Thermal ion measurements on board Interball Auroral Probe by the Hyperboloid experiment     

N. Dubouloz  J.-J. Berthelier  M. Malingre  L. Girard  Y. Galperin  J. Covinhes  D. Chugunin  M. Godefroy  G. Gogly  C. Guérin  J.-M. Illiano  P. Kossa  F. Leblanc  F. Legoff  T. Mularchik  J. Paris  W. Stzepourginski  F. Vivat  L. Zinin 《Annales Geophysicae》1998,16(9):1070-1085

Hyperboloid is a multi-directional mass spectrometer measuring ion distribution functions in the auroral and polar magnetosphere of the Earth in the thermal and suprathermal energy range. The instrument encompasses two analyzers containing a total of 26 entrance windows, and viewing in two almost mutually perpendicular half-planes. The nominal angular resolution is defined by the field of view of individual windows 13° × 12.5°. Energy analysis is performed using spherical electrostatic analyzers providing differential measurements between 1 and 80 eV. An ion beam emitter (RON experiment) and/or a potential bias applied to Hyperboloid entrance surface are used to counteract adverse effects of spacecraft potential and thus enable ion measurements down to very low energies. A magnetic analyzer focuses ions on one of four micro-channel plate (MCP) detectors, depending on their mass/charge ratio. Normal modes of operation enable to measure H⁺, He⁺, O⁺⁺, and O⁺ simultaneously. An automatic MCP gain control software is used to adapt the instrument to the great flux dynamics encountered between spacecraft perigee (700 km) and apogee (20 000 km). Distribution functions in the main analyzer half-plane are obtained after a complete scan of windows and energies with temporal resolution between one and a few seconds. Three-dimensional (3D) distributions are measured in one spacecraft spin period (120 s). The secondary analyzer has a much smaller geometrical factor, but offers partial access to the 3D dependence of the distributions with a few seconds temporal resolution. Preliminary results are presented. Simultaneous, local heating of both H⁺ and O⁺ ions resulting in conical distributions below 80 eV is observed up to 3 Earths radii altitudes. The thermal ion signatures associated with large-scale nightside magnetospheric boundaries are investigated and a new ion outflow feature is identified associated to the polar edge of the auroral oval. Detailed distribution functions of injected magnetosheath ions and ouflowing cleft fountain ions are measured down to a few eVs in the dayside.  相似文献   

Solar wind contribution to the average population of energetic He+ and He++ ions in the Earth’s magnetosphere     

G. Kremser  R. Rasinkangas  P. Tanskanen  B. Wilken  G. Gloeckler 《Annales Geophysicae》1994,12(2-3):152-168

Measurements with the ion charge-energy-mass spectrometer CHEM on the AMPTE/CCE spacecraft were used to investigate the origin of energetic He⁺ and He⁺⁺ ions observed in the equatorial plane at 3\leqL\leq9. Special emphasis was laid on the dependence of long-term average distributions on magnetic local time (MLT) and the geomagnetic activity index K_p. The observations are described in terms of the phase space densities f₁ (for He⁺) and f₂ (for He⁺⁺). They confirm preliminary results from a previous study: f₁ is independent of MLT, whereas f₂ is much larger on the nightside than on the dayside. They show, furthermore, that f₁ increases slightly with K_p on intermediate drift shells, but decreases on high drift shells (L\geq7). f₂ increases with K_p on all drift shells outside the premidnight sector. Within this sector a decrease is observed on high drift shells. A simple ion tracing code was developed to determine how and from where the ions move into the region of observations. It provides ion trajectories as a function of the ion charge, the magnetic moment and K_p. The ion tracing enables a distinction between regions of closed drift orbits (ring current) and open convection trajectories (plasma sheet). It also indicates how the outer part of the observation region is connected to different parts of the more distant plasma sheet. Observations and tracing show that He⁺⁺ ions are effectively transported from the plasma sheet on convection trajectories. Their distribution in the observation region corresponds to the distribution of solar wind ions in the plasma sheet. Thus, energetic He⁺⁺ ions most likely originate in the solar wind. On the other hand, the plasma sheet is not an important source of energetic He⁺ ions. Convection trajectories more likely constitute a sink for He⁺ ions, which may diffuse onto them from closed drift orbits and then get lost through the magnetopause. An ionospheric origin of energetic He⁺ ions is unlikely as well, since the source mechanism should be almost independent of K_p. There is considerable doubt, however, that a plausible mechanism also exists during quiet periods that can accelerate ions to ring current energies, while extracting them from the ionosphere. It is concluded, therefore, that energetic He⁺ ions are mainly produced by charge exchange processes from He⁺⁺ ions. This means that most of the energetic He⁺ ions constituting the average distributions also very likely originate in the solar wind. Additional ionospheric contributions are possible during disturbed periods.  相似文献   

