EXCITATION OF LOW-FREQUENCY WAVES IN THE SOLAR WIND BY NEWBORN INTERSTELLAR PICKUP IONS H<sup>+</sup>AND He<sup>+</sup>AS SEEN BY VOYAGER AT 4.5 AU

Joyce, Colin J.; Smith, Charles W.; Isenberg, Philip A.; Murphy, Neil; Schwadron, N. A.

doi:10.1088/0004-637x/724/2/1256

Cited by 35 publications

(34 citation statements)

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“…As a result, the density has fallen to 0.7 p + cm −3 , the average magnetic field is | B | = 4.7 nT and almost radially aligned with Θ B R = 9.6°, and the Alfvén speed is elevated to 123 km s −1 . Past studies [ Joyce et al , ; Cannon et al , , ] have suggested that waves due to newborn interstellar pickup ions are most readily found in rarefaction regions and in other situations where the background turbulence is low.…”

Section: Discussionmentioning

confidence: 99%

“…A database of 502 such observations in the Ulysses data was developed from the spectrogram observations and subsequently analyzed [ Smith et al , ; Cannon et al , , , ]. Joyce et al [] reported one observation of He + ‐excited waves in the Voyager data set at 4.5AU. Although both H + ‐ and He + ‐excited waves are predicted to be ubiquitous [ Lee and Ip , ], they are actually relatively rare.…”

Section: Introductionmentioning

confidence: 99%

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ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

Argall

Fisher

Joyce

et al. 2015

Geophysical Research Letters

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We report low‐frequency magnetic waves that were observed by the Advanced Composition Explorer (ACE) spacecraft on day of year 180 of 1999 with characteristics consistent with the predictions of waves excited by newborn interstellar pickup He+ ions. This event was found by examining daily spectrograms of MAG data, a new data product that is now available to the community via the ACE Science Center. The event shown here is one of approximately 20 similar events that will be analyzed in future studies. This event is fairly typical of those we have found so far. The waves exist at spacecraft‐frame frequencies between the He+ cyclotron frequency and approximately twice the H+ cyclotron frequency. Fluctuations are transverse to the mean magnetic field, are noncompressive, circularly polarized, have field‐aligned minimum variance directions, and are left‐hand polarized in the spacecraft frame as predicted by theory. The event lasts for just under 1 h.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

Argall

Fisher

Joyce

et al. 2015

Geophysical Research Letters

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“…Among others, these include the instabilities caused by newborn ions originating from the pickup neutrals, that have been studied in the past 40 years. The growth time of such instabilities (Wu & Davidson 1972;Wu & Hartle 1974) can be a few hundred of seconds only, but they can also have wavelengths that are measured up to about 10 10 m (Joyce et al 2010). Some other phenomena imply heating in the solar wind (Smith et al 2001;Gary et al 2006;Breech et al 2009), with the effects of the temperature anisotropy T ⊥ > T , and T ⊥ < T , where ⊥, stand for the perpendicular and parallel directions with respect to the ambient magnetic field vector, respectively, and with numerous evidences for T ⊥α > T ⊥p , T α > T p , where α, p denote respectively the alpha particles and protons (Tam & Chang 1999;Gary et al 2006;Kasper et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Transport and diffusion of particles due to transverse drift waves

Vranjes

2011

A&A

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Transport and diffusion of plasma particles perpendicular and parallel to the magnetic field is discussed in the framework of the transverse drift wave theory. The starting model includes the density and magnetic field gradients perpendicular to the magnetic field vector. In such an inhomogeneous environment the transverse drift wave naturally develops. The transverse drift wave is a low frequency mode, with the frequency far below the ion gyro-frequency, it is driven by these gradients and it propagates perpendicular to them. The mode is also purely perpendicular to the magnetic field and it is electromagnetically transverse, which implies that when its wave vector is perpendicular to the magnetic field vector, the perturbed electric field is along the equilibrium magnetic field, while in the same time the perturbed magnetic field is in the direction of the background gradients. In application to the solar wind, it is shown that very small wave electric field amplitude, of the order of 10 −7 V/m, within one wave period can produce the drift of protons in both directions, perpendicular to the ecliptic plane and also along the background magnetic field, to distances measured in millions of kilometers. The electric field along the magnetic field vector implies particle acceleration in the same direction. When a critical threshold velocity of the particle is achieved, the particle motion becomes stochastic. This is a completely new nonlinear stochastic mechanism which follows from the very specific geometry of the transverse drift mode. Particle drift perpendicular to the magnetic field vector means a diffusion of particles, with the effective diffusion coefficient for ions that is at least 11 orders of magnitude larger than the classic diffusion coefficient. The features of this diffusion are: within certain time interval, initially faster particles will diffuse to larger distances, and the same holds for protons in comparison to heavier ions. For electrons the effective diffusion coefficient can easily match the one obtained from observations, i.e., to become of the order of 10 17 m 2 /s. It is also expected that the wave-induced stochastic motion will considerably increase the effective collision frequency in such an environment which is, with respect to its mean parameters, practically collision-lees. Hence, the solar wind regions affected by such a stochastic acceleration may show various unexpected features that are typical for collisional plasmas.

