scholarly journals High frequency ion sound waves associated with Langmuir waves in type III radio burst source regions

2004 ◽  
Vol 11 (3) ◽  
pp. 411-420 ◽  
Author(s):  
G. Thejappa ◽  
R. J. MacDowall
Keyword(s):  
Short Wavelength ◽  
Langmuir Wave ◽  
Linear Process ◽  
Radio Bursts ◽  
Sound Waves ◽  
Burst Source ◽  
Langmuir Waves ◽  
Type Iii ◽  
Resonant Wave ◽  
Source Regions

Abstract. Short wavelength ion sound waves (2-4kHz) are detected in association with the Langmuir waves (~15-30kHz) in the source regions of several local type III radio bursts. They are most probably not due to any resonant wave-wave interactions such as the electrostatic decay instability because their wavelengths are much shorter than those of Langmuir waves. The Langmuir waves occur as coherent field structures with peak intensities exceeding the Langmuir collapse thresholds. Their scale sizes are of the order of the wavelength of an ion sound wave. These Langmuir wave field characteristics indicate that the observed short wavelength ion sound waves are most probably generated during the thermalization of the burnt-out cavitons left behind by the Langmuir collapse. Moreover, the peak intensities of the observed short wavelength ion sound waves are comparable to the expected intensities of those ion sound waves radiated by the burnt-out cavitons. However, the speeds of the electron beams derived from the frequency drift of type III radio bursts are too slow to satisfy the needed adiabatic ion approximation. Therefore, some non-linear process such as the induced scattering on thermal ions most probably pumps the beam excited Langmuir waves towards the lower wavenumbers, where the adiabatic ion approximation is justified.

Ulysses Observations of Nonlinear Wave-wave Interactions in the Source Regions of Type III Solar Radio Bursts

2000 ◽  
Vol 179 ◽  
pp. 447-450
Author(s):  
G. Thejappa ◽  
R. J. MacDowall
Keyword(s):  
Acoustic Waves ◽  
Modulational Instability ◽  
Langmuir Wave ◽  
Wave Interactions ◽  
Burst Source ◽  
Langmuir Waves ◽  
Type Iii ◽  
Source Regions ◽  
Ion Acoustic ◽  
Solar Type

AbstractThe Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons, suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak turbulence processes, such as electrostatic decay, in a few type III burst source regions.

Type III Radio Bursts and Langmuir Wave Excitation

2020 ◽  
Author(s):  
Gottfried Mann ◽  
Christian Vocks ◽  
Mario Bisi ◽  
Eoin Carley ◽  
Bartosz Dabrowski ◽  
...  
Keyword(s):  
Distribution Function ◽  
Interplanetary Space ◽  
Langmuir Wave ◽  
Velocity Distribution Function ◽  
Radio Bursts ◽  
Radio Waves ◽  
Langmuir Waves ◽  
Low Frequencies ◽  
Energetic Electrons ◽  
Type Iii

<p>Type III radio bursts are a common phenomenon the Sun’s nonthermal radio radiation. They appear as stripes of enhanced radio emission with a rapid drift from high to low frequencies in dynamic radio spectra. They are considered as the radio signatures of beams of energetic electrons travelling along magnetic field lines from the solar corona into the interplanetary space. With the ground based radio interferometer LOFAR and the instrument FIELDS onboard NASA’s “Parker Solar Probe” (PSP) , type III radio bursts can be observed simultaneously from high (10-240 MHz) to low frequencies (0.01-20 MHz) with LOFAR and PSP’s FIELDs, respectively. That allows to track these electron beams from the corona up to the interplanetary space. Assuming that a population of energetic electrons is initially injected, the velocity distribution function of these electrons evolves into a beam like one. Such distribution function leads to the excitation of Langmuir waves which convert into radio waves finally observed as type II radio bursts. Numerical calculations of the electron-beam-plasma interaction reveal that the Langmuir waves are excited by different parts of the energetic electrons at different distances in the corona and interplanetary space. This result is compared with special type III radio bursts observed with LOFAR and PSP’s FIELDS.</p>

scholarly journals Detection of Langmuir Solitons: Implications for Type III Burst Emission Mechanisms at 2ωPE

1996 ◽  
Vol 154 ◽  
pp. 195-198
Author(s):  
G. Thejappa ◽  
R.G. Stone ◽  
M.L. Goldstein
Keyword(s):  
Second Harmonic ◽  
Theoretical Models ◽  
Burst Source ◽  
Langmuir Waves ◽  
Type Iii ◽  
Source Regions ◽  
Envelope Solitons ◽  
Turbulence Regime ◽  
Solar Type ◽  
Langmuir Solitons

