Hannover 2016 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 12: Poster Session: Magnetic Confinement
P 12.5: Poster
Dienstag, 1. März 2016, 16:30–19:00, Empore Lichthof
Dependence of intermittent density fluctuations on collisionality in TJ-K — •Kyle Reuther1, Stephen Garland1, Peter Manz2, and Mirko Ramisch1 — 1Institut für Grenzflächenverfahrenstechnikund Plasmatechnologie, Universität Stuttgart — 2Physik-Department E28, Technische Universität München, Garching
Particle and heat transport losses due to edge turbulence are well known phenomena commonly seen in toroidal magnetic confinement devices. Furthermore in the scrape-off layer (SOL), turbulent density fluctuations are often observed to be intermittent and dominate particle transport to the vessel walls. In the adiabatic limit (small collisionality), of the two-field Hasegawa-Wakatani model, simulated turbulent density fluctuations are observed to couple to potential fluctuations and exhibit Gaussian behavior. However, in the hydrodynamic limit (large collisionality) the density and potential decouple. As a result, the density becomes passively advected, evolves towards the vorticity, and exhibits intermittent behavior.
The relationship between collisionality and intermittency is investigated experimentally at the stellarator TJ-K. To vary the plasma collisionality, which is related to electron density and temperature, parameters such as gas type, neutral gas pressure, magnetic field, and heating power are varied. Radial profiles of plasma density, temperature, floating potential, and vorticity are recorded via a scanning 7-tip Langmuir probe array. First results will be presented.