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11 results on '"Sotnikov, Vladimir I."'

3. Experimental study of the dynamics of large- and small-scale structures in the plasma column of wire array Z-pinches

Author

Ivanov, V.V., Sotnikov, Vladimir I., Sarkisov, Gennady, Astanovitskiy, A.L., Laca, P.J., Cowan, T.E., Jones, Brent, Deeney, Christopher, Oliver, Bryan V., Mehlhorn, Thomas A., and Leboeuf, Jean-Noel G.

Subjects
Plasma (Ionized gases) -- Research, Perturbation (Mathematics) -- Usage, Electromagnetic fields -- Analysis, Business, Chemistry, Electronics, Electronics and electrical industries
Abstract

The dynamics of large- and small-scale plasma structures is investigated in the precursor of 1-MA wire array Z-pinches by laser probing diagnostics. It is found that plasma streams from the wires induce density perturbations in the precursor. Small-scale perturbations and large-scale cells arise in the nonlinear stage before implosion. The spatial and temporal scales of the observed structures are in agreement with the theoretical investigation for current-driven excitation of electromagnetic flute modes. Index Terms--Flute modes, plasma turbulence, wire array Z-pinches.

Published
2007

4. Investigation of magnetic fields in 1-MA wire arrays and X-pinches

Author

Ivanov, Vladimir V., Sarkisov, Gennady S., Laca, Paul J., Sotnikov, Vladimir I., Kantsyrev, Victor L., Jones, Brent M., Coverdale, Christine A., LePell, P. David, Deeney, Christopher, Struve, Kenneth W., Astanovitskiy, A.L., Fedin, Dmitry A., Le Galloudec, Bruno, Nalajala, Vidya, Shrestha, Ishor, and Cowan, Thomas E.

Subjects
Magnetic fields -- Research, Turbulence -- Measurement, Business, Chemistry, Electronics, Electronics and electrical industries
Abstract

A Faraday rotation diagnostic was applied for the investigation of magnetic fields in plasma of 1-MA wire arrays and X-pinches. Laser-probing diagnostics at the Zebra generator include a four-channel polarointerferometer and a four-frame shadowgraphy. The Faraday rotation diagnostic consists of shadow and Faraday channels, shearing air-wedge interferometer, and an additional schlieren channel. The implosion dynamics of the wire arrays were studied. A current in the plasma column of AI low-wire number arrays was found by the Faraday rotation diagnostic. Optical diagnostics showed a turbulent plasma and bubblelike objects in the plasma column of Al wire arrays. The Faraday rotation diagnostic demonstrated a complicated structure of magnetic fields in X-pinch plasma. Index Terms--Faraday effect, laser probing, plasma turbulence, wire-array Z-pinch, Z-pinch plasmas.

Published
2006

5. Investigation of electromagnetic-flute-mode instability in a high-beta Z-pinch plasma

Author

Sotnikov, Vladimir I., Ivanov, Vladimir V., Cowan, Thomas E., Leboeuf, Jean-Noel G., Oliver, Brian V., Coverdale, Christine A., Jones, Brent M., Deeney, Christopher, Mehlhorn, Thomas A., Sarkisov, Gennady S., and LePell, P. David

Subjects
Turbulence -- Measurement, Plasma physics -- Research, Magnetic fields -- Research, Business, Chemistry, Electronics, Electronics and electrical industries
Abstract

Recent experiments (laser multiframe shadowgraphy and Faraday rotation diagnostics) with Al imploding wire arrays in the 1-MA 'Zebra' accelerator at the Nevada Terawatt Facility have demonstrated that a significant amount of current is going through the central region of the high-beta precursor plasma. With time, the perturbations develop both long scale structures and short-wavelength oscillations in the directions perpendicular to the magnetic field. The most likely candidate for the observed phenomena is the flutelike electromagnetic modes. These are excited in the current-carrying high-beta inhomogeneous precursor plasma due to the curvature of the magnetic field produced by the current. These modes may also play a role in the stagnation phase of Z-pinches. In this paper, nonlinear equations describing electromagnetic-flute-type oscillations in the high-beta precursor plasma are derived, and the linear stage of instability of these waves is examined. A comparison with the experimental results is performed as well. Index Terms--Flute modes, nonlinear cascades, turbulence, Z-pinch plasmas.

