共查询到20条相似文献,搜索用时 31 毫秒
1.
针对高超声速飞行器防热, 搭建了螺线管磁控热防护系统的物理模型. 采用低磁雷诺数磁流体数学模型, 分析了外加磁场强度及磁场形态对磁控热防护效果的影响. 对比了三种磁场类型(磁偶极子、螺线管、均布磁场)下磁控热防护效果的差异, 分析了螺线管几何参数对磁控热防护效果的影响. 研究表明, 磁场降低表面热流作用存在“饱和现象”; 三种磁场形态的磁控热防护能力从小到大依次为磁偶极子、螺线管、均布磁场; 相同驻点磁感应强度条件下, 增大螺线管半径有利于提高磁控热防护效果, 缩短螺线管与驻点距离不利于驻点和肩部防热, 螺线管长度对磁控热防护效果影响相对较小. 相似文献
2.
A one-dimensional stability transport code has been developed to simulate the evolution of tokamak plasma discharges. Explicit
finite-difference methods have been used to follow the temporal evolution of the electron temperature equation. The poloidal
field diffusion equation has been solved at every time step. The effects of MHD instabilities have been incorporated by solving
equations for MHD mixing and tearing modes as and when required. The code has been applied to follow the evolution of tokamak
plasma discharges obtained in the Saha Institute of Nuclear Physics (SINP) tokamak. From these simulations, we have been able
to identify the possible models of thermal conductivity, diffusion and impurity contents in these discharges. Effects of different
MHD modes have been estimated. It has been found that in low q
0 discharge m=1, n=1 and m=2, n=1 modes play major role in discharge evolution. These modes are found to result in the positive jump in the loop voltage
which was also observed in the experiments. Hollow current density profile j
φ
and negative shear in the q profile have also been found in the rising phase of a discharge. 相似文献
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简化理论研究液态包层通道插件流体MHD效应 总被引:3,自引:2,他引:1
基于先前的普通管道中的MHD效应的实验结果和质量守恒定律(或液态流体不可压缩原理)、洛仑磁力定律和电荷守恒定律,再利用有源网络等效方法,发展出一种简化而有效的分析带通道插件(FCI)管道的磁流体动力学(MHD)效应的方法。简化理论预测结果表明:采用FCI可有效地降低MHD压降;FCI的电导率存在一个临界值时,当大于这个值时,中心区流速将小于边界区流速;管道结构、FCI电导率、液态金属种类等存在着一个最佳组合参数,能最有效地减少MHD压降。 相似文献
5.
For accurate spectroscopic diagnostics in the solar corona, the principle of spectral diagnostics of electron density is discussed by collision excitation model. Variation in electron density in the solar corona is calculated by this method using the observed signal ratio of spectral lines produced by the magnesium XII ion in the solar corona. Results show that with increasing signal ratio, the electron density will decrease; furthermore, the electron density is on the order of 1010?cm?3, which is a reasonable value in the solar corona. Finally, variation in temperature with different signal ratio is discussed. This investigation will be significant for solar plasma diagnostics and study on the solar coronal. 相似文献
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在HT-7装置实验研究中,利用主动反馈调制低杂波(LHW)实时有效地抑制了MHD不稳定性。介绍了用DAQ2010高速采集卡为硬件的系统对HT-7装置实验中MHD的实时检测和控制。 相似文献
8.
E. G. Sheĭkin 《Technical Physics》2007,52(5):537-545
Approximate analytic expressions for calculating the electron density in both steady and unsteady plasmas produced by pulsed electron beams are derived and proved to agree well with numerical calculations. It is shown that the algorithm for calculating the parameters of a nonequilibrium plasma in the channel of an MHD plasma generator depends on the type of generator. The effect of the magnetic field strength on the electron density and electric conductivity of the air plasma produced by an electron beam in the channel of a Faraday MHD generator is investigated. The influence of the parameters of the flow and ionizer on the efficiency of an MHD generator with a nonequilibrium conductivity is analyzed. 相似文献
9.
ABSTRACTFor spectral diagnostics in the solar transition region under the collision–equilibrium condition, the method for electron density diagnostics by the collisional excitation is discussed in this paper. By using observed signal ratio of spectral lines produced by the oxygen VI ion, we discuss the electron density by this method. We find that this method is valid for a large region of signal ratio (from 2.001 to 4.162). We obtain that the electron density increases with increasing signal ratio of the oxygen VI doublet, and the plasma has an electron density on the order of magnitude of 106–107?cm?3. This discussion will be significant for study on spectral diagnostics of the solar transition region. 相似文献
10.
在J-TEXT托卡马克上研制了一套高速单色成像系统用于研究等离子体杂质行为与磁流体力学(MHD)不稳定性之间的关系.用STRAH代码模拟估算了碳杂质(CV227.09nm,CIII464.7nm)辐射强度.采用光纤耦合方法设计了系统光路结构,光路覆盖高场侧区域0.3a~0.95a(a为小半径),其空间分辨率为1.3cm... 相似文献
11.
