Huang Guang-li

Effect of Electron Drift Velocity on Whistler Instability in Collisionless Magnetic Reconnection

The whistler instability is studied under the condition that the electron and ion velocities can be described in a bi-Maxwellian distribution with a field-aligned electron outflow drift velocity. It is found that the electron outflow drift velocity might obviously make the threshold condition of whistler instability decrease when this velocity is parallel to the magnetic field, whereas the electron outflow drift velocity might increase the threshold condition when this velocity is anti-parallel to the magnetic field in collisionless magnetic reconnection.

Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum

Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum are investigated with a model in a magnetic dipole field. It is found that the gyroresonance absorption and self absorption suppress substantially the gyrosynchrotron radiation at lower frequencies where the radio source is optically thick. The suppression of the gyroresonance absorption on the spectrum increases with the increasing temperature and density of thermal electrons. The suppression of the self absorption on the spectrum increases as increasing number density of the nonthermal electrons. The influences of the gyroresonance absorption and the self one on the spectrum are compared quantitatively. It is shown that only when the number density of the nonthermal electron reaches a higher value of about 3 x 10(4) cm(-3) above 10 keV, can the effect of the self absorption on the spectrum compare with the effect of the gyroresonance absorption.

Particle Acceleration at Reconnecting X points in Solar Flares by Electrostatic Waves

In the impulsive phase of solar flares, the electrostatic waves can be excited during magnetic reconnection. The proton and electron at reconnecting X points can be accelerated by perpendicular propagating electrostatic waves.

A Quasi-Periodic Solar Radio Fluctuation at Microwave Band

A rare but interesting solar radio fine structure, quasi-periodic fluctuations, on 25 August 1999 was observed at microwave band for the first time. They fluctuated initially at a nearly stable frequency level then at a reverse drift component up to 5.49 GHz. The individual fluctuation consists of a bi-directional drift component. The features are characterized by narrow bandwidth of Delta f/f <= 3%, quasi-periodicity of similar to 100 ms as well as a slowly reverse and a rapidly normal drift rates on the bi-directional drift component. The associated data of the Yohkoh soft and hard x-ray telescope and Nobeyama radio heliograph at 17GHz showed that there are several bright spots (i.e. inhomogeneities) along the soft x-ray loop, and the locations of both radio and soft x-ray sources are closely consistent. Therefore, the fluctuations are most likely caused by the inhomogeneities within a Bare loop. Based on the two-component atmospheric model, we suggest a three-component atmospheric model with large scale length lambda and small scale lengths lambda(1) and lambda(2) to describe equilibrium atmosphere and inhomogeneity, With the beam model, the characters of fluctuations may be interpreted reasonably by the quasi-equidistant inhomogeneity along a Rare loop.

A Special Flare-CME Event on April 21, 2002

The time and location of magnetic reconnection are indicated by radio (Nobeyama Radio Heliograph and Polarimeters, Hiraiso and Chinese radio spectrographs) and multi-wavelength (SOHO and TRACE satellites) data in a selected flare-CME event on April 21, 2002. Two hour radio burst started at high frequencies (maximum around 10 GHz). After that, a radio ejection at 17 GHz from one foot point was coincident with the expanded flare and post-flare loops. The reversal of polarization sense at the radio loop-top is associated with the strong coherent emissions around 2 GHz, which should be located above the loop-top at 17/34 GHz. The radio ejection and coherent emissions are also associated with a pair of moving type

Evidence of coronal loop interaction in a flare-CME event

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Observation of a type of sporadic solar mass ejection and its physical interpretation with numerical simulation

bursts at 0.2-2 GHz from high to low frequencies and 2.6-3.8 GHz from low to high frequencies, respectively. High time resolution (8 ms) data show three components of the frequency drifts at 2.6-3.8 GHz: very slow (5 MHz/s) of moving type

A method of calculation of the solar radio flux density for high spatial resolution observations

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The direct excitation of electromagnetic waves by beam instabilities and explanation for solar type-III radio bursts AAnS 13/1 (1993) 53–61

, slow (50 MHz/s) of zebra strips, and fast (several GHz/s) of type

Upgrading the Terminal System on the Fine-structure Heliograph at Gan-Yu Station of Purple Mountain Observatory and Some New Observational Results

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