Speaker
Nikolai Bakharev
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1065.pdf
Toroidal magnetic field increase in the Globus-M spherical tokamak
N.N. Bakharev, F.V. Chernyshev, V.K. Gusev, N.A. Khromov, E.O. Kiselev, G.S. Kurskiev,
A.D. Melnik, V.B. Minaev, I.V. Miroshnikov, M.I. Patrov, Yu.V. Petrov, N.V. Sakharov,
P.B. Shchegolev, A.D. Sladkomedova, V.V. Solokha, A.Yu. Telnova, V.A. Tokarev, S.Yu.
Tolstyakov
Ioffe Institute, St. Petersburg, Russia
Globus-M spherical tokamak (ST) was a compact machine (R ≈ 36 cm, a ≈ 24 cm,
plasma-wall distance of a several centimeters) with toroidal magnetic field Btor = 0.4 T and
unique features such as high normalized Larmor radius ( ) and high heating power
density. This year a new Globus-M2 ST with the same vacuum chamber, 2.5 times increased
Btor and Ip, and upgraded heating and diagnostic systems will be launched. A significant
expansion of the experimental parameter range will provide an opportunity to get closer to the
operating conditions of the compact fusion neutron sources (CFNS) and, hopefully, answer
the question, if the pros of the ST configuration outweigh the cons when used as a basis for a
CFNS .
In the final Globus-M experimental campaign [1] Btor and Ip were raised by 25% up to
0.5 T and 250 kA respectively. As a result an overall improvement in plasma performance
was observed. Plasma total stored energy and energy confinement time grew by about 30% in
the discharges with density up to 6·1019m-3. D-D beam-plasma neutron rate increased
significantly at the same NB heating power. The main reasons for this effect, in order of
importance, are the electron temperature rise and the fast ion confinement improvement.
Decrease of first orbit, sawtooth-induced and TAE-induced fast ion losses was recorded.
Energy confinement time growth proportional to toroidal magnetic field was observed.
Acquired in the experiments energy confinement time scaling and power decay length
scaling, based on the Langmuir probe measurements, were in a reasonable agreement with
scalings, based on MAST [2] and NSTX [3] data.
References:
1. Minaev V.B. et al. 2017 Nucl. Fusion 57 066047
2. Valovic M. et al 2009 Nucl. Fusion 49 075016
3. Kaye S M et al 2006 Nucl. Fusion 46 848–57
