ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    London : Periodicals Archive Online (PAO)
    Journal of historical geography. 15:2 (1989:Apr.) 196 
    ISSN: 0305-7488
    Topics: Geography
    Description / Table of Contents: The British Isles and the European Mainland
    Notes: Reviews
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A system has been developed to provide accurate calibration of electron detectors measuring in the energy range from approximately 10 eV to 50 keV. The principal component of the system is a large area (730 cm2), monoenergetic electron beam which is tunable in energy. This beam is produced by illuminating, in vacuum, a thin gold film deposited onto a quartz flat with ultraviolet light, such that photoelectrons are ejected from the gold surface. With the gold film floated at an adjustable negative voltage, the photoelectrons ejected from the surface are accelerated towards an electrically grounded screen which is positioned in front of the quartz flat. All high voltages in the beam system are guarded so as to eliminate any significant leakage current. The current leaving the gold surface which determines the beam intensity is measured using a specially designed picoammeter. Electron beam intensities of ∼106 electrons/cm2 s are produced by illuminating the gold photocathode with light from a 2-W mercury vapor lamp which has 90% of its output at 2537 A(ring). The resulting beam has an energy spread of 0.41 eV. Electron beam intensities of ∼107 electrons/cm2 s are produced with a 200 W medium pressure mercury arc lamp. For this case, the beam has a width in energy of 0.55 eV. Detectors to be calibrated are mounted within a set of computer-controlled rotational and translational tables. The tables allow the look direction of the detector to be oriented with respect to the beam in two orthogonal angles and two orthogonal directions. The entire calibration system operates within a set of Helmholtz coils that allow the Earth's magnetic field to be canceled. The voltage on the gold surface, the angular and spatial positioning of the detector, and the accumulation and display of the data are all controlled by a minicomputer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2011-08-19
    Description: High-resolution magnetic field and charged-particle data acquired on March 25, 1986 by the Viking and DMSP-F7 satellites, as they traversed the dawn sector auroral zone on nearly antiparallel trajectories within 40 min of each oher, are analyzed. Magnetic field measurements by Viking at 0850 MLT and by DMSP at 0630 MLT indicate the presence of a large-scale earthward-directed region 1 Birkeland current and an upward-flowing region 2 current. Both satellites also observed a third Birkeland current adjacent to and poleward of the region 1 system with opposite flow. This poleward system is about 0.5 deg invariant latitude wide and has a current density comparable to the region 1 and 2 systems. The highest-latitude current is identified as region 0. Its charged-particle signatures were used to infer field line mapping to the equatorial plane.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 14; 423-426
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2016-06-07
    Description: Spacecraft charging has been widely observed in geosynchronous orbit on the ATS-5 and ATS-6 pair and on the SCATHA spacecraft. An adequate theory for explaining the observations exist. Neither the data or theory can be exported to low polar orbit and its drastically different environment. Evidence of charging on the DMSP F6 spacecraft is presented. A simple model is set up explaining the observations. Two independent instruments on the spacecraft showed charging to a moderate (44 volts) negative potential. The selection spectrometer showed a flux of 2 billion electrons per sq. cm. sec. ster. peaked at 9.5 keV. This was marginally sufficient to overcome the flux of cold ambient ions. Charging calculations are presented showing where simplications are justified and where serious uncertainties exist. More serious charging is predicted for the Shuttle in polar orbit.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Spacecraft Environ. Interactions Technol., 1983; p 125-130
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2016-06-07
    Description: Questions are addressed concerning how large space structures in polar orbit will interact with auroral environments. Because spacecraft charging at ionospheric attitudes does not seriously threaten the operation of today's relatively small polar satellites the subject of environment interactions has not received the widespread attention given to it at geostationary altitude. As a matter of economics it is desirable to apply as much as possible of what was learned about spacecraft interactions at geostationary orbit to low Earth orbits. The environment at auroral latitudes in the ionosphere differs from that encountered at geostationary altitude in at least two major aspects. (1) There is a large reservoir of high-density, cold plasma which tends to mitigate charging effects by providing a large source of charged particles from which neutralizing currents maybe drawn. Significant wake effects behind large structures will introduce new problems with differential charging. (2) Between the magnetic equator and the ionosphere, auroral electrons frequently undergo field-aligned accelerations of several kilovolts. In such environments, fluxes of energetic protons are usually below the levels of instrumentation sensitivity.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Spacecraft Environ. Interactions Technol., 1983; p 109-123
