Abstract of talk
Coherent filamentary structures erupt from the boundary of magnetic fusion plasmas and determine the exhaust of the particle and energy towards the walls of the experimental device. Next generation reactor relevant machines are expected to operate in conditions where the plasma/wall interaction, unless properly controlled, might become extremely problematic for the lifetime of the plasma facing components.
Indeed, experiments in the last 20 years showed that, rather universally across machines, the time averaged midplane density and electron temperature profiles, generated by the turbulent filaments, tend to flatten at a certain distance from the separatrix. This has practical consequences since broad profiles redirect the plasma towards the first wall rather than towards the divertor components, which are specifically designed to sustain the large fluxes associated with the exhaust.
In this talk, I will describe the physics of the plasma filaments, from both an experimental and theoretical point of view. These large and intermittent perturbations show a rich nonlinear dynamics and a fascinating phenomenology. Using statistical approaches, the population of filaments will then be linked to the time averaged profiles in the plasma edge, thus providing a way of interpreting the emergence of features in the profiles (such as their flattening) by using the filaments as building blocks of the transport.
Room F-N6115, Origo building north 6th floor, Fysikgården 1
25 August, 2016, 10:00
25 August, 2016, 11:00