X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Composition and Dynamics of Plasma in Saturn's Magnetosphere
    American Association for the Advancement of Science (AAAS) ; 2005
    In:  Science Vol. 307, No. 5713 ( 2005-02-25), p. 1262-1266
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 307, No. 5713 ( 2005-02-25), p. 1262-1266
    Abstract: During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 R S (where R S is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with ∼3% N + . Over the A and B rings, we found an ionosphere in which O 2 + and O + are dominant, which suggests the possible existence of a layer of O 2 gas similar to the atmospheres of Europa and Ganymede.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.1106151
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2005
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 2
    Online Resource
    Online Resource
    Cassini Plasma Spectrometer Investigation
    Springer Science and Business Media LLC ; 2004
    In:  Space Science Reviews Vol. 114, No. 1-4 ( 2004-9), p. 1-112
    Details
    In: Space Science Reviews, Springer Science and Business Media LLC, Vol. 114, No. 1-4 ( 2004-9), p. 1-112
    Type of Medium: Online Resource
    ISSN: 0038-6308 , 1572-9672
    URL: Article
    DOI: 10.1007/s11214-004-1406-4
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2004
    detail.hit.zdb_id: 2017804-9
    detail.hit.zdb_id: 2561549-X
    SSG: 16,12
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 3
    Online Resource
    Online Resource
    Active spacecraft potential control for Cluster – implementation and first results
    Copernicus GmbH ; 2001
    In:  Annales Geophysicae Vol. 19, No. 10/12 ( 2001-09-30), p. 1289-1302
    Details
    In: Annales Geophysicae, Copernicus GmbH, Vol. 19, No. 10/12 ( 2001-09-30), p. 1289-1302
    Abstract: Abstract. Electrostatic charging of a spacecraft modifies the distribution of electrons and ions before the particles enter the sensors mounted on the spacecraft body. The floating potential of magnetospheric satellites in sunlight very often reaches several tens of volts, making measurements of the cold (several eV) component of the ambient ions impossible. The plasma electron data become contaminated by large fluxes of photoelectrons attracted back into the sensors. The Cluster spacecraft are equipped with emitters of the liquid metal ion source type, producing indium ions at 5 to 9 keV energy at currents of some tens of microampere. This current shifts the equilibrium potential of the spacecraft to moderately positive values. The design and principles of the operation of the instrument for active spacecraft potential control (ASPOC) are presented in detail. Experience with spacecraft potential control from the commissioning phase and the first two months of the operational phase are now available. The instrument is operated with constant ion current for most of the time, but tests have been carried out with varying currents and a "feedback" mode with the instrument EFW, which measures the spacecraft potential . That has been reduced to values according to expectations. In addition, the low energy electron measurements show substantially reduced fluxes of photoelectrons as expected. The flux decrease in photoelectrons returning to the spacecraft, however, occurs at the expense of an enlarged sheath around the spacecraft which causes problems for boom-mounted probes.Key words. Space plasma physics (spacecraft sheaths, wakes, charging); Instruments and techniques; Active perturbation experiments
    Type of Medium: Online Resource
    ISSN: 1432-0576
    URL: Article
    DOI: 10.5194/angeo-19-1289-2001
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2001
    detail.hit.zdb_id: 1458425-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 4
    Online Resource
    Online Resource
    Results from active spacecraft potential control on the Geotail spacecraft
    American Geophysical Union (AGU) ; 1995
    In:  Journal of Geophysical Research: Space Physics Vol. 100, No. A9 ( 1995-09), p. 17253-17259
    Details
    In: Journal of Geophysical Research: Space Physics, American Geophysical Union (AGU), Vol. 100, No. A9 ( 1995-09), p. 17253-17259
    Abstract: A low and actively controlled electrostatic potential on the outer surfaces of a scientific spacecraft is very important for accurate measurements of cold plasma electrons and ions and the DC to low‐frequency electric field. The Japanese/NASA Geotail spacecraft carries as part of its scientific payload a novel ion emitter for active control of the electrostatic potential on the surface of the spacecraft. The aim of the ion emitter is to reduce the positive surface potential which is normally encountered in the outer magnetosphere when the spacecraft is sunlit. Ion emission clamps the surface potential to near the ambient plasma potential. Without emission control, Geotail has encountered plasma conditions in the lobes of the magnetotail which resulted in surface potentials of up to about +70 V. The ion emitter proves to be able to discharge the outer surfaces of the spacecraft and is