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“…For a general orientation of the ambient magnetic field a ring-beam distribution function is generated and both the temperature anisotropy and the differential velocity could be a source of free energy for kinetic instabilities (Vandas & Hellinger 2015). The pick-up ion driven instabilities are active in the solar wind as indicated by in situ observation of the generated waves (Joyce et al 2010;Cannon et al 2014b,a;Aggarwal et al 2016). The linear and nonlinear studies of pick-up ion driven instabilities usually assume a homogeneous plasma that is at odds with ubiquitous turbulent fluctuations observed in the distant solar wind (Fraternale et al 2016).…”

mentioning

confidence: 99%

“…The linear and nonlinear studies of pick-up ion driven instabilities usually assume a homogeneous plasma that is at odds with ubiquitous turbulent fluctuations observed in the distant solar wind (Fraternale et al 2016). In situ observations of enhanced wave activity (Joyce et al 2010;Cannon et al 2014b,a;Aggarwal et al 2016) indicate that the pick-up ion driven instabilities are active in the solar wind. This is supported by direct hybrid simulations of Hellinger et al (2015) showing that kinetic instabilities may coexist with turbulence.…”

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confidence: 99%

Proton Heating by Pick-Up Ion Driven Cyclotron Waves in the Outer Heliosphere: Hybrid Expanding Box Simulations

Hellinger

Trávníček

2016

ApJ

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Using one-dimensional hybrid expanding box model we investigate properties of the solar wind in the outer heliosphere. We assume a proton-electron plasma with a strictly transverse ambient magnetic field and, beside the expansion, we take into account influence of a continuous injection of cold pickup protons through the charge-exchange process between the solar wind protons and hydrogen of interstellar origin. The injected cold pick-up protons form a ring distribution function that rapidly becomes unstable and generate Alfvén cyclotron waves. The Alfvén cyclotron waves scatter pick-up protons to a spherical shell distribution function that thickens over that time owing to the expansiondriven cooling. The Alfvén cyclotron waves heat solar wind protons in the perpendicular direction (with respect to the ambient magnetic field) through the cyclotron resonance. At later times, the Alfvén cyclotron waves become parametrically unstable and the generated ion acoustic waves heat protons in the parallel direction through the Landau resonance. The resulting heating of the solar wind protons is efficient on the expansion time scale.

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EXCITATION OF LOW-FREQUENCY WAVES IN THE SOLAR WIND BY NEWBORN INTERSTELLAR PICKUP IONS H⁺AND He⁺AS SEEN BY VOYAGER AT 4.5 AU

Cited by 35 publications

References 38 publications

ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

Transport and diffusion of particles due to transverse drift waves

Proton Heating by Pick-Up Ion Driven Cyclotron Waves in the Outer Heliosphere: Hybrid Expanding Box Simulations

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EXCITATION OF LOW-FREQUENCY WAVES IN THE SOLAR WIND BY NEWBORN INTERSTELLAR PICKUP IONS H+AND He+AS SEEN BY VOYAGER AT 4.5 AU

Cited by 35 publications

References 38 publications

ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

ACE observations of magnetic waves arising from newborn interstellar pickup helium ions

Transport and diffusion of particles due to transverse drift waves

Proton Heating by Pick-Up Ion Driven Cyclotron Waves in the Outer Heliosphere: Hybrid Expanding Box Simulations

Contact Info

Product

Resources

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EXCITATION OF LOW-FREQUENCY WAVES IN THE SOLAR WIND BY NEWBORN INTERSTELLAR PICKUP IONS H⁺AND He⁺AS SEEN BY VOYAGER AT 4.5 AU