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Roles of Trapped Electrons on Turbulence Driven
Toroidal Momentum and Heat Transport
W.X. Wang
Princeton Plasma Physics Laboratory
Using global gyrokinetic simulation, a robust residual stress is found to be nonlinearly
generated in both ion temperature gradient (ITG) and trapped electron mode (TEM)
turbulence via symmetry breaking in the parallel wave number spectrum, which is
induced by turbulence self-generated flow shear. This residual stress represents a
significant, universal, non-diffusive component of toroidal momentum transport,
which may play an important role for the generation of intrinsic rotation in tokamak
experiments. In the ITG marginality regime, trapped electron physics is shown to play
a critical role in determining plasma transport, not only producing the proper ion heat
flux in experiments but also largely enhancing the residual stress generation. However,
trapped electrons do not change the qualitative phase space structure of ITG driven
momentum and heat fluxes. On the other hand, TEM driven momentum transport is
made by ions from different regions and in a different way in the phase space. Further,
a momentum pinch is shown via simulations using different rigid rotations. Finally,
very impressive observations of large eddy formation from earlier phase fine
streamers, along with dramatic nonlinear energy cascades to longer wavelengths, in
electron temperature gradient driven TEM turbulence is reported.
Study of density fluctuation during LHCD on HT-7 tokamak
章文扬，李亚东
Institute of Plasma Physics, Chinese Academy of Sciences and Center for Magnetic
Fusion Theory, Chinese Academy of Sciences, Hefei 230031, China
在 HT-7 tokamak 上建造了 CO2 激光相干散射系统，用于测量密度涨落的信号。在低杂
波加热的情况下，固定其他参数，进行低杂波的功率扫描。发现在没有形成 e-ITB 之前，TEM
和 ETG 区间的微观湍流模的稳定和 q 的分布有关，并且在曲率 pinch 和热扩散效应的共同
作用下，整个等离子体的密度分布是中空的。如果形成的 e-ITB，发现 TEM 区间的微观湍
流模趋于稳定，而在 ETG 区间的微观湍流模会增长。但即使 e-ITB 没有形成，但等离子体
的电子温度分布函数的梯度有明显变化，TEM 和 ETG 区间的微观湍流模也会变化。
Experiment progresses of zonal flow and GAM in the edge
plasma of HL-2A tokamak
K. J. Zhao, J. Q. Dong, L. W. Yan, W. Y. Hong, Q. Li, J. Qian, J. Chen, Yi Liu, Y.
Huang, Q. Li, X. M. Song, Q. W. Yang, X. T. Ding, X. R. Duan, Yong Liu
1) Southwestern Institute of Physics, P. O. Box 432, Chengdu, China
2) Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou, China
Measurements with a three dimensional set of Langmuir probe arrays have
completely proven the co-existence of low frequency zonal flows (LFZFs) and
geodesic acoustic modes (GAMs) in the edge of HL-2A tokamak plasma by verifying
the spatial characteristics and the nonlinear couplings with ambient turbulence.
Besides, their radial wave number of the LFZF and GAM demonstrated clearly linear
dispersion relations. The analysis of the modulation in ambient turbulence envelopes
have revealed that their spatio-temporal structures are similar to those observed in
zonal flows and GAMs. The findings provide concrete evidences that the envelope
modulation should be caused by the zonal flows, and strengthen the feasibility of the
indirect method to detect the zonal flows through the density fluctuation envelopes
that could be measured with various diagnostics. ECRH heating (300-700kW) and q
(3.5-6.2) scaling experiments indicate that the intensity of zonal flow increases with
higher ECRH heating power and lower edge safety factor.
Physics and control of the resistive wall mode
Yueqiang Liu
UKAEA Culham, UK
Resistive wall mode (RWM) is one class of the MHD instability, that may give severe
limitation on the operational space of advanced tokamaks. Understanding the physics
of this mode and the possibility of its active control using magnetic feedback coils has
been an intensive research area during the recent years, both in experiments and in
theory.
