论文标题

磁换回α颗粒的密度和速度波动

Density And Velocity Fluctuations of Alpha Particles in Magnetic Switchbacks

论文作者

McManus, M. D., Verniero, J. L., Bale, S. D., Bowen, T. A., Larson, D. E., Kasper, J. C., Livi, R., Matteini, L., Rahmati, A., Romeo, O., Whittlesey, P. L., Woolley, T.

论文摘要

到目前为止,磁性折返或磁场径向上的突然逆转是迄今为止帕克太阳能探针(PSP)的更引人注目的观察之一。尽管它们的精确生产机制仍然未知,但这两个主要理论是通过交换重新连接事件和原位生成的。在这种工作密度和α粒子的丰度变化中,在内部和外部单个折返方面进行了研究。我们发现α粒子丰度比,$ n_ {αp} $,内部与外部没有一致的组成差异,在根据$ v_ {αp}/v_ {pw} $分离折返时,我们也不会观察到任何签名,即Alpha-proton差异速度的比率,以使alpha-proton差速器速度速度速度(速度速度)。我们认为,由于PSP与假定的互换重新连接事件之间的距离,这些测量不能用于统治一个生产机制而不是另一个生产机制。此外,我们检查了单个折返中质子和α颗粒的3D速度波动。虽然折返始终与质子速度的增加相关,但α速度可能会增强,不变或减小。这是由于$ v_ {pW} $和$ v_ {αp} $之间的相互作用,而alpha粒子的alfvénic运动消失了,因为差额$ | v_ {pw} - v_ {pW} - v_ {αp} | $降低。我们展示了如何通过折返来理解alpha和质子的藻类运动,可以理解为围绕波浪框架位置的近似刚性的臂旋转,并说明可以单独使用粒子测量值估算波形,并通过球形拟合进行估算。

Magnetic switchbacks, or sudden reversals in the magnetic field's radial direction, are one of the more striking observations of Parker Solar Probe (PSP) thus far in its mission. While their precise production mechanisms are still unknown, the two main theories are via interchange reconnection events and in-situ generation. In this work density and abundance variations of alpha particles are studied inside and outside individual switchbacks. We find no consistent compositional differences in the alpha particle abundance ratio, $n_{αp}$, inside vs outside, nor do we observe any signature when separating the switchbacks according to $V_{αp}/V_{pw}$, the ratio of alpha-proton differential speed to the wave phase speed (speed the switchback is travelling). We argue these measurements cannot be used to rule in favour of one production mechanism over the other, due to the distance between PSP and the postulated interchange reconnection events. In addition we examine the 3D velocity fluctuations of protons and alpha particles within individual switchbacks. While switchbacks are always associated with increases in proton velocity, alpha velocities may be enhanced, unchanged, or decrease. This is due to the interplay between $V_{pw}$ and $V_{αp}$, with the Alfvénic motion of the alpha particles vanishing as the difference $|V_{pw} - V_{αp}|$ decreases. We show how the Alfvénic motion of both the alphas and the protons through switchbacks can be understood as approximately rigid arm rotation about the location of the wave frame, and illustrate that the wave frame can therefore be estimated using particle measurements alone, via sphere fitting.

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