Oxygen ion energization observed at high altitudes

Abstract. We present a case study of significant heating (up to 8 keV) perpendicular to the geomagnetic field of outflowing oxygen ions at high altitude (12 RE) above the polar cap. The shape of the distribution functions indicates that most of the heating occurs locally (within 0.2–0.4 RE in altitude). This is a clear example of local ion energization at much higher altitude than usually reported. In contrast to many events at lower altitudes, it is not likely that the locally observed wave fields can cause the observed ion energization. Also, it is not likely that the ions have drifted from some nearby energization region to the point of observation. This suggests that additional fundamentally different ion energization mechanisms are present at high altitudes. One possibility is that the magnetic moment of the ions is not conserved, resulting in slower outflow velocities and longer time for ion energization.

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

Annales Geophysicae ◽

10.5194/angeo-24-1665-2006 ◽

2006 ◽

Vol 24 (6) ◽

pp. 1665-1684 ◽

Cited By ~ 20

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.

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The structure of high altitude O<sup>+</sup> energization and outflow: a case study

Annales Geophysicae ◽

10.5194/angeo-22-2497-2004 ◽

2004 ◽

Vol 22 (7) ◽

pp. 2497-2506 ◽

Cited By ~ 24

Author(s):

H. Nilsson ◽

S. Joko ◽

R. Lundin ◽

H. Rème ◽

J.-A. Sauvaud ◽

...

Keyword(s):

High Altitude ◽

Flow Direction ◽

Correlation Coefficients ◽

Dispersion Analysis ◽

Observation Point ◽

Ion Density ◽

Oxygen Ion ◽

Ion Energization ◽

Upstream Flow

Abstract. Multi-spacecraft observations from the CIS ion spectrometers on board the Cluster spacecraft have been used to study the structure of high-altitude oxygen ion energization and outflow. A case study taken from 12 April 2004 is discussed in more detail. In this case the spacecraft crossed the polar cap, mantle and high-altitude cusp region at altitudes between 4RE and 8RE and 2 of the spacecraft provided data. The oxygen ions were seen as a beam with narrow energy distribution, and increasing field-aligned velocity and temperature at higher altitude further in the upstream flow direction. The peak O+ energy was typically just above the highest energy of observed protons. The observed energies reached the upper limit of the CIS ion spectrometer, i.e. 38keV. Moment data from the spacecraft have been cross-correlated to determine cross-correlation coefficients, as well as the phase delay between the spacecraft. Structures in ion density, temperature and field-aligned flow appear to drift with the observed field-perpendicular drift. This, together with a velocity dispersion analysis, indicates that much of the structure can be explained by transverse heating well below the spacecraft. However, temperature isotropy and the particle flux as a function of field-aligned velocity are inconsistent with a single altitude Maxwellian source. Heating over extended altitude intervals, possibly all the way up to the observation point, seem consistent with the observations.

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Ionospheric irregularities observed during the St. Patrick’s Day 2015 severe geomagnetic storm over the southern high latitude polar cap region: a case study from Antarctic Circle

2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) ◽

10.23919/ursiap-rasc.2019.8738261 ◽

2019 ◽

Author(s):

Bapan Paul ◽

Arup Patari ◽

Barin Kumar De ◽

Anirban Guha

Keyword(s):

Geomagnetic Storm ◽

High Latitude ◽

Ionospheric Irregularities ◽

Polar Cap ◽

Southern High Latitude

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Local geomagnetic field variations of external origin: A case study of Armenia

Izvestiya Physics of the Solid Earth ◽

10.1134/s1069351307060109 ◽

2007 ◽

Vol 43 (6) ◽

pp. 524-531 ◽

Cited By ~ 2

Author(s):

A. G. Grigorian

Keyword(s):

Geomagnetic Field

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Reliability-based covariate analysis for complex systems in heterogeneous environment: Case study of mining equipment

Proceedings of the Institution of Mechanical Engineers Part O Journal of Risk and Reliability ◽

10.1177/1748006x18807091 ◽

2018 ◽

Vol 233 (4) ◽

pp. 593-604

Author(s):

Amin Moniri-Morad ◽

Mohammad Pourgol-Mohammad ◽

Hamid Aghababaei ◽

Javad Sattarvand

Keyword(s):

Complex Systems ◽

Cox Regression ◽

Reliability Evaluation ◽

Distribution Functions ◽

Heterogeneous Environment ◽

Mining Equipment ◽

Data Set ◽

Explanatory Variables ◽

The Impact

Operational heterogeneity and harsh environment lead to major variations in production system performance and safety. Traditional probabilistic model is dealt with time-to-event data analysis, which does not have the capability of quantifying and simulation of these types of complexities. This research proposes an integrated methodology for analyzing the impact of dominant explanatory variables on the complex system reliability. A flexible parametric proportional hazards model is developed by focusing on standard parametric Cox regression model for reliability evaluation in complex systems. To achieve this, natural cubic splines are utilized to create a smooth and flexible baseline hazards function where the standard parametric distribution functions do not fit into the failure data set. A real case study is considered to evaluate the reliability for multi-component mechanical systems such as mining equipment. Different operational and environmental explanatory variables are chosen for the analysis process. Research findings revealed that precise estimation of the baseline hazards function is a major part of the reliability evaluation in heterogeneous environment. It is concluded that an appropriate maintenance strategy potentially mitigate the equipment failure intensity.

