Characterisation of arc channel

During a lighting strike a lighting channel is formed between the cloud and point of strike on the ground. This channel is used to transfer the charge from the cloud to the ground. But the channel itself dissipates some of the energy.

To evaluate the amount of energy dissipated by the channel the measurements on the channel should be performed, but since the channel is very long this is impossible. Therefore the experiments can be performed on the arcs, which can be created in the laboratory. The length of such arcs is only a few cm but the current flowing through them is equal as in the lightning channel.

In this work the measurements shall be performed on arcs of different lengths. The amplitude of the arc current shall also be varied. During each test voltage and current waveshapes shall be recorded. The measurements will include tests in high voltage laboratory. The results of measurements shall be analysed by looking to the energy dissipated in the arc at different current amplitudes. In the same way the resistance of the arc channel shall be analysed.

The tasks to perform:

* Literature survey and study of breakdown phenomenon
* Measurements of voltage current characteristics of arcs
* Analysis of measured data
* Work report

The work shall be performed at Division for Electricity and lightning Research, Department of Material Science, Uppsala University.