Application of artificial irregularities for thermal parametric instability excitation for oblique ionospheric radiation

Abstract. Simultaneous HF scattering from the different regions of the heated volume is used to investigate characteristics of the small-scale field-aligned irregularities in the F-region. Time of growth, decay rate and saturation level for different pump powers are deduced from the observations and are compared with their behaviour predicted by the thermal parametric instability model. As a result, the estimates of the density and of the temperature modifications inside of the irregularities are obtained.Key words. Ionosphere (ionospheric irregularities)

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Excitation of upper-hybrid waves by a thermal parametric instability

Journal of Plasma Physics ◽

10.1017/s002237780000129x ◽

1983 ◽

Vol 30 (3) ◽

pp. 463-478 ◽

Cited By ~ 55

Author(s):

M. C. Lee ◽

S. P. Kuo

Keyword(s):

Ohmic Heating ◽

Parametric Instability ◽

Wave Interaction ◽

Present Theory ◽

Magnetized Plasma ◽

Coupling Mechanism ◽

Ionospheric Heating ◽

Plasma Line ◽

Thermal Parametric Instability ◽

Hybrid Waves

A purely growing instability characterized by a four-wave interaction has been analysed in a uniform, magnetized plasma. Up-shifted and down-shifted upper-hybrid waves and a non-oscillatory mode can be excited by a pump wave of ordinary rather than extraordinary polarization in the case of ionospheric heating. The differential Ohmic heating force dominates over the ponderomotive force as the wave–wave coupling mechanism. The beating current at zero frequency produces a significant stabilizing effect on the excitation of short-scale modes by counterbalancing the destabilizing effect of the differential Ohmic heating. The effect of ionospheric inhomogeneity is estimated, showing a tendency to raise the thresholds of the instability. When applied to ionospheric heating experiments, the present theory can explain the excitation of field-aligned plasma lines and ionospheric irregularities with a continuous spectrum ranging from metre-scale to hundreds of metre-scale. Further, the proposed mechanism may become a competitive process to the parametric decay instability and be responsible for the overshoot phenomena of the plasma line enhancement at Arecibo.

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Thermal parametric instability in ionospheric plasma at frequencies close to ?He and 2?He

Radiophysics and Quantum Electronics ◽

10.1007/bf01034532 ◽

1979 ◽

Vol 22 (5) ◽

pp. 357-363 ◽

Cited By ~ 11

Author(s):

S. M. Grach

Keyword(s):

Ionospheric Plasma ◽

Parametric Instability ◽

Thermal Parametric Instability

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Effect of recombination processes and nonisothermality of the ionospheric plasma on the thermal parametric instability

Radiophysics and Quantum Electronics ◽

10.1007/bf01081226 ◽

1979 ◽

Vol 22 (6) ◽

pp. 492-495

Author(s):

S. M. Grach ◽

S. V. Polyakov ◽

V. O. Rapoport

Keyword(s):

Ionospheric Plasma ◽

Parametric Instability ◽

Recombination Processes ◽

Thermal Parametric Instability

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Parametric instability in a free-evolving warped protoplanetary disc

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3504 ◽

2020 ◽

Vol 500 (3) ◽

pp. 4248-4256

Author(s):

Hongping Deng ◽

Gordon I Ogilvie ◽

Lucio Mayer

Keyword(s):

Wave Equations ◽

Hydrodynamic Instability ◽

Parametric Instability ◽

Low Viscosity ◽

Crossing Time ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

First Time ◽

Bending Wave ◽

Grid Based

ABSTRACT Warped accretion discs of low viscosity are prone to hydrodynamic instability due to parametric resonance of inertial waves as confirmed by local simulations. Global simulations of warped discs, using either smoothed particle hydrodynamics or grid-based codes, are ubiquitous but no such instability has been seen. Here, we utilize a hybrid Godunov-type Lagrangian method to study parametric instability in global simulations of warped Keplerian discs at unprecedentedly high resolution (up to 120 million particles). In the global simulations, the propagation of the warp is well described by the linear bending-wave equations before the instability sets in. The ensuing turbulence, captured for the first time in a global simulation, damps relative orbital inclinations and leads to a decrease in the angular momentum deficit. As a result, the warp undergoes significant damping within one bending-wave crossing time. Observed protoplanetary disc warps are likely maintained by companions or aftermath of disc breaking.

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