Experimental Investigation of Ion Response to Propagating Alfvén Waves

拟议的项目涉及在快速太阳风的加速区域的离子加热的实验室调查。已经提出了一些在快速太阳风中加热离子的机制，本项目将研究离子直接被Alfvn波的离子回旋阻尼加热的可能性，或者反向传播的低频Alfvn波产生湍流级联，通过激发高频波加热离子，然后对离子进行阻尼。实验将在空间相关的实验室等离子体中进行，该等离子体具有足够的诊断能力，以研究多数和少数离子与传播的Alfvn波相互作用时离子速度空间分布函数的演变，观察Alfvn波接近并可能从Alfven速度的强梯度反射时的Alfvn波，并且如果由反向传播的波产生，则检测非线性级联的产生。横向流动对阿尔芬波传播的影响也将进行调查和混合代码模拟的等离子体将与experiments.The拟议的活动的基本知识价值是受控的实验室实验的现象，可能发挥关键作用的快速太阳风的加速和加热的性能。虽然阿尔芬波的传播已经被一些不同的实验室等离子体研究小组研究，等离子体的不均匀性，如阿尔芬速度梯度，和等离子体流的影响，直到最近才成为实验关注的主题。通过选择理论预测明确定义结果的等离子体条件，拟议的实验将为目前应用于快速太阳风加速区域的理论提供强有力的测试。

The proposed project concerns a laboratory investigation of ion heating in the acceleration region of the fast solar wind. A number of mechanisms for ion heating in the fast solar wind have been proposed and this project will examine the possibility that the ions are directly heated by ion-cyclotron damping of Alfvn waves or that counter-propagating, low-frequency, Alfvn waves generate a turbulent cascade that heats ions by exciting higher frequency waves that then damp on the ions. 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 Alfvn waves, to observe Alfvn waves as they approach and possibly reflect from a strong gradient in the Alfven speed, and detect the generation of a nonlinear cascade if created by the counter-propagating waves. The effects of transverse flow on Alfven wave propagation will also be investigated and hybrid code modeling of the plasma will be performed in parallel with the experiments.The essential intellectual merit of the proposed activity is the performance of controlled laboratory experiments on phenomena that may play a key role in the acceleration and heating of the fast solar wind. Although Alfven wave propagation has been investigated by a number of different laboratory plasma research teams, the effects of plasma inhomogeneities, such as an Alfven speed gradient, and plasma flow have only recently been the subject of experimental attention. By choosing plasma conditions for which theory predicts a clearly defined outcome, the proposed experiments will provide a strong test of the theories now being applied to the acceleration region of the fast solar wind.