Studies of charged particle populations in the solar wind using Solar Orbiter SWA data.

UCL/MSSL是一个国际联盟的首席研究员（PI）研究所，为欧空局太阳轨道飞行器任务提供太阳风分析仪套件（SWA）。利用3个科学传感器，SWA将在距离太阳0.28天文单位（即大约太阳到地球距离的四分之一）和太阳高纬度的不同距离取样电子、质子、α粒子和重离子的数量。特别是，UCL/MSSL为SWA套件设计并构建了电子分析仪系统（EAS）。SWA在法国、意大利和美国的合作伙伴为该套件提供了重离子传感器（HIS）和质子α传感器（PAS）。该任务目前的基准是在2020年2月发射，后备计划在2020年10月发射。SWA数据将在启动后的几周内提供，因此对这个新数据集的分析可以在博士课程的第一年开始。特别是，我们的目标是利用3个SWA传感器的巡航阶段测量来研究太阳风粒子群的性质、它们的可变性以及它们与太阳的联系。在博士开始和发射之间的（希望很短的）时间内，我们将使用以前任务的数据进行背景/准备研究。许多潜在的研究项目都在任务科学计划的范围内（如PI和ESA在https://issues.cosmos.esa.int/solarorbiterwiki/display/SOSP/SAP-related+work上生成的任务“科学活动计划”中的详细内容），因此将在资助期开始时根据学生的具体背景和兴趣确定一个具体的初始项目。作为一个可能的例子，已知太阳风电子种群一般由3个部分组成：最冷电子的“核心”种群几乎是各向同性的-在任何方向都可以检测到给定能量的大约相同的电子通量；“光晕”人口出现在更高的能量上，并且显示相对于核心的平均速度略有变化，因此在太阳风中提供了“热通量”；最后，“斯特劳”种群通常被视为沿磁场流动的高能粒子束。总之，这些不同的电子居群包含了在太阳源区域发生的过程的信息，采样等离子体与太阳的磁连接，以及可能在太阳风本身发生的等离子体过程（例如湍流、波粒相互作用和磁重联）。分离这些过程的影响是一项复杂的任务，需要高节奏、高分辨率的数据，这些数据将从SWA EAS中获得。作为这里可能进行的科学研究的另一个例子，学生可以研究行星际冲击的全球驱动因素和局部特性。冲击和其他波锋是由多种形式的太阳活动（例如，日冕物质抛射喷发，共旋转相互作用区域）驱动的。在SWA和其他原位仪器上执行触发模式时，这些激波锋面将以前所未有的细节被捕获。这些项目的结果对整个欧空局太阳轨道飞行器计划的成功至关重要，因此该学生也将成为MSSL科学和科学规划团队不可或缺的一部分。该学生还将有机会与我们在法国、意大利和美国的合作伙伴合作，他们为SWA套件提供了HIS和PAS传感器。这个项目将使学生处于一个良好的位置，更广泛地合作，并找到未来的职位，例如在国际太阳能轨道飞行器社区。

UCL/MSSL is the Principal Investigator (PI) Institute on an international consortium providing the Solar Wind Analyser suite (SWA) of instruments for the ESA Solar Orbiter mission. Using 3 scientific sensors, SWA will sample electron, proton, alpha particle and heavy ion populations at various distances down to 0.28 AU from the Sun (i.e. around a quarter the distance from the Sun to the Earth) and at high solar latitudes. In particular, UCL/MSSL has designed and built the Electron Analyser System (EAS) for the SWA suite. SWA partners in France, Italy and the USA have provided the Heavy Ion Sensor (HIS) and Proton-Alpha Sensor (PAS) for the suite.The mission is currently baselined for launch in Feb 2020, with a back-up in October 2020. SWA data will be available within a few weeks of the launch, and thus analysis of this new data set can begin within the first year of this PhD program. In particular, we aim to use cruise-phase measurements from the 3 SWA sensors to undertake studies of the nature of the solar wind particle populations, their variability and their links to the Sun. In the (hopefully short) period between the start of the PhD and launch we will undertake background/ preparatory studies using data from previous missions.Many potential research projects fall within the scope of the mission science plan (as detailed, for example, in the mission 'Science Activity Plan' at https://issues.cosmos.esa.int/solarorbiterwiki/display/SOSP/SAP-related+work generated by the PI's and ESA) and so a specific initial project will be identified at the start of the funded period according to the specific background and interests of the student. As a possible example, it is known that the solar wind electron population in general consists of 3 components: A 'core' population of the coldest electrons which is nearly isotropic - approximately the same flux of electrons of a given energy may be detected in any direction; A 'halo' population occurs at somewhat higher energies, and shows a slight shift in average velocity with respect to the core, and thus provides a 'heat flux' in the solar wind; Finally, a 'strahl' population is often seen as a more energetic beam of particles streaming along the magnetic field. Together these different electron populations contain information about the processes occurring at the source region on the Sun, the magnetic connections of the sampled plasma back to the Sun and on the plasma processes (e.g. turbulence, wave-particle interactions and magnetic reconnection) which may be occurring within the solar wind itself. Separating the effects of these processes is a complicated task requiring high-cadence, high resolution data of the type that will be available from SWA EAS. As a further example of the kind of scientific research possible here, the student might undertake studies of both the global drivers and local properties of interplanetary shocks. Shocks and other wave fronts are driven through the solar wind by many forms of solar activity (for example, CME eruption, co-rotating interaction regions). These shock fronts will be captured in unprecedented detail as they pass the spacecraft by the execution of a trigger mode on SWA and other in situ instruments.The results of such projects are critical to the success of the overall ESA Solar Orbiter program, and the student will thus also be an integral part of the MSSL science and science-planning team. The student will also have the opportunity to collaborate with our partners in France, Italy and the USA, who have provided the HIS and PAS sensors for the SWA suite. This project will place the student in a good position to collaborate more generally and to find future positions e.g. within the Solar Orbiter community internationally.