排序方式: 共有11条查询结果,搜索用时 15 毫秒
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Sotnikov N. V. Antonova E. E. Ryazantseva M. O. Barinova V. O. Rubinshtein I. A. Mit’ S. K. 《Geomagnetism and Aeronomy》2019,59(2):136-146
Geomagnetism and Aeronomy - This paper studies the position of the trapping boundary of electrons with energies of >100 keV relative to the equatorial boundary of the auroral oval during a... 相似文献
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V. I. Sotnikov H. Ruhl R. Presura T. Cowan J. N. Leboeuf P. Hellinger P. Travnicek 《Astrophysics and Space Science》2005,298(1-2):369-374
The problem of producing collisionless shocks in the laboratory is of great interest for space and astrophysical plasmas.
One approach is based on the idea of combining strong magnetic field (up to 100 Tesla) created during a Z-pinch discharge
with a plasma flow produced in the process of the interaction of a laser pulse with a solid target. In support of laboratory
experiments we present hybrid simulations of the interaction of the plasma flow with frozen in it magnetic field, with the
spherical obstacle. Parameters of the flow correspond to a laser plasma ablation produced in the laboratory during irradiation
of the target by a 3 J laser. Magnetic fields in the plasma flow and around the obstacle are created by the currents produced
by the pulse power ZEBRA voltage generator. With the appropriate set of initial conditions imposed on the flow collisionless
shocks can be created in such a system. Using independent generators for plasma flow and magnetic field allows for the exploration
of a wide range of shock parameters. We present simulations of the formation of supercritical collisionless shock relevant
to the experiment, performed with the 2D version of the hybrid code based on the CAM-CL algorithm [Planet. Space Sci. 51,
649, 2003]. 相似文献
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V. Fiala P. Tříska E. N. Kruchina V. I. Shevchenko G. I. Soloviev V. I. Sotnikov 《Studia Geophysica et Geodaetica》1990,34(3):284-287
Summary The radiation power a VLF loop antenna with an arbitrary orientation of the loop's plane relative to the direction of the external magnetic field is calculated and its portion, transferred to the electromagnetic part of the excited spectrum, is determined.
am umaa m uu am c nu umau nmu uma n m¶rt; a¶rt;um¶rt; n u n¶rt;a ma am mu uu, u¶rt;a ma¶rt;um am am cnma ¶rt;a au.相似文献
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R. Presura V. V. Ivanov Y. Sentoku V. I. Sotnikov P. J. Laca N. Le Galloudec A. Kemp R. Mancini H. Ruhl A. L. Astanovitskiy T. E. Cowan T. Ditmire C. Chiu W. Horton P. Valanju S. Keely 《Astrophysics and Space Science》2005,298(1-2):299-303
An experimental simulation of planetary magnetospheres is being developed to investigate the formation of collisionless shocks
and their effects. Two experimental situations are considered. In both, the solar wind is simulated by laser ablation plasmas.
In one case, the “solar wind” flows across the magnetic field of a high-current discharge. In the other, a transverse magnetic
field is embedded in the plasma flow, which interacts with a conductive obstacle. The ablation plasma is created using the
“Tomcat” laser, currently emitting 5 J in a 6 ns pulse at 1 μm wavelength and irradiance above 1013 W/cm2. The “Zebra” z-pinch generator, with load current up to 1 MA and voltage up to 3.5 MV produces the magnetic fields. Hydrodynamic modeling
is used to estimate the plasma parameters achievable at the front of the plasma flow and to optimize the experiment design.
Particle-in-cell simulations reveal details of the interaction of the “solar wind” with an external magnetic field, including
flow collimation and heating effects at the stopping point. Hybrid simulations show the formation of a bow shock at the interaction
of a magnetized plasma flow with a conductor. The plasma density and the embedded field have characteristic spatial modulations
in the shock region, with abrupt jumps and fine structure on the skin depth scale. 相似文献
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V. I. Sotnikov R. Presura V. V. Ivanov T. E. Cowan J. N. Leboeuf B. V. Oliver 《Astrophysics and Space Science》2007,307(1-3):99-101
Laboratory experiments on the interaction of a plasma flow, produced by laser ablation of a solid target with the inhomogeneous
magnetic field from the Zebra pulsed power generator demonstrated the presence of strong wave activity in the region of the
flow deceleration. The deceleration of the plasma flow can be interpreted as the appearance of a gravity-like force. The drift
due to this force can lead to the excitation of flute modes. In this paper a linear dispersion equation for the excitation
of electromagnetic flute-type modes with plasma and magnetic field parameters, corresponding to the ongoing experiments is
examined. Results indicate that the wavelength of the excited flute modes strongly depends on the strength of the external
magnetic field. For magnetic field strengths ∼0.1 MG the excited wavelengths are larger than the width of the laser ablated
plasma plume and cannot be observed during the experiment. But for magnetic field strengths ∼1 MG the excited wavelengths
are much smaller and can then be detected. 相似文献
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J. Bošková P. Tříska Yu. A. Omelchenko V. D. Shapiro V. I. Sotnikov 《Studia Geophysica et Geodaetica》1992,36(2):177-187
Summary VLF quarter-gyrofrequency emissions, whose experimental characteristics differ from those of discrete plasmaspheric emissions usual during active times, have been observed by low-altitude Intercosmos 24 and Magion 2 satellites within the plasmasphere during periods of quieting geomagnetic activity. A new kind of instability is proposed which could lead to the production of these emissions. It is shown that quasi-electrostatic whistler waves can be generated in the eqquatorial region due to the fan instability, with maximum growth rate and spectral energy density in a frequency band below one half of the equatorial electron gyrofrequency. The observations of low-energy electrons and plasma waves in the equatorial region within or in the vicinity of the plasmapause, which could support our hypothesis experimentally, are discussed. 相似文献