Excitation of ion temperature gradient and trapped electron modes in HL-2A tokamak The 3 th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015 Huarong Du, 1 Zheng-Xiong Wang, 1,* J. Q. Dong, 2,3 and S. D. Song 3 1 School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China 2 Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China 3 Southwestern Institute of Physics, Chengdu 610041, China * E-mail: [email protected]1
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Excitation of ion temperature gradient and trapped electron modes in HL-2A tokamak The 3 th Annual Workshop on Fusion Simulation and Theory, Hefei, March.
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Excitation of ion temperature gradient and trapped electron modes in HL-2A
tokamak
The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Huarong Du,1 Zheng-Xiong Wang,1,*
J. Q. Dong,2,3 and S. D. Song3
1School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China2Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China3Southwestern Institute of Physics, Chengdu 610041, China* E-mail: [email protected]
2The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Background Physics Model and Equations
Numerical Results
Conclusion
Outline
3The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
BackgroundThe dominant source of anomalous transport in fusion plasmas on ion scales is turbulence driven by trapped electron mode (TEM) and ion temperature gradient (ITG) mode.
The application of several auxiliary heating, such as ECRH, NBI, ICRH, and LHCD, leads to the temperature and density perturbations that provide a source of free energy to drive both the TEM and ITG mode instabilities simultaneously.
W. L. Zhong et al PRL (2013)F Jenko et al PPCF 47 (2005)F. Merz and F. Jenko NF 50 (2010)
4The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Background
The theory of particle transport driven by ITG and TEM instabilities is applied to study the density profile under experimental conditions with central electron heating.
Investigations of the coexistence of the two modes and the phenomena of transitions between the TEM and ITG dominant regimes have recently been reported for tokamak experiments, such as DIII-D, ASDEX upgrade, Alcator C-Mod, and Tore Supra.
We carry out the gyrokinetic simulation of the dominant TEM and ITG modes for Ohmic heating and ECRH of the HL-2A tokamak.
5The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Background Physics Model and Equations
Numerical Results
Conclusion
Outline
6
Model and Equations
The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
12The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Background Physics Model and Equations
Numerical Results
Conclusion
Outline
13The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Equilibrium profileHL-2A shot # 22805
The equilibrium profiles of temperature and density for TEM and ITG driven instability.
The electron and ion temperature increase, while the temperature gradient decrease.
The density reduction called ‘particle pump-out’ is well known as a typical behaviour when the ECRH is turned on, which is in consistence with the theoretically predicted outward particle thermal diffusion in case of dominant TEM instabilities.
19 3
1.65
0.4
175
1.33
(1.5 3.5) 10
180
1.6
p
T
e
ohimc
ECRH
R m
r m
I KA
B T
n m
P KW
P MW
14The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Numerical Results
Two independent unstable modes, which propagate in electron and ion diamagnetic drift directions, corresponding to TEM and ITG mode, respectively, are found to coexist in the region considered of HL-2A plasmas.
/e iT T
Ohimc phase
ECRH phase
/e iT T
15The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Numerical Results
The instability changes from predominantly ITG to TEM with the application of ECRH. The dominant ITG-TEM transition also depends on .
In HL-2A ECRH discharge experiments , thus the TEM is the dominate instability in the ECRH phase.
Ohimc phase ECRH phase
/ 4e iT T
/e iT T
ITG and TEM instabilities clearly coexist in ITG dominant cases in the Ohimc phase.in TEM dominant cases in the ECRH phase.
16The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Numerical Results effect/e iT T
Increasing stabilizes (destabilizes) the pure TEM (ITG) mode. The ITG mode can be stabilized by increasing with TE effect.
/e iT T/e iT T
Interchange type toroidal ITG instability
*e
Di Tii
T
T
17The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Numerical Results effect/e iT T
Increasing destabilizes the dominant TEM mode. The TEM can be stabilized by increasing , when the drive of the ITG mode is small and/or the dynamics of the ITG mode is ignored.
/e iT T/e iT T
18The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Numerical Results particle flux
Both the TEM and ITG modes lead to outward particle transport.The dominated TEM induces electron heat transport for low R/LTi (large R/LTe) . The dominated ITG instabilities induce strong ion heat transport for low R/LTe (large R/LTi) .
The quasilinear model is applied to study the particle transport driven by TEM and ITG mode, and the present model has been checked by reproducing the relevant simulation results done by F. Merz and F. Jenko (Nucl. Fusion 50, 2010)
r
iknv n
B
.
B B E E
E
/ /rv E B B
FOR
19The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
Background Physics Model and Equations
Numerical Results
Conclusion
Outline
20The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015
With the gyrokinetic code HD7, the TEM and ITG instabilities in HL-2A tokamak are numerically investigated .
For pure Ohmic heating , the ITG mode is the dominate instability due to large ion temperature gradient.
For Ohmic heating +ECRH, the dominant mode changes from ion temperature gradient (ITG) mode to trapped electron mode (TEM). Increasing destabilizes the TEM, while stabilizes the ITG mode.
The dominated TEM instabilities induce large electron heat transport in the ECRH phase.
Conclusions
/e iT T
The 3th Annual Workshop on Fusion Simulation and Theory, Hefei, March 23-25, 2015