Physicists working in space plasmas have made clever use of the Ulysses spacecraft and the solar minimum to create a massive virtual lab bench to provide a unique test for the science underlying turbulent flows…
However University of Warwick plasma astrophysicists Professor Sandra Chapman and Dr Ruth Nicol have found a particularly elegant solution to fill the…experimental gap employing Ulysses spacecraft and two solar minimum to map the turbulence in the energies of the turbulence in the solar wind – a magnetohydrodynamic (MHD) flow.
Normally the ‘noise’ from violent eruptions on the sun would disturb the turbulent flow. Ulysses’ controllers had cleverly contrived for the spacecraft to pass over each of the Sun’s poles during two different solar minima making it possible not only to gather data but also to be able to compare two different energy levels in a turbulent flow. The level of turbulence is down by a factor of 2 in the most recent solar minimum compared with the previous one.
The spacecraft was able to record the state of the turbulent flows flowing past it at 750kms a second at a distance of up to 2.83 Astronomical units from the Sun. This in effect allowed the spacecraft to record the developing turbulence as it flowed up to the satellite’s position which then became like a weir in space creating a virtual confined laboratory box to test the development of flows over a time – but a confined box which was over 200 million miles in size…
They found that in all the polar passes of the spacecraft the evolution of turbulence in the Solar wind was governed by the same generalised scaling function no matter how much energy was in the system. This suggest that there is a universal basic property governing the evolution of magnetohydrodynamic turbulence over finite distances – in this case a finite distance of over 200 million miles.
Professor Sandra Chapman notes…the results come to the attention of colleagues interested in how turbulence evolves in confined plasmas on earth – which will aid their efforts to generate fusion energy.