标题： 内日球层中的线性稳定性：重新评估Helios 显示英文标题

标题： Linear Stability in the Inner Heliosphere: Helios Reëvaluated

摘要： 由偏离局域热动平衡引起的波粒不稳定性被认为在控制太阳风动力学中起作用。 我们使用Nyquist稳定性准则的数值评估计算了大量Helios I和II快速太阳风观测数据的线性稳定性统计变化，考虑了与质子和氦相关的多个自由能来源，包括温度各向异性和相对漂移。 我们发现88%的调查区间是线性不稳定的。 不稳定模式的中位增长率在一个数量级内接近湍流传递率，快到有可能影响湍流尺度间的能量传递。 这一速率随径向距离没有显著变化，尽管不稳定的性质以及哪些离子成分负责驱动这些不稳定性确实有所不同。 离子-离子碰撞对稳定性的影响被发现是显著的；碰撞较年轻的风比碰撞较老的风更不稳定，两种风中存在的不稳定性类型非常不同。 显示英文摘要

摘要： Wave-particle instabilities driven by departures from local thermodynamic equilibrium have been conjectured to play a role in governing solar wind dynamics. We calculate the statistical variation of linear stability over a large subset of Helios I and II fast solar wind observations using a numerical evaluation of the Nyquist stability criterion, accounting for multiple sources of free energy associated with protons and helium including temperature anisotropies and relative drifts. We find that 88\% of the surveyed intervals are linearly unstable. The median growth rate of the unstable modes is within an order of magnitude of the turbulent transfer rate, fast enough to potentially impact the turbulent scale-to-scale energy transfer. This rate does not significantly change with radial distance, though the nature of the unstable modes, and which ion components are responsible for driving the instabilities, does vary. The effect of ion-ion collisions on stability is found to be significant; collisionally young wind is much more unstable than collsionally old wind, with very different kinds of instabilities present in the two kinds of wind.