TJ-II:Comparison of transport of on-axis and off-axis ECH-heated plasmas: Difference between revisions

Particle transport of ECH plasmas<ref>Yokoyama 2005 NF</ref> is not well understood, as neoclassical simulations seem to overestimate the radial particle flux of on-axis heated ECH-plasmas; on the other hand, preliminary analyses show that this problem does not exist for off-axis ECH-heated plasmas. A comparison between these two situations (including neoclassical and gyrokinetic simulations and corresponding measurements) may shed some light on this problem, probably relevant for assessing the fuelling requirements of reactor plasmas<ref>Maassberg 1999 NF</ref>. Even if the results along this line are finally not conclusive, the experimental and theoretical characterization of turbulence with different profiles (peaked/hollow <math>T_e</math> with hollow/peaked <math>n_e</math>) is itself relevant. We will also have a look at impurity transport, as off-axis heated plasmas have been predicted to have negative radial electric field in the core and positive radial electric field closer to the edge, contrary to typical ECH plasmas.