Ion Acoustic Wave Turbulence in Ionospheric Plasmas

这项研究将调查在电离层顶部产生离子声波湍流的源机制，该湍流可能导致强后向散射雷达回波，从而导致错误的卫星探测信号。麻省理工学院将对这一问题进行理论研究，而阿雷西博天文台计划进行实地实验，以模拟产生离子声波湍流的电离层条件。提出的源机制是一个非线性模式耦合过程，粒子沉淀诱导的朗缪尔波可以通过非线性相互作用产生离子声模波。将对这种非线性相互作用过程进行详细的描述，将高能粒子的真实能谱与数值分析结合起来。在阿雷西博的模拟实验中，高频加热器在电离层中产生的VLF波预计会导致辐射带中原来被俘获的电子的俯仰角散射。这些沿地球磁场沉淀到电离层的超热电子将形成产生大幅度离子声波的势源。430 MHz和50 MHz雷达都将用于诊断Aercibo上的电离层。Aercibo实验将主要在1991年专门研究计划的电离层加热运动中进行。

This study will investigate a source mechanism generating ion acoustic wave turbulence in the topside ionosphere that can cause strong backscatter radar echoes leading to false satellite detection signals. Theoretical investigation of the problem will be conducted at MIT, while field experiments are planned at the Arecibo Observatory to simulate the ionospheric conditions for the generations of ion acoustic wave turbulence. The proposed source mechanism is a nonlinear mode coupling process whereby Langmuir waves induced by particle precipitation can interact nonlinearly to produce ion acoustic mode waves. Detailed formulation of this nonlinear interaction process will be carried out, incorporating realistic energy spectra of high particles with a numerical analysis. In the simulation experiments at Arecibo, the VLF waves induced in the ionosphere by the HF heater are expected to cause the pitch angle scattering of originally trapped electrons in the radiation belts. These suprathermal electrons precipitated into the ionosphere along the earth's magnetic field will form a potential source producing large amplitude ion acoustic waves. Both the 430 MHz and 50 MHz radars will be employed to diagnose the ionoaphere over Aercibo. The Aercibo experiments will be conducted primarily in the 1991 ionosphere heating campaign for the dedicated research program.