Speaker
Anna Telnova
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1070.pdf
Influence of the collisionality and the safety factor on the
transport in the Globus-M spherical tokamak
A.Yu. Telnova1, G.S. Kurskiev1, N.N. Bakharev1, V.K. Gusev1, E.O. Kiselev1,
N.A. Khromov1, D.M. Larionova1, M.M. Larionova1, V.B. Minaev1, I.V. Miroshnikov1,
M.I. Patrov1, Yu.V. Petrov1, N.V. Sakharov1, A.D. Sladkomedova1, P.B. Shchegolev1,
V.V. Solokha1, V.A. Tokarev1, S.Yu. Tolstyakov1
1
Ioffe Institute, St. Petersburg, RF
The presentation is devoted to analysis of the thermal energy confinement in
Globus-M [1]. Globus-M was a spherical tokamak with the major radius R=0.36 m, minor
radius a=0.24 m, the ranges of operational current and toroidal magnetic field were
Ip=100-250 kA and BT=0.3-0.5 T correspondingly. The aim of the research was to identify
the thermal insulation efficiency in a compact spherical device in terms of the electron and
ion diffusion coefficients for different discharge conditions. The experimentally measured
electron and ion temperature profiles as well as more accurate estimations of the NBI
absorbed power allowed us to provide increased accuracy of the transport modelling using
ASTRA code [2]. It was found that both BT and IP increase had a strong effect on the electron
and ion heat diffusivities (χe and χi respectively). The comparison of χi with neoclassical
theory was performed and the role of the collisionality (ν*) and safety factor (q) on the
transport was analyzed. The influence of the q=1 resonant surface presence on the plasma
performance was studied. The NBI at the current ramp-up phase permitted distinguishing the
relatively long phase with inversed q profile, while minimum value of q (qmin) in the plasma
core was more than one (AT-like q profile). Such modes can be characterized by improved
core confinement and are usually accompanied by formation of the internal transport barriers
(ITB). The ITB formation is also relevant for the pure ohmic heated plasma.
References
[1] Gusev V. K. et al, 1999 Tech. Phys. 44 1054.
[2] Pereverzev G. and Yushmanov P. N., 2002, Max-Plank IPP Report 5/98.