Published
2006

6. Parametric Interaction of VLF and ELF Waves in the Ionosphere

Author

Sotnikov, Vladimir I.

Subjects
Science / Physics
Abstract

In this Chapter we analyze a non-linear parametric interaction between Very Low Frequency (VLF) and Extremely Low Frequency (ELF) waves in the ionosphere. We demonstrate that nonlinear parametric coupling between quasi-electrostatic Lower Oblique Resonance (LOR) and ELF waves significantly contributes to the VLF electromagnetic whistler wave spectrum. Analytical and numerical results are compared with experimental data obtained during active space experiments and satellite data. These data clearly show that presence of VLF waves in the region of plasmasphere boundary layer, where there are no injected due to substorm/storm activity energetic electrons with energies of tens keV can strongly affect the radiation belt boundary.

Published
2018

7. Propagation of beam-driven VLF waves from the ionosphere toward the ground

Author

Schriver, David, Sotnikov, Vladimir I, Ashour-Abdalla, Maha, and Ernstmeyer, James

Subjects
Geophysics
Abstract

As part of the Cooperative High Altitude Rocket Gun Experiment (CHARGE-2B) rocket mission, an electron beam was injected into the ionosphere with a modulated beam current in an effort to generate very low frequency (VLF) waves. The propagation of the beam-driven VLF waves through the ionosphere is examined here to determine whether it is possible to detect these wave emissions with ground receivers. The paths of the VLF waves from where they were generated near the rocket were followed to the bottom of the ionosphere and the decrease in wave amplitude due to wave-particle resonance and collisional damping was calculated. It was found that due to collisional damping, which for these VLF waves becomes large at altitudes below about 150 km, wave amplitudes were decreased below the background atmospheric noise level. A number of different beam injection events have been examined and in all of these cases studied the waves were sufficiently damped such that detection on the ground would not be possible. This is in agreement with observations on the ground in which no wave emissions were observed during the CHARGE-2B mission. Control parameters that would be more favorable for beam-generated VLF propagation to the ground are discussed for future experiments of this type.

Published
1995
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9. Experimental Study of the Dynamics of Large- and Small-Scale Structures in the Plasma Column of Wire Array $Z$-Pinches

Author

Ivanov, V. V., primary, Sotnikov, Vladimir I., additional, Sarkisov, Gennady, additional, Astanovitskiy, A. L., additional, Laca, P. J., additional, Cowan, T. E., additional, Jones, Brent, additional, Deeney, Christopher, additional, Oliver, Bryan V., additional, Mehlhorn, Thomas A., additional, and Leboeuf, Jean-Noel G., additional

Published
2007
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11. Hybrid Simulations of Current-Carrying Instabilities in Z-Pinch Plasmas with Sheared Axial Flow.

Author

Sotnikov, Vladimir I., Makhin, Volodymyr, Bauer, Bruno S., Hellinger, Petr, Travnicek, Pavel, Fiala, Vladimir, and Leboeuf, Jean-Noel

Subjects
*Z bosons, *PLASMA gases
Abstract

The development of instabilities in z-pinch plasmas has been studied with three-dimensional (3D) hybrid simulations. Plasma equilibria without and with sheared axial flow have been considered. Results from the linear phase of the hybrid simulations compare well with linear Hall magnetohydrodynamics (MHD) calculations for sausage modes. The hybrid simulations show that sheared axial flow has a stabilizing effect on the development of both sausage and kink modes. [ABSTRACT FROM AUTHOR]

Published
2002

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