We study the RWM stability under the influence of the plasma toroidal flow, as well
as certain drift kinetic resonances. The modelling results with a self-consistent, full
toroidal MHD-kinetic hybrid code suggests a strong stabilisation effect of the kinetic
damping on the mode.
The RWM interacts strongly with the conductors (the resistive walls) surrounding the
plasma. A realistic modelling of the mode stability and control involves detailed 3D
geometrical effects of the conductors. Simulation is carried out using a recently
developed MHD-eddy current code, for various tokamak plasmas, such as DIII-D and
ITER.
Reconnection properties in Hall MHD Plasmas*
MA Zhiwei (马志为)1,2, Lu Xingqiang (路兴强)1, and Hou Yawei (侯雅巍)2
1Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China
2Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
Abstract: Dynamics and properties of magnetic reconnection with an asymmetry
initial condition are studied by using Hall MHD simulation. In the early phase of the
magnetic reconnection, the geometry of the magnetic field in the near reconnection
region tends to form a Y-type structure under an asymmetry initial condition instead
of to exhibit an X-type structure in the symmetry initial condition.
The growth rate
of the current density in the early stage is proportional to the square of the ion inertial
length. In the late phase, the thin elongated current sheet associated with the Y-type
geometry of the magnetic field breaks-up to form a magnetic island due to the
secondary tearing instability.
It is found that the onset time of the secondary tearing
instability is inversely dependent on the square root of the ion inertia length. The
generated Hall electric field and net charge are larger in the region inside than outside
the magnetic island. The strengths of the Hall electric field and net charge density
linearly increase with the increase of the ion inertia length.
*Supported by National Science Foundation of China under Grant No. 40536030, and
the National Basic Research Program of China under Grant No 2008CB717806
Magnetic reconnection with pressure tensor in electron
magnetohydrodynamics
Huishan Cai（蔡辉山）
Department of Modern Physics, University of Science and Technology of China,
Hefei 230026, P. R. C
The effects of electron pressure tensor and electron inertia at tearing mode with guide
magnetic field are analyzed systematically in electron magnetohydrodynamics. The
behavior of tearing mode depends not only on the magnitude of pressure gradient, but
also on the relative magnitude between the parallel and perpendicular pressure
gradient. When electron inertia dominates over pressure gradient, the pressure
gradient only modifies the growth rate of tearing mode slightly. When pressure
gradient is dominant, pressure gradient drives reconnection if the perpendicular
pressure gradient is larger than parallel pressure gradient. Otherwise, tearing mode is
suppressed completely when pressure gradient is large enough.
Influence of circulating energetic ions on fishbone instabilities driven by
trapped energetic ions
Deng Zhou
Institute of Plasma Physics, Chinese Academy of Sciences and Center for Magnetic
Fusion Theory, Chinese Academy of Sciences, Hefei 230031, China
Fishbone modes were excited in experiments with nearly perpendicular neutral beam
injection, but only in the co-injection cases. No fishbone was observed in a
counter-injection experiment [K. McGuire K. et al. 1983 Phys. Rev. Lett. 50 891].
The previous theoretical work did not address this problem. In this paper, the role of
the passing energetic ions is included. The influence of the passing ions on internal
kink modes is different for co- and counter- passing ions when their orbit intersects
the q  1 surface, where q is the usual safety factor. The co-passing ions cross the
region enclosed by the q  1 surface mostly on the high field side, where the direction
of the ion magnetic drift is opposite to the mode propagation. So no resonance
occurs between the mode and these co-circulating ions. While for counter-injection,
the situation is reversed and a resonance may occur between the mode and these
counter-circulating ions. This resonance causes a negative imaginary part in the
potential functional which increases the threshold beta value of the trapped hot ions to
excite a fishbone. The work leads to an important implication that the fusion alpha
particles can not destabilize fishbone modes.
