空间科学学报

1994 Vol. 14, No. 4

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THE PHYSICAL NATURE OF THE ERUPTIVE PROCESS OF HELICAL PROMINENCES

Wu Gui-ping, Xu Ao-ao

1994, 14(4): 249-253. doi: 10.11728/cjss1994.04.249

Abstract(2710) PDF 2475KB(985)

Abstract:
With the Kuperus-Raadu model to describe the interaction between a prominence bud the background magnetic field, and Lundquist field to describe the distribution of current and magnetic field inside the prominence, the observational data of eruptive prominence on August 18, 1980 is systametically analysed and the physical nature in its eruptive process is discussed. The results show:(1)the physical cause of prominence to erupt is the kink-instabity of Lundquist field;(2)in the eruptive process, the magnetic energy of prominence releases fast so that the current intensity decreases continuously and prominence goes up and approaches stable state gradually;(3)the eruption of prominence may be one of the most important factorcausing CMEs.

LANGMUIR WAVES SPONTANEOUSLY EMITTED BY ENERGETIC ELECTRONS IN THE SOLAR WIND

Zhou Gong-cheng, C. s. Wu

1994, 14(4): 254-259. doi: 10.11728/cjss1994.04.254

Abstract(2116) PDF 2471KB(969)

Abstract:
In this paper, the spontaneous emission of Langmuir waves is discuss due to energetic electrons produced by solar flares in the solar wind. It is found that the electric field of the spontaneously emitted Langmuir waves can be as large as 10^-3-10^-2mV/m(depending upon the distribution of the electrons),if considering a characteristic time of γ_km^-1, where γ_km is the peak growth rate. This results is a great deal lower than the electric field associated with Langmuir waves observed with spacecraft in the solar wind. Thus, compared with induced processes,the spontaneous emission of Langmuir waves in general is negligible.

THE PLASMA WAKE FIELD BY SOLAR HIGHENERGY ELECTRONS IN SOLAR CORONA

Wang Xue-yi, Huang Yong-nian

1994, 14(4): 260-268. doi: 10.11728/cjss1994.04.260

Abstract(2024) PDF 530KB(913)

Abstract:
In this paper we have calculated the plasma wake fields(PWFs)excited by the interaction of high-energy electron beam with cold and hot plasma, and discussed the effects of electron beam speed, density and its length on PWFs. Based on the obtained results, we have studied τ-profiles of PWFs resulted from the interactions of high energy electron beams produced during a solar impulsive flare with the cororonal plasma, and acceleration of lower energy electrons by this PWFs in the corona. Here τ=ω_p(t-x/v_b)where ω_p =(4πn_oe²/m_e)^1/2 and t is time, x the axis along the diraction of electron beam velocity, v_b the speed of electron beam, n₀ plasmadensity in the corona, and m_e the rest mass of electron.

A CONTINUOUS NEUTRAL SHEET MODEL AND A NORMAL CURVE COORDINATE SYSTEM IN THE MAGNETOTAIL

Zhu Ming, Xu Rong-lan

1994, 14(4): 269-276. doi: 10.11728/cjss1994.04.269

Abstract(2386) PDF 535KB(1029)

Abstract:
Amodel of the continuous equatorial-neutral sheet is developed. This model is expressed with a smooth function, whose parameters are determined by the magnetic data of the ISEE-2 satellite, and it can very smoothly connect the geomagnetic equatorial plane with the magnetotail neutral sheet changing about with the earth's tilt angle. Based on this analytic model, a normal curve coordinate system is set up, in which the neutral sheet become one of the coordinate surface. The new coordinate system will change with the earth's tilt angle and thus can almost offset the tilted effect on the pattern of geomagnetic field in the magnetotail region.

THE PRINCIPLE OF GENERALIZED DIGISONDE DRIFT ANALYSIS

Guo Jian-shan, Bodo W. Reinisch, ZHENG Hong, ZHANG Qi-wei, XU Chu-fu

1994, 14(4): 277-285. doi: 10.11728/cjss1994.04.277

Abstract(2431) PDF 509KB(939)

Abstract:
he utility of Digisonde Drift Analysis(DDA)is demonstrated recently in the polar region ionospheric convection measurements. However, the assumption of uniform velocity in the field of view of sounder made in DDAis not always correct. Therefore a Generalized Digisonde Drift Analysis(GDDA)is introduced that is not limited to the condition of uniform velocity and thus makes it possible that the Digisonde drift measurement can be used in the complicated ionospheric motion analysis such as velocity shears, divergence and convergence. The main concept of GDDAand some promising simulation results are presented in the paper.

THE NONLINEAR INTERACTION OF FORCED ROSSBY WAVE PACKETS IN THE MIDDLE ATMOSPHERE Ⅱ. NUMERICAL COMPUTATION

Xiong Jian-gang, Yi Fan, Li Jun

1994, 14(4): 286-292. doi: 10.11728/cjss1994.04.286

Abstract(2642) PDF 457KB(874)

Abstract:
The problem of the stability of .the forced Rossby wave packets which are nonlinearly interacted resonantly in the middle atmosphere is examined numerically. The results are in agreement with our theorical analysis. When there is only one forced wave packet with middle wavelength, the stationary state may bifurcates to another stable one. Specially, when the Rossby wave packet with middle wavelength is the only one which isn't forced, there may exist multi-stationary states. The stationary states may generate cusp catastrophe in some domain of the intensity of the forcing. The stationary state that the system can really tends to is not only relateto the way in which the intensity of the forcing varies but also depends on the initial state.