Origin of energetic ions in the polar cusp inferred from ion composition measurements by the Viking satellite     

G. Kremser  J. Woch  K. Mursula  P. Tanskanen  B. Wilken  R. Lundin 《Annales Geophysicae》1995,13(6):595-607

The magnetospheric ion composition spectrometer MICS on the Swedish Viking satellite provided measurements of the ion composition in the energy range 10.1 keV/e\leqE/Q\leq326.0 keV/e. Data obtained during orbit 842 were used to investigate the ion distribution in the northern polar cusp and its vicinity. The satellite traversed the outer ring current, boundary region, cusp proper and plasma mantle during its poleward movement. H⁺ and He⁺⁺ ions were encountered in all of these regions. He⁺ ions were present only in the ring current. The number of O⁺ and O⁺⁺ ions was very small. Heavy high-charge state ions typical for the solar wind were observed for the first time, most of them in the poleward part of the boundary region and in the cusp proper. The H⁺ ions exhibited two periods with high intensities. One of them, called the BR/CP event, appeared at energies up to 50 keV. It started at the equatorward limit of the boundary region and continued into the cusp proper. Energy spectra indicate a ring current origin for the BR/CP event. Pitch angle distributions show downward streaming of H⁺ ions at its equatorward limit and upward streaming on the poleward side. This event is interpreted as the result of pitch angle scattering of ring current ions by fluctuations in the magnetopause current layer in combination with poleward convection. The other of the two periods with high H⁺ ion intensities, called the accelerated ion event, was superimposed on the BR/CP event. It was restricted to energies \leq15 keV and occurred in the poleward part of the boundary region. This event is regarded as the high-energy tail of magnetosheath ions that were accelerated while penetrating into the magnetosphere. The cusp region thus contains ions of magnetospheric as well as of magnetosheath origin. The appearance of the ions depends, in addition to the ion source, on the magnetic field configuration and dynamic processes inside and close to the cusp.  相似文献   

Spatial structure of the plasma sheet boundary layer at distances greater than 180 RE as derived from energetic particle measurements on GEOTAIL     

D. V. Sarafopoulos  E. T. Sarris  V. Angelopoulos  T. Yamamoto  S. Kokubun 《Annales Geophysicae》1997,15(10):1246-1256

We have analyzed the onsets of energetic particle bursts detected by the ICS and STICS sensors of the EPIC instrument on board the GEOTAIL spacecraft in the deep magnetotail (i.e., at distances greater than 180 RK). Such bursts are commonly observed at the plasma-sheet boundary layer (PSBL) and are highly collimated along the magnetic field. The bursts display a normal velocity dispersion (i.e., the higher-speed particles are seen first, while the progressively lower speed particles are seen later) when observed upon entry of the spacecraft from the magnetotail lobes into the plasma sheet. Upon exit from the plasma sheet a reverse velocity dispersion is observed (i.e., lower-speed particles disappear first and higher-speed particles disappear last). Three major findings are as follows. First, the tailward-jetting energetic particle populations of the distant-tail plasma sheet display an energy layering: the energetic electrons stream along open PSBL field lines with peak fluxes at the lobes. Energetic protons occupy the next layer, and as the spacecraft moves towards the neutral sheet progressively decreasing energies are encountered systematically. These plasma-sheet layers display spatial symmetry, with the plane of symmetry the neutral sheet. Second, if we consider the same energy level of energetic particles, then the H layer is confined within that of the energetic electron, the He⁺⁺ layer is confined within that of the proton, and the oxygen layer is confined within the alpha particle layer. Third, whenever the energetic electrons show higher fluxes inside the plasma sheet as compared to those at the boundary layer, their angular distribution is isotropic irrespective of the Earthward or tailward character of fluxes, suggesting a closed field line topology.  相似文献   

