Speaker
Ms
Natalia Kirneva
(Russian Federation)
Description
This paper reports on recent TCV experiments performed to investigate the confinement of electron-heated discharges simulating reactor relevant conditions with dominant electron heating. The dependence of the L-mode confinement properties on the electron heating power density profile width has been analyzed for the first time. Discharges with on-axis peaked ECR heating profiles with half-width varying between 15 and 40% of the minor radius have been performed in the range of heating power 0.5-2 MW and at line-averaged density 2*10^19 m^-3=0.15 n_Gw. A scenario with off-axis heating peaked at rho~0.7 but the same total heating power has also been studied for comparison. The following features have been found [1]: (i) the confinement is largely independent of the power deposition profile width, provided a significant fraction occurs inside the q=1 radius; (ii) the energy confinement time scales with the heating power as tau_E~ (P_tot)^-0.73, independent of the heating profile width, when the power is peaked on-axis; (iii) off-axis heating results in stronger confinement degradation (tau_E~ (P_tot)^-0.9). An investigation of the plasma confinement in high-density discharges has also been performed. A limit density close to and even exceeding the Greenwald limit n_e_lim~(0.6-1.1)*n_Gw has been achieved in ohmically heated plasmas, depending on the q_edge value.
[1] N A Kirneva, K A Razumova, A Pochelon et al, Plasma Physics Control. Fusion 54 (2012) 015011
Country or International Organization of Primary Author
Russian Federation
Collaboration (if applicable, e.g., International Tokamak Physics Activities)
Scientific and Technological Cooperation Programme Switzerland Russia
Primary author
Ms
Natalia Kirneva
(Russian Federation)
Co-authors
Dr
Alexander Karpushov
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Antoine Pochelon
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Basil P Duval
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Mr
Benoit Labit
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Mr
Miguel Silva
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Olivier Sauter
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Roland Behn
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Stefano Coda
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
Dr
Timothy P Goodman
(Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom- Confédération Suisse, CH-1015 Lausanne, Switzerland)
