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Ruhr Universität Bochum

FlareLab

A numerical and experimental simulation of solar flares

Part of the research group 1048

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Experiment

The Experiment

Aufbau

In order to understand the behaviour of "solar flares", an experiment was constructed to simulate this kind of plasmas in our laboratory. Above two electrodes an arc-shaped magnetic field is located. One of these electrodes can be charged up to +3kV, the other one symmetrically down to -3kV. Hydrogen gas is injected in front of these electrodes and an electrical discharge is initiated.

This discharge only lasts for some microseconds, so a fast framing camera is necessary to follow the evolution of the plasma flare. Also other detecting methods (triple probe, pick up coils) are in development.

 

Evolution of a discharge

Bildserie

This movie is made of pictures of different discharges. The plasma arc starts at 2 µs after the voltage is coneccted to the electrodes and it leaves the viewable range of the camera after 7 µs. The pictures were made in an interval of 200 ns.

Progress of the experiment

ablauf

The first image (on the left hand side) shows us the ground state of the experiment. The green streamlines of the magnetic field are created by permanent magnets. In the first step of the experiment hydrogen gas is injected into the chamber (image in the middle). When the hydrogen gas has spread out in front of the electrodes, the voltage between both of the electrodes is switched on and the plasma is ignited (on the right hand side). In some circumstances the plasma arc is drawn together. This effect is called self-pinching.

Modification of the plasma source

titovdemoulin

In order to build a plasma source which fulfils the model for solar flares from Titov und Demoulin (left picture, 1999), a new one was constructed (right picture). The electrodes can be charged up, like the former electrodes, to +3 kV one the one side and to -3 kV on the other side. The current setup is not longer been driven by a permanent magnet but a line current.

The permanent magnets were replaced by a line current between the both electrodes which can create a magnetic field strength of about 0.4 T in a distance of 4 cm around the line current. Therefor a current of about 25 kA is needed which will be provided by a pulse forming network.