Speaker
Nadezhda Kasyanova
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1072.pdf
Study of the transport coefficient dependence on the heating power in
self-organized plasma in the T-10 tokamak
N.V. Kasyanova1,2, K.A. Razumova1, A.A. Borschegovskij1, M.M. Dremin1, N.A.
Kirneva1,3, S.V. Krylov1, T.B. Myalton1, G.E. Notkin1, Yu.D. Pavlov1, D.V. Ryzhakov1,
D.V. Sarychev1, D.S. Sergeev1, M.V. Chukanov1
1
National Research Center “Kurchatov Institute”, Moscow, Russia
2
Moscow Institute of Physics and Technology, Dolgoprudny, Russia
3
National Research Nuclear University MEPhI, Moscow, Russia
Effect of the energy confinement enhancement during impurity gas puffing in the
T-10 tokamak is studied. Experiments were carried out with Ne and He puffing in various
regimes with ohmic heating (OH) and on- and off-axis ECR heating (Ipl=230 kA, Bz= 1.9 -
2.3 T, ne=1.5-4x1019 m-3, PECRH=0.45-1.3 MW). It was shown that in both OH and ECRH
regimes the stored energy first increased with growth of the radiation losses in the plasma
edge due to the impurity gas puffing and then it reached a saturation level Wsat. It is found
that for on-axis ECRH deposited in a narrow area in the center of the plasma the energy
saturation level depends only on ECRH power and doesn't depend on the kind of impurity.
In this work, the explanation of the observed effect from a plasma self-organization
position is offered. This approach assumes that the plasma pressure profile is self-consistent.
Relaxation of the pressure profile distorted by external impact is described by the energy
balance equation obtained in [1]. In this equation the transport coefficient χ can be written as
follows: χ = θ(χ0+χ1). The first term χ0 corresponds to the undistorted self-consistent pressure
profile, the second term χ1(Γ1) depends on the radial heat flux Γ1 disturbing the pressure
profile. During impurity gas puffing the radiation losses in the plasma periphery increase
resulting in decrease of the radial heat flux Γ1, hence the transport coefficient χ in the plasma
edge reduces until it reaches the minimum value χ0. As a result the stored energy of plasma
increases and reaches the saturation level. The value χ0 doesn't depend on the heating power
and can be determined from the energy saturation level Wsat. The value χ1 is obtained from
dependence of the stored energy on the power of OH and ECR heating. The dependence of
Wsat on plasma parameters is defined by the coefficient θ ~ p0β0/qL.
[1] K.S. Dyabilin and K.A. Razumova. Nucl. Fusion 55 (2015) 053023