capable of keeping the surface potential stable at about +2 V. This potential is measured with respect to one of the electric field probes which are current biased and thus kept at a potential slightly above the ambient plasma potential. The instrument uses the liquid metal field ion emission principle to emit indium ions. The ion beam energy is about 6 keV and the typical total emission current amounts to about 15 µA. Neither variations in the ambient plasma conditions nor operation of two electron emitters on Geotail produce significant variations of the controlled surface potential as long as the resulting electron emission currents remain much smaller than the ion emission current. Typical results of the active potential control are shown, demonstrating the surface potential reduction and its stability over time.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/95JA01552
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1995
    detail.hit.zdb_id: 2033040-6
    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 5
    Online Resource
    Online Resource
    A novel medium-energy ion emitter for active spacecraft potential control
    AIP Publishing ; 1993
    In:  Review of Scientific Instruments Vol. 64, No. 8 ( 1993-08-01), p. 2293-2297
    Details
    In: Review of Scientific Instruments, AIP Publishing, Vol. 64, No. 8 ( 1993-08-01), p. 2293-2297
    Abstract: An ion emission instrument has been developed to actively control the electrostatic surface potential of a spacecraft in orbit. Spacecraft surfaces tend to charge positive when their conductive surfaces are partially sunlit, and photoelectrons emitted, and the spacecraft is positioned outside of the very dense plasma region which is referred to as plasmasphere. A small, lightweight instrument with a lifetime of more than 104 h at a nominal emission current of 10 μA was the design goal. The ion emitter is based on the liquid metal ion source principle; a constant stream of liquified indium is evaporated from the tip of a needle and ionized; the ions are then extracted by a strong electric field. The size of the instrument is about 18 by 15 by 23 cm (length×width×height) and the entire instrument weighs about 1.9 kg and consumes 2.4 W of electrical power in the nominal emission mode. An instrument of this type is already operational on the Japanese Geotail spacecraft, while five more instruments are at the stage of flight model assembly for integration on the Russian Interball satellite and the ESA/NASA four-spacecraft Cluster mission. The Geotail instrument is functioning as expected. Preliminary results show that the ion emitter is able to reduce surface potentials of +70 V (highest value observed up to now) down to 2–4 V.
    Type of Medium: Online Resource
    ISSN: 0034-6748 , 1089-7623
    URL: Article
    DOI: 10.1063/1.1143924
    Language: English
    Publisher: AIP Publishing
    Publication Date: 1993
    detail.hit.zdb_id: 209865-9
    detail.hit.zdb_id: 1472905-2
    SSG: 11
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 6
    Online Resource
    Online Resource
    Electron density estimations derived from spacecraft potential measurements on Cluster in tenuous plasma regions : ELECTRON DENSITY IN TENUOUS PLASMAS
    American Geophysical Union (AGU) ; 2008
    In:  Journal of Geophysical Research: Space Physics Vol. 113, No. A7 ( 2008-07), p. n/a-n/a
    Details
    In: Journal of Geophysical Research: Space Physics, American Geophysical Union (AGU), Vol. 113, No. A7 ( 2008-07), p. n/a-n/a
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2007JA012636
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2008
    detail.hit.zdb_id: 2033040-6
    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 7
    Online Resource
    Online Resource
    Plasma transport in the magnetotail lobes
    Copernicus GmbH ; 2009
    In:  Annales Geophysicae Vol. 27, No. 9 ( 2009-09-28), p. 3577-3590
    Details
    In: Annales Geophysicae, Copernicus GmbH, Vol. 27, No. 9 ( 2009-09-28), p. 3577-3590
    Abstract: Abstract. The Earth's magnetosphere is populated by particles originating from the solar wind and the terrestrial ionosphere. A substantial fraction of the plasma from these sources are convected through the magnetotail lobes. In this paper, we present a statistical study of convective plasma transport through the Earth's magnetotail lobes for various geomagnetic conditions. The results are based on a combination of density measurements from the Electric Field and Waves Experiment (EFW) and convection velocities from the Electron Drift Instrument (EDI) on board the Cluster spacecraft. The results show that variations in the plasma flow is primarily attributed to changes in the convection velocity, whereas the plasma density remains fairly constant and shows little correlation with geomagnetic activity. During disturbed conditions there is also an increased abundance of heavier ions, which combined with enhanced convection, cause an accentuation of the mass flow. The convective transport is much slower than the field aligned transport. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet.
