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 共查询到10条相似文献,搜索用时 31 毫秒
1.
彭黎黎  高喆 《中国物理快报》2008,25(11):4065-4067
The electron temperature gradient mode is investigated in elongated toroidal plasmas with a gyrokinetic integral eigenmode equation code. Dependence of the critical electron temperature gradient on the elongation is calculated. It is found that when the elongation increases, the growth rate spectrum is greatly shifted towards shorter poloidal wavelength, and then the poloidal wavenumber at which the mode is destabilizing critically in elongated plasmas will be larger than that in circular plasmas.  相似文献   

2.
The geodesic acoustic mode (GAM), first predicted by Winsor, Johnson and Dawson in an attempt to explain some experimentally observed low frequency oscillations in stellarators, is a special electrostatic fluid mode with low mode number and coupled with the so-called geodesic curvature of a toroidally confined plasma. The recent on this mode are due to the close relevance of the stabi- lization of drift turbulence by both the zonal flow and the GAM. Previously, the GAM was illustrated in very simple geometries,  相似文献   

3.
Acoustic rotation modes in complex plasmas are investigated in a cylindrical system with an axial symmetry. The linear mode solution is derived. The mode in an infinite area is reduced to a classical dust acoustic wave in the region away from the centre. When the dusty plasma is confined in a finite region, the breathing and rotating-void behaviour are observed. Vivid structures of different mode number solutions are illustrated.  相似文献   

4.
高喆 《中国物理快报》2004,21(5):881-883
A new unstable short wavelength mode is identified in sheared slab plasmas using a fully kinetic integral equation code. This mode is driven by the electron temperature gradient and propagates in the ion diamagnetic direction. The instability occurs due to the electron inverse Landau damping effect at short cross-field wavelength regions.  相似文献   

5.
王传兵  李定 《中国物理》1999,8(12):908-912
he general dispersion relation for toroidally coupled tearing mode including pressure and other O(ε2) order corrections is naturally derived based on the structure of ideal magnetohydro-dynamic solutions in the outer region. It is found that the inclusion of the O(ε2) order terms in the diagonal element of E-matrix does not change physical properties of the toroidally coupled tearlng mode and only make negligible contribution to the magnitude of growth rate.  相似文献   

6.
Microturbulence excited by ion temperature gradient(ITG)-dominant and trapped electron mode(TEM)-dominant instabilities is compared in the fusion plasmas using gyrokinetic simulations based on the realistic equilibrium data from DⅢ-D discharges.Collisions make a difference between two plasmas and give rise to similar results to those found in previous research experiments[Chin.Phys.Lett.35(2018)105201].The mode structures and frequency spectrum of the most unstable modes characterized by the ITG-dominant and TEM-dominant instabilities are excited in the lower and higher T. plasmas in the linear simulations.In the nonlinear simulations,contour plots of the perturbed potential are shown in the saturated stage,with the radial correlation lengths being microscopic on the order of the ion thermal gyroradius ρi in both the ITG and the TEM microturbulences.The dominant mode wavelengths of the perturbed potential increase when evolving from linear to nonlinear stages in both simulations, with the fluctuation energy spreading from the linearly dominant modes to the nonlinearly dominant modes.The radial correlation lengths are about 4ρi and the electron density fluctuation intensities are about 0.85% in the nonlinear saturated stage,which are in agreement with the experimental results.  相似文献   

7.
The growth rate of the peeling mode instability with large toroidal mode number is calculated for general axisymmetric toroidal plasmas, including tokamaks and the spherical torus(ST) equilibia by using formalism presented by Connor et al.Analytic equilibia with non-zero edge current density and quasi-uniform current profiles are assumed. It is found that in sharp D-shape tokamak plasma, the derivative of the safety factor with respect to the poloidal flux becomes very large,making the perturbed poloidal motion very large, in turn making a significant reduction of the growth rate of the peeling mode, similar to the X-point effect in diverted plasma. The large aspect ratio effect is also studied, which reduces the growth rate further.  相似文献   

8.
This report consists of two main research activities : The first one is the study of MHD ballooning stability of tokamak plasmas, the second is about some fundamental aspect in the ECR wave propagation and power deposition. Main results are summarized here in three parts briefly. In the first part, the instabilities of tokamak plasma in the negative shear regime is studied and characteristics of the unstable mode is described, the scaling law of the growth rate over plasma parameters is given. In the second part, by using the restrict Solov'ev configuration, the correctness of the usual s,α model in ballooning mode theory is analyzed. In the third part, the deposition of the power density of the ECR ordinary wave in the HL-2A plasma is calculated.  相似文献   

9.
Changes of the electron dynamics in hydrogen (H2) radio-frequency (RF) inductively coupled plasmas are investigated using a hairpin probe and an intensified charged coupled device (ICCD). The electron density, plasma emission intensity, and input current (voltage) are measured during the E to H mode transitions at different pressures. It is found that the electron density, plasma emission intensity, and input current jump up discontinuously, and the input voltage jumps down at the E to H mode transition points. And the threshold power of the E to H mode transition decreases with the increase of the pressure. Moreover, space and phase resolved optical emission spectroscopic measurements reveal that, in the E mode, the RF dynamics is characterized by one dominant excitation per RF cycle, while in the H mode, there are two excitation maxima within one cycle.  相似文献   

10.
董亚林  赵斌  郑坚 《中国物理》2007,16(12):3742-3746
Non-local electron transport in laser-produced plasmas under inertial confinement fusion (ICF) conditions is studied based on Fokker-Planck (FP) and hydrodynamic simulations. A comparison between the classical Spitzer-Harm (SH) transport model and non-local transport models has been made. The result shows that among those non-local models the Epperlein and Short (ES) model of heat flux is in reasonable agreement with the FP simulation in overdense region. However, the non-local models are invalid in the hot underdense plasmas. Hydrodynamic simulation is performed with the flux limiting model and the non-local model, separately. The simulation results show that in the underdense region of the laser-produced plasmas the temperature given by the flux limiting model is significantly higher than that given with the non-local model.  相似文献   

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