What is plasma current and what is a pulse?
A large currrent is generated in the plasma for two reasons. The current produces a powerful magnetic field which, in addition to externally generated fields, confines the plasma within the tokamak vessel. It also heats the plasma up to high temperatures (just like a current in a wire heats the wire up). The pulse is the short plasma that we generate in any of the tokamak experiments we run (e.g. JET) – it only last a few seconds due to the large amounts of energy required to maintain it. We then study it and conduct experiments to try and improve its performance etc.
