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  • 1
    Electronic Resource
    Electronic Resource
    Spacecraft potential control aboard Equator-S as a test for Cluster-II (1999)
    Springer
    Annales geophysicae 17 (1999), S. 1582-1591 
    Details
    ISSN: 0992-7689
    Keywords: Space plasma physics (active perturbation experiments ; spacecraft sheaths ; wakes ; charging ; instruments and techniques)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The payload of Equator-S was complemented by the potential control device (PCD) to stabilise the electric potential of the spacecraft with respect to the ambient plasma. Low potentials are essential for accurate measurements of the thermal plasma. The design of PCD is inherited from instruments for Geotail and Cluster and utilises liquid metal ion sources generating a beam of indium ions at several keV. The set-up of the instrument and its interaction with the plasma instruments on board is presented. When the instrument was switched on during commissioning, unexpectedly high ignition and operating voltages of some ion emitters were observed. An extensive investigation was initiated and the results, which lead to an improved design for Cluster-II, are summarised. The cause of the abnormal behaviour could be linked to surface contamination of some emitters, which will be monitored and cured by on-board procedures in future. The mission operations on Equator-S were not at all affected, because of the high redundancy built into the instrument so that a sufficient number of perfectly operating emitters were available and were turned on routinely throughout the mission. Observations of the effect of spacecraft potential control on the plasma remained limited to just one event on January 8, 1998, which is analysed in detail. It is concluded that the ion beam lead to the predicted improvement of the particle measurements even outside the low density regions of the magnetosphere where the effect of spacecraft potential control would have been much more pronounced, and that the similar instruments for the four Cluster-II spacecraft to be launched in 2000 will be very important to ensure accurate plasma data from this mission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-1582-3
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetopause boundary structure deduced from the high-time resolution particle experiment on the Equator-S spacecraft (1999)
    Springer
    Annales geophysicae 17 (1999), S. 1574-1581 
    Details
    ISSN: 0992-7689
    Keywords: Magnetospheric physics (magnetopause ; cusp ; and boundary layers ; magnetospheric configuration and dynamics ; solar wind ; magnetosphere interactions)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An electrostatic analyser (ESA) onboard the Equator-S spacecraft operating in coordination with a potential control device (PCD) has obtained the first accurate electron energy spectrum with energies &7 eV-100 eV in the vicinity of the magnetopause. On 8 January, 1998, a solar wind pressure increase pushed the magnetopause inward, leaving the Equator-S spacecraft in the magnetosheath. On the return into the magnetosphere approximately 80 min later, the magnetopause was observed by the ESA and the solid state telescopes (the SSTs detected electrons and ions with energies &20–300 keV). The high time resolution (3 s) data from ESA and SST show the boundary region contains of multiple plasma sources that appear to evolve in space and time. We show that electrons with energies &7 eV–100 eV permeate the outer regions of the magnetosphere, from the magnetopause to &6Re. Pitch-angle distributions of &20–300 keV electrons show the electrons travel in both directions along the magnetic field with a peak at 90° indicating a trapped configuration. The IMF during this interval was dominated by Bx and By components with a small Bz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-1574-3
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for electron excitation of type III radio burst emission (1972)
    Springer
    Solar physics 26 (1972), S. 468-473 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Type III radio bursts observed at kilometric wavelengths (≲ 0.35 MHz) by the OGO-5 spacecraft are compared with 〉 45 keV solar electron events observed near 1 AU by the IMP-5 and Explorer 35 spacecraft for the period March 1968–November 1969. Fifty-six distinct type III bursts extending to ≲ 0.35 MHz (≳ 50 R ⊙ equivalent height above the photosphere) were observed above the threshold of the OGO-5 detector; all but two were associated with solar flares. Twenty-six of the bursts were followed ≲ 40 min later by 〉 45 keV solar electron events observed at 1 AU. All of these 26 bursts were identified with flares located west of W 09 solar longitude. Of the bursts not associated with electron events only three were identified with flares west of W 09, 18 were located east of W 09 and 7 occurred during times when electron events would be obscured by high background particle fluxes. Thus almost all type III bursts from the western half of the solar disk observed by OGO-5 above a detection flux density threshold of the order of 10−13 Wm−2 Hz−1 at 0.35 MHz are followed by 〉 45 keV electrons at 1 AU with a maximum flux of ≳ 10 cm−2 s−1 ster−1. If particle propagation effects are taken into account it is possible to account for lack of electron events with the type III bursts from flares east of the central meridian. We conclude that streams of ≈ 10–100 keV electrons are the exciting agent for type III bursts and that these same electrons escape into the interplanetary medium where they are observed at 1 AU. The total number of 〉 45 keV electrons emitted in association with a strong kilometer wavelength type III burst is estimated to be ⩾ 5 × 1032.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165288
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative comparisons of type III radio burst intensity and fast electron flux at 1 AU (1976)
    Springer
    Solar physics 46 (1976), S. 437-446 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We compare the flux of fast solar electrons and the intensity of the type III radio emission generated by these particles at 1 AU. We find that there are two regimes in the generation of type III radiation: one where the radio intensity is linearly proportional to the electron flux, and the second regime, which occurs above a threshold electron flux, where the radio intensity is proportional to the ∼2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149865