Global aspects of solar wind–ionosphere interactions     

《Journal of Atmospheric and Solar》2007,69(3):265-278

Recent observations have quantified the auroral wind O⁺ outflow in response to magnetospheric inputs to the ionosphere, notably Poynting energy flux and precipitating electron density. For moderate to high activity periods, ionospheric O⁺ is observed to become a significant or dominant component of plasma pressure in the inner plasma sheet and ring current regions. Using a global circulation model of magnetospheric fields and its imposed ionospheric boundary conditions, we evaluate the global ionospheric plasma response to local magnetospheric conditions imposed by the simulation and evaluate magnetospheric circulation of solar wind H⁺, polar wind H⁺, and auroral wind O⁺. We launch and track the motions of millions of test particles in the global fields, launched at randomly distributed positions and times. Each particle is launched with a flux weighting and perpendicular and parallel energies randomly selected from defined thermal ranges appropriate to the launch point. One sequence is driven by a two-hour period of southward interplanetary magnetic field for average solar wind intensity. A second is driven by a 2-h period of enhanced solar wind dynamic pressure for average interplanetary field. We find that the simulated ionospheric O⁺ becomes a significant plasma pressure component in the inner plasma sheet and outer ring current region, particularly when the solar wind is intense or its magnetic field is southward directed. We infer that the reported empirical scalings of auroral wind O⁺ outflows are consistent with a substantial pressure contribution to the inner plasma sheet and plasma source surrounding the ring current. This result violates the common assumption that the ionospheric load is entirely confined to the F layer, and shows that the ionosphere is often an important dynamic element throughout the magnetosphere during moderate to large solar wind disturbances.  相似文献   

Theoretical developments on the causes of ionospheric outflow     

《Journal of Atmospheric and Solar》2000,62(6):399-420

It is now well known that there is a substantial outflow of ionospheric plasma from the terrestrial ionosphere at high latitudes. The outflow consists of light thermal ions (H⁺, He⁺) as well as both light and heavy energized ions (H⁺, He⁺, O⁺, N⁺, NO⁺, O₂⁺, N₂⁺). The thermal ion outflows tend to be associated with the classical polar wind, while the energized ions are probably associated with either auroral energization processes or nonclassical polar wind processes. Part of the problem with identifying the exact cause of a given outflow relates to the fact that the ionosphere continuously convects into and out of the various high-latitude regions (sunlight, cusp, polar cap, nocturnal oval) and the time-constant for outflow is comparable to the convection time. Therefore, it is difficult to separate and quantify the possible outflow mechanisms. Some of these mechanisms are as follows. In sunlit regions, the photoelectrons can heat the thermal electrons and the elevated electron temperature acts to increase the polar wind outflow rate. At high altitudes, the escaping photoelectrons can also accelerate the polar wind as they drag the thermal ions with them. In the cusp and auroral oval, the precipitating magnetospheric electrons can heat the thermal electrons in a manner similar to the photoelectrons. Also, energized ions, in the form of beams and conics, can be created in association with field-aligned auroral currents and potential structures. The cusp ion beams and conics that have been convected into the polar cap can destabilize the polar wind when they pass through it at high altitudes, thereby transferring energy to the thermal ions. Additional energization mechanisms in the polar cap include Joule heating, hot magnetospheric electrons and ions, electromagnetic wave turbulence, and centrifugal acceleration.Some of these causes of ionospheric outflow will be briefly reviewed, with the emphasis on the recent simulations of polar wind dynamics in convecting flux tubes of plasma.  相似文献   

