极光带下层区电双层及密度空穴
Double layers and density cavitons in downward current region of aurora
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摘要: 为了得到极光带下层区电双层及密度空穴的形成和演化过程，分析了在静态极限下，强湍动等离子中低频电势、高频调制场及密度扰动之间的非线性耦合方程，并对其进行了数值计算。结果表明，在极光带下层区，坍塌的高频场导致了电双层及密度空穴的形成。所得的电双层为双双层，是一种非线性的实体，即腔子，其电势峰值范围为14～40 V，厚度为100～200 m，几十个Debye尺度；空穴的最大密度扰动率达到80%以上，这与FAST卫星观测结果相一致。Abstract: The nonlinear coupling equations of low-frequency potential, high-frequency modulation field and density disturbance in strong turbulent plasmas were numerically calculated in the static limit case. The evolutions of double layers and density cavitons were obtained. The results show that the double layer in downward current region of aurora is formed by localized drop in density owing to collapsed high frequency field. The structure is a double-double layer and a nonlinear entity: caviton. The ramp potential of the double layer is in range of 14 to 40 V, and the thickness of the structure is between 100 and 200 m, roughly tens of Debye lengths; the maximum density perturbation rate is up to more than 80%, which are all in harmony with the measurements by the Fast Auroral Snapshot satellite
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Key words:
- electric double layer /
- density caviton /
- plasma /
- aurora /
- numerical calculation
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