Study of Internal Kink Modes Excited by Barely Passing or Barely
Trapped Energetic Particles in Tokamak Plasmas
Hongda He1, Jiaqi Dong1,2, G.Y. Fu3
1
Southwestern Institute of Physics, Chengdu, Sichuan, 610041, China
2
Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou, 310027, China
3
Princeton Plasma Physics Laboratory, Princeton, NJ, USA
Internal kink (fishbone) modes, driven by barely passing or barely trapped
energetic particles (EPs), are numerically studied and the preliminary results are
presented. The spatial distribution of the EPs is taken into account. A new branch of
the modes with frequencies comparable to toroidal precession frequency  d (~104) or
diamagnetic drift frequency of hot ions *h (~105) is demonstrated to be driven by
density gradient of barely passing energetic ions through resonant or non-resonant
excitation. The unstable modes of different frequencies are found dependent on the
spatial distribution of the EPs, or heating position of neutral beam injection (NBI).
The low frequency (comparable to  d ) modes can be resonantly excited in the case of
positive spatial density gradient of the EPs, F / r  0 (i.e. off-axis heating),
whereas a negative spatial density gradient F / r  0 (i.e. on-axis heating) can drive
the high frequency (comparable to *h ) modes. Interestingly, it is also numerically
found that there exists a second stable regime for the modes, similar to that of the
ballooning mode. The results show that a damping due to magnetic gradient B and

  
curvature b  b ( b  B / B ) drifts as well as spatial density gradient of the hot
passing ions results in the formation of the second stable regime.
Electron and Ion Acceleration by Ultrahigh Intensity Lasers
M. Y. Yu（郁明阳）12
1.Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China
2.Institute for Theoretical Physics I, Ruhr University, Bochum D-44780, Germany
The fast-ignition schemes of inertial confinement fusion rely on the availability of
very high energy electrons and ions, which can be produced by the interaction of
ultrahigh-intensity lasers with plasmas. Several novel schemes have been proposed or
discovered. Here the basic physical processes involved in the laser acceleration of
charged particles shall be reviewed.
Controlling Strong-Nonlinear Dynamics: From Chaos to Turbulence
Xingang Wang （王新刚）
Institute of Modern Physics, Zhejiang University, Hangzhou 310027, China
In this talk, starting from the models of low-dimensional ODE systems, I will briefly
introduce the basic ideas involved in controlling strong-nonlinear dynamics. Nextly, I
will show in detail how to implement these ideas in PDE systems. Special attentions
will be paid to the technique of pinning control, and demonstrations of this technique
to the control of turbulence will be shown. Finally, I will conjecture/highlight the
possible applications of pinning control to the MHD turbulence.
HL-2A 装置高能粒子物理的实验研究
陈伟*, 丁玄同, 刘仪, 杨青巍, 宋宪英, 周俊, 雷光玖, 董家齐，段旭如，and HL-2A team.
