Physical mechanism of generation of the new modes of ultra-low-frequency (ULF) electromagnetic planetary waves in <em>F</em>-region of the spherical ionosphere due to the latitudinal inhomogeneity of the g...Physical mechanism of generation of the new modes of ultra-low-frequency (ULF) electromagnetic planetary waves in <em>F</em>-region of the spherical ionosphere due to the latitudinal inhomogeneity of the geomagnetic field is suggested. The frequency spectra, phase velocity, and wavelength of these perturbations are determined. It is established, that these perturbations are self-localized as nonlinear solitary vortex structures in the ionosphere and moving westward or eastward along the parallels with velocities much greater than the phase velocities of the linear waves. The properties of the wave structures under investigation are very similar to those of low-frequency perturbations observed experimentally in the ionosphere at middle latitudes.展开更多
Many observations in the ionospheric heating experiment, by a powerful high frequency electromagnetic wave with ordinary polarization launched from a ground-based facility, is attributed to parametric instability （PI...Many observations in the ionospheric heating experiment, by a powerful high frequency electromagnetic wave with ordinary polarization launched from a ground-based facility, is attributed to parametric instability （PI）. In this paper, the general dispersion relation and the threshold of the PI excitation in the heating experiment are derived by considering the inhomogeneous spatial distribution of pump wave field. It is shown that the threshold of PI is influenced by the effective electron and ion collision frequencies and the pump wave frequency. Both collision and Landau damping should be considered in the PI calculation. The derived threshold expression has been used to calculate the required threshold for excitation of PI for several ionospheric conditions during heating experiments conducted employing EISCAT high frequency transmitter in TromsФ, Norway, on 2nd October 1998, 8th November 2001, 19th October 2012 and 7th July 2014. The results indicate that the calculated threshold is in good agreement with the experimental observations.展开更多
A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz mic...A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz microwave source, a coastal 3A./4 TEM-mode microwave resonance applicator, column and cylindrical Nd-Fe-P magnets, a quartz bell-shaped discharge chamber, a gas inlet system and a plasma-diffusing bore. The preliminary experiment demonstrated that ambi-polar diffusion plasma stream into the simulator (-500 mm long) formed an environment with following parameters: a plasma density ne of 104 cm-3 - 106 cm-3, an electron temperature Te < 5 eV at a pressure P of 10-1 Pa-10-3 Pa, a Plasma uniformity of > 80% over the experimental target with a 160-mm-in-diameter, satisfying primarily the requirement of simulating in a severe ionosphere environment.展开更多
文摘Physical mechanism of generation of the new modes of ultra-low-frequency (ULF) electromagnetic planetary waves in <em>F</em>-region of the spherical ionosphere due to the latitudinal inhomogeneity of the geomagnetic field is suggested. The frequency spectra, phase velocity, and wavelength of these perturbations are determined. It is established, that these perturbations are self-localized as nonlinear solitary vortex structures in the ionosphere and moving westward or eastward along the parallels with velocities much greater than the phase velocities of the linear waves. The properties of the wave structures under investigation are very similar to those of low-frequency perturbations observed experimentally in the ionosphere at middle latitudes.
基金supported by National Natural Science Foundation of China (NSFC grants 41204111, 41574146, 41774162 and 41704155)China Postdoctoral Science Foundation (2017M622504)
文摘Many observations in the ionospheric heating experiment, by a powerful high frequency electromagnetic wave with ordinary polarization launched from a ground-based facility, is attributed to parametric instability （PI）. In this paper, the general dispersion relation and the threshold of the PI excitation in the heating experiment are derived by considering the inhomogeneous spatial distribution of pump wave field. It is shown that the threshold of PI is influenced by the effective electron and ion collision frequencies and the pump wave frequency. Both collision and Landau damping should be considered in the PI calculation. The derived threshold expression has been used to calculate the required threshold for excitation of PI for several ionospheric conditions during heating experiments conducted employing EISCAT high frequency transmitter in TromsФ, Norway, on 2nd October 1998, 8th November 2001, 19th October 2012 and 7th July 2014. The results indicate that the calculated threshold is in good agreement with the experimental observations.
文摘A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz microwave source, a coastal 3A./4 TEM-mode microwave resonance applicator, column and cylindrical Nd-Fe-P magnets, a quartz bell-shaped discharge chamber, a gas inlet system and a plasma-diffusing bore. The preliminary experiment demonstrated that ambi-polar diffusion plasma stream into the simulator (-500 mm long) formed an environment with following parameters: a plasma density ne of 104 cm-3 - 106 cm-3, an electron temperature Te < 5 eV at a pressure P of 10-1 Pa-10-3 Pa, a Plasma uniformity of > 80% over the experimental target with a 160-mm-in-diameter, satisfying primarily the requirement of simulating in a severe ionosphere environment.
