Input impedance of a short dipole antenna in a warm anisotropic plasma, 1, Kinetic theory

Nakatani, D.; Kuehl, H. H.

doi:10.1029/rs011i005p00433

Cited by 25 publications

(15 citation statements)

References 32 publications

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“…Cyclotron harmonic effects were noted and attributed to the propagation of Bernstein waves or cyclotron harmonic waves [Hall and Landauer, 1971]. These harmonic effects are predicted if the anisotropic warm plasma is described by the kinetic theory, a model which we have used to derive the kinetic theory input impedance of a short, cylindrical dipole [Nakatani and Kuehl, 1976]. Here, we present the experimental results confirming the predictions of the kinetic theory formulation.…”

Section: Introductionsupporting

confidence: 66%

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Input impedance of a short dipole antenna in a warm anisotropic plasma, 2, Experiment

Nakatani¹,

Kuehl²

1976

Radio Science

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The measured input impedance of a short, cylindrical dipole immersed in a pulsed, RF discharge, anisotropic, argon plasma is presented. The experimental results show that the input impedance undergoes a pronounced change when the antenna frequency passes through the harmonics of the electron cyclotron frequency, which is in agreement with the predictions of kinetic theory. In general, the correlations between experimental and theoretical results are judged as fair to very good over a wide range of plasma parameters. Effects of the plasma sheath are found to be important and a sheath correction term based on a simple sheath model is included for correlating experimental and theoretical results. Using a curve‐fitting technique, a sheath thickness of 3λD was determined. Impedance measurements at dipole frequencies above the harmonics showed anomalous results which are explained by kinetic theory.

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Section: Introductionsupporting

confidence: 66%

“…Substituting these values into Z r yields the theoretical loci also shown in Figure 8. The value of to/to = 1.95 represents an upper limit before c the approximation (14) [Nakatani and Kuehl, 1976] is seriously violated. A similar outward movement of the impedance locus is noted.…”

Section: Cyclotron Harmonicsmentioning

confidence: 99%

Input impedance of a short dipole antenna in a warm anisotropic plasma, 2, Experiment

Nakatani¹,

Kuehl²

1976

Radio Science

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“…In the past 50 years, extensive studies have been conducted to understand the impedance properties of the antennas in plasma, treating the plasma around the antennas as a medium with given constant dielectric tensor [e.g., Balmain , 1964; Kuehl , 1966; Nakatani and Kuehl , 1976; Nikitin and Swenson , 2001]. In a recent simulation study, Ward et al [2005] developed a finite difference time domain (FDTD) model to investigate the impedance of a short dipole antenna in a magnetized plasma.…”

Section: Introductionmentioning

confidence: 99%

Plasma sheath structures around a radio frequency antenna

Song

Reinisch

2008

J. Geophys. Res.

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A one‐dimensional particle‐in‐cell (PIC) simulation code is developed to investigate plasma sheath structures around a high‐voltage transmitting antenna in the inner magnetosphere. We consider an electrically short dipole antenna assumed to be bare and perfectly conducting. The oscillation frequency of the antenna current is chosen to be well below the electron plasma frequency but higher than the ion plasma frequency. The magnetic field effects are neglected in the present simulations. Simulations are conducted for the cases without and with ion dynamics. In both cases, there is an initial period, about one‐fourth of an oscillation cycle, of antenna charging because of attraction of electrons to the antenna and the formation of an ion plasma sheath around the antenna. With the ion dynamics neglected, the antenna is charged completely negatively so that no more electrons in the plasma can reach the antenna after the formation of the sheath. When the ion dynamics are included, the electrons impulsively impinge upon the antenna while the ions reach the antenna in a continuous manner. In such a case, the antenna charge density and electric field have a brief excursion of slightly positive values during which there is an electron sheath. The electron and ion currents collected by the antenna are weak and balance each other over each oscillation cycle. The sheath–plasma boundary is a transition layer with fine structures in electron density, charge density, and electric field distributions. The sheath radius oscillates at the antenna current frequency. The calculated antenna reactance is improved from the theoretical value by 10%, demonstrating the advantage of including the plasma sheath effects self‐consistently using the PIC simulations. The sheath tends to shield the electric field from penetrating into the plasma. There is, however, leakage of an electric field component with significant amplitude into the plasma, implying the applicability of the high‐voltage antennas in whistler wave transmission in the inner magnetosphere.

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“…On the other hand, for ω ∼ ω p the antenna capacitance increases and is strongly peaked at the plasma frequency for L ant / L D >5 [ Schiff , ; Nakatani and Kuehl , ]. The effect of collisions is visible through “damping” of the plasma oscillations in similar way as for the QTN spectra, with the peak disappearing for ν / ω p >0.1.…”

Section: Quasi‐thermal Noise In Collisional Plasmasmentioning

confidence: 99%

Electrostatic thermal noise in a weakly ionized collisional plasma

et al. 2017

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Quasi‐thermal noise (QTN) spectroscopy is a plasma diagnostic technique which enables precise measurements of local electron velocity distribution function moments. This technique is based on measurements and analysis of voltage fluctuations at the antenna terminals, induced by thermal motion of charged particles. In this work, we accommodate, for the first time, this technique to weakly ionized collisional plasmas. It turns out that the QTN spectrum is modified both at low frequencies, increasing the level of power spectrum, and around the plasma frequency, where collisions damp the plasma oscillations and therefore broaden and reduce the amplitude of so called “plasma peak,” while the spectrum at high frequencies is nearly unmodified compared to the collisionless case. Based on these results, we show that QTN spectroscopy enables independent measurements of the collision frequency, electron density, and temperature, provided the ratio of collision frequency to plasma frequency is ν/ωp∼0.1. The method presented here can be used for precise estimation of plasma parameters in laboratory devices and unmagnetized ionospheres, while application in the ionosphere of Earth is possible but limited to small, low‐frequency range due to magnetic field influence.

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Input impedance of a short dipole antenna in a warm anisotropic plasma, 1, Kinetic theory

Cited by 25 publications

References 32 publications

Input impedance of a short dipole antenna in a warm anisotropic plasma, 2, Experiment

Input impedance of a short dipole antenna in a warm anisotropic plasma, 2, Experiment

Plasma sheath structures around a radio frequency antenna

Electrostatic thermal noise in a weakly ionized collisional plasma

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