Switchbacks, defined as Alfvénic reversals in magnetic field polarity, can dissipate their magnetic energy with heliocentric distance. To further investigate this, two distinct solar wind parcels tracing back to a similar solar source region were examined during a radial alignment between Parker Solar Probe (@25.8RS) and Solar Orbiter (@152RS). The one caveat was that the two probes were located on opposite sides of the heliospheric current sheet during the alignment. The two parcels contained a multitude of switchbacks—the parcel closer to the Sun was characterized as a switchback patch (SBP), where background proton velocity (vp) is comparable to the pristine solar wind (vsw), while the parcel farther from the Sun showed characteristics attributable to a microstream (MS; vp > vsw). It was found that (1) MS contains, on average, 30% fewer switchbacks than SBP, and (2) dynamic and thermal pressures decreased by up to 20% across switchback boundaries in SBP and relatively unchanged in MS. Magnetic relaxation can explain the lower number of switchbacks in MS compared to SBP. Switchback relaxation inside SBP can, in turn, accelerate plasma inside SBP over time and heliocentric distance, thus resulting in vp > vsw in MS. Therefore, it is hypothesized that magnetic relaxation of switchbacks may cause SBPs to evolve into MSs over time and heliocentric distance.

中文翻译：

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之字形贴片通过磁弛豫演变成微流


之字形，定义为磁场极性的 Alfvénic 反转，可以通过日心距离耗散其磁能。为了进一步研究这一点，在帕克太阳探测器 （@25.8RS） 和太阳轨道飞行器 （@152RS） 之间的径向对准过程中，检查了两个可追溯到相似太阳源区域的不同太阳风地块。需要注意的是，在对准过程中，两个探针位于日球层洋流片的相对两侧。这两个地块包含大量之字形区域——靠近太阳的地块被描述为之字形斑块 （SBP），其中背景质子速度 （vp） 与原始太阳风 （vsw） 相当，而离太阳较远的地块则显示出可归因于微流的特性 （MS;vp > vsw）。研究发现，（1） MS 包含的之字压力比 SBP 平均少 30%，并且 （2） 在 SBP 中，动态压力和热压力在之字形边界上降低了 20%，而在 MS 中则相对没有变化。反过来，SBP 内部的之字形弛豫会随着时间的推移和日心距离加速 SBP 内的等离子体，从而导致 MS 中的 vp > vsw。因此，假设之字形的磁弛豫可能导致 SBP 随着时间的推移和日心距离演变为 MS。