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超热电子-离子的产生和输运在传统的ICF方案和“快点火”方案中都是很重要的问题.讨论了电子-离子碰撞对参量不稳定性产生超热电子的过程和超热电子输运过程的影响.指出电子-离子弱碰撞项的加入增强了碰撞吸收,提高了热电子温度,降低了静电波破裂时的场能.这些改变了超热电子的总能量和分布,使之更集中于静电波的相速;电子-离子碰撞的存在还增强了自洽电场,阻碍了超热电子的输运,同样也是超热电子能量下降的原因之一.同时,为确保计算结果的可靠,讨论了初条件对PIC模拟计算的影响,指出空间位置随机热启动容易引入非物理因素,对
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《物理学报》2021,(13)
电子输运系数是确保低温等离子体建模准确性的关键因素,通过模拟电子的输运过程可对其数值求解.在模拟电子输运时,电子和中性粒子碰撞后的散射和能量分配方式有多种处理方法.为了研究不同处理方法对电子输运系数的影响,本文基于蒙特卡罗碰撞方法,建立了电子输运系数的计算模型,模拟约化电场10—1000 Td (1 Td=10~(–21) V·m~2)氢原子气中的电子输运过程.计算结果表明,各向同性假设对电子输运系数的影响随电场强度增加而增加,但即使对于较低的约化电场(10 Td),各向异性散射假设下电子的平均能量、通量迁移率和通量扩散系数也分别比各向同性假设下的值高38.34%, 17.38%和119.18%.不同的能量分配方式对中高电场强度下( 200 Td)的电子输运系数影响较为显著.在高电场时,均分法计算得出的电子平均能量、通量迁移率和通量扩散系数均小于零分法对应的值,汤森电离系数则相反. Opal法得出的电子输运系数介于均分法和零分法之间.此外,考虑各向异性散射时,不同能量分配方式对输运系数的影响高于各向同性.本研究表明,在计算电子输运系数时需要考虑各向异性的电子散射,高电场条件下尤其要注意能量分配方式的选择. 相似文献
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本文从离子动力学方程出发,利用LB碰撞模型研究了离子-离子碰撞效应对前鞘等离子体输运的影响。电子分布假定为等温麦克斯韦-玻耳兹曼分布。结果表明,在低碰撞频率和高碰撞频率下,LB碰撞模型都能较好地描述前鞘等离子体中的离子-离子碰撞行为。离子-离子碰撞对表面等离子体的输运行为有较大影响。 相似文献
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利用调制送气过程中观察到的冷脉冲传播,研究了在HL-2A装置欧姆放电条件下的电子热输运。从扰动输运方程出发,分析了电子热输运过程,利用在实验中获得的数据,进行了曲线拟合和数值计算,得到了在HL-2A装置欧姆放电条件下强场侧电子热输运系数的分布特征为χ=15-14(1-r2)2m2.s-1。 相似文献
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电子离子碰撞激发速率系数在超组态碰撞辐射模型中真实模拟非局域热动力学平衡Au激光等离子体M带谱 5f 3d跃迁中各种复杂电荷态离子的电离态特性 (譬如离子的平均电离度 ,相对丰度和能级布居数 )是必不可少的。基于准相对论多组态Hartree Fock方法和扭曲波玻恩交换近似 ,采用自编的扭曲波程序ACDW (9)和Fit(9) ,从头计算了Au等离子体M带 5f 3d电子离子碰撞激发速率系数。结果表明 :在“神光II”实验装置诊断的电子温度约 2keV ,电子密度约 6× 10 2 1cm-3 范围内 ,这些电子离子碰撞激发参数有利于采用超组态碰撞辐射模型模拟Au的激光等离子体M带 5f~ 3d细致谱的平均电离度和电荷态分布。 相似文献
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曲文孝 《核聚变与等离子体物理》2001,21(4):193-199
从通常的局部输运模型的角度分析,托卡马克等离子体中有相当多的输运现象会被视为“奇怪”的或“反常”的,即难于被正确的理解,也难于给出统一的描述方式。基于温度剖面不变性的--这里称炎这相容模型的描述方法,在不涉及非局部输运任何具体物理机制的情况下,给出了包含非局部效应的热导系数及其与局部反常热导系数的关系。利用这种相容热导模型统一地描述并分析了一些看似奇怪或反常的输运现象。 相似文献
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Kolesnichenko YI Yakovenko YV Weller A Werner A Geiger J Lutsenko VV Zegenhagen S 《Physical review letters》2005,94(16):165004
Enhanced plasma heat conductivity in the presence of kinetic Alfvén waves (KAW) is predicted theoretically. The enhancement is shown to be strongest when the electron collision frequency exceeds the particle transit frequency in the wave field. Alfvén waves (both KAW and ideal MHD Alfvén eigenmodes generating the KAW) are studied in a shot of the Wendelstein 7-AS stellarator. On the basis of these results, strong thermal crashes observed during bursting Alfvénic activity in the mentioned shot are explained. 相似文献
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K. F. Grebenkin A. L. Zherebtsov A. L. Kutepov V. V. Popova 《Technical Physics》2002,47(11):1458-1460
An experiment for verifying the semiconductor model of detonation is described. Within this model, the electron thermal conductivity is the decisive parameter in initiating the detonation of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), a low-sensitivity explosive. The idea of the experiment is to detect an increase in the electron concentration in the conduction band and to estimate the electron thermal conductivity from the electrical conductivity of TATB compressed by shock waves of subthreshold intensity. 相似文献
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J. F. Hofmann H. Stöcker W. Scheid W. Greiner V. Ceausescu E. Badralexe 《Zeitschrift für Physik A Hadrons and Nuclei》1977,280(2):131-135
In the collision of heavy atoms compression waves in the atomic electron clouds are predicted. The bulk properties of electronic matter are estimated. Reaction cross sections for electron emission are calculated in a schematic model. 相似文献
