Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field

Verscharen, Daniel; Chandran, Benjamin D. G.; Bourouaine, Sofiane; Hollweg, Joseph V.

doi:10.1088/0004-637x/806/2/157

Cited by 32 publications

(37 citation statements)

References 86 publications

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“…In the fast solar wind at r < 0.3 AU, the (fractional) cross helicity is high (i.e., E + ≫ E − ), and δB in is indeed small compared to B 0 (Bavassano et al 2000;Cranmer & van Ballegooijen 2005). Moreover, the background magnetic field at r = 0.3 AU is nearly in the radial direction, because the Parker-spiral magnetic field begins to deviate appreciably from the radial direction only at larger r in the fast wind (Verscharen et al 2015). Hence, in high-crosshelicity fast-wind streams at r = 0.3 AU, the function e + defined by Equations (6.3) and (6.4) corresponds to a good approximation to the frequency spectrum of outwardpropagating AWs observed by a spacecraft in the solar wind.…”

Section: Comparison With Helios Measurementsmentioning

confidence: 97%

Parametric instability, inverse cascade and the range of solar-wind turbulence

Chandran

2018

J. Plasma Phys.

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In this paper, weak-turbulence theory is used to investigate the nonlinear evolution of the parametric instability in three-dimensional low-β plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are strongly damped. It is shown analytically that the parametric instability leads to an inverse cascade of Alfvén wave quanta, and several exact solutions to the wave kinetic equations are presented. The main results of the paper concern the parametric decay of Alfvén waves that initially satisfy e + e − , where e + and e − are the frequency ( f ) spectra of Alfvén waves propagating in opposite directions along the magnetic field lines. If e + initially has a peak frequency f 0 (at which fe + is maximized) and an 'infrared' scaling f p at smaller f with −1 < p < 1, then e + acquires an f −1 scaling throughout a range of frequencies that spreads out in both directions from f 0 . At the same time, e − acquires an f −2 scaling within this same frequency range. If the plasma parameters and infrared e + spectrum are chosen to match conditions in the fast solar wind at a heliocentric distance of 0.3 astronomical units (AU), then the nonlinear evolution of the parametric instability leads to an e + spectrum that matches fast-wind measurements from the Helios spacecraft at 0.3 AU, including the observed f −1 scaling at f 3 × 10 −4 Hz. The results of this paper suggest that the f −1 spectrum seen by Helios in the fast solar wind at f 3 × 10 −4 Hz is produced in situ by parametric decay and that the f −1 range of e + extends over an increasingly narrow range of frequencies as r decreases below 0.3 AU. This prediction will be tested by measurements from the Parker Solar Probe.

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Section: Comparison With Helios Measurementsmentioning

confidence: 97%

Parametric instability, inverse cascade and the range of solar-wind turbulence

Chandran

2018

J. Plasma Phys.

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“…Using empirical profiles for B, p ⊥j , n j , and U j for j = p and j = α then gives the empirical heating rates Q ⊥p and Q ⊥α . Adapted from Verscharen et al (2015).…”

Section: Multiple Sources Of Free Energymentioning

confidence: 99%

The multi-scale nature of the solar wind

Verscharen¹,

Klein²,

Maruca³

2019

Living Rev Sol Phys

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336

285

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The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions,

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“…These processes are thermodynamically relevant since they not only generate electromagnetic fluctuations but also equilibrate the plasma, change the temperatures of the plasma components, and regulate the heat flux in the system (Hellinger & Trávníček 2013;Verscharen et al 2015;Hellinger et al 2017;Riquelme et al 2018). We expect that the relevance of the acting mechanisms depends on location, the source regions of the solar wind, the magnetic configuration and connectivity, and the solar cycle.…”

Section: What Mechanisms Heat the Corona And Heat Andmentioning

confidence: 99%

The Solar Orbiter mission

Müller

Cyr

Zouganelis

et al. 2020

A&A

736

281

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Aims. Solar Orbiter, the first mission of ESA’s Cosmic Vision 2015–2025 programme and a mission of international collaboration between ESA and NASA, will explore the Sun and heliosphere from close up and out of the ecliptic plane. It was launched on 10 February 2020 04:03 UTC from Cape Canaveral and aims to address key questions of solar and heliospheric physics pertaining to how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To answer these, the mission carries six remote-sensing instruments to observe the Sun and the solar corona, and four in-situ instruments to measure the solar wind, energetic particles, and electromagnetic fields. In this paper, we describe the science objectives of the mission, and how these will be addressed by the joint observations of the instruments onboard. Methods. The paper first summarises the mission-level science objectives, followed by an overview of the spacecraft and payload. We report the observables and performance figures of each instrument, as well as the trajectory design. This is followed by a summary of the science operations concept. The paper concludes with a more detailed description of the science objectives. Results. Solar Orbiter will combine in-situ measurements in the heliosphere with high-resolution remote-sensing observations of the Sun to address fundamental questions of solar and heliospheric physics. The performance of the Solar Orbiter payload meets the requirements derived from the mission’s science objectives. Its science return will be augmented further by coordinated observations with other space missions and ground-based observatories.

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Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field

Cited by 32 publications

References 86 publications

Parametric instability, inverse cascade and the range of solar-wind turbulence

Parametric instability, inverse cascade and the range of solar-wind turbulence

The multi-scale nature of the solar wind

The Solar Orbiter mission

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