Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. II. High-frequency electron-acoustic solitons

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

Download Full-text

Effective coffision frequency and electron temperature in a weakly ionized argon plasma

Journal of Plasma Physics ◽

10.1017/s0022377800022315 ◽

1980 ◽

Vol 23 (2) ◽

pp. 271-282

Author(s):

C. P. Schneider

Keyword(s):

Electron Temperature ◽

High Frequency ◽

Collision Frequency ◽

Argon Plasma ◽

Angular Frequency ◽

Weak Electric Field ◽

Hard Sphere Model ◽

Plasma Conductivity ◽

Gas Plasma ◽

Weakly Ionized

Herein is described a calculation of the effective coffision frequency νeffof a low- density, shock-heated argon plasma under the influence of a weak electric field which oscillates harmonically with angular frequency ω. It is shown that, for the high frequency case ω >whereis the collision frequency in a Maxwellian gas plasma, one has νeff⋍ 2, provided that the imaginary part of the argon plasma conductivity is negligibly small in comparison to the real part. The influence of the theoretical model used to calculate νeffon the values of the electron temperatureTederived from measurements is compared with the results obtained in a data reduction for which the hard-sphere model for particle encounters was utilized.

Download Full-text

Variation in altitude of high-frequency enhanced plasma line by the pump near the 5th electron gyro-harmonic

10.5194/angeo-2019-23 ◽

2019 ◽

Author(s):

Jun Wu ◽

Jian Wu ◽

Michael T. Rietveld ◽

Ingemar Haggstrom ◽

Haisheng Zhao ◽

...

Keyword(s):

Electron Temperature ◽

High Frequency ◽

Langmuir Wave ◽

Decisive Role ◽

Bragg Condition ◽

Pump Frequency ◽

Ionospheric Heating ◽

Lower Altitude ◽

Incoherent Scatter ◽

Plasma Line

Abstract. During an ionospheric heating campaign carried out at the European Incoherent Scatter Scientific Association (EISCAT), the ultra high frequency incoherent scatter (IS) radar observed a systematic variation in the altitude of the high-frequency enhanced plasma line (HFPL), which behaves depending on the pump frequency. Specifically, the HFPL altitude becomes lower when the pump lies above the 5th gyro-harmonic. The analysis shows that the enhanced electron temperature plays a decisive role in the descent in the HFPL altitude. That is, on the traveling path of the enhanced Langmuir wave, the enhanced electron temperature can only be matched by the low electron density at a lower altitude so that the Bragg condition can be satisfied, as expected from the dispersion relation of Langmuir wave.

Download Full-text