PHYS brown bag seminar: An instability and a wave inside a microturbulent fusion plasma

Presenter: Antti Snicker (Fusion and Plasma Physics Group, Department of Applied Physics, Aalto University)

Abstract:

In this talk, I will describe a system of three waves in tokamak plasmas. The first wave, called NTM, is generated by the plasma itself, and is harmful for the performance and, therefore, traditionally mitigated using external wave called ECRH. However, this ECRH wave needs to travel through the turbulent plasma (which is the third wave of the system) in order to mitigate the NTM. Depending on the plasma, ECRH wave, and turbulence parameters, the interaction of ECRH with the turbulence can be either very moderate or seriously harmful.
Within this talk, I will describe a numerical model studying this problem: the propagation of ECRH wave in a fluctuating plasma. The problem is that ECRH wave needs to be absorbed inside the NTM, that is small compared to size of the plasma, in order to be mitigate the NTM. The turbulence has a diffusive effect on the ECRH wave and can possibly result in a ECRH wave that is too wide to mitigate the NTM. Such scenario is predicted by our numerical simulations to happen in the coming large fusion experiments (ITER and European DEMO) and, therefore, this research is very topical.
Interestingly, the numerical method underlying the numerical model was developed originally in the 60's for randomly fluctuating quantum mechanical systems but, to our knowledge, the code we are using is the only numerical implementation that exists.

Join us for science and pizza in the Nanotalo lobby!