydrodynamic Waves

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。该项目涉及一项实验室调查，该调查假设离子加热过程发生在快速太阳风的加速区。这里提出的实验将继续研究当Alfvén波传播到强Alfvén速度梯度区时对离子速度分布函数的修改；测量Alfvén波色散的变化，并继续在强Alfvén速度梯度区寻找反射和导管的证据；确定离子加热是否发生在湍流级联到单物种和多离子物种等离子体中的超回旋频率的高k波期间；研究大横向密度梯度处剪切Alfvén波的参数衰减；探索驱动的快MHD波在密度梯度大的区域的传播，并寻找在密度梯度区自发激发的剪切Alfvén波和压缩Alfvén波之间的非线性相互作用；并将实验结果与包含强梯度影响的计算代码和分析理论进行比较。这些实验将在与空间有关的实验室等离子体中进行，具有足够的诊断能力来研究大多数离子和少数离子与传播的Alfvén波相互作用时离子速度空间分布函数的演变，测量等离子体中Alfvén波的详细性质，并非侵入性地探测和测量垂直传播波的波数谱。这项研究涉及对等离子体物理新研究生的培训，提高女性和未被充分代表的群体获得物理学高级学位的比例，让本科生参与尖端科学研究，并通过基于机器人的推广计划，让K-12学生和教师积极参与科学和数学活动。拟议项目中的国际合作将为年轻科学家提供发展国际合作的机会，并获得在国际团队和机构工作的经验-从而为下一代科学家在未来可能涉及大量国际科学合作的研究生涯做好准备。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project concerns a laboratory investigation of ion heating processes that are hypothesized to occur in the acceleration region of the fast solar wind. The experiments proposed here will continue studies of modifications to the ion velocity distribution function that occur when Alfvén waves propagate into region of strong Alfvén speed gradients; measure changes in Alfvén wave dispersion and continue to look for evidence of reflection and ducting in regions of strong Alfvén speed gradients; determine if ion heating occurs during a turbulent cascade to high k waves at super-cyclotronic frequencies, in single specie and multi-ion species plasmas; investigate parametric decay of shear Alfvén waves at large transverse density gradients; explore the propagation of driven fast MHD waves in regions with large density gradients and look for nonlinear interactions between shear and compressional Alfvén waves with spontaneously excited MHD fast waves in the density gradient region; and compare experimental results to computational codes and analytic theories that include the effects of strong gradients. The experiments will be performed in a space-relevant, laboratory plasma with sufficient diagnostic capability to investigate the evolution of the ion velocity space distribution function of majority and minority ions as they interact with propagating Alfvén waves, to measure the detailed properties of the Alfvén waves in the plasma, and to non-invasively detect and measure the wave number spectrum of perpendicularly propagating waves. The research involves the training of new graduate students in plasma physics, improvement of the percentage of women and underrepresented groups obtaining advanced degrees in physics, involvement of undergraduates in cutting-edge scientific research, and the active engagement of K-12 students and teachers in science and math activities through a robotics-based outreach program. The international collaboration built into the proposed project will provide young scientists an opportunity to develop international collaborations and gain experience working in international teams and institutions - thereby preparing the next generation of scientists for productive research careers in a future that is likely to involve considerable international collaboration in science