标题： 太阳高能质子的反速度弥散观测及其激波加速解释 显示英文标题

标题： Inverse Velocity Dispersion of Solar Energetic Protons Observed by Solar Orbiter and Its Shock Acceleration Explanation

摘要： 太阳爆发期间的粒子加速和传输过程是空间等离子体物理中的关键且长期存在的问题。 经过数十年的研究，人们普遍接受在太阳爆发期间释放的高能粒子比低能粒子更早到达观测者，这在动态能量谱中形成了一种被称为粒子速度色散（VD）的著名结构，经常被航天任务所观测到。 然而，这一图景受到了NASA的帕克太阳探测器和ESA的太阳轨道器新观测结果的挑战，这些观测结果显示了一种意想不到的反向速度色散（IVD）现象，其中高能粒子较晚到达观测者。 面对这一挑战，我们在此报告了由太阳轨道器观测到的10个太阳高能质子事件中此类IVD结构的最新发现，然后分析导致这种异常现象的机制。 我们认为，相对于磁重联而言，激波扩散加速可能是这类事件中将质子加速到几十MeV的主要机制，因为在这些事件中，粒子需要更长时间才能达到更高的能量。 我们创新性地确定了实际激波加速过程中无法直接观测到的物理条件和时间尺度。 显示英文摘要

摘要： The particle acceleration and transport process during solar eruptions is one of the critical and long-standing problems in space plasma physics. Through decades of research, it is well accepted that particles with higher energies released during a solar eruption arrive at observers earlier than the particles with lower energies, forming a well-known structure in the dynamic energy spectrum called particle velocity dispersion (VD), as frequently observed by space missions. However, this picture is challenged by new observations from NASA's Parker Solar Probe and ESA's Solar Orbiter which show an unexpected inverse velocity dispersion (IVD) phenomenon, where particles with higher-energies arrive later at the observer. Facing on the challenge, we here report the recent discovery of such IVD structures with 10 solar energetic proton events observed by Solar Orbiter, and then analyze the mechanisms causing this unusual phenomenon. We suggest that shock diffusive acceleration, with respect to magnetic reconnection, is probably a dominant mechanism to accelerate protons to tens of MeV in such events where particles need longer time to reach higher energies. And we determine, innovatively, the physical conditions and time scales during the actual shock acceleration process that cannot be observed directly.