THE NONLINEAR INTERACTION OF A RADIO-FREQUENCY WAVE WITH AN INHOMOGENEOUS PLASMA SLAB: I. KINETICS OF HIGH-TEMPERATURE AIR IN THE PRESENCE OF AN ELECTROMAGNETIC FIELD

A radio-frequency wave is normally incident upon an inhomogeneous plasma slab. The plasma slab is composed of partially ionized high-temperature air corresponding to the characteristics of the plasma sheath surrounding hypersonic reentry vehicles. The isotropic part of the electron velocity distribution function is Maxwellian because of electron–electron collisions. The electromagnetic wave is intense enough to heat selectively the electron gas, altering the various electron production and loss processes. The high-frequency limit is considered, and expressions are obtained for the electron number density and effective collision frequency as a function of electron temperature. The effective collision frequency takes into account the effects of electron–neutral and electron–ion collisions for momentum transfer. From an energy balance equation, the electron temperature is found to be a function of both the frequency and field strength of the wave. The electron temperature is found also to exhibit an instability that gives rise to a hysteresis effect.

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THE NONLINEAR INTERACTION OF A RADIO-FREQUENCY WAVE WITH AN INHOMOGENEOUS PLASMA SLAB: II. NONLINEAR REFLECTION AND TRANSMISSION COEFFICIENTS OF AN INHOMOGENEOUS PLASMA SLAB

Canadian Journal of Physics ◽

10.1139/p65-196 ◽

1965 ◽

Vol 43 (11) ◽

pp. 2036-2044 ◽

Cited By ~ 2

Author(s):

Robert J. Papa ◽

Carl T. Case

Keyword(s):

Collision Frequency ◽

Inhomogeneous Plasma ◽

Critical Value ◽

Effective Dielectric Constant ◽

Reflection And Transmission ◽

Electric Field Amplitude ◽

Transmission Coefficients ◽

Effective Collision Frequency ◽

Plasma Slab ◽

Effective Collision

When a radio-frequency plane wave is incident upon an inhomogeneous, lossy plasma slab, part of the electromagnetic energy is reflected, part is absorbed by the plasma medium, and part is transmitted. At sufficiently high power levels (about 1 watt cm2 at X-band frequencies), the equation of state of the plasma is altered, which produces a change in the effective dielectric constant of the medium. In the high-frequency limit, the effective dielectric constant of the medium is expressed as a function of the electron density and an effective collision frequency. The electron density and effective collision frequency at each point in the medium are functions of the electron temperature. In Part I, the electron temperature (Te) at each point (z) in the slab has been expressed in terms of the local value of E2/ω2, where E = electric field amplitude and ω = signal frequency, i.e., Te = Te(z, E2/ω2). Using the predetermined functional dependence of Te on z and E2/ω2, the electromagnetic field distribution and the net reflection and transmission coefficients of the plasma slab are computed by employing the Runge–Kutta technique to integrate Maxwell's equations numerically step by step. For each value of ω, relatively small changes in the reflection and transmission coefficient are produced as [Formula: see text] is increased up to a critical value of [Formula: see text], where Einc = incident electric field amplitude. For values of [Formula: see text] greater than this critical value, there is a sharp increase in the reflection coefficient and a sharp drop in the transmission coefficient.

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Theory of energy flux and polarization changes of a radio wave with two magnetoionic components undergoing self demodulation in the ionosphere

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1974.0192 ◽

1974 ◽

Vol 341 (1626) ◽

pp. 361-381 ◽

Cited By ~ 10

Keyword(s):

Electron Temperature ◽

Radio Wave ◽

Phase Difference ◽

Incident Wave ◽

Unit Volume ◽

Collision Frequency ◽

Lower Ionosphere ◽

Effective Collision Frequency ◽

Composite Wave ◽

Effective Collision

The absorption of a powerful plane radio wave vertically incident on the lower ionosphere is studied. If it contains the two magnetoionic components with roughly equal amplitudes, the power absorbed per unit volume can be either greater or less than the sum of the powers for the separate components, depending on their phase difference. This is determined by the polarization of the incident wave, and the heights where the absorption is a maximum can be changed by changing this polarization. The power absorbed causes an increase in the electron temperature and thence in the effective collision frequency. This is studied first for an unmodulated wave. If the wave is amplitude modulated, the increase of collision frequency varies periodically in the modulation cycle. This results in self demodulation which is different for the two magnetoionic components because of their different rates of absorption. The result is that the polarization of the composite wave varies periodically over the modulation cycle.

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