5 results on '"Igor Kaganovich"'
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2. Evolution of a Relativistic Electron Beam for Tracing Magnetospheric Field Lines
- Author
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Jay R. Johnson, Andrew Powis, David Shaw, Michael Greklek-McKeon, Ennio R. Sanchez, Igor Kaganovich, Kailas S. Amin, and Peter Porazik
- Subjects
computational modeling ,lcsh:Astronomy ,Field line ,Gyroradius ,Cyclotron ,Magnetosphere ,Space weather ,01 natural sciences ,law.invention ,lcsh:QB1-991 ,law ,0103 physical sciences ,Relativistic electron beam ,nonneutral plasmas ,010303 astronomy & astrophysics ,Physics ,beam envelope ,010308 nuclear & particles physics ,lcsh:QC801-809 ,Astronomy and Astrophysics ,relativistic particle beam ,Radius ,Computational physics ,field-line mapping ,lcsh:Geophysics. Cosmic physics ,electron beams (e-beams) ,Physics::Space Physics ,Physics::Accelerator Physics ,Beam (structure) - Abstract
Tracing magnetic field-lines of the Earth's magnetosphere using beams of relativistic electrons will open up new insights into space weather and magnetospheric physics. Analytic models and a single-particle-motion code were used to explore the dynamics of an electron beam emitted from an orbiting satellite and propagating until impact with the Earth. The impact location of the beam on the upper atmosphere is strongly influenced by magnetospheric conditions, shifting up to several-degrees in latitude between different phases of a simulated storm. The beam density cross-section evolves due to cyclotron motion of the beam centroid and oscillations of the beam envelope. The impact density profile is ring shaped, with major radius $\sim 22$ meters, given by the final cyclotron radius of the beam centroid, and ring thickness $\sim 2$ meters given by the final beam envelope. Motion of the satellite may also act to spread the beam, however it will remain sufficiently focused for detection by ground-based optical and radio detectors. An array of such ground stations will be able to detect shifts in impact location of the beam, and thereby infer information regarding magnetospheric conditions.
- Published
- 2019
- Full Text
- View/download PDF
3. Method for Approximating Field-Line Curves Using Ionospheric Observations of Energy-Variable Electron Beams Launched From Satellites
- Author
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Ennio R. Sanchez, Jake M. Willard, Jesse M. Snelling, Jay R. Johnson, Andrew Powis, and Igor Kaganovich
- Subjects
Physics ,Earth's orbit ,lcsh:Astronomy ,010308 nuclear & particles physics ,Field line ,lcsh:QC801-809 ,Degrees of freedom (statistics) ,Magnetosphere ,Astronomy and Astrophysics ,Curvature ,beam injection from space ,01 natural sciences ,Computational physics ,lcsh:QB1-991 ,lcsh:Geophysics. Cosmic physics ,field-line geometry ,Data assimilation ,field-line approximation ,0103 physical sciences ,energy-variable accelerator ,Ionosphere ,data assimilation ,010303 astronomy & astrophysics ,Arc length - Abstract
Using electron beam accelerators attached to satellites in Earth orbit, it may be possible to measure arc length and curvature of field-lines in the inner magnetosphere if the accelerator is designed with the capability to vary the beam energy. In combination with additional information, these measurements would be very useful in modeling the magnetic field of the inner magnetosphere. For this purpose, a three step data assimilation modeling approach is discussed. The first step in the procedure would be to use prior information to obtain an initial forecast of the inner magnetosphere. Then, a family of curves would be defined that satisfies the observed geometric attributes measured by the experiments, and the prior forecast would then be used to optimize the curve with respect to the allowed degrees of freedom. Finally, this approximation of the field-line would be used to improve the initial forecast of the inner magnetosphere, resulting in a description of the system that is optimally consistent with both the prior information and the measured curvature and arc length. This article details the method by which a family of possible approximations of the field-line may be defined via a numerical procedure, which is central to the three step approach. This method serves effectively as a pre-conditioner for parameter estimation problems using field-line curvature and arc length measurements in combination with other measurements.
