标题： 日球层激波对湍流参数的影响 显示英文标题

标题： Effect of interplanetary shock waves on turbulence parameters

摘要： 我们进行了广泛的统计研究，以调查太阳风快前锋激波如何影响某些湍流参数，即交叉螺旋度$\sigma_c$、剩余能量$\sigma_r$和磁螺旋度$\sigma_m$。 分析了“风”号探测器在1天文单位处探测到的总计371个激波和“太阳轨道器”号探测器在0.3-0.5天文单位处探测到的7个激波。 我们探讨了上述湍流参数及其在激波中的变化如何依赖于激波特性，包括气体压缩比、上游等离子体β值、速度跳跃和激波角度。 在激波附近，波动平均表现出向反太阳方向的不平衡（当校正到帕克螺旋方向时测量为$\sigma_c>0$），磁能占主导（$\sigma_r<0$）以及零$\sigma_m$，这些都是典型的太阳风性质。 随着激波速度跳跃的增加和上游β值及激波角度的减小，反太阳方向的不平衡和等能性（$\sigma_r \sim0$）在上游越来越普遍。 具有大速度跳跃和气体压缩比的激波在下游比上游有更平衡的（$\sigma_c\sim0$）和更磁化的小尺度波动。 从上游到下游，我们还发现满足严格阿尔文波动（AFs）标准的时间段通常减少，而满足小尺度磁通绳（SFRs）标准的时间段增加。 AF时段的发生率在准平行激波、大速度跳跃和小上游贝塔值时达到峰值。 SFRs的发生率随着气体压缩比和上游贝塔值的增加而增加。 由太阳轨道器在0.5天文单位以下观测到的激波显示出与在1天文单位处检测到的相似的湍流参数分布和上游到下游的变化。 这些结果对于理解无碰撞激波中的湍流和带电粒子加速具有相关性。 显示英文摘要

摘要： We have performed an extensive statistical investigation of how interplanetary fast forward shocks affect certain turbulence parameters, namely, the cross-helicity, $\sigma_c$, residual energy, $\sigma_r$, and magnetic helicity, $\sigma_m$. A total of 371 shocks detected by Wind at 1 au and seven shocks by Solar Orbiter at 0.3-0.5 au have been analysed. We explore how the aforementioned turbulence parameters and their variation across the shock depend on shock characteristics including the gas compression ratio, upstream plasma beta, velocity jump and shock angle. In the shock vicinity, fluctuations tend on average to show antisunward imbalance (measured as $\sigma_c>0$ when rectified to the Parker spiral direction), a dominance of magnetic energy ($\sigma_r<0$) and zero $\sigma_m$, all being typical solar wind properties . Antisunward imbalance and equipartition ($\sigma_r \sim0$) in the upstream is increasingly prevalent with increasing shock velocity jump and decreasing upstream beta and shock angle. Shocks with large velocity jumps and gas compression ratios have considerably more balanced ($\sigma_c\sim0$) and more magnetically dominated fluctuations downstream than upstream. From upstream to downstream, we also find that the occurrence of time periods fulfilling strict criteria for Alfv\'enic fluctuations (AFs) usually decreases, while those meeting the criteria for small-scale flux ropes (SFRs) increases. The occurrence of AF periods peaks for quasi-parallel shocks with large velocity jumps and small upstream beta. The occurrence of SFRs increases with increasing gas compression ratio and upstream beta. The shocks observed by Solar Orbiter below 0.5 au display similar distributions of turbulence parameters and upstream-to-downstream changes to those detected at 1 au. These results are relevant for understanding turbulence and charged-particle acceleration at collisionless shocks.