scholarly journals Mode Coupling in the Solar Corona. I. Coupling Near the Plasma Level

1974 ◽  
Vol 27 (1) ◽  
pp. 31 ◽  
Author(s):  
DB Melrose
Keyword(s):  
Plasma Level ◽  
Solar Corona ◽  
Mode Coupling ◽  
Solar Radio ◽  
Plasma Frequency ◽  
Type I ◽  
Radio Radiation ◽  
Coupling Ratio ◽  
Solar Radio Radiation ◽  
Solar Type

The theory of mode coupling in the radiation from solar type I storms is extended to treat coupling when the frequency! is near the plasma frequency!p. It is found that Cohen's coupling ratio Q = U/It)4, where It is the transition frequency (f'P It for strong coupling), is to be multiplied by a factor (1-!~/ J2)5/2 for QT regions, i.e. coupling is relatively suppressed close to the plasma level. The implications on the handedness of solar radio radiation are discussed. The possibility of depolarization due to mode coupling is considered briefly.

On the Interpretation of Solar Radio-Burst Positions in a Scattering Corona

1972 ◽  
Vol 2 (3) ◽  
pp. 148-150 ◽  
Author(s):  
A. C. Riddle
Keyword(s):  
Plasma Level ◽  
Point Source ◽  
Solar Radio ◽  
Plasma Frequency ◽  
Second Harmonic ◽  
Source Size ◽  
Spherically Symmetric ◽  
Extended Source ◽  
True Source ◽  
Solar Bursts

Current observations and theories of solar bursts of types I, II and III suggest that the observed radiation may be emitted at a frequency close to the (fundamental) plasma frequency or its second harmonic. Refraction in a spherically symmetric corona would prevent radiation at the plasma frequency from reaching the observer except when the source is near the centre of the solar disk. However, it is found that fundamental frequency bursts are observed from anywhere on the disk. Recent analyses by Steinberg et al. and Riddle, in which the scattering of the radiation by coronal inhomogeneities was considered (in addition to refraction in an otherwise spherically symmetric corona), show that the radiation can escape from the plasma level and be observed for sources positioned almost anywhere on the disk. In addition, these authors and Fokker showed that a point source of radiation at the plasma frequency, or its harmonic, would be observed as an extended source with dimensions comparable with those observed. One implication was that the true source size is much smaller than the observed size.

scholarly journals 67. Solar radio emission and the acceleration of magnetic-storm particles

1957 ◽  
Vol 4 ◽  
pp. 356-357 ◽  
Author(s):  
A. Schlüter
Keyword(s):  
Gravitational Field ◽  
Radio Emission ◽  
Solar Corona ◽  
Magnetic Storm ◽  
Solar Radio ◽  
Plasma Frequency ◽  
Solar Radio Emission ◽  
The Sun ◽  
Lower Frequencies

The shift of the emitted frequencies towards lower frequencies during a solar outburst is usually interpreted as due to a progressive rarefaction of the emitting gas. If one assumes that the emitted frequency is identical with the plasma frequency and furthermore that the density of the emitting plasma is similar to the density of the solar corona at the location of the radiating material, then it follows that this material is subject to an acceleration throughout the solar corona which compensates or exceeds the effect of the gravitational field of the sun.

scholarly journals Electron Acceleration at Quasi-Parallel Shocks in The Solar Corona and Its Signature in Solar Type II Radio Bursts

1994 ◽  
Vol 142 ◽  
pp. 577-581
Author(s):  
G. Mann ◽  
H. Lühr
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Radio Bursts ◽  
Type Ii ◽  
Radio Radiation ◽  
Earth’S Bow Shock ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Field Geometry ◽  
The Magnetic Field

AbstractRecently, strong large amplitude magnetic field structures (SLAMS) have been observed as a common phenomenon in the vicinity of the quasi-parallel region of Earth’s bow shock. A quasi-parallel shock transition can be considered as a patchwork of SLAMS. Using the data of the AMPTE/IRM magnetometer the properties of SLAMS are studied. Within SLAMS the magnetic field is strongly deformed and, thus, the magnetic field geometry is locally swung into a quasi-perpendicular regime. Therefore, electrons can locally be accelerated to high energies within SLAMS. Assuming that SLAMS also exist in the vicinity of supercritical, quasi-parallel shocks in the solar corona, they are able to generate radio radiation via the enhanced Langmuir turbulence excited by the accelerated electrons. Since SLAMS are connected with strong density enhancements, the aforementioned mechanism can explain the multiple-lane structure often occurred in solar Type II radio bursts.Subject headings: acceleration of particles — Earth — shock waves — Sun: corona — Sun: radio radiation

scholarly journals Solar Radio Radiation Bursts on 1998 April 15

2000 ◽  
Vol 52 (5) ◽  
pp. 919-924 ◽  
Author(s):  
Zongjun Ning ◽  
Qijun Fu ◽  
Quankang Lu
Keyword(s):  
Solar Radio ◽  
Radio Radiation ◽  
Solar Radio Radiation

scholarly journals Solar radio bright spots at 88-cm wavelength

1959 ◽  
Vol 9 ◽  
pp. 136-139 ◽  
Author(s):  
J. Firor
Keyword(s):  
Solar Radio ◽  
Wavelength Region ◽  
Bright Spot ◽  
Radio Radiation ◽  
Noise Storm ◽  
Bright Spots ◽  
Solar Radio Radiation

During 1957 we studied the solar radio radiation at a wavelength intermediate between the centimeter region with its slowly varying bright spots and the meter-wavelength region with its noise storms. At this intermediate wavelength (88 cm) the slowly varying bright-spot and the noise-storm producing regions merge into two aspects of the same persistent, bright, solar radio regions.

scholarly journals The Quiet Sun at cm- and mm-Wavelengths

1980 ◽  
Vol 86 ◽  
pp. 25-39 ◽  
Author(s):  
E. Fürst
Keyword(s):  
Solar Atmosphere ◽  
Solar Radio ◽  
Theoretical Estimate ◽  
Sunspot Cycle ◽  
Active Regions ◽  
Spectral Lines ◽  
Radio Radiation ◽  
Quiet Sun ◽  
Solar Radio Radiation ◽  
Active Centres

Soon after the first detection of radio emission from the sun two components of the solar radio radiation were identified: The emission related to active centres on the disk and the radiation of the undisturbed, static solar atmosphere, in which the active regions are embedded. The undisturbed component is observed to vary only slightly during the solar sunspot cycle, it is called the emission of the quiet sun. A theoretical estimate of this component was first given by Martyn (1946) and subsequently developed in more detail by many other authors. The basic observations were performed with poor angular resolution. Still at present most experimental data are taken with angular resolutions of about 1 to 4 arc min, too low to discriminate between the different solar atmospheric fine structures, clearly seen in various spectral lines. The quiet component of the solar radio radiation therefore represents the average emission of an inhomogenous solar atmosphere.

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