Tonks-Langmuir problem for a bi-Maxwellian plasma

An analytical solution of the Tonks-Langmuir (TL) problem with a bi-Maxwellian electron energy distribution function (EEDF) is obtained for a plasma slab. The solution shows that the ambipolar potential, the plasma density distribution, and the ion flux to the wall are mainly governed by the cold electrons, while the ionization rate and voltage drop across the wall sheath are governed by the hot electrons. The ionization rate by direct electron impact is found to be spatially rather uniform, contrary to the T-L solution where it is proportional to the plasma density distribution. The temperature of hot electrons defined by the ionization balance is found to be close to that of the T-L solution for a mono-Maxwellian EEDF, and is in reasonable agreement with experiments carried out in a low pressure capacitance RF discharge. The energy balance for cold electrons in this discharge shows that their heating by hot electrons via Coulomb interaction is equalized by the cold electrons' escape to the RF electrodes during collapse of the RF sheath     

Fusion reaction rate for a plasma boiler moving in an ambient plasma

The enhancement of the fusion reaction rate for a thermal plasma moving as a boiler through an ambient plasma is calculated. The anisotropy of the neutron emission is discussed and the calculations are applied to measurements on a small Mather type focus device.     

Enhancement of soft X-ray emission from a pinch plasma using a rotating plasma for pre-ionization

An experimental study on the enhancement of soft X-ray emission from a pinch plasma has been carried out by using a rotating plasma for pre-ionization. The rotating plasma is produced by a pulsed J×B cross-field discharge between coaxial electrodes, and subjected to a pinch discharge. Under an optimized discharge condition, it has been observed that UV emission of 251.6 nm (Ar III) soft X-ray intensity increases with increasing applied axial magnetic field B. At 400 G, the X-ray intensity is enhanced by a factor of 3 compared to that without the rotating plasma. It is considered that this result is due to the improved characteristics of the pre-ionization rotating plasma, which influences the uniformity and stability of subsequent pinch plasma.     

X-ray calculations for a NLTE Ar plasma

A model is developed to calculate emission spectrum of non-local thermodynamic equilibrium(NLTE) plasmas. The Collisional-Radiative model is adopted for non-LTE population calculations. Configuration-averaged rate coefficients that needed in the rate equations are obtained based on the first order perturbation theory. The Hatree-Fock-Slater self-consistent-field method is used to calculate electron wave functions. The present model is applied to the calculation of emissivity from a Ar plasma. The features of the spectra are in good agreement with those calculated by other theoretical models, but the data of the integrated emissivity differ by a factor 2～8.     

Magnetic trap for confining a hot plasma

The magnetic field of a two-helix Tornado trap has all the properties needed to efficiently confine a hot plasma. However, its practical utilization has been restricted because of the ponderomotive interaction between the turns of the helices, which disrupts the structure of the magnetic field. A modification of a Tornado trap, which permits significant reduction of the ponderomotive interaction is considered, and arguments in favor of using a magnetic field to maintain the properties of the field in an unmodified trap are presented. Zh. Tekh. Fiz. 67, 25–28 (September 1997)     

Generalized bohm criterion for a multicomponent plasma

We have formulated the generalized Bohm criterion regulating the existence of a stationary charged near-electrode sheath in a multