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Magnetic Islands

Contact person: Koki Imada


MCF Pages

1: Helical magnetic field lines confine the plasma, keeping the core at high density and temperature.
2: Filamentation of plasma current (δJ||) leads to the formation of a magnetic island chain.
3: Across the island transport of particles and heat is increased, degrading the confinement.

Nuclear fusion is what powers the Sun. On the Earth, the fusion reaction involving hydrogen isotopes is a potential solution to the world’s energy problem. One of the ways to confine the fuel, which is in plasma state at 108K, is to use magnetic fields, in a device such as a tokamak. One of the challenges a tokamak faces is plasma instabilities, which degrade the confinement. One example is neoclassical tearing modes (NTMs), characterised by evolution of “magnetic islands”. In order to control NTMs, it is essential to understand “threshold physics”, in which sufficiently small islands tend to heal themselves. Here in York, we are investigating the role of trapped ion “banana orbits” in the NTM threshold, which could be vital for future machines, such as ITER.