Investigating solar wind acceleration and non-adiabatic expansion with the Parker Solar Probe and Solar Orbiter missions

该项目将侧重于内日光层和靠近太阳的太阳风等离子体的性质：起源和加速；行星际空间的扩张。研究活动将利用美国国家航空航天局帕克太阳探测器(PSP)任务(2018年发射)和不久的将来太阳轨道器(2019年2月发射)在巡航阶段进行的新测量。这包括对电场和磁场以及构成不同日心距离的太阳风等离子体的粒子(离子和电子)进行高分辨率的现场观测。该项目将利用这一事实，即PSP正在收集以前从未探索过的近太阳区域的测量数据，其最接近的方法将继续逐步减少--在项目的3年时间里，从~30个太阳半径减少到不到20个太阳半径。这些情况将使详细研究太阳风等离子体热力学状态及其随径向距离的演化成为可能，以便确定在膨胀过程中负责粒子和场之间的能量交换的过程，并最终导致等离子体加热和太阳风湍动级联的消散。所采用的方法将主要基于数据分析和相关的解释性建模。将利用英国和国外空间物理小组现有的和新的科学合作，对结果进行批判性审查，并与最先进的理论和数字预测进行比较。

The project will focus on the inner Heliosphere and the properties of the Solar Wind plasma close to the Sun: origin and acceleration; expansion in interplanetary space. The research activity will exploit new measurements by the NASA Parker Solar Probe (PSP) mission (launched in 2018) and in the near future by Solar Orbiter (launch in February 2019) during the cruise phase. These include high-resolution in situ observations of electric and magnetic fields and particles (ions and electrons) that compose the solar wind plasma at different heliocentric distances. The project will take advantage of the fact that PSP is collecting measurements in close-Sun regions unexplored before and its closest approach will continue to gradually reduce - from ~30 Solar radii to less than 20 during the 3 years of the project. These circumstances will make possible detailed studies of the solar wind plasma thermodynamic state and its evolution with radial distance, in order to identify processes responsible for the energy exchanges between particles and fields during the expansion and ultimately leading to the heating of the plasma and the dissipation of the solar wind turbulent cascade. The methodology adopted will be mostly based on data analysis and the associated interpretative modelling. Results will be critically reviewed and compared with state-of-art theoretical and numerical predictions, exploiting both existing and new scientific collaborations of the Space Physics Group, in the UK and abroad.