Speaker
Yury Petrov
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1040.pdf
Toroidal Alfven Eigenmode study on the Globus-M Spherical Tokamak
Yu.V. Petrov1, N.N. Bakharev1, V.V. Bulanin2, V.K. Gusev1, G.S.
Kurskiev1,A.A. Martynov,3 S.Yu Medvedev3, V.B. Minaev1, M.I. Patrov1, A.V. Petrov2,
N.V. Sakharov1, P.B. Shchegolev1, A.Yu. Telnova, S.Yu. Tolstyakov1, A.Yu. Yashin2.
1
Ioffe Institute, St. Petersburg, Russia
2
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
3
Keldysh Institute of Applied Mathematics, Moscow, Russia.
In this report we describe the latest results of investigation of the toroidal Alfvén
eigenmodes (TAE), which were identified earlier in experiments with NBI heating on the
spherical tokamak Globus-M [1]. The experiments were continued at increased magnetic field
from 0.4 to 0.5 T and plasma current from 200 to 250 kA. The mode character has changed with
the increase of the field. While the TAE bursts became more frequent, the fast particle losses
induced by them became weaker. The dependence of fast particle losses and redistribution
induced by TAE on the values of magnetic field and plasma current are presented.
During the last experimental campaign, the multichannel Doppler backscattering
reflectometry (DBS) was applied for the first time to study TAE localization [2].
Multichannel probing at frequencies of 20, 29, 39 and 48 GHz was applied. It allowed us to
observe the TAE fluctuations at four locations on major radius simultaneously. The
measurements have shown that the TAE fluctuations registered by means of DBS are
localized on the periphery of the plasma column, in the region of normalized minor radii of
ρ=0.5-0.75. Modeling of the Alfven continuum and TAE mode structure for Globus-M
conditions were made by means of a software package base on the modified KINX and
CAXE codes [3]. Comparison of the experimental data and calculated spectra, as well as the
analysis of the structure of the global modes, showed that the oscillation frequencies
observed in the experiment are closer to the frequencies of the TAE modes localized near the
plasma boundary in the region of magnetic surfaces with safety factor values q = 2.5, 3.5 .
[1] Petrov Yu. V. et al. 2015 J. PLASMA PHYS. 81 515810601
[2] Bulanin V.V. et al. 2017 TECH. PHYS. LETT. 43 1067-1070
[3] Gusev V.K. et al. 2018 TECH. PHYS. LETT. 44 65 in Russian
