scholarly journals Van Allen Probes Observations of Oxygen Ions at the Geospace Plume

2021 ◽  
Vol 8 ◽  
Author(s):  
John C. Foster ◽  
Philip J. Erickson
Keyword(s):  
Lower Energy ◽  
Outer Edge ◽  
Ion Energy ◽  
Oxygen Ions ◽  
Ion Drift ◽  
Highly Sensitive ◽  
Van Allen Probes ◽  
L Value ◽  
Field Lines ◽  
Plume Flow

The geospace plume couples the ionosphere, plasmasphere, and magnetosphere from sub-auroral regions to the magnetopause, on polar field lines, and into the magnetotail. We describe Van Allen Probes observations of ionospheric O+ ions at altitudes of 3–6 RE in the near vicinity of the geospace plume in the noon and post-noon sector. The temporal variation of warm ion fluxes observed as a function of time on a moving spacecraft is complicated by changing spacecraft position and complex ion drift paths and velocities that are highly sensitive to ion energy, pitch angle and L value. In the “notch” region of lower density plasma outside the morning-side plasmapause, bi-directionally field aligned fluxes of lower energy (<5 keV) ions, following corotation-dominated drift trajectories from the midnight sector, are excluded from geospace plume field lines as they are deflected sunward in the plume flow channel. In general, O+ at ring current energies (∼10 keV) is bi-directionally field aligned on plume field lines, while lower energy O+ (<3 keV) are absent. The observation of ion plumes with energies increasing from ∼1 keV–>20 keV in the dusk sector outer plasmasphere is interpreted as evidence for localized ionospheric O+ outflow at the outer edge of the geospace plume with subsequent O+ acceleration to >50 keV in <30 min during the ions’ sunward drift.

scholarly journals A multi-satellite study of accelerated ionospheric ion beams above the polar cap

2006 ◽  
Vol 24 (6) ◽  
pp. 1665-1684 ◽  
Author(s):  
R. Maggiolo ◽  
J. A. Sauvaud ◽  
D. Fontaine ◽  
A. Teste ◽  
E. Grigorenko ◽  
...  
Keyword(s):  
Electric Field ◽  
Potential Drop ◽  
Auroral Zone ◽  
Ion Beams ◽  
Distribution Functions ◽  
Convection Velocity ◽  
Polar Cap ◽  
Ion Energy ◽  
Polar Cusp ◽  
Oxygen Ions

Abstract. This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5–9 RE. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio EO+ / EH+, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity. In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5 Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H+ and O+. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability.

scholarly journals O<sup>+</sup> transport in the dayside magnetosheath and its dependence on the IMF direction

2015 ◽  
Vol 33 (3) ◽  
pp. 301-307 ◽  
Author(s):  
R. Slapak ◽  
H. Nilsson ◽  
L. G. Westerberg ◽  
R. Larsson
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Ion Flux ◽  
Opposite Hemisphere ◽  
Oxygen Ions ◽  
Upper Limit ◽  
Field Lines ◽  
Lobe Reconnection ◽  
Open Magnetic Field ◽  
The Imf

Abstract. Recent studies have shown that the escape of oxygen ions (O+) into the magnetosheath along open magnetic field lines from the terrestrial cusp and mantle is significant. We present a study of how O+ transport in the dayside magnetosheath depends on the interplanetary magnetic field (IMF) direction. There are clear asymmetries in the O+ flows for southward and northward IMF. The asymmetries can be understood in terms of the different magnetic topologies that arise due to differences in the location of the reconnection site, which depends on the IMF direction. During southward IMF, most of the observed magnetosheath O+ is transported downstream. In contrast, for northward IMF we observe O+ flowing both downstream and equatorward towards the opposite hemisphere. We observe evidence of dual-lobe reconnection occasionally taking place during strong northward IMF conditions, a mechanism that may trap O+ and bring it back into the magnetosphere. Its effect on the overall escape is however small: we estimate the upper limit of trapped O+ to be 5%, a small number considering that ion flux calculations are rough estimates. The total O+ escape flux is higher by about a factor of 2 during times of southward IMF, in agreement with earlier studies of O+ cusp outflow.

scholarly journals AN EFFECT OF SURFACE FINISH AND SPACING BETWEEN DISCS ON THE PERFORMANCE OF DISC TURBINE

2012 ◽  
pp. 250-255
Author(s):  
BORATE H . P ◽  
MISAL N. D
Keyword(s):  
High Velocity ◽  
Lower Energy ◽  
Outer Edge ◽  
Centrifugal Forces ◽  
Test Rig ◽  
Convergent Nozzle ◽  
Nikola Tesla ◽  
Exit Port ◽  
Velocity Water ◽  
Effect Of Surface