Southwestern Institute of Physics, P.O.Box 432 Chengdu 610041, China
E-mail contact of main authors: [email protected], [email protected]
在未来的燃烧等离子体中，D-T 反应会产生大量的高能  粒子(3.5MeV)，同时也会存
在大量的高能离子和高能电子。因此，研究这些高能粒子行为对聚变反应是及其重要的。高
能粒子由于能量高，轨道半径比热离子或热电子的轨道半径大得多，因此它的轨道偏移也很
大，在同样磁场的条件下它比热粒子更难约束，极易引起粒子和能量损失，致使 D-T 反应不
能持续进行。同时，高能粒子会轰击聚变反应器部件，使反应器受到破坏而带来很大损失。
高能粒子物理的研究内容主要包括：1）高能粒子与磁流体不稳定性(MHD)的相互作用；
2）高能粒子与等离子体湍流的相互作用等。国际上，对高能粒子的研究已经开展将近 30
年，在理论和实验上都取得了很多重要成果，但是目前还有很多现象没有认识清楚，比如阿
尔芬本征模和鱼骨模的非线性激发及其在相空间中动理学问题等。同时，高能粒子对低频磁
流体不稳定性（如动力气球模和局域内交换模等）的影响及与输运之间的联系也是重要的研
究内容。在强辅助加热（ECRH+NBI）条件下，在 HL-2A 装置上进行高能粒子物理的研究，包
括鱼骨模不稳定性和剪切阿尔芬本征模等。利用新的诊断系统 CdTe 进一步开展了电子鱼骨
模不稳定性的研究。其中，包括电子鱼骨模频率的各种 chirping 行为，模频率的跳跃问题，
模强弱场侧激发及模传播方向等问题，特别是模激发和高能电子之间的关系。在大功率的中
性束加热的情况下，开展了离子鱼骨模不稳定性的研究。实验上观测到三种类型的离子鱼骨
模，它们分别是锯齿混杂型，连续型和经典型。这些模的在频率 6-20kHz，极向传播在离子
的逆磁漂移方向上，它们具有强弱场不对称性，它们和 m=3 或 m=4 的模之间存在环向耦合，
并且引起了很大的温度和密度扰动，这表明离子鱼骨模导致了很大的粒子和能量损失。另外，
中性束产生的 Sub-Alfvenic 离子会通过 Sideband 共振激发 AE，实验上也观测到了
Pitch-fork 现象，这为相空间动理学的研究提供了实验基础。在欧姆加热的情况下，特别
是在电流的下降段，观察到大的磁岛与测地声曲率耦合，提供足够高的自由能，进而激发
BAE。实验上发现这种 BAE 一般成对出现，在相反方向传播，形成驻波结构。实验结果表明
撕裂模频率决定了两支 BAE 模的频差。在 ECRH 加热情况下，观测高能电子也可以激发 BAE，
这可能与高能电子激发的 TAE 和 EAE 类似。
Nonlinear evolution of double tearing mode in Hall MHD
Zhang Chenglong (张城龙)，MA Zhiwei (马志为)
Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China
Nonlinear evolution of a double tearing mode for different resistivities and ion inertial
lengths is investigated using Hall magnetohydrodynamics simulations. In the Hall
dominant regime, the magnetic field configuration in the reconnection region evolves
from Y-type to X-type geometry, which leads to fast reconnection in the nonlinear
growth phase. The maximum reconnection rate
in the explosive growth phase is
found to have a scaling and the maximum total kinetic energy scales as . In the
regime with weak Hall effect, it is found that the elongated thin current sheet formed
in the early phase is broken into two X-points, forming a magnetic island in the late
stage, instead of shrinking to an X-type geometry.
Nonlinear evolution of resistive tearing mode with
sub-Alfvenic shear flow
Jiahui Li （李家辉）
Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou, 310027, China
Abstract:
A two-dimensional incompressible MHD model is employed for
studying the nonlinear evolution of tearing instability with equilibrium parallel shear
flow. The equations are solved with numerical method in slap geometry. Only
sub-Alfvenic shear flow is used in present work. We find that the flow can have either
stabilizing effect or destabilizing effect on the tearing mode. When the flow shear
length is larger than a critical value, the shear flow always has a destabilizing effect
on the tearing modes.
Floating potential of ablating insulated probe in plasma
S.Mercurio
North University of China, Taiyuan, Shanxi
By floating potential is meant the electric potential of the isolated body surrounded by
plasma. The insulated wall of the electric discharge chamber, the electrically isolated
Langmuir probe and any injected pellet, globule o macro-particle in plasma are just
few important examples. Since the plasma potential surrounding the probe is higher
than that of the isolated probe potential (when the probe is negatively charged) there
is a positively charged layer (sheath) between the (quasi) neutral plasma and the
negatively charged surface of the solid globule. In this paper we are showing how the
change of the solid layer of the probe (heated by energy flow from the plasma) into
fluid phase, affects the electric field distribution in the sheath and therefore how the
electric potential of the ablating solid be obtained.