Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cross Helicity of the November 2018 Magnetic Cloud Observed by the
  Parker Solar Probe   Magnetic clouds are large-scale transient structures in the solar wind with
low plasma $\beta$, low-amplitude magnetic field fluctuations, and twisted
field lines with both ends often connected to the Sun. Their inertial-range
turbulent properties have not been examined in detail. In this Letter, we
analyze the normalized cross helicity, $\sigma_c$, and residual energy,
$\sigma_r$, of plasma fluctuations in the November 2018 magnetic cloud observed
at 0.25 au by the Parker Solar Probe. A low value of $|\sigma_c|$ was present
in the cloud core, indicating that wave power parallel and anti-parallel to the
mean field was approximately balanced, while the cloud's outer layers displayed
larger amplitude Alfv\'enic fluctuations with high $|\sigma_c|$ values and
$\sigma_r\sim0$. These properties are discussed in terms of the cloud's solar
connectivity and local interaction with the solar wind. We suggest that low
$|\sigma_c|$ is likely a common feature of magnetic clouds given their
typically closed field structure. Anti-sunward fluctuations propagating
immediately upstream of the cloud had strongly negative $\sigma_r$ values.

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The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph