scholarly journals Artificial plasma cusp generated by upper hybrid instabilities in HF heating experiments at HAARP

2013 ◽  
Vol 118 (5) ◽  
pp. 2734-2743 ◽  
Author(s):  
Spencer Kuo ◽  
Arnold Snyder
Keyword(s):  
Hf Heating ◽  
Artificial Plasma

The first experimental HF heating of plasma at ion cyclotron frequencies in the Globus-M spherical tokamak

2004 ◽  
Vol 30 (8) ◽  
pp. 690-692 ◽  
Author(s):  
V. K. Gusev ◽  
V. V. D’yachenko ◽  
F. V. Chernyshev ◽  
Yu. V. Petrov ◽  
N. V. Sakharov ◽  
...  
Keyword(s):  
Spherical Tokamak ◽  
Ion Cyclotron ◽  
Hf Heating

GPS-TEC variations, generated in midlatitude and highlatitude ionosphere by powerful HF-heating

2011 ◽  
Author(s):  
V. E. Kunitsyn ◽  
A. M. Padokhin ◽  
E. S. Andreeva ◽  
V. L. Frolov ◽  
G. P. Komrakov ◽  
...  
Keyword(s):  
Gps Tec ◽  
Hf Heating

Generation of extra and very low-frequency (ELF/VLF) radiation by ionospheric electrojet modulation using high-frequency (HF) heating waves

2002 ◽  
Vol 68 (4) ◽  
pp. 267-284 ◽  
Author(s):  
S. P. KUO
Keyword(s):  
High Frequency ◽  
Thermal Instability ◽  
Loss Rate ◽  
Inelastic Collision ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Heating Power ◽  
Very Low Frequency ◽  
Hf Heating ◽  
Heating Wave

Extra and very low-frequency (ELF/VLF) wave generation by modulated polar electrojet currents is studied numerically. Through Ohmic heating by the amplitude-modulated high-frequency heating wave, the conductivity and thus the current of the electrojet are modulated accordingly to set up the ionospheric antenna current. Stimulated thermal instability, which can further enhance the electrojet current modulation, is studied. It is first analysed analytically to determine the threshold heating power for its excitation. The nonlinear evolutions of the generated ELF/VLF waves enhanced by the instability are then studied numerically. Their spectra are also evaluated. The field intensity of the emission at the fundamental modulation frequency is found to increase with the modulation frequency in agreement with the Tromso observations. The efficiency enhancement by the stimulated thermal instability is hampered by inelastic collisions of electrons with neutral particles (mainly due to vibration excitation of N2), which cause this instability to saturate at low levels. However, the electron inelastic collision loss rate drops rapidly to a low value in the energy regime from 3.5 to 6 eV. As the heating power exceeds a threshold level, significant electron heating enhanced by the instability is shown, which indeed causes a steep drop in the electron inelastic collision loss rate. Consequently, this instability saturates at a much higher level, resulting to a near step increase (of about 10–13 dB depending on the modulation wave form) in the spectral intensity of ELF radiation. The dependence of the threshold power of the HF heating wave on the modulation frequency is determined.

scholarly journals Ionospheric observations ofFregion artificial plasma turbulence, modified by powerful X-mode radio waves

1999 ◽  
Vol 104 (A6) ◽  
pp. 12695-12704 ◽  
Author(s):  
V. L. Frolov ◽  
L. M. Kagan ◽  
E. N. Sergeev ◽  
G. P. Komrakov ◽  
P. A. Bernhardt ◽  
...  
Keyword(s):  
Plasma Turbulence ◽  
Radio Waves ◽  
Artificial Plasma

scholarly journals HF-Induced Modifications of the Electron Density Profile in the Earth’s Ionosphere Using the Pump Frequencies near the Fourth Electron Gyroharmonic