The turbine, invented by Nikola Tesla (1856-1943), is a bladeless turbine. Tesla disc turbine and a flexible test rig have been designed and manufactured, and experimental results are presented. An analysis of the performance and efficiency of the disc turbine is carried out. The design philosophy of the flexible test rig has been explained. Notice that there are no blades whatsoever – parallel, closely spaced discs used. Resistance to fluid flow between the plates results in energy transfer to the shaft. High velocity water enters the disk pack through inlet nozzle path tangent to the outer edge of the discs. Convergent nozzle imparts high velocity water jet tangentially on disc thickness. Lower-energy water spirals toward the central exit port, adhesion, drag and centrifugal forces continue to convert kinetic energy to shaft rotational power. The results of the study represent the step towards development boundary layer turbine. It has been determined that surface roughness and spacing affects the performance of the multiple disc turbines significantly. Efficiency may be improved at least up to 45%, which has been deemed achievable by Professor Warren Rice [2].

scholarly journals Magnetospheric magnetic field modelling for the 2011 and 2012 HST Saturn aurora campaigns – implications for auroral source regions

2014 ◽  
Vol 32 (6) ◽  
pp. 689-704 ◽  
Author(s):  
E. S. Belenkaya ◽  
S. W. H. Cowley ◽  
C. J. Meredith ◽  
J. D. Nichols ◽  
V. V. Kalegaev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ring Current ◽  
Hubble Space Telescope ◽  
Current System ◽  
Outer Edge ◽  
Local Times ◽  
Closed Field ◽  
Principal Connection ◽  
Magnetic Field Model ◽  
Field Lines

Abstract. A unique set of images of Saturn's northern polar UV aurora was obtained by the Hubble Space Telescope in 2011 and 2012 at times when the Cassini spacecraft was located in the solar wind just upstream of Saturn's bow shock. This rare situation provides an opportunity to use the Kronian paraboloid magnetic field model to examine source locations of the bright auroral features by mapping them along field lines into the magnetosphere, taking account of the interplanetary magnetic field (IMF) measured near simultaneously by Cassini. It is found that the persistent dawn arc maps to closed field lines in the dawn to noon sector, with an equatorward edge generally located in the inner part of the ring current, typically at ~ 7 Saturn radii (RS) near dawn, and a poleward edge that maps variously between the centre of the ring current and beyond its outer edge at ~ 15 RS, depending on the latitudinal width of the arc. This location, together with a lack of response in properties to the concurrent IMF, suggests a principal connection with ring-current and nightside processes. The higher-latitude patchy auroras observed intermittently near to noon and at later local times extending towards dusk are instead found to straddle the model open–closed field boundary, thus mapping along field lines to the dayside outer magnetosphere and magnetopause. These emissions, which occur preferentially for northward IMF directions, are thus likely associated with reconnection and open-flux production at the magnetopause. One image for southward IMF also exhibits a prominent patch of very high latitude emissions extending poleward of patchy dawn arc emissions in the pre-noon sector. This is found to lie centrally within the region of open model field lines, suggesting an origin in the current system associated with lobe reconnection, similar to that observed in the terrestrial magnetosphere for northward IMF.

Effects of oxygen ion energy on the growth of CuO films by molecular beam epitaxy using mass-separated low-energy O+ beams

1994 ◽  
Vol 9 (5) ◽  
pp. 1280-1283 ◽  
Author(s):  
Ryusuke Kita ◽  
Kenichi Kawaguchi ◽  
Takashi Hase ◽  
Takeshi Koga ◽  
Rittaporn Itti ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
High Energy ◽  
Photoemission Spectroscopy ◽  
Diffraction Reflection ◽  
X Ray Diffraction ◽  
Ion Energy ◽  
Rocking Curve ◽  
X Ray ◽  
Oxygen Ions ◽  
Oxygen Ion

We have studied the effects of the kinetic energy of mass-separated O+ beams on the growth of CuO thin films deposited on unheated MgO(001) and at 510 °C, in energy ranging from 10 to 200 eV by x-ray photoemission spectroscopy, x-ray diffraction, reflection high-energy electron diffraction, and scanning electron microscopy. The films deposited at 510 °C show a full width at the half maximum (FWHM) of 0.06°for the rocking curve through the (111) peak, regardless of the kinetic energy of oxygen ions. CuO has been epitaxially grown on MgO(001) without heating it in a vacuum of 4 × 10−7 Pa. The x-ray diffraction intensity of the CuO(111) increases with an increase in the kinetic energy of O+, and its FWHM approaches that of the CuO film grown at 510 °C. The surface morphology is improved for the films deposited on unheated substrates.

scholarly journals Radiation pressure acceleration of protons from structured thin-foil targets

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
Tim Arniko Meinhold ◽  
Naveen Kumar
Keyword(s):  
Radiation Pressure ◽  
Lower Energy ◽  
Target Surface ◽  
Thin Foil ◽  
Radiation Reaction ◽  
Energy Spread ◽  
Ion Energy