The polar wind: Recent observations     

《Journal of Atmospheric and Solar》2007,69(16):1936-1983

The polar wind is an ambipolar outflow of thermal plasma from the high-latitude ionosphere to the magnetosphere, and it primarily consists of H⁺, He⁺ and O⁺ ions and electrons. Statistical and episodic studies based primarily on ion composition observations on the ISIS-2, DE-1, Akebono and Polar satellites over the past four decades have confirmed the existence of the polar wind. These observations spanned the altitude range from 1000 to ∼50,500 km, and revealed several important features in the polar wind that are unexpected from “classical” polar wind theories. These include the day–night asymmetry in polar wind velocity, which is 1.5–2.0 times larger on the dayside; appreciable O⁺ flow at high altitudes, where the velocity at 5000–10,000 km is of 1–4 km/s; and significant electron temperature anisotropy in the sunlit polar wind, in which the upward-to-downward electron temperature ratio is 1.5–2. These features are attributable to a number of “non-classical” polar wind ion acceleration mechanisms resulting from strong ionospheric convection, enhanced electron and ion temperatures, and escaping atmospheric photoelectrons. The observed polar wind has an averaged ion temperature of ∼0.2–0.3 eV, and a rate of ion velocity increase with altitude that correlates strongly with electron temperature and is greatest at low altitudes (<4000 km for H⁺). The rate of velocity increase below 4000 km is larger at solar minimum than at solar maximum. Above 4000 km, the reverse is the case. This suggests that the dominant polar wind ion acceleration process may be different at low and high altitudes, respectively. At a given altitude, the polar wind velocity is highly variable, and is on average largest for H⁺ and smallest for O⁺. Near solar maximum, H⁺, He⁺, and O⁺ ions typically reach a velocity of 1 km/s near 2000, 3000, and 6000 km, respectively, and velocities of 12, 7, and 4 km/s, respectively, at 10,000 km altitude. Near solar minimum, the velocity of all three species is smaller at high altitudes. Observationally it is not always possible to unambiguously separate an energized “non-polar-wind” ion such as a low-energy “cleft ion fountain” ion that has convected into a polar wind flux tube from an energized “polar-wind” ion that is accelerated locally by “non-classical” polar-wind ion acceleration mechanisms. Significant questions remain on the relative contribution between the cleft ion fountain, auroral bulk upflow, and the topside polar-cap ionosphere to the O⁺ polar wind population at high altitudes, the effect of positive spacecraft charging on the lowest-energy component of the H⁺ polar wind population, and the relative importance of the various classical and non-classical ion acceleration mechanisms. These questions pose several challenges in future polar wind observations: These include measurement of the lowest-energy component in the presence of positive spacecraft potential, definitive determination and if possible active control of the spacecraft potential, definitive discrimination between polar wind and other inter-mixed thermal ion populations, measurement of the three-dimensional ion drift velocity vector and the parallel and perpendicular ion temperatures or the detailed three-dimensional velocity distribution function, and resolution of He⁺ and other minor ion species in the polar wind population.  相似文献   

Two-dimensional drift velocities from the IMAGE EUV plasmaspheric imager     

《Journal of Atmospheric and Solar》2007,69(3):341-350

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) Mission extreme ultraviolet (EUV) imager observes He⁺ plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the sun, images of the He⁺ distribution are available every 10 min for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He⁺ is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion of He⁺ transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global EUV images of the plasmasphere might yield two-dimensional pictures of mesoscale to macroscale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUV analysis that appears capable of following thermal plasma motion on a global basis.  相似文献   

A comparison of solar wind and ionospheric plasma contributions to the September 24–25, 1998 magnetic storm     