2021 ◽  
Vol 13 (23) ◽  
pp. 4895
Author(s):  
Alexey V. Shindin ◽  
Evgeny N. Sergeev ◽  
Savely M. Grach ◽  
Gennady M. Milikh ◽  
Paul Bernhardt ◽  
...  
Keyword(s):  
Density Profile ◽  
Ionospheric Plasma ◽  
Pump Wave ◽  
Electromagnetic Emission ◽  
Electron Density Profile ◽  
Radio Waves ◽  
F Region ◽  
Plasma Density Profile ◽  
Hybrid Region ◽  
Hf Heating

We discuss results on plasma density profile modifications in the F-region ionosphere that are caused by HF heating with the frequency f0 in the range [(−150 kHz)–(+75 kHz)] around the fourth electron gyroharmonic 4fc. The experiments were conducted at the HAARP facility in June 2014. A multi-frequency Doppler sounder (MDS), which measures the phase and amplitude of reflected sounding radio waves, complemented by the observations of the stimulated electromagnetic emission (SEE) were used for the diagnostics of the plasma perturbations. We detected noticeable plasma expulsion from the reflection region of the pumping wave and from the upper hybrid region, where the expulsion from the latter was strongly suppressed for f0 ≈ 4fc. The plasma expulsion from the upper hybrid region was accompanied by the sounding wave’s anomalous absorption (AA) slower development for f0 ≈ 4fc. Furthermore, slower development and weaker expulsion were detected for the height region between the pump wave reflection and upper hybrid altitudes. The combined MDS and SEE allowed for establishing an interconnection between different manifestations of the HF-induced ionospheric turbulence and determining the altitude of the most effective pump wave energy input to ionospheric plasma by using the dependence on the offset between f0 and 4fc.

On the efficiency of ELF/VLF generation using HF heating of the auroral electrojet

2003 ◽  
Vol 29 (7) ◽  
pp. 561-565 ◽  
Author(s):  
K. Papadopoulos ◽  
T. Wallace ◽  
M. McCarrick ◽  
G. M. Milikh ◽  
X. Yang
Keyword(s):  
Auroral Electrojet ◽  
Hf Heating

scholarly journals Selected Physicochemical Properties of Diamond Like Carbon (DLC) Coating on Ti-13Nb-13Zr Alloy Used for Blood Contacting Implants

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5077
Author(s):  
Magdalena Antonowicz ◽  
Roksana Kurpanik ◽  
Witold Walke ◽  
Marcin Basiaga ◽  
Jozef Sondor ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Physicochemical Properties ◽  
Fundamental Problem ◽  
Circulatory System ◽  
Titanium Implants ◽  
Diamond Like Carbon ◽  
Dlc Coating ◽  
13Zr Alloy ◽  
Artificial Plasma ◽  
Modification Of Titanium

Despite high interest in the issues of hemocompatibility of titanium implants, particularly those made of the Ti-13Nb-13Zr alloy, the applied methods of surface modification still do not always guarantee the physicochemical properties required for their safe operation. The factors that reduce the efficiency of the application of titanium alloys in the treatment of conditions of the cardiovascular system include blood coagulation and fibrous proliferation within the vessel’s internal walls. They result from their surfaces’ physicochemical properties not being fully adapted to the specifics of the circulatory system. Until now, the generation and development mechanics of these adverse processes are not fully known. Thus, the fundamental problem in this work is to determine the correlation between the physicochemical properties of the diamond like carbon (DLC) coating (shaped by the technological conditions of the process) applied onto the Ti-13Nb-13Zr alloy designed for contact with blood and its hemocompatibility. In the paper, microscopic metallographic, surface roughness, wettability, free surface energy, hardness, coating adhesion to the substrate, impendence, and potentiodynamic studies in artificial plasma were carried out. The surface layer with the DLC coating ensures the required surface roughness and hydrophobic character and sufficient pitting corrosion resistance in artificial plasma. On the other hand, the proposed CrN interlayer results in better adhesion of the coating to the Ti-13Nb-13Zr alloy. This type of coating is an alternative to the modification of titanium alloy surfaces using various elements to improve the blood environment’s hemocompatibility.

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