Modulated Langmuir waves: Observations from Freja and SCIFER

Bonnell, J. W.; Kintner, P. M.; Wahlund, Jan‐Erik; Holtet, J. A.

doi:10.1029/97ja01499

Cited by 47 publications

(70 citation statements)

References 15 publications

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“…Indeed, Cairns and Menietti (2001) and Burinskaya et al (2000) analyse the statistics of Langmuir-like waves driven by electron beams in the more strongly magnetized plasma of the polar cap, finding agreement with SGT. On the other hand, nonlinear three-wave processes involving Langmuir and lower hybrid waves arguably cause modulation of auroral Langmuir waves observed in satellite and rocket experiments (Ergun et al, 1991b;Bonnell et al, 1997;Khotyaintsev et al, 2001;Lizunov et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Statistics of auroral Langmuir waves

2008

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Abstract. The Physics of Auroral Zone Electrons II (PHAZE II) sounding rocket was launched in February 1997 into active pre-midnight aurora. The resulting high frequency wave data are dominated by Langmuir waves. Consistent with many previous observations the Langmuir waves are sporadic, occurring in bursts lasting up to a few hundred ms. We compute statistics of the electric field amplitudes of these Langmuir waves, with two results. First, the shape of the distribution of running averages of the electric field amplitudes remains approximately stationary for a large range of widths of running average less than ∼0.3 ms and for a large range of widths exceeding about 1 ms. The interpretation of this transition timescale is unclear but appears unlikely to be of instrumental origin. Second, for 2.6-ms running averages, corresponding to the latter range, the distribution of the logarithm of electric field amplitudes matches a Gaussian form very well for all nine cases studied in detail, hence the statistics are lognormal. These distributions are consistent with stochastic growth theory (SGT).

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Section: Introductionmentioning

confidence: 99%

Statistics of auroral Langmuir waves

2008

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“…Cairns and Robinson, 1992;Cairns et al, 1998;Pottelette et al, 1999;Matsukiyo et al, 2004;Soucek et al, 2005) or lower hybrid waves (e.g. Stasiewicz et al, 1996;Bonnell et al, 1997;Lizunov et al, 2001). Note that Cairns et al (1998) demonstrated that electron-beam-driven Langmuir wave packets observed in the magnetosphere lie well outside the region of parameter space for which the modulational instability can proceed.…”

Section: Strongly Modulated Waveforms and Packets Of Langmuirmentioning

confidence: 99%

“…Correspondence to: T. Umeda (umeda@stelab.nagoya-u.ac.jp) waves were also observed in various regions of the magnetosphere, such as in the auroral ionosphere (Ergun et al, 1991;Stasiewicz et al, 1996;Bonnell et al, 1997;Pottelette et al, 1999;Lizunov et al, 2001), in the solar wind (Gurnett et al, 1993;Bale et al, 1996;Kellogg et al, 1999b), in the electron foreshock region (Kellogg et al, , 1999aSoucek et al, 2005), and in the magnetotail (Kojima et al, 1997).…”

Section: Strongly Modulated Waveforms and Packets Of Langmuirmentioning

confidence: 99%

Vlasov simulation of Langmuir wave packets

Umeda

2007

Nonlin. Processes Geophys.

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Abstract. Amplitude modulation and packet formation of Langmuir waves are commonly observed during a nonlinear interaction between electron beams and plasmas. In this paper, we briefly review the history of Langmuir wave packets as developed by recent spacecraft observations and computer simulations. New one-dimensional electrostatic Vlasov simulations are performed to study their formation processes. It is found that the formation of Langmuir wave packets involves both an incoherent turbulent process and a coherent nonlinear trapping process. Existence of cold ions does not affect nonlinear processes of the weak-electron-beam instability in which the ion distribution is hardly modified by the excited Langmuir wave packets.

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“…Modulational processes have been observed in laboratory experiments of nonmagnetized plasmas in the presence of an external electric field 1 and in Nd-laser beat-wave experiments in a homogeneous plasma 2 . In space plasmas, modulational processes can explain the detection of modulated wave envelopes observed in the auroral region 3,4 .…”

Section: Introductionmentioning

confidence: 99%

“…The theory of nonlinear modulational processes can explain the generation of modulated wave envelopes commonly observed in laboratory plasmas 1,2 , space and astrophysical plasmas [3][4][5] and oceans 6 . For example, modulational Langmuir processes in plasmas refer to the mechanism by which initially small fluctuations of electrostatic Langmuir waves produce density accumulation towards regions where the electric field is weaker.…”

Section: Introductionmentioning

confidence: 99%

Chaotic saddles in nonlinear modulational interactions in a plasma

2012

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A nonlinear model of modulational processes in the subsonic regime involving a linearly unstable wave and two linearly damped waves with different damping rates in a plasma is studied numerically. We compute the maximum Lyapunov exponent as a function of the damping rates in a two-parameter space, and identify shrimp-shaped self-similar structures in the parameter space. By varying the damping rate of the low-frequency wave, we construct bifurcation diagrams and focus on a saddle-node bifurcation and an interior crisis associated with a periodic window. We detect chaotic saddles and their stable and unstable manifolds, and demonstrate how the connection between two chaotic saddles via coupling unstable periodic orbits can result in a crisis-induced intermittency. The relevance of this work for the understanding of modulational processes observed in plasmas and fluids is discussed.

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Modulated Langmuir waves: Observations from Freja and SCIFER

Cited by 47 publications

References 15 publications

Statistics of auroral Langmuir waves

Statistics of auroral Langmuir waves

Vlasov simulation of Langmuir wave packets

Chaotic saddles in nonlinear modulational interactions in a plasma

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