《Journal of Atmospheric and Solar》2007,69(3):212-222

We have used a global time-dependent magnetohydrodynamic (MHD) simulation of the magnetosphere and particle tracing calculations to determine the access of solar wind ions to the magnetosphere and the access of ionospheric O⁺ ions to the storm-time near-Earth plasma sheet and ring current during the September 24–25, 1998 magnetic storm. We found that both sources have access to the plasma sheet and ring current throughout the initial phase of the storm. Notably, the dawnside magnetosphere is magnetically open to the solar wind, allowing solar wind H⁺ ions direct access to the near-Earth plasma sheet and ring current. The supply of O⁺ ions from the dayside cusp to the plasma sheet varies because of changes in the solar wind dynamic pressure and in the interplanetary magnetic field (IMF). Most significantly, ionospheric O⁺ from the dayside cusp loses access to the plasma sheet and ring current soon after the southward turning of the IMF, but recovers after the reconfiguration of the magnetosphere following the passage of the magnetic cloud. On average, during the first 3 h after the sudden storm commencement (SSC), the number density of solar wind H⁺ ions is a factor of 2–5 larger than the number density of ionospheric O⁺ ions in the plasma sheet and ring current. However, by 04:00 UT, ∼4 h after the SSC, O⁺ becomes the dominant species in the ring current and carries more energy density than H⁺ ions in both the plasma sheet and ring current.  相似文献   

Time-dependent simulations of the global polar wind     

《Journal of Atmospheric and Solar》2007,69(16):2028-2047

It has been clearly established that there is a substantial outflow of ionospheric plasma from the Earth's ionosphere in both the northern and southern polar regions. The outflow consists of both light thermal ions (H⁺ and He⁺) and an array of energized ions (NO⁺, O₂⁺, N₂⁺, O⁺, N⁺, He⁺, and H⁺). If the outflow is driven by thermal pressure gradients in the ionosphere, the outflow is called the “classical” polar wind. On the other hand, if the outflow is driven by energization processes either in the auroral oval or at high altitudes in the polar cap, the outflow is called the “generalized” polar wind. In both cases, the field-aligned outflow occurs in conjunction with magnetospheric convection, which causes the plasma to drift into and out of the sunlit hemisphere, cusp, polar cap, nocturnal auroral oval, and main trough. Because the field-aligned and horizontal motion are both important, three-dimensional (3-D) time-dependent models of the ionosphere–polar wind system are needed to properly describe the flow. Also, as the plasma executes field-aligned and horizontal motion, charge exchange reactions of H⁺ and O⁺ with the background neutrals (H and O) act to produce low-energy neutrals that flow in all directions (the neutral polar wind). This review presents recent simulations of the “global” ionosphere–polar wind system, including the classical, generalized, and neutral polar winds. The emphasis is on displaying the 3-D and dynamical character of the polar wind.  相似文献   

CRRES/Ground-based multi-instrument observations of an interval of substorm activity     

T. K. Yeoman  H. Lühr  R. W. H. Friedel  S. Coles  M. Grandé  C. H. Perry  M. Lester  P. N. Smith  H. J. Singer  D. Orr 《Annales Geophysicae》1994,12(12):1158-1173

Observations are presented of data taken during a 3-h interval in which five clear substorm onsets/intensifications took place. During this interval ground-based data from the EISCAT incoherent scatter radar, a digital CCD all sky camera, and an extensive array of magnetometers were recorded. In addition data from the CRRES and DMSP spacecraft, whose footprints passed over Scandinavia very close to most of the ground-based instrumentation, are available. The locations and movements of the substorm current system in latitude and longitude, determined from ground and spacecraft magnetic field data, have been correlated with the locations and propagation of increased particle precipitation in the E-region at EISCAT, increased particle fluxes measured by CRRES and DMSP, with auroral luminosity and with ionospheric convection velocities. The onsets and propagation of the injection of magnetospheric particle populations and auroral luminosity have been compared. CRRES was within or very close to the substorm expansion phase onset sector during the interval. The onset region was observed at low latitudes on the ground, and has been confirmed to map back to within L=7 in the magnetotail. The active region was then observed to propagate tailward and poleward. Delays between the magnetic signature of the substorm field aligned currents and field dipolarisation have been measured. The observations support a near-Earth plasma instability mechanism for substorm expansion phase onset.  相似文献   

A theoretical interpretation of ion composition measured on board the ‘Active’ satellite in the European sector during April 10-12, 1990 geomagnetic storm     