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  • 5
    Electronic Resource
    Electronic Resource
    Energetic particles in space (1980)
    Springer
    Solar physics 67 (1980), S. 393-399 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Particles ranging in energy from just above solar wind, ≳1 keV, to galactic cosmic rays of many GeV or greater are observed to be always present in the interplanetary medium. These suprathermal particles appear to come from many different sources: among them the galaxy and nearby interstellar medium, the Sun, planetary magnetospheres and bow shock waves. Recent studies have shown that the interplanetary medium itself is a major source of low energy, ≲102 MeV ions, particularly during solar quiet times. Although the physical mechanisms by which various suprathermal particle populations are produced are not well understood, it appears that collisionless shock waves are often involved in the acceleration of these particles. Here we review previous observations of these suprathermal particles and present some preliminary new observations of low energy, 〈102 keV particles from experiments aboard the ISEE-1, 2, and 3 spacecraft.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149816
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  • 6
    Electronic Resource
    Electronic Resource
    Comparisons of solar flare X-ray producing and escaping electrons from ∼ 2 TO 100 keV (1984)
    Springer
    Solar physics 91 (1984), S. 345-357 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using observations from the ISEE-3 spacecraft, we compare the X-ray producing electrons and escaping electrons from a solar flare on 8 November, 1978. The instantaneous 5 to 75 keV electron spectrum in the X-ray producing region is computed from the observed bremsstrahlung X-ray spectrum. Assuming that energy loss by Coulomb collisions (thick target) is the dominant electron loss process, the accelerated electron spectrum is obtained. The energy spectrum of the escaping electrons observed from 2 to 100 keV differs significantly from the spectra of the X-ray producing electrons and of the accelerated electrons, even when the energy loss which the escaping electrons experienced during their travel from the Sun to the Earth is taken into account. The observations are consistent with a model where the escaping electrons come from an extended X-ray producing region which ranges from the chromosphere to high in the corona. In this model the low energy escaping electrons (2–10 keV) come from the higher part of the extended X-ray source where the overlying column density is low, while the high energy electrons (20–100 keV) come from the entire X-ray source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146304
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  • 7
    Electronic Resource
    Electronic Resource
    A study of abrupt climate change in a simple nonlinear climate model (1990)
    Springer
    Climate dynamics 4 (1990), S. 253-261 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We use a seasonal energy balance climate model to study the behavior of the snowline cycle as a function of external parameters such as the solar constant. Our studies are confined in this study to cases with zonally symmetric land-sea distributions (bands or caps of land). The model is nonlinear in that the seasonally varying snow/sea ice line modifies the energy receipt through its different albedo from open land or water. The repeating steady-state seasonal cycle of the model is solved by a truncated Fourier series in time. This method is several thousand times faster than a time stepping approach. The results are interesting in that a number of bifurcations in the snowline behavior are found and studied for various geographies. Polar land caps and land bands positioned near the poles exhibit a variety of discontinuous summer snow cover behaviors (abrupt transitions as a parameter such as solar constant is slowly varied), which may be relevant to the inception and decay of continental ice sheets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211062
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  • 8
    Electronic Resource
    Electronic Resource
    A study of long-term climate change in a simple seasonal nonlinear climate model (1991)
    Springer
    Climate dynamics 6 (1991), S. 35-41 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Solar radiation cycles, earth-orbital changes, and continental drift drive long to very long term (103−106 years) climatic changes. Lin and North used the stationary solutions of a simple energy balance model (EBM) to study the equilibrium climatic stages. In this paper, we study time dependent solutions and, in particular, transition processes. We make use of two time scales: a seasonal cycle (fast variation) and a long term time change (slow variation). Variations over short time scales are solved using a Fourier transform in time and long term variations are studied using a 4th order Runge-Kutta method. The energy balance equation is a parabolic type equation and it is well posed. Climate changes depend mainly on external forcing and the state of the climate is determined by the slow time scale forcing. In other words, transitions from one climate stage (snow-covered) to another (snow-free) at bifurcation points are monotonic, despite 20% to 50% shortperiod random fluctuations in the solar energy. This smooth transition is especially noticeable when the land bands lie close to the north pole (70° N to 90° N) or at high latitudes (50° N to 75° N).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210580
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  • 9
    Electronic Resource
    Electronic Resource
    Biological monitoring of exposure to fenitrothion by high performance liquid chromatography (1995)
    Springer
    Bulletin of environmental contamination and toxicology 55 (1995), S. 29-35 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212385
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  • 10
    Electronic Resource
    Electronic Resource
    Biological Monitoring of Exposure to Chlorpyrifos by High Performance Liquid Chromatography (1996)
    Springer
    Bulletin of environmental contamination and toxicology 56 (1996), S. 367 -374 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289900053
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