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CPD Experiment Objectives
 
Large flares at the sun and magnetic storms and substorms in the Earth's magnetosphere may generate intense radiation of high-energy charged particles, mostly electrons, protons and alpha - particles, which add to the steady background of cosmic radiation. This high-energy radiation is an important element of the fundamental physical processes at the sun, in the interplanetary space and in the near-earth space. The high-energy particles are also important elements of substorm generation and dynamics and of importance for various aspects of upper atmosphere conditions. The high-energy charged particles of solar or magnetospheric origin may be temporarily trapped in the Earth's magnetic field until lost by precipitation into the atmosphere. The precipitation is particularly intense in the polar and auroral regions where the energetic radiation may produce substantially enhanced ionization at low altitudes. Such ionization can cause black-out of HF radio communication circuits used, among other, for the air and sea traffic. In addition, the high-energy particle precipitation increases the conductivity of the atmosphere thereby changing its global electrical properties. The precipitation may even produce modifications of the lower atmospheric chemistry and composition, for instance, the nitric- oxide and ozone abundance. The energetic particle radiation may have various adverse effects e.g. on space systems, on communications and on the environment.

The high-energy radiation during large solar flares may cause severe damage on spacecraft systems in particular on solar panels and complex electronic systems. The high-energy charged particles are important in a number of research fields such as investigations of solar wind-magnetosphere boundary conditions and other essential geomagnetic morphological problems like the distinguishing between 'open' and 'closed' magnetospheric regions. The high-energy precipitation events may offer essential advantages for atmospheric observations. The ionization produced at low altitudes makes the upper atmosphere 'visible' for electromagnetic probing and thus enable various forms of radar observations of winds and turbulence in the 'middle atmosphere' which is difficult to explore by other methods. The solid-state high energy charged particle detector (CPD) experiment was proposed in 1991 for the Danish small satellite named ØRSTED. It is aiming at the detection of electrons in the energy range from 50 keV to 1 Mev and protons and alpha - particles from 300 keV to 300 MeV. The primary objectives for the satellite particle experiment are:

  • detection of the energetic particle radiation in the upper polar atmosphere to be combined with absorption data from imaging riometer installations on the ground in order to detect the atmospheric reactions and the dynamical features of polar and auroral particle precipitation events.
  • investigation of the properties of the radiation trapped in the Earth's magnetic field and monitoring of the long-term high-energy particle radiation dose at the satellite for investigations of possible radiation damages on other on-board experiments and systems.
  • monitoring of the level of solar-geophysical activity during events like major solar flares and geomagnetic storms where intense and variable high-energy particle radiation may occur.

Peter Stauning, CPD Principal Investigator

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