M. Förster  V. Mikhailov  A. Mikhailov  J. Smilauer 《Annales Geophysicae》1995,13(6):608-616

Ion composition measurements on board the ACTIVE satellite during the recovery phase of a strong geomagnetic storm of 10–12 April 1990 revealed extremely high concentrations (up to 10³ cm⁻³) of the NO⁺, O⁺₂, N⁺₂ molecular ions in the topside F2-region of the European high-latitude zone. Concentrations of O⁺, N⁺, He⁺, H⁺ light ions were slightly decreased relative to prestorm quite conditions. Theoretical calculations were used to analyze the observed variations in ion concentration. Increased neutral temperature and [O₂], [N₂] are shown to be the main reasons for the observed ion concentration variations.  相似文献   

EISCAT/CRRES observations: nightside ionospheric ion outflow and oxygen-rich substorm injections     

N. G. J. Gazey  M. Lockwood  M. Grande  C. H. Perry  P. N. Smith  S. Coles  A. D. Aylward  R. J. Bunting  H. Opgenoorth  B. Wilken 《Annales Geophysicae》1997,14(10):1032-1043

We present combined observations made near midnight by the EISCAT radar, all-sky cameras and the combined released and radiation efects satellite (CRRES) shortly before and during a substorm. In particular, we study a discrete, equatorward-drifting auroral arc, seen several degrees poleward of the onset region. The arc passes through the field-aligned beam of the EISCAT radar and is seen to be associated with a considerable upflow of ionospheric plasma. During the substorm, the CRRES satellite observed two major injections, 17 min apart, the second of which was dominated by O⁺ ions. We show that the observed are was in a suitable location in both latitude and MLT to have fed O⁺ ions into the second injection and that the upward flux of ions associated with it was sufficient to explain the observed injection. We interpret these data as showing that arcs in the nightside plasma-sheet boundary layer could be the source of O⁺ ions energised by a dipolarisation of the mid- and near-Earth tail, as opposed to ions ejected from the dayside ionosphere in the cleft ion fountain.  相似文献   

The ionospheric up-flowing He ion distribution in the magnetosphere     

J.K. Shi  J.G. Guo  K. Torkar  Z.X. Liu 《Journal of Atmospheric and Solar》2009,71(16):1630-1635

Based on ion distribution function found from the dynamic equation, the density distribution of He⁺ ions originating from the polar ionosphere and up-flowing along the magnetic field line is studied during quiet and weakly disturbed geomagnetic conditions. The results show the following. (1) The ionospheric up-flowing He⁺ ions mainly reside in the inner magnetosphere and their density has a negative radial gradient. (2) The ionospheric up-flowing He⁺ ion distributions along the magnetic field line are mainly controlled by gravity and the geomagnetic field configuration. Larger the gravity, larger is the ion density. Smaller the intensity of magnetic field, smaller is the ion density. (3) If the geomagnetic activity index K_p is high, more up-flowing He⁺ ions will enter the magnetosphere and the region where the up-flowing ions are dominant will grow. This is consistent with observations of ionospheric up-flowing ions. Some features of the geopause can be understood based on our theoretical results.  相似文献   

Ion Chemistry of the Ionosphere at E- and F-Region Altitudes: A Review   总被引：2，自引：2，他引：0  

A. V. Pavlov 《Surveys in Geophysics》2012,33(5):1133-1172

The current state of knowledge of E- and F-region ion chemistry is reviewed. Considerable attention is given to the progress in the chemistry of unexcited N₂ ⁺, O₂ ⁺, NO⁺, O⁺(⁴S), N⁺, H⁺, He⁺, Fe⁺, Mg⁺, Na⁺, Ca⁺, and K⁺ ions and electronically excited O⁺(²D), O⁺(²P), O⁺(⁴P), and $ {\text{O}}^{ + } (^{2} {\text{P}}^{*} ) $ ions. Achievements in our understanding of the role of vibrationally excited N₂ ⁺, O₂ ⁺, and NO⁺ ions in the ionosphere are discussed.  相似文献   

Pulsating of the generalized ion and neutral polar winds   总被引：1，自引：1，他引：0  

Larry C. Gardner  Robert W. Schunk 《Journal of Atmospheric and Solar》2008,70(11-12):1408-1418

