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@article{Matteini:2015:1/11,
author = {Matteini, L and Horbury, TS and Pantellini, F and Velli, M and Schwartz, SJ},
doi = {1/11},
journal = {Astrophysical Journal},
title = {Ion kinetic energy conservation and magnetic field strength constancy in multi-fluid solar wind alfvénic turbulence},
url = {http://dx.doi.org/10.1088/0004-637X/802/1/11},
volume = {802},
year = {2015}
}

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TY  - JOUR
AB  - We investigate the properties of plasma fluid motion in the large-amplitude, low-frequency fluctuations of highlyAlfvénic fast solar wind. We show that protons locally conserve total kinetic energy when observed from aneffective frame of reference comoving with the fluctuations. For typical properties of the fast wind, this frame canbe reasonably identified by alpha particles which, due to their drift with respect to protons at about the Alfvénspeed along the magnetic field, do not partake in the fluid low-frequency fluctuations. Using their velocity totransform the proton velocity into the frame of Alfvénic turbulence, we demonstrate that the resulting plasmamotion is characterized by a constant absolute value of the velocity, zero electric fields, and aligned velocity andmagnetic field vectors as expected for unidirectional Alfvénic fluctuations in equilibrium. We propose that thisconstraint, via the correlation between velocity and magnetic field in Alfvénic turbulence, is the origin of theobserved constancy of the magnetic field; while the constant velocity corresponding to constant energy can only beobserved in the frame of the fluctuations, the corresponding constant total magnetic field, invariant for Galileantransformations, remains the observational signature in the spacecraft frame of the constant total energy in theAlfvén turbulence frame
AU  - Matteini,L
AU  - Horbury,TS
AU  - Pantellini,F
AU  - Velli,M
AU  - Schwartz,SJ
DO  - 1/11
PY  - 2015///
SN  - 1538-4357
TI  - Ion kinetic energy conservation and magnetic field strength constancy in multi-fluid solar wind alfvénic turbulence
T2  - Astrophysical Journal
UR  - http://dx.doi.org/10.1088/0004-637X/802/1/11
UR  - http://hdl.handle.net/10044/1/25437
VL  - 802
ER  -

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