MAST is a fusion experiment at the Culham Centre for Fusion Energy near Oxford. It stands for Mega Amp Spherical Tokamak (Mega amp means it can have about a million amps of electrical current in the plasma and there is a picture of a spherical tokamak on my profile 🙂 )
A magnetic island is something that can form inside the plasma in a fusion experiment. They’re bad because they can cause the plasma to cool down and make less fusion happen.
My experiment was to make the magnetic island disappear by changing the pressure inside the fusion reactor and measure it in lots of details while it disappeared. By seeing what happens when they disappear we can learn how to stop them growing in the first place.