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非磁化等离子体中的电子碰撞频率 总被引:12,自引:2,他引:10
电子碰撞频率是非磁化等离子体的一个重要参数,它对等离子体与电磁波相互作用的性质具有较大影响。基于产生等离子体的气压条件不同,其电子碰撞频率具有较大变化范围。研究了它对非磁化等离子体吸波能力的影响,得出了当电子碰撞频率与等离子体频率和入射波频率相当时,等离子体对电磁波具有较大吸收的结论,给出了对应于最大吸收的最佳碰撞频率值。分析了通过选择放电气体来调整等离子体的电子碰撞频率。 相似文献
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It is shown that the propagation of nonlinear ion-acoustic waves in a collisional plasma is governed by the modified Korteweg-de Vries-Burgers or the Burgers equation. The stationary shock like solution of the KdV-Burgers and Burgers equations is discussed for the medium in which the electron thermal conductivity is very large. 相似文献
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HL—1装置热脉冲传播分析 总被引:1,自引:1,他引:0
本文通过解析推导和数值计算,得到了适合于反转半径较小时用峰值时间差法计算电子热导率的解析公式,并对HL-1装置的实验数据进行处理,获得了等离子体电子热导率在4≤r≤9cm区域内的平均值为7.4m~2/s。并讨论了计算电子热导率的一种新方法,即强制边界条件法,结果表明,该方法是可行的。 相似文献
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A. L. Khomkin A. S. Shumikhin 《Journal of Experimental and Theoretical Physics》2017,124(6):1001-1009
We have proposed a peculiar model of the plasma of dense metal vapors, containing atoms embedded into the electron jelly, as well as free (thermally ionized) electrons and ions. The main feature of the model is the presence of the electron jelly existing at any density of the atomic component. The number of electrons in the jelly increases under compression. The process of its formation can be called the “cold” ionization, or pressure ionization. The composition of the gas–plasma mixture, including the concentration of atoms and electrons in the jelly, as well as the concentration of free thermally ionized electrons and ions, has been calculated. The conductivity of dense vapors is determined by the sum of the conductivities of thermal electrons (which is calculated using the Frost formula) and jelly electrons (which is calculated by the Regel–Ioffe formula for the minimal metal-type conductivity). The concentration of thermal electrons decreases and the concentration of jelly electrons increases upon compression of the vapor. Accordingly, the conductivity varies from the conductivity of thermal electrons to the conductivity of jelly electrons, continuously passing through the minimum. The calculated values of the conductivity of supercritical metal vapors are in satisfactory agreement with experimental results. 相似文献
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The present investigation concerns the propagation of surface waves at the vacuum-solid interface of a solid which is isotropic and thermoviscoelastic, i.e., for which the effects of heat conductivity need to be taken into account. Calculations show that, in addition to the Rayleigh wave, a thermal surface wave propagates that couples both the thermal and the elasticity effects. This latter wave is interpreted in terms of evanescent plane waves. The displacement field associated with this wave is calculated and interpreted. Some experimental results are also presented. 相似文献
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Thermal conductivity of ozone-safe liquid refrigerant R507 was studied by the method of high-frequency thermal waves within
the temperature range of 297.95 … 332.55 K and pressures from the saturation line up to 3.7 MPa. The estimated errors of temperature,
pressure, and thermal conductivity measurements are 0.1 K, 3 kPa, and 1.5 %, correspondingly. Thermal conductivity of liquid
R507 was calculated on the saturation line. Approximation dependences for thermal conductivity were derived for the whole
range of studied temperatures and pressures and on the saturation line.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 07-08-00295-a). 相似文献