Solar energetic particles associated with solar flares and coronal mass ejections (CMEs) are key agents of space weather phenomena, posing severe threats to spacecraft and astronauts. Recent observations by Parker Solar Probe indicate that the magnetic flux ropes of a CME can trap energetic particles and act as barriers, preventing other particles from crossing. In this Letter, we introduce the novel COCONUT+PARADISE model to investigate the confinement of energetic particles within a flux rope and the effects of cross-field diffusion (CFD) on particle transport in the solar corona, particularly in the presence of a CME. Using the global magnetohydrodynamic coronal model COolfluid COroNal UnsTructured (COCONUT), we generate background configurations containing a CME modeled as a Titov–Démoulin flux rope (TDFR). We then utilize the particle transport code PArticle Radiation Asset Directed at Interplanetary Space Exploration (PARADISE) to inject monoenergetic 100 keV protons inside one of the TDFR legs near its footpoint and evolve the particles through the COCONUT backgrounds. To study CFD, we employ two different approaches regarding the perpendicular proton mean free path (MFP): a constant MFP and a Larmor radius-dependent MFP. We contrast these results with those obtained without CFD. While particles remain fully trapped within the TDFR without CFD, we find that even relatively small perpendicular MFP values allow particles on the outer layers to escape. In contrast, the initially interior trapped particles stay largely confined. Finally, we highlight how our model and this Letter's results are relevant for future research on particle acceleration and transport in an extended domain encompassing both the corona and inner heliosphere.

中文翻译：

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跨场扩散对太阳日冕通量绳中粒子传输的影响


与太阳耀斑和日冕物质抛射 （CME） 相关的太阳高能粒子是空间天气现象的关键因素，对航天器和宇航员构成严重威胁。帕克太阳探测器最近的观察表明，CME 的磁通绳可以捕获高能粒子并充当屏障，防止其他粒子穿过。在这封信中，我们介绍了新颖的 COCONUT+PARADISE 模型，以研究高能粒子在磁通绳内的限制以及交叉场扩散 （CFD） 对日冕中粒子传输的影响，尤其是在存在 CME 的情况下。使用全局磁流体动力学冠状模型 COolfluid COroNal Unstructured （COCONUT），我们生成了包含建模为 Titov-Démoulin 磁通绳 （TDFR） 的 CME 的背景配置。然后，我们利用粒子传输代码 PArticle Radiation Asset Directed to Interplanetary Space Exploration （PARADISE） 在其脚点附近的一条 TDFR 腿内注入单能 100 keV 质子，并通过 COCONUT 背景演化粒子。为了研究 CFD，我们采用了两种不同的方法来研究垂直质子平均自由程 （MFP）：常数 MFP 和 Larmor 半径依赖性 MFP。我们将这些结果与没有 CFD 的结果进行对比。虽然颗粒在没有 CFD 的情况下仍然完全被捕获在 TDFR 中，但我们发现，即使是相对较小的垂直 MFP 值也允许外层的颗粒逸出。相比之下，最初内部捕获的颗粒在很大程度上保持受限。最后，我们强调了我们的模型和这封信的结果如何与未来在包括日冕层和内日球层在内的扩展域中的粒子加速和传输研究相关。