    Type of Medium: Online Resource
    ISSN: 1432-0576
    URL: Article
    DOI: 10.5194/angeo-27-3577-2009
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1458425-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 8
    Online Resource
    Online Resource
    Irregular structures observed below 71 km in the night-time polar D-region
    Copernicus GmbH ; 2000
    In:  Annales Geophysicae Vol. 18, No. 2 ( 2000-02-29), p. 215-222
    Details
    In: Annales Geophysicae, Copernicus GmbH, Vol. 18, No. 2 ( 2000-02-29), p. 215-222
    Abstract: Abstract. A new rocket range, SvalRak, was opened in November 1997 at Ny-Ålesund (79°N) in the Svalbard archipelago. The first instrumented rocket was launched on 20 November, 1997, at 1730 UT during geomagnetically quiet conditions. The payload was instrumented to measure plasma parameters in the mesosphere and lower thermosphere, but the payload only reached an altitude of 71 km. This resulted in a very flat trajectory through the lower D-region. The positive ion concentrations were larger than expected, and some unexpected plasma irregularities were observed below 71 km. The irregularities were typically 100 m in spatial extent, with plasma densities a factor of two to five above the ambient background. In the dark polar night the plasma below 71 km must consist mainly of positive and negative ions and the only conceivable ionising radiation is a flux of energetic particles. Furthermore only relativistic electrons have the large energies and the small gyro radii required in order to explain the observed spatial structure. The source of these electrons is uncertain. Key words: Ionosphere (ionospheric irregularities; ionization mechanisms) - Magnetospheric physics (polar cap phenomena)
    Type of Medium: Online Resource
    ISSN: 1432-0576
    URL: Article
    DOI: 10.1007/s00585-000-0215-7
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2000
    detail.hit.zdb_id: 1458425-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 9
    Online Resource
    Online Resource
    Spacecraft potential control aboard Equator-S as a test for Cluster-II
    Copernicus GmbH ; 1999
    In:  Annales Geophysicae Vol. 17, No. 12 ( 1999-12-31), p. 1582-1591
    Details
    In: Annales Geophysicae, Copernicus GmbH, Vol. 17, No. 12 ( 1999-12-31), p. 1582-1591
    Abstract: 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.Key words. Space plasma physics (active perturbation experiments; spacecraft sheaths · wakes · charging; instruments and techniques)
    Type of Medium: Online Resource
    ISSN: 1432-0576
    URL: Article
    DOI: 10.1007/s00585-999-1582-3
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 1999
    detail.hit.zdb_id: 1458425-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 10
    Online Resource
    Online Resource
    The ECOMA 2007 campaign: rocket observations and numerical modelling of aerosol particle charging and plasma depletion in a PMSE/NLC layer
    Copernicus GmbH ; 2009
    In:  Annales Geophysicae Vol. 27, No. 2 ( 2009-02-17), p. 781-796
    Details
    In: Annales Geophysicae, Copernicus GmbH, Vol. 27, No. 2 ( 2009-02-17), p. 781-796
    Abstract: Abstract. The ECOMA series of rocket payloads use a set of aerosol particle, plasma, and optical instruments to study the properties of aerosol particles and their interaction with the ambient plasma environment in the polar mesopause region. In August 2007 the ECOMA-3 payload was launched into a region with Polar Mesosphere Summer Echoes (PMSE) and noctilucent clouds (NLC). An electron depletion was detected in a broad region between 83 and 88 km, coincident with enhanced density of negatively charged aerosol particles. We also find evidence for positive ion depletion in the same region. Charge neutrality requires that a population of positively charged particles smaller than 2 nm and with a density of at least 2×108 m−3 must also have been present in the layer, undetected by the instruments. A numerical model for the charging of aerosol particles and their interaction with the ambient plasma is used to analyse the results, showing that high aerosol particle densities are required in order to explain the observed ion density depletion. The model also shows that a very high photoionisation rate is required for the particles smaller than 2 nm to become positively charged, indicating that these may have a lower work function than pure water ice.
    Type of Medium: Online Resource
    ISSN: 1432-0576
    URL: Article
    DOI: 10.5194/angeo-27-781-2009
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 1458425-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
Nothing or not found what you are looking for? Please check your search query or use the Interlibrary Loan Search.
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages