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首页> 外文学位 >Electron density and electron neutral collision frequency in the ionosphere using plasma impedance probe measurements on sounding rockets.
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Electron density and electron neutral collision frequency in the ionosphere using plasma impedance probe measurements on sounding rockets.

机译：在探空火箭上使用等离子体阻抗探针测量电离层中的电子密度和电子中性碰撞频率。

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摘要

The Plasma Impedance Probe (PIP) is an RF-instrument that is used to measure plasma electron density and electron neutral collision frequency. Radio Frequency probe techniques for the determination of plasma parameters are attractive especially because the RF response is not susceptible to spacecraft charging problems at frequencies above the electron plasma frequency where ion sheath effects are negligible. The work done in this thesis is presented as a compendium of two papers, the first paper dealing with PIP measurements on a sounding rocket mission and the second being a qualitative study of the effects of spacecraft aerodynamics on the impedance of antennas.;Swept Impedance Probe measurements in a sporadic E-Layer observed during the Sudden Atomic Layer (SAL) sounding rocket mission are analyzed in the first paper to obtain absolute electron densities and electron neutral collision frequencies accurately. Three sets each of upleg and downleg impedance data are selected for the analysis. Initial estimates of the plasma parameters are obtained through a least mean square fit of the measured impedance data against the analytical impedance formula of Balmain. These initial parameters are used as a starting point to drive a finite difference computational model of an antenna immersed in a plasma called the Plasma Fluid Finite Difference Time Domain (PF-FDTD) model. The parameters are then tuned until a close fit is obtained between the measured impedance data and the numerical impedance data calculated by the PF-FDTD simulation. The electron neutral collision frequencies obtained from the more accurate PF-FDTD simulation were up to 20% lower than the values predicted by Balmain's formula. The obtained collision frequencies are also lower than the quiet time values predicted by Schunk and Nagy when used in conjunction with neutral densities and electron temperature from the MSISE-90 model.;Plasma impedance probe measurements on sounding rockets are affected by aerodynamics of the spacecraft body. The second paper analyzes the effects of density gradients and wake effects on the impedance of a dipole antenna. A Direct Simulation Monte Carlo (DSMC) code is used to simulate the aerodynamic conditions encountered during a typical sounding rocket flight. Conical electron density flow structure is used to approximate the density distribution around a spinning rocket flying through the lower ionosphere. The PF-FDTD code is modified to simulate the impedance of a dipole antenna under different flow conditions. A methodology is developed to find correction factors to rectify errors introduced due to spin modulation on sounding rockets, and the technique is applied for the SAL sounding rocket mission.
机译：等离子体阻抗探针（PIP）是一种RF仪器，用于测量等离子体电子密度和电子中性碰撞频率。用于确定等离子体参数的射频探针技术具有吸引力，特别是因为在高于电子等离子体频率的频率（离子鞘效应可忽略不计）下，RF响应不容易受到航天器充电问题的影响。本文完成的工作由两篇论文组成，第一篇论文涉及探空火箭任务的PIP测量，第二篇论文是对航天器空气动力学对天线阻抗影响的定性研究。在第一篇论文中，分析了在突然的原子层（SAL）探测火箭任务期间观察到的零星电子层的测量结果，从而准确地获得了绝对电子密度和电子中性碰撞频率。分别选择三组上肢和下肢阻抗数据进行分析。血浆参数的初始估计值是通过将测得的阻抗数据与Balmain的分析阻抗公式进行最小均方拟合得出的。这些初始参数用作驱动浸入等离子体的天线的有限差分计算模型的起点，该模型称为等离子流体有限差分时域（PF-FDTD）模型。然后调整参数，直到在测得的阻抗数据和通过PF-FDTD仿真计算出的数字阻抗数据之间获得紧密拟合为止。通过更精确的PF-FDTD模拟获得的电子中性碰撞频率比Balmain公式预测的值低多达20％。当与MSISE-90模型的中性密度和电子温度结合使用时，获得的碰撞频率也低于Schunk和Nagy预测的安静时间值。探空火箭的等离子体阻抗探针测量受航天器空气动力学的影响。第二篇论文分析了密度梯度和尾流效应对偶极天线阻抗的影响。直接模拟蒙特卡洛（DSMC）代码用于模拟典型的探空火箭飞行期间遇到的空气动力学条件。圆锥形电子密度流动结构用于近似估计绕过低电离层飞行的旋转火箭周围的密度分布。修改了PF-FDTD代码，以模拟不同流量条件下的偶极天线的阻抗。开发了一种方法来找到校正因数，以纠正由于在探空火箭上进行自旋调制而引入的误差，并且该技术已应用于SAL探空火箭的任务。

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  • 作者

    Patra, Swadesh.;

  • 作者单位

    Utah State University.;

  • 授予单位 Utah State University.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 M.S.
  • 年度 2009
  • 页码 69 p.
  • 总页数 69
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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