Helmholtz-Zentrum Dresden-Rossendorf (HZDR) researchers have developed a laboratory model in order to find out the behavioural patterns of plasma waves or Alfvén waves of Sun. The findings of the research have been published in the journal Physical Review Letters.
Sun’s corona sometimes becomes several million degrees Celsius hot and why it happens is a big mystery to scientists. Scientists discovered a “hot” trail just below the corona which will explain this trend. In this region sound waves and plasma waves have the same frequency. The scientists from HZDR have used molten alkali metal rubidium to make their model.
The centre of the Sun is 15 million degrees Celsius hot. The surface of the Sun is 6000 degrees Celsius hot. The team of the scientists have conducted research on physics of celestial bodies. To scientists, corona heating is one of the great mysteries of solar physics.
The magnetic fields play a major role in heating the sun’s corona. But it is controversial if this happens because of a sudden change in magnetic field structures or if depends upon the dampening of different waves. The new research has focused upon Alfvén waves. These waves occur below the corona. These waves are permeated by magnetic fields. The magnetic fields act as ionized particles and these resemble a guitar string. The frequency of Alfvén wave increases as the strength of the magnetic field increases.
A difficult experiment
The Alfvén wave was first detected in 1942. It was detected by the liquid-metal experiments. It is studied in details in the plasma physics. The magnetic canopy is crucial for corona heating. But till now it has remained inaccessible to experimenters.
Alfvén speed is much higher in the large plasma experiments. But liquid-metal experiments have also lessened now. The reason behind this is, low magnetic field strength is about 20 Tesla.
HZDR’s Dresden High Magnetic Field Laboratory (HLD) have generated pulsed magnetic fields of 100 tesla. By experimenting with the properties of liquid metals the scientists came to a conclusion that alkali metal rubidium reaches till 54 Tesla.
But the scientists fears that this experiment can be dangerous as rubidium ignites in air and reacts violently with water. But their fear was dispelled.
But it was still a difficult experiment. As the pressures were 50 times higher than atmospheric air pressure in the pulsed magnetic field. The melted rubidium was contained in a sturdy stainless-steel container. Scientists have injected alternating current at the bottom of the container. They have also exposed it to magnetic field at the same time. They have finally produced Alfvén waves in the melt. The upward motion of the waves was of expected speed.
The sun’s corona is the outer layer of the atmosphere of sun. This layer is usually hidden by the bright light of sun. This is why we cannot see it with our bare eyes. We need special instruments to see it. This corona can be seen in the time of a total solar eclipse.