Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection

M. Valisa, L. Carraro, I. Predebon, M.E. Puiatti, C. Angioni, I. Coffey, C. Giroud, L. Lauro Taroni, B. Alper, M. Baruzzo, P. Belo Dasilva, P. Buratti, L. Garzotti, D. Van Eester, E. Lerche, P. Mantica, V. Naulin, T. Tala, M. Tsalas

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Abstract

The scan of ion cyclotron resonant heating (ICRH) power has been used to systematically study the pump out effect of central electron heating on impurities such as Ni and Mo in H-mode low collisionality discharges in JET. The transport parameters of Ni and Mo have been measured by introducing a transient perturbation on their densities via the laser blow off technique. Without ICRH Ni and Mo density profiles are typically peaked. The application of ICRH induces on Ni and Mo in the plasma centre (at normalized poloidal flux ρ = 0.2) an outward drift approximately proportional to the amount of injected power. Above a threshold of ICRH power of about 3 MW in the specific case the radial flow of Ni and Mo changes from inwards to outwards and the impurity profiles, extrapolated to stationary conditions, become hollow. At mid-radius the impurity profiles become flat or only slightly hollow. In the plasma centre the variation of the convection-to-diffusivity ratio v/D of Ni is particularly well correlated with the change in the ion temperature gradient in qualitative agreement with the neoclassical theory. However, the experimental radial velocity is larger than the neoclassical one by up to one order of magnitude. Gyrokinetic simulations of the radial impurity fluxes induced by electrostatic turbulence do not foresee a flow reversal in the analysed discharges. © 2011 IAEA, Vienna.
Original languageEnglish
Article number033002
Pages (from-to)-
JournalNuclear Fusion
Volume51
Issue number3
DOIs
Publication statusPublished - Mar 2011
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Valisa, M., Carraro, L., Predebon, I., Puiatti, M. E., Angioni, C., Coffey, I., Giroud, C., Lauro Taroni, L., Alper, B., Baruzzo, M., Belo Dasilva, P., Buratti, P., Garzotti, L., Van Eester, D., Lerche, E., Mantica, P., Naulin, V., Tala, T., & Tsalas, M. (2011). Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection. Nuclear Fusion, 51(3), -. [033002]. https://doi.org/10.1088/0029-5515/51/3/033002