A three-dimensional, time-dependent model of the ion and neutral polar winds was used to study their dynamic evolution during the May 4, 1998 magnetic storm. The simulation tracked the dynamics of five species (O⁺, H⁺, H_s, O_s, and electrons) and covered a 9-h period. During the storm, D_st decreased to −210 nT, Ap reached 300, and K_p was elevated. The IMF B_z component was southward at the start of the storm and for several hours thereafter and then turned northward. However, the magnetospheric energy input to the ionosphere exhibited a 50-min oscillation, with the plasma convection and particle precipitation patterns expanding and contracting in a periodic manner. As a consequence, the ion and neutral polar winds pulsated with an approximate 50-min period. The H⁺ and O⁺ ions displayed cyclic upflows and downflows in the topside ionosphere as well as a highly structured spatial distribution that varied with time. The vertical flux of the neutral H_s atoms was upward at the top of the ionosphere, but the magnitude varied in a cyclic manner in response to the oscillating stormtime energy input. The vertical flux of neutral O_s atoms was downward at the top of the ionosphere and varied significantly with the stormtime energy input. For H⁺, O⁺, and H_s, the maximum total (integrated) vertical flux during the storm was upward at the top of the ionosphere, with values of 8–9×10²⁵ particles/s for H⁺, 2–4×10²⁶ particles/s for O⁺, and 2–3×10²⁷ particles/s for H_s. The corresponding total vertical O_s flux was predominately downward, with only localized areas with positive fluxes.  相似文献   

Energetic Particles Observed in the CUSP Region During a Storm Recovery Phase     

S. Y. Fu  Q. G. Zong  Z. Y. Pu  C. J. Xiao  A. Korth  P. Daly  H. Reme 《Surveys in Geophysics》2005,26(1-3):241-254

In this paper we report energetic ion behavior and its composition variations observed by the Cluster/RAPID instrument when the spacecraft was travelling in the high latitude magnetospheric boundary region on the day of the 31 March, 2001, strongest magnetic storm in the past 50 years. The Dst index reached −360 nT at about 09:00 UT. During its early recovery phase, large amounts of oxygen and helium ions were observed; the ratio of oxygen to hydrogen in the RAPID energy range reached as high as 250%, which suggests that the observed energetic particles might be of magnetospheric origin. The observations further show that enhanced energetic electron fluxes are confined in a very narrow region, while protons have occupied a larger region, and heavy ions have been observed in an even larger region. The flux of energetic electrons show a slight enhancement in a region where the magnetic field magnitude is around zero. These observed energetic ions could be quasi-trapped by the current sheet in the stagnation region of the cusp.  相似文献   

A mathematical model of the middle and high latitude ionosphere   总被引：5，自引：0，他引：5  

R. W. Schunk 《Pure and Applied Geophysics》1988,127(2-3):255-303

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Evaluation of radiation-damage halos in quartz by cathodoluminescence as a geochronological tool     

T. Okumura  H. Nishido  S. Toyoda  T. Kaneko  S. Kosugi  Y. Sawada  K. Komuro 《Quaternary Geochronology》2008,3(4):342-345

Detailed quantitative cathodoluminescence (CL) imaging analysis was carried out for radiation-damage halos observed by CL (CL halo) created in natural quartz by implantation of 4 MeV He⁺ ions. The band of CL halo was approximately 14 μm in width and was constant for any He⁺ ion dose. The width of the halo is consistent with the theoretical range of ⁴He ions in quartz. A quantitative response of CL intensity to He⁺ ion dose was obtained, leading to the application of CL halos to geodosimetrical use. The CL intensity increases exponentially in the luminescent band from the implantation surface to the inside, until it reaches a maximum at 14 μm depth, with a rapid decrease beyond this point. This result is as predicted by Bragg's law, although we find some differences between the CL intensity and the theoretical stopping power.  相似文献   

Simulations of the seasonal and universal time variations of the high-latitude thermosphere and ionosphere using a coupled,three-dimensional,model   总被引：1，自引：0，他引：1  

T. J. Fuller-Rowell  D. Rees  S. Quegan  R. J. Moffett  G. J. Bailey 《Pure and Applied Geophysics》1988,127(2-3):189-217

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