THE SHEATH STRUCTURE FORMED BY ELECTRON BEAM CONTINUOUS INJECTION INTO VACUUM

Zang Zhen-qun, Fu Zhu-feng

1994, 14(4): 293-297. doi: 10.11728/cjss1994.04.293

Abstract(2133) PDF 295KB(885)

Abstract:
Aone-dimensional, two-stream analytical code has been developed to study the sheath structure formed by electron beam continuously injected into vacuum. Injected electrons will be decelerated and then drawn back to the surface of the spacecraft by the positive charges due to the electron beam injection into the vacuum from the spacecraft. The injection beam and return beam form two electron streams with the same density and velocity distribution in the sheath. The stagnetion point is at x=v_o/(3ω_o)(where v_o is the initial velocity of beam injection, ω_o is the plasmafrequancy of incipient injected electrons). Also, electric field distribution and electron density distribution in the sheath are given out in this paper.

AN INVERSION ANALYSIS IN DETERMINING THE PHASE VELOCITY OF TID_s BASED ON RADIO ASTRONOMICAL OBSERVATION

Han Wen-jun, T. A. Th. Spoelstra

1994, 14(4): 298-304. doi: 10.11728/cjss1994.04.298

Abstract(1893) PDF 300KB(812)

Abstract:
Considering the generation mechanisms of the atmospheric gravity waves and measurement techniques for TID_s, some useful rules for explaination of the measurements are drawn. It is shown that: TID_s consist of two harmonic waves which are orthogonal to each other, and both the measurement techniques for TID_s i.e. the total electron content measurement and the electron density measurement are equally effective. Accordingly inversion formulas for determination of the phase velocity of TID_s from radio astronomical data are derived, and the suppressing effects on wave amplitude are discussed.

A COMPARISON OF THE INTERNATIONAL REFERENCE IONOSPHERE(IRI-90)WITH THE ELECTRON DENSITY PROFILE OF THE IONOSPHERE OBSERVED IN CHINA

Luo Fa-geng, Dai Kai-liang, Quan Kun-hai, Liu Rui-yuan

1994, 14(4): 305-311. doi: 10.11728/cjss1994.04.305

Abstract(2666) PDF 376KB(1625)

Abstract:
Asystematic comparison is made between the electron density profiles observed at four of the Chinese ionospheric stations during high solar activity periods and the International Reference ionosphere IRI-90.It is indicated that the bottomside values of IRI-90 are generally greater than measured ones. In detail, the IRI-90 predicted electron content values are more close to the measured ones in daytime than in nighttime, and more close at mid latitudes than at low latitudes.

THE ENERGY DEPOSITION OF A MHD SHOCK IN THE INTERPLANETARY MEDIUM

Liu Shao-liang, Wang Zhi-xiang

1994, 14(4): 312-319. doi: 10.11728/cjss1994.04.312

Abstract(2863) PDF 466KB(987)

Abstract:
The relation of energy flux increment in downstream of a MHD shock relative to the upstream are deduced, and the radial evolution of the parameters of the solar wind in different flow speed is given in the form of power-law from the data observed by spacecrafts Helios A, B. Using above power-law of solar wind parameters as the upstream medium parameters of a shock, the rate of energy deposition dE/dR of the shock at different heliocentric distances for magnetic energy, internal energy. kinetic energy and the total energy are computed respectively. The result shows that across a MHD fast shock the increment of kinetic energy is the most important, next is the internal energy and the magnetic energy is the least; the rate of total energy deposition is larger near the sun, but its decreasing is faster. The total energy deposition increases with the initial shock Alfven number A₁₀ in the range of0.3-1.0 AU, and the computed values are agreeable with the observed.

THE ORBITAL VARIATIONS OF BALLOON SATELLITES 1990-81B AND 1990-81C AND DETERMINATION OF AIR DENSITY

Liu Ya-ying

1994, 14(4): 320-327. doi: 10.11728/cjss1994.04.320

Abstract(2465) PDF 377KB(1078)

Abstract:
The orbital variations of two balloon satellites, DQ-1A(1990-81B)and DQ-1C(1990-81C), are determined and presented in this paper. Apractical method for determining air density from the decay rate of nearly circular orbit is used and the upper atmospheric densities and variations at heights of 500-900km during the period when solar activity was just at a high level have been obtained from two balloon satellites. The results show that two sets of the density and variations determined respectively from two balloon satellites with different area/mess ratios are good agreement with each other and the variations of density with daily and 27 days periodically time scales of solar activity are very obvious. Acomparison between observed density and the COSPAR International Reference Atmosphere 1972 and 1986 is made in this paper. The analytic results are valuable for the study of space environments and the application of upper atmosphere model.