In Situ Observations of Ionospheric Heating Effects: First Results from a Joint SURA and NorSat-1 Experiment
This work presents the first results of measurements of artificial plasma disturbance characteristics using the low-orbit NorSat-1 satellite, which are excited when the ionospheric F2 layer is modified by powerful high-frequency (HF) waves emitted by the SURA heating facility. NorSat-1 carries the multineedle Langmuir probe instrument, which is capable of sampling the electron density at a nominal rate up to 1 kHz. The uniqueness of this experiment lies in the fact that the satellite passes very close to the center of the HF-perturbed magnetic flux tube and in situ observations are first carried out in winter when the absorption is still small in the morning as the Sun is low above the horizon. There are HF-induced plasma temperature and density variations at satellite altitudes of about 580 km. Plasma irregularities are detected by in situ measurements down to 200 m at the southern border of the SURA heating region.