HL-1M感应与低杂波组合电流驱动研究 总被引:1,自引:1,他引:0
本文结合HL-1M的基本参数,利用准线性的低杂波电流驱动理论和等离子体的电回路方程.研究了在控制等离子体总电流不变情形下欧姆感应和低杂波注入组合驱动电流的问题。结果表明,这一组合驱动方案对HL-1M装置的运行是可行的,其驱动电流分布可以通过改变低杂波注入功率、波谱形状、等离子体电子温度、密度以及总等离子体电流等加以控制。组合驱动的电流分布将优于欧姆驱动的电流分布,并可能抑制诸如锯齿振荡等一些MHD不稳定性。 相似文献
12.
Tobias BJ Classen IG Domier CW Heidbrink WW Luhmann NC Nazikian R Park HK Spong DA Van Zeeland MA 《Physical review letters》2011,106(7):075003
Two-dimensional images of electron temperature perturbations are obtained with electron cyclotron emission imaging (ECEI) on the DIII-D tokamak and compared to Alfvén eigenmode structures obtained by numerical modeling using both ideal MHD and hybrid MHD-gyrofluid codes. While many features of the observations are found to be in excellent agreement with simulations using an ideal MHD code (NOVA), other characteristics distinctly reveal the influence of fast ions on the mode structures. These features are found to be well described by the nonperturbative hybrid MHD-gyrofluid model TAEFL. 相似文献
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本文从处理湍流场的普遍方法──“任一物理量都可分解成平均值与涨落值之和”出发,利用量纲估计和磁流体力学湍流近似对磁流体力学基本方程进行讨论,得出有关磁流体力学湍流场的一些结论.这些结论对研究目前阶段的磁流体力学湍流理论是很有用的。 相似文献
15.
A numerical procedure based on a five-wave MHD model associated with non-ideal, low magnetic Reynolds number MHD flows was
developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical
procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction
with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would
take place near the downstream edge of the second electrode, where the local adverse pressure gradient is large, and the core
of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The
electric current lines would be increasingly distorted as the magnetic interactive parameter increases, and even induce an
eddy current. Induced eddy current was also found in the different cross-sections along the axial direction, all of these
would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along
the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the
insulator cross-section, which, in turn, induces the corner eddy current at the corner. A numerical parametric study was also
performed, and the computed performance parameters for the MHD generator suggest that, in order to enhance the performance
of MHD generator, the magnetic interaction parameter should be elevated. 相似文献
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17.
Andrei N. Kozlov 《等离子体物理论文集》2020,60(3):e201900174
Properties of compressible flows in the quasi-stationary plasma accelerator have been studied in the presence of an additional longitudinal magnetic field and the arising rotation of plasma flow. Numerical study was carried out within the framework of two-dimensional magnetic hydrodynamics (MHD) model of the axisymmetric plasma flows taking into account the finite conductivity of medium and radiation transport. Dynamics of compressible plasma flows is accompanied by the MHD dynamo effect or generation of magnetic field on a conical shock wave forming at the outlet from the accelerator. 相似文献
18.
We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed. 相似文献
19.
Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak 总被引:1,自引:0,他引:1
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Multi-channel soft x-ray (SX) detectors are applied to generate images of
magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data
from SX cameras are analysed by using the
Fourier--Bessel harmonic reconstruction method and the singular value
decomposition. The image
reconstruction of SX emissivity is obtained on the assumption of plasma
rigid rotation. One of the important phenomena in the HT-7 discharge is the
transition from the sawtooth oscillations to the MHD oscillations when the
plasma density grows higher. The MHD structure
observed in the SX tomography is featured as follows: the magnetic surface of MHD
structure is made up of the crescent-shaped ``hot core' and the circular
``cold bubble'. The structure of the magnetic surface is relatively stable.
It rotates in the direction of the electron diamagnetic drift at a
frequency being the oscillation frequency of the MHD oscillations. 相似文献
20.
采用FLUENT软件分别对外加均匀横向磁场的等截面三维充分发展液态金属管流的层流模型和低雷诺数湍流Lam/Bremhost(LB)模型进行了数值模拟,分析了外加磁场对普通方管LB模型速度分布和压降的影响。比较在相同哈特曼数下,层流和湍流模型方管截面上速度分布和管道中MHD压降。其中,对电流的计算采用磁感应方程来求得。数值模拟结果证明了用低雷诺数LB湍流模型解决方管磁流体流动的可行性。通过层流模型和湍流模型的对比可知,层流模型有较短的入口长度,但管内流体的压降却很大;而湍流模型管内速度更加平均化,管内压降较小,但管内入口长度较长。 相似文献