Transport of argon and iron during a resonant magnetic perturbation at TEXTOR-DED

Since ergodic divertors are proposed to control the impurity concentration in tokamak plasmas the influence of a resonant magnetic perturbation (RMP) from the dynamic ergodic divertor (DED) in the m/n = 3/1 mode on argon impurity transport is studied at the tokamak TEXTOR. Although the application of a DED current below the threshold for m/n = 3/1 tearing mode excitation in an NBI-heated L-mode plasma does not change the argon transport coefficients in r/a < 0.8, an additional transport mechanism within an error of 34% cannot be excluded. Observed changes of the iron ion density distribution for r/a < 0.6 can only be explained by a change of the transport. In addition the argon injection experiments show that an RMP reduces the inflow of particles into r/a < 0.8 and that a tearing mode seems to increase the local transport although at first view the experimental data indicate a reduction of the transport.

Fusion Physics