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Aurora and open magnetic flux during isolated substorms, sawteeth, and SMC events

Annales Geophysicae ◽

10.5194/angeo-25-1865-2007 ◽

2007 ◽

Vol 25 (8) ◽

pp. 1865-1876 ◽

Cited By ~ 30

Author(s):

A. D. DeJong ◽

X. Cai ◽

R. C. Clauer ◽

J. F. Spann

Keyword(s):

Magnetic Flux ◽

Temporal Variations ◽

Auroral Oval ◽

Polar Cap ◽

Expansion Phase ◽

Magnetospheric Convection ◽

Open Magnetic Flux ◽

Open Flux ◽

The Individual

Abstract. Using Polar UVI LBHl and IMAGE FUV WIC data, we have compared the auroral signatures and polar cap open flux for isolated substorms, sawteeth oscillations, and steady magnetospheric convection (SMC) events. First, a case study of each event type is performed, comparing auroral signatures and open magnetic fluxes to one another. The latitude location of the auroral oval is similar during isolated substorms and SMC events. The auroral intensity during SMC events is similar to that observed during the expansion phase of an isolated substorm. Examination of an individual sawtooth shows that the auroral intensity is much greater than the SMC or isolated substorm events and the auroral oval is displaced equatorward making a larger polar cap. The temporal variations observed during the individual sawtooth are similar to that observed during the isolated substorm, and while the change in polar cap flux measured during the sawtooth is larger, the percent change in flux is similar to that measured during the isolated substorm. These results are confirmed by a statistical analysis of events within these three classes. The results show that the auroral oval measured during individual sawteeth contains a polar cap with, on average, 150% more magnetic flux than the oval measured during isolated substorms or during SMC events. However, both isolated substorms and sawteeth show a 30% decrease in polar cap magnetic flux during the dipolarization (expansion) phase.

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X-ray diffraction study of oxygen-conducting compoundsLn2Mo2O9(Ln= La, Pr)

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520614006623 ◽

2014 ◽

Vol 70 (4) ◽

pp. 669-675 ◽

Cited By ~ 3

Author(s):

Alexander M. Antipin ◽

Olga A. Alekseeva ◽

Natalia I. Sorokina ◽

Alexandra N. Kuskova ◽

Michail Yu. Presniakov ◽

...

Keyword(s):

Room Temperature ◽

Cubic Phase ◽

X Ray Diffraction ◽

Ion Migration ◽

Transmission Microscopy ◽

Coordination Environment ◽

X Ray ◽

Oxygen Ions ◽

Oxygen Ion ◽

Oxygen Ion Migration

The La2Mo2O9(LM) and Pr2Mo2O9(PM) single crystals are studied using precision X-ray diffraction and high-resolution transmission microscopy at room temperature. The crystal structures are determined in the space groupP213. La and Pr atoms, as well as Mo1 and O1 atoms, are located in the vicinity of the threefold axes rather than on the axes as in the high-temperature cubic phase. In both structures studied, the O2 and O3 positions are partially occupied. The coexistence of different configurations of the Mo coordination environment facilitates the oxygen-ion migration in the structure. Based on the X-ray data, the activation energies of O atoms are calculated and the migration paths of oxygen ions in the structures are analysed. The conductivity of PM crystals is close to that of LM crystals. The O2 and O3 atoms are the main contributors to the ion conductivity of LM and PM.

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Polar cap geomagnetic field responses to solar sector changes

Journal of Geophysical Research Atmospheres ◽

10.1029/ja081i025p04731 ◽

1976 ◽

Vol 81 (25) ◽

pp. 4731-4744 ◽

Cited By ~ 22

Author(s):

Wallace H. Campbell

Keyword(s):

Geomagnetic Field ◽

Polar Cap

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Microstructural and Compositional Characterization of SiC-On-Insulator Structures

Microscopy and Microanalysis ◽

10.1017/s1431927600017177 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 770-771

Author(s):

Manabu Ishimaru ◽

Robert M. Dickerson ◽

Kurt E. Sickafus

Keyword(s):

Ion Implantation ◽

Integrated Circuit ◽

High Speed ◽

Scanning Transmission Electron Microscope ◽

Oxygen Ions ◽

Oxygen Ion ◽

Transmission Electron ◽

Scanning Transmission ◽

Oxygen Ion Implantation

As the size of Si integrated circuit structures is continually reduced, interest in semiconductor-oninsulator (SOI) structures has heightened. SOI structures have already been developed for Si using oxygen ion implantation. However, the application of Si devices is limited due to the physical properties of Si. As an alternative to Si, SiC is a potentially important semiconductor for high-power, high-speed, and high-temperature electronic devices. Therefore, this material is a candidate for expanding the capabilities of Si-based technology. In this study, we performed oxygen ion implantation into bulk SiC to produce SiC-on-insulator structures. We examined the microstructures and compositional distributions in implanted specimens using transmission electron microscopy and a scanning transmission electron microscope equipped with an energy-dispersive X-ray spectrometer (STEM-EDX).Figures 1(a) and 2(a) show bright-field images of 6H-SiC implanted with 180 keV oxygen ions at 650 °C to fluences of 7xl017 and 1.4xl018 cm−2, respectively. Three regions with distinct image contrast are apparent in Figs. 1(a) and 2(a), as indicated by A, B, and C.

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