Speaker
Huarong Du
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1100.pdf
Properties of ion temperature gradient mode in tokamak plasmas with
inverted density profiles
Huarong Du1, Zhengxiong Wang2, Yuhong Xu1
1
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong
University, Chengdu 610031, China
2
Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics
and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024, China
The ion temperature gradient (ITG) mode in tokamak plasmas with inverted density profiles
are numerically investigated with the gyrokinetic integral eigenmode equation. From
comprehensive local parametric scans, we obtain stability diagrams for ITG mode and
trapped electron mode (TEM) in terms of density and temperature gradient scale lengths [1].
In addition, deviations are found on the ITG threshold from an early analytic theory in
sheared slab geometry with the adiabatic electron response [2]. Results show that, for the
inverted density profile, there exists a normalized threshold temperature gradient above
which the ITG mode and TEM are either separately or simultaneously unstable [3]. Besides,
the trapped electrons are observed to stabilize the ITG mode with typical scale length
k i 1 , which is different from the conventional ITG mode in the long wavelength region.
The critical ion temperature gradient R / LTic of the ITG mode for negative R / Ln
( Ln n / n ) is somewhat higher (lower) than that for positive R / Ln in the moderate
(steep) density gradient region. Moreover, the effects of different physics elements (such as
safety factor, temperature ratio, magnetic shear, and toroidicity) have also been studied.
[1] Huarong Du, Zheng-Xiong Wang, et al., Phys. Plasmas 21, 052101(2014).
[2] T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989).
[3] Huarong Du, Hogun Jhang, T. S. Hahm, et al., Phys. Plasmas 24, 122501(2017).