The process of radiation pressure acceleration (RPA) of ions is investigated with the aim of suppressing the Rayleigh–Taylor-like transverse instabilities in laser–foil interaction. This is achieved by imposing surface and density modulations on the target surface. We also study the efficacy of RPA of ions from density modulated and structured targets in the radiation dominated regime where the radiation reaction effects are important. We show that the use of density modulated and structured targets and the radiation reaction effects can help in achieving the twin goals of high ion energy (in GeV range) and lower energy spread.

scholarly journals Drifting of the line-tied footpoints of CME flux-ropes

2019 ◽  
Vol 621 ◽  
pp. A72 ◽  
Author(s):  
Guillaume Aulanier ◽  
Jaroslav Dudík
Keyword(s):  
Standard Model ◽  
Extreme Ultraviolet ◽  
Current Model ◽  
Three Dimensional ◽  
Flux Rope ◽  
Outer Edge ◽  
Flare Loop ◽  
Flare Loops ◽  
Field Lines ◽  
Line Tying

Context. Bridging the gap between heliospheric and solar observations of eruptions requires the mapping of interplanetary coronal mass ejection (CME) footpoints down to the Sun’s surface. But this not straightforward. Improving the understanding of the spatio-temporal evolutions of eruptive flares requires a comprehensive standard model. But the current model is only two-dimensional and cannot address the question of interplanetary CME footpoints. Aims. Existing 3D extensions to the standard model show that flux-rope footpoints are surrounded by curved-shaped quasi-separatrix layer (QSL) footprints that can be related with hook-shaped flare-ribbons. We build upon this finding and further address the joint questions of their time-evolution, and of the formation of flare loops at the ends of the flaring polarity inversion line (PIL) of the erupting bipole, which are both relevant for flare understanding in general and for interplanetary CME studies in particular. Methods. We calculated QSLs and relevant field lines in an MHD simulation of a torus-unstable flux-rope. The evolving QSL footprints are used to define the outer edge of the flux rope at different times, and to identify and characterize new 3D reconnection geometries and sequences that occur above the ends of the flaring PIL. We also analyzed flare-ribbons as observed in the extreme ultraviolet by SDO/AIA and IRIS during two X-class flares. Results. The flux-rope footpoints are drifting during the eruption, which is unexpected due to line-tying. This drifting is due to a series of coronal reconnections that erode the flux rope on one side and enlarge it on the other side. Other changes in the flux-rope footpoint-area are due to multiple reconnections of individual field lines whose topology can evolve sequentially from arcade to flux rope and finally to flare loop. These are associated with deformations and displacements of QSL footprints, which resemble those of the studied flare ribbons. Conclusions. Our model predicts continuous deformations and a drifting of interplanetary CME flux-rope footpoints whose areas are surrounded by equally evolving hooked-shaped flare-ribbons, as well as the formation of flare loops at the ends of flaring PILs which originate from the flux-rope itself, both of which being due to purely three-dimensional reconnection geometries. The observed evolution of flare-ribbons in two events supports the model, but more observations are required to test all its predictions.

scholarly journals Radial Transport of Higher-Energy Oxygen Ions Into the Deep Inner Magnetosphere Observed by Van Allen Probes

2018 ◽  
Vol 45 (10) ◽  
pp. 4534-4541 ◽  
Author(s):  
K. Mitani ◽  
K. Seki ◽  
K. Keika ◽  
M. Gkioulidou ◽  
L. J. Lanzerotti ◽  
...  
Keyword(s):  
Radial Transport ◽  
Inner Magnetosphere ◽  
Oxygen Ions ◽  
Van Allen Probes

Dispersion ion-drift hydrodynamics

1987 ◽  
Vol 38 (3) ◽  
pp. 387-405 ◽  
Author(s):  
V. P. Lakhin ◽  
S. V. Makurin ◽  
A. B. Mikhailovskii ◽  
O. G. Onishchenko
Keyword(s):  
Gravitational Force ◽  
Larmor Radius ◽  
Drift Waves ◽  
Hydrodynamic Equations ◽  
Integrals Of Motion ◽  
Ion Drift ◽  
Dispersion Effects ◽  
Vortex Theory ◽  
Field Lines ◽  
The Magnetic Field

The set of hydrodynamic equations for the ion component of a magnetized low-pressure plasma, including the nonlinear ion drift and waves related to it, taking into account dispersion effects of order k2⊥ρ2i (k⊥is the characteristic transverse wavenumber and ρi is the ion Larmor radius), is obtained. The reduction of these equations using the standard assumptions of vortex theory is given. The problem of the integrals of motion of the simplified equations is discussed. Account is taken of the gravitational force (which models curvature of the magnetic field lines), the three-dimensionality of the perturbations (drift-Alfvén effects) and plasma rotation. It is suggested that the ion-drift hydrodynamics discussed here should be the basis for the analysis of the ion drift and the vortices related to it, as well as for the theory of decay processes with participation of the ion-drift waves.

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