Excitation of Langmuir waves in interplanetary space

Yoon, Peter H.; Ziebell, L. F.; Wu, C. S.

doi:10.1029/2000ja000230

Cited by 2 publications

(2 citation statements)

References 25 publications

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“…Although a bump occurring at some nonzero pitch angle can generate Langmuir waves [Yoon et al, 2000], we shall limit ourselves to the more robust instability criterion requiring a localized positive gradient ∂f (v k )/∂v k > 0 in the reduced electron distribution functionf , easier to compare with the present low time resolution observations. It is not obvious to explain how such a positive slope in the electron distribution function may be formed in a magnetic hole, especially if one takes into account the fact that linear instability theory shows that "slow beams" (i.e., with velocity such that v b ≈ v te ) with a beam temperature similar to core electron temperature and density smaller (not necessarily much smaller) than the core plasma density are not sufficient to drive the plasma unstable [Gary, 1985].…”

Section: Wave Generation Mechanismmentioning

confidence: 99%

Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations

et al. 2010

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[1] Magnetic depressions are common structures of the interplanetary medium. These magnetic holes can be just isolated dips of the amplitude of the field or they can be associated with discontinuities in the field orientation (tangential or rotational). Electrostatic waves at the plasma frequency (Langmuir waves) are often observed in these magnetic structures. The aim of the present paper is to provide the main characteristics of these waves and to propose a mechanism to explain their formation. The study is based on a statistical analysis of observations performed by STEREO (between March 2007 and August 2009) and Cluster (between 2002 and 2005 when each mission was in the free solar wind. Complementary information is provided by the two missions through the different instrumental configurations. We first provide new characteristics of the waves (polarization, energy, spectrum, occurrence). We then show that the occurrence of Langmuir waves activity inside a hole is closely linked to the presence of a significant electron strahl outside the hole. Finally, we propose a scenario for the generation of the Langmuir waves inside the holes.Citation: Briand, C., J. Soucek, P. Henri, and A. Mangeney (2010), Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations,

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Section: Wave Generation Mechanismmentioning

confidence: 99%

Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations

et al. 2010

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“…In the standard scenario (Ginzburg & Zhelezniakov 1958), the non-linear interaction of beam-driven plasma waves leads to the appearance of rather strong radio emission -type III solar/interplanetary radio bursts. The observations of type III solar bursts and energetic particles (Lin et al 1981;Ergun et al 1998;Gosling et al 2003;Krucker et al 2007) as well as hamish@astro.gla.ac.uk, eduard@astro.gla.ac.uk theoretical (Zheleznyakov & Zaitsev 1970;Zaitsev et al 1972;Mel'Nik 1995) and numerical investigations (Magelssen & Smith 1977;Grognard 1982;Kontar' et al 1998;Yoon et al 2000;Kontar 2001b;Li et al 2006a;Ledenev et al 2004;Krasnoselskikh et al 2007) provide strong support to the standard type III model.…”

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confidence: 99%

Solar Wind Density Turbulence and Solar Flare Electron Transport From the Sun to the Earth

Reid

Kontar

2010

ApJ

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Solar flare accelerated electron beams propagating away from the Sun can interact with the turbulent interplanetary media, producing plasma waves and type III radio emission. These electron beams are detected near the Earth with a double power-law energy spectrum. We simulate electron beam propagation from the Sun to the Earth in the weak turbulent regime taking into account the selfconsistent generation of plasma waves and subsequent wave interaction with density fluctuations from low frequency MHD turbulence. The rate at which plasma waves are induced by an unstable electron beam is reduced by background density fluctuations, most acutely when fluctuations have large amplitudes or small wavelengths. This suppression of plasma waves alters the wave distrubtion which changes the electron beam transport. Assuming a 5/3 Kolmogorov-type power density spectrum of fluctuations often observed near the Earth, we investigate the corresponding energy spectrum of the electron beam after it has propagated 1 AU. We find a direct correlation between the spectrum of the double power-law below the break energy and the turbulent intensity of the background plasma. For an initial spectral index of 3.5, we find a range of spectra below the break energy between 1.6-2.1, with higher levels of turbulence corresponding to higher spectral indices.

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Excitation of Langmuir waves in interplanetary space

Cited by 2 publications

References 25 publications

Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations

Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations

Solar Wind Density Turbulence and Solar Flare Electron Transport From the Sun to the Earth

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