Density cavities generated by plasma--field interactions in the far wake region of a space vehicle

Under the consideration of non-steady case, a set of equations is derived, which describes the non-steady nonlinear interactions between plasma and field in the far wake region of a space vehicle. Numerical calculations are also made and the numerical results show that density cavities and electromagnetic solitary waves are generated due to the modulation instability, if the envelope of high frequency modulation field is strong enough. This is of great significance to the detection of disguised space vehicles.     

Scaling Law of Exponents in Cosmological Clustering

The density of N-clusters(the clusters which contain N galaxies)in the Universe is shown from observations to scale with N as nN ∝ N^-τ with τ=3/γ 1 and the correlation exponent γ≈1.8.Correspondingly,a acaling relation τ=29-9γ/12-4γ between the two exponents,which agrees with the observations,is found analytically in our naive clustering model.     

等离子体天体物理中的强湍动

本文对等离子体天体物理中的强湍动进行了评述,并强调了等离子体的基本相互作用。 分析了控制强湍动现象的查哈罗夫方程。讨论了一些天体物理中的重要问题,例如加速、爆发、双层、飞行体与等离子体相互作用,自引力系统非线性结构以及自生磁场等。     

等离子体中磁单极子的辐射和能量损失

本文对磁单极子在等离子体中的辐射和能量损失作了仔细的研究,文中推导出产生磁单极子辐射的一般公式;获得了与荷电粒子颇不相同的Cerenkov辐射功率和谱;求出了在宇宙等离子体中和金属内它的能量损失。并指出,基于等离子体在普通介质中的Cerenkov辐射,因此可用来检测磁单极子的可能性。     

Magnetic Instability in Accretion Disks with Anomalous Viscosity

Using the new model of anomalous viscosity, we investigate the magnetic instability in the accretion disks and give the dispersion formula. On the basis of the dispersion relation obtained, it is numerically shown that the instability condition of viscous accretion disk is well consistent with that of the ideal accretion disk, namely there would be magneto-rotational instability in the presence of a vertical weak magnetic field. For a given distance R from the centre of the disk, the growth rate in the anomalous case deviates from the ideal case more greatly when the vertical magnetic field is smaller. The large viscosity limits to the instability. In the two cases, the distributions of growth rate with wave number κ approach each other when the magnetic field increases. It greatly represses the effect of viscosity.     

等离子体天体物理中的强湍动

本文对等离子体天体物理中的强湍动进行了评述，并强调了等离子体的基本相互作用。分析了控制强湍动现象的查哈罗夫方程。讨论了一些天体物理中的重要问题，例如加速、爆发、双层、飞行体与等离子体相互作用，自引力系统非线性结构以及自生磁场等。     

强激光在磁化等离子体中的调制不稳定性

采用洛伦兹变换推导出左旋椭圆偏振强激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出激光场包络的非线性控制方程,分析了在磁化等离子体中左旋椭圆偏振激光的调制不稳定性,得到了调制不稳定的时间增长率。分析结果表明,磁化等离子体中自调制不稳定的极大增长率较非磁化情况明显减小,且在激光等离子体临界面附近处调制不稳定性的时间增长率显著增大。     

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采用洛伦兹变换推导出左旋椭圆偏振强激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出激光场包络的非线性控制方程,分析了在磁化等离子体中左旋椭圆偏振激光的调制不稳定性,得到了调制不稳定的时间增长率。分析结果表明,磁化等离子体中自调制不稳定的极大增长率较非磁化情况明显减小,且在激光等离子体临界面附近处调制不稳定性的时间增长率显著增大。     

Dynamical behaviour of transverse plasmons in pair plasmas

This paper analytically investigates the nonlinear behaviour of transverse plasmons in pair plasmas on the basis of the nonlinear governing equations obtained from Vlasov--Maxwell equations. It shows that high frequency transverse plasmons are modulationally unstable with respect to the uniform state of the pair plasma. Such an instability would cause wave field collapse into a localized region. During the collapse process, ponderomotive expulsion is greatly enhanced for the increase of wave field strength, leading to the formation of localized density cavitons which are significant for the future experimental research in the interaction between high frequency electromagnetic waves and pair plasmas.     

FORMATING DOUBLE LAYER MECHANISM BY ELECTRIC CHARGED PARTICLE STREAM IN PLASMA

In this paper, two-fluid equations have been solved after having considered magnetic field generated by charged particle stream. Finally, the distribution of electric field E_z(z,r) and its growth rate γ in plasma have been obtained. From the expression of E_z(z,r) it can be known that the double layer has been formed. With the increase of disturbance γ will be larger, and finally this will result in the interruption of electric current and occurrence of burst.