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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
    On-board data analysis techniques for space plasma particle instruments (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 372-380 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes the on-board data analysis techniques used on two recent space plasma particle instruments to compute meaningful parameters of three-dimensional plasma distributions in real time. These parameters may be transmitted with much higher time resolution than the full distribution within the limited telemetry. In addition, they greatly reduce the ground processing requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140441
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  • 4
    Electronic Resource
    Electronic Resource
    A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind (2006)
    [s.l.] : Nature Publishing Group
    Nature 439 (2006), S. 175-178 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Magnetic reconnection in a current sheet converts magnetic energy into particle energy, a process that is important in many laboratory, space and astrophysical contexts. It is not known at present whether reconnection is fundamentally a process that can occur over an extended region in space or ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature04393
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  • 5
    Electronic Resource
    Electronic Resource
    In situ detection of collisionless reconnection in the Earth's magnetotail (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 412 (2001), S. 414-417 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Magnetic reconnection is the process by which magnetic field lines of opposite polarity reconfigure to a lower-energy state, with the release of magnetic energy to the surroundings. Reconnection at the Earth's dayside magnetopause and in the magnetotail allows the solar wind into the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35086520
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  • 6
    Electronic Resource
    Electronic Resource
    Mapping the composition of planetary surfaces by Auger electron spectroscopy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 660-666 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We explore the feasibility of Auger electron spectroscopy as a remote sensing technique to map the composition of the sunlit surfaces of planetary bodies without atmospheres. Solar x rays eject photoelectrons from the planetary surface. The resulting ions relax by emission of fluorescence x rays or Auger electrons, with energies characteristic of the element which is ionized. The spectrum of Auger electrons and photoelectrons is computed for a variety of elements and for representative lunar rock types illuminated by soft x-ray line and continuum emission typical of solar long-lived coronal active regions. The Auger electron lines for O, Si, Mg, Al, Fe, and Ca in lunar rocks stand well above the continuum background from photoelectrons and backscattered interplanetary electrons, with typical line-to-continuum ratios of ∼20 to (approximately-greater-than)103. An ideal Auger electron spectroscopy instrument to map the elemental composition of planetary surfaces should have a combination of high energy resolution ((approximately-less-than)2 eV) and large geometric factor ((approximately-greater-than)0.1 cm2 sr). This technique could be applied to the Moon, Mercury, asteroids, comets, and perhaps the moons of outer planets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142064
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  • 7
    Electronic Resource
    Electronic Resource
    Probable detection of organic-dust-borne aromatic C 3 H 3 + ions in the coma of comet Halley (1989)
    [s.l.] : Nature Publishing Group
    Nature 337 (1989), S. 53-55 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The PICCA (positive-ion-cluster-composition analyser) instrument uses an electrostatic analyser and measures the ratio Fig. 1 Three consecutive measurements of mass spectra. The time is given in spacecraft event time and corresponds to cometocentric distances of (top to bottom) 4,450, 4,230 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/337053a0
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  • 8
    Electronic Resource
    Electronic Resource
    Mass spectra of heavy ions near comet Halley (1986)
    [s.l.] : Nature Publishing Group
    Nature 321 (1986), S. 335-336 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Spectral observations of comets from the ground as well as from Earth-orbiting satellites have revealed a variety of neutral and ionic species. However, reliable cometocentric radial profiles of the number densities of individual species, which are required for comparison with atmospheric/ ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/321335a0
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  • 9
    Electronic Resource
    Electronic Resource
    Comet Halley–solar wind interaction from electron measurements aboard Giotto (1986)
    [s.l.] : Nature Publishing Group
    Nature 321 (1986), S. 349-352 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] One of the two instruments of the RPA-Copernic experiment1 consists of a spectrometer (the electron electrostatic analyser, RPA1-EESA) designed to measure the three-dimensional distributions of electrons with energies between lOeV and 30keV. This instrument includes a symmetrical quadrispherical ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/321349a0
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  • 10
    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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