AbstractWe present the experimental verification of existing theoretical models of emission mechanisms of solar type III bursts at the second harmonic of the plasma frequency, ωpe. This study is based on the detection of Langmuir and envelope solitons by the Ulysses spacecraft inside three type III burst source regions. We show that the oscillating-two-stream instability, coherent radiation by Langmuir solitons and stochastic phase mixing of the Langmuir waves in the strong turbulence regime are the appropriate emission mechanisms at 2ωpe.

scholarly journals The Mechanism Responsible for 'Shadow' Type III Solar Radio Bursts. II. Absorption due to Ion Sound Turbulence

1974 ◽  
Vol 27 (2) ◽  
pp. 271 ◽  
Author(s):  
DB Melrose
Keyword(s):  
Energy Density ◽  
Solar Radio ◽  
Plasma Frequency ◽  
Radio Bursts ◽  
Sound Waves ◽  
Solar Radio Bursts ◽  
Langmuir Waves ◽  
Transverse Waves ◽  
Type Iii ◽  
Ion Plasma

The hypothesis is explored that ion sound turbulence generated by the exciting agency for type III bursts is responsible for shadow type III events. The possible absorption mechanisms are listed: the most favourable are the coalescence of transverse waves and ion sound waves into Langmuir waves or the decay of transverse waves into Langmuir waves and ion sound waves. These mechanisms can operate only if the background source emits at the fundamental plasma frequency and the absorbing region is directly above it (;$ 3 x 104 km). It is found that the event discussed by Kai (1973) can be explained in terms of such absorption with reasonable parameters, e.g. with an energy density in ion sound turbulence W' ~ 10-12 ergcm- 3 at frequencies co' ~ O�3cop! (where cop! is the ion plasma frequency).

Scattering of Langmuir waves produced by a beam with finite transverse dimensions

1972 ◽  
Vol 7 (3) ◽  
pp. 523-543
Author(s):  
G. Berthomieu
Keyword(s):  
Simple Model ◽  
Plasma Waves ◽  
Radio Bursts ◽  
Nonlinear Processes ◽  
Langmuir Waves ◽  
Type Iii

It has been proposed by Smith that type III radio bursts may be produced by streams of protons with radius of the order of 7 km, which is of the same order as the characteristic lengths of the nonlinear processes which are supposed to take place in the dynamics of these bursts. In this paper, we consider a method for studying systems with finite transverse dimensions and apply it to a simple model: the scattering of a beam of plasma waves by acoustic turbulence and by the particles of the plasma.

scholarly journals Satellite Observations of Solar Radio Bursts

1980 ◽  
Vol 86 ◽  
pp. 387-400
Author(s):  
J.L. Steinberg
Keyword(s):  
Solar Radio ◽  
Source Size ◽  
Type I ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Burst Source ◽  
Radiation Mechanism ◽  
3 Dimensional ◽  
Type Iii ◽  
Group Delays

Space observations of solar radio bursts have provided the following information:– From a single spacecraft:Measurements within the burst source or close to it: fundamental and harmonic type III radio emission, the corresponding plasma waves and spectra of the exciting electrons.– From a spacecraft and the earth or from two spacecrafts:A better evaluation of the influence of the ionosphere on some ground-based observations.Measurements of the beaming of the emission which yield constraints on the radiation mechanism and/or the role of coronal propagation in determining the source size and directivity (type I and III's).Measurements of the differential time delay which yield for type III:At short (m- and dam-) wavelengths, some evidence of group delays,At long (hm- and km-) wavelengths one coordinate of the source.Complete (3-dimensional) localization of the source at long wavelengths and therefore maps of the heliosphere magnetic field and electron density as well as the source size and, in the future, its polarization.The results of these observations and their interpretation are reviewed and discussed.

scholarly journals Dependence of Langmuir wave polarization on electron beam speed in type III solar radio bursts

2011 ◽  
Vol 38 (13) ◽  
pp. n/a-n/a ◽  
Author(s):  
David M. Malaspina ◽  
Iver H. Cairns ◽  
Robert E. Ergun
Keyword(s):  
Electron Beam ◽  
Solar Radio ◽  
Langmuir Wave ◽  
Radio Bursts ◽  
Wave Polarization ◽  
Solar Radio Bursts ◽  
Type Iii
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