- Published
- 2019
- Full Text
- View/download PDF
4. Effect of Field-Line Curvature on the Ionospheric Accessibility of Relativistic Electron Beam Experiments
- Author
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Jay R. Johnson, Ennio R. Sanchez, Jake M. Willard, Andrew Powis, Igor Kaganovich, and Jesse M. Snelling
- Subjects
lcsh:Astronomy ,Field line ,loss cone ,Magnetosphere ,Curvature ,01 natural sciences ,Relativistic particle ,lcsh:QB1-991 ,Current sheet ,0103 physical sciences ,energy-variable accelerator ,Relativistic electron beam ,010303 astronomy & astrophysics ,Physics ,010308 nuclear & particles physics ,lcsh:QC801-809 ,Plasma sheet ,Astronomy and Astrophysics ,beam injection from space ,accessibility ,Computational physics ,Magnetic field ,field-line mapping ,lcsh:Geophysics. Cosmic physics ,field-line curvature ,Physics::Space Physics - Abstract
Magnetosphere-ionosphere coupling is a particularly important process that regulates and controls magnetospheric dynamics such as storms and substorms. However, in order to understand magnetosphere-ionosphere coupling it is necessary to understand how regions of the magnetosphere are connected to the ionosphere. It has been proposed that this connection may be established by firing electron beams from satellites that can reach an ionospheric footpoint creating detectable emissions. This type of experiment would greatly aid in identifying the relationship between convection processes in the magnetotail and the ionosphere and how the plasma sheet current layer evolves during the growth phase preceding substorms. For practical purposes, the use of relativistic electron beams with kinetic energy on the order of 1 MeV would be ideal for detectability. However, Porazik et al. \cite{Porazik2014} has shown that, for relativistic particles, higher order terms of the magnetic moment are necessary for consideration of the ionospheric accessibility of the beams. These higher order terms are related to gradients in the magnetic field and curvature and are typically unimportant unless the beam is injected along the magnetic field direction, such that the zero order magnetic moment is small. In this article, we address two important consequences related to these higher order terms. First, we investigate the consequences for satellites positioned in regions subject to magnetotail stretching and demonstrate systematically how curvature affects accessibility. We find that curvature can reduce accessibility for beams injected from the current sheet, but can increase accessibility for beams injected just above the current sheet. Second, we investigate how detectability of ionospheric precipitation of variable energy field-aligned electron beams could be used as a constraint on field-line curvature, which would be valuable for field-line reconstruction and/or stability analysis.
- Published
- 2019
- Full Text
- View/download PDF
5. Non-local electron energy probability function in a plasma expanding along a magnetic nozzle
- Author
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Roderick Boswell, Igor Kaganovich, Christine Charles, and Kazunori Takahashi
- Subjects
Physics ,Materials Science (miscellaneous) ,Kinetics ,Nozzle ,double layers ,Biophysics ,General Physics and Astronomy ,Probability density function ,Plasma ,Electron ,Kinetic energy ,plasma expansion ,electron energy probability function ,lcsh:QC1-999 ,Magnetic field ,low-temperature plasmas ,Physics::Fluid Dynamics ,non-local effect ,Atomic physics ,Physical and Theoretical Chemistry ,Voltage drop ,lcsh:Physics ,Mathematical Physics - Abstract
Electron energy probability functions (eepfs) have been measured along the axis of a low pressure plasma expanding in a magnetic nozzle. The eepf at the maximum magnetic field of the nozzle shows a depleted tail commencing at an energy corresponding to the measured potential drop in the magnetic nozzle. The eepfs measured along the axis demonstrate that the sum of potential and kinetic energies of the electrons is conserved thus confirming the validity of non-local approach to kinetics of the electron dynamics of a low-pressure plasma expanding in a magnetic nozzle.
- Published
- 2015
- Full Text
- View/download PDF
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