New diagnostics to measure the density and wave processes in the ionospheric plasma on board of microsatellite «TRABANT»

An original technique for measuring small plasma density using a resonant microwave probe has been developed, which allows to significantly expand the dynamic range of the measuring system. The probe is a quarter-wave segment of a two-wire line. Measurements are carried out at a fixed frequency corresponding to the eigenfrequency of the probe without plasma. Minor variations in the resonance frequency of the system are recorded by the method of amplitude-phase measurements.

This technique will be used for the first time to measure the density of ionospheric plasma and its perturbations on board the «TRABANT» microsatellite with an orbit height of 500km. The length of the probe is 40cm, the eigenfrequency is 180MHz, the weights of the antenna and receiving equipment are 0.2kg and 1kg, respectively. The diagnostics will allow the exploring small-scale spatial inhomogeneities of the plasma density with a size of 8m and more, and the wide frequency range of the sensor (up to 1MHz) will make it possible to detect small fluctuations of the plasma density with the perturbation δn/n~10^-3, caused by wave processes in the ionosphere. Due to the limited resources of the telecommunication equipment and large data flows, the frequency range of the sensor is 0-40kHz. The measuring system to be installed on board the «TRABANT» was tested on a unique large-scale plasma system «IONOSPHERE». It was found that the sensor confidently registers the value of the plasma density in the 10^3-10^6cm^-3 range, which is characteristic of the altitude of the satellite`s orbit.