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2016-06-07
    Description: The precipitation electrons in the auroral environment are highly variable in their energy and intensity in both space and time. As such they are a source of potential hazard to the operation of the Space Shuttle and other large spacecraft operating in polar orbit. In order to assess these hazards both the average and extreme states of the precipitating electrons must be determined. Work aimed at such a specification is presented. First results of a global study of the average characteristics are presented. In this study the high latitude region was divided into spatial elements in magnetic local time and corrected geomagnetic latitude. The average electron spectrum was then determined in each spatial element for seven different levels of activity as measured by K sub p using an extremely large data set of auroral observations. Second a case study of an extreme auroral electron environment is presented, in which the electrons are accelerated through field aligned potential as high as 30,000 volts and in which the spacecraft is seen to charge negatively to a potential approaching .5 kilovolts.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Spacecraft Environ. Interactions Technol., 1983; p 131-153
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2019-07-12
    Description: Auroral zone conductances can be estimated from the energy flux and average energy of precipitating electrons. Revised expressions are presented that relate height-integrated Hall and Pedersen conductance to the flux and average energy of a Maxwellian. It is shown that the accuracy of this method depends on the minimum and maximum energy within which the distribution is integrated to get the energy flux and average energy. It is also confirmed that the conductances produced by some of the more common auroral spectral distributions are similar to those produced by a Maxwellian with the same average energy and energy flux. The application of these results is demonstrated using precipitating electron measurements made by the Hilat satellite during a pass over Greenland.
    Keywords: GEOPHYSICS
    Type: AD-A180362 , AFGL-TR-87-0152 , Journal of Geophysical Research (ISSN 0148-0227); 92; 2565-256
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2019-07-12
    Description: The statistical occurrence of spacecraft charging at near-geosynchronous orbit in daylight is studied with reference to results of an experiment conducted on the SCATHA satellite. In particular, it is found that: (1) the external current that creates high negative satellite frame potentials is the high-energy electron current from the electron population with energies greater than about 30 keV; (2) the electron current to the satellite from particles with energies less than about 30 keV neither drives the frame potential nor provides the current to balance the high-energy populations; and (3) the ion current provided from the entire range of measured ions is also not the primary source of the balancing current.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AD-A165444 , AFGL-TR-86-0057 , Journal of Geophysical Research (ISSN 0148-0227); 91; 1474-149
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2019-07-12
    Description: Results are presented from the Polar Ionospheric Irregularities Experiment (PIIE), conducted from Sondrestrom, Greenland, on March 15, 1985, designed for an investigation of processes which lead to the generation of small-scale (less than 1 km) ionospheric irregularities within polar-cap F-layer auroras. An instrumented rocket was launched into a polar cap F layer aurora to measure energetic electron flux, plasma, and electric circuit parameters of a sun-aligned arc, coordinated with simultaneous measurements from the Sondrestrom incoherent scatter radar and the AFGL Airborne Ionospheric Observatory. Results indicated the existence of two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability.
    Keywords: GEOPHYSICS
    Type: AD-A214008 , Journal of Geophysical Research (ISSN 0148-0227); 94; 6692-671
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2013-08-31
    Description: The results of the Trapped Radiation Effects Panel for the Space Environmental Effects on Materials Workshop are presented. The needs of the space community for new data regarding effects of the space environment on materials, including electronics are listed. A series of questions asked of each of the panels at the workshop are addressed. Areas of research which should be pursued to satisfy the requirements for better knowledge of the environment and better understanding of the effects of the energetic charged particle environment on new materials and advanced electronics technology are suggested.
    Keywords: CHEMISTRY AND MATERIALS (GENERAL)
    Type: NASA(SDIO Space Environmental Effects on Materials Workshop, Part 2; p 597-605
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...