Scientific experiment

A novel Langmuir probe system for determination of absolute electron density in ionospheric plasma has been developed at the University of Oslo (UiO). Previous Langmuir probe systems have had a spatial resolution of several hundred meters, while the multi-Needle Langmuir Probe (m-NLP) system achieves a spatial resolution down to sub-meter scale. The world-leading performance of the system leads the way for the birth of a new space weather project, the CubeSTAR student satellite.

For verification of the measurement principle, the system has been tested in the plasma chamber at the European Space Research and Technology Centre (ESTEC) in The Netherlands. These tests have shown very good linearity for both the probes and the readout electronics.

For concept proofing the m-NLP system has been successfully flown on the ICI-2 sounding rocket from Svalbard in December 2008, and in the ECOMA campaign in December 2010 from And°ya Rocket Range, consisting of three sounding rocket payloads.
For all four flights the m-NLP system has provides high quality measurements of ionospheric electron density (Figure left: One second of data from ICI-2, showing small-scale electron density structures of importance for GNSS signals and HF radio communication).

The probes, with a typical diameter of 0.51 mm and a length of 25 mm, are mounted on spring-loaded booms, which is slided against the inner walls of the POD during deployment. The electronics consists of several components developed at UiO, amongst others a high-performance pre-amplifier with in-flight programmable automatic gain control, and a custom adaptable DSP unit for the Altera FPGA to handle the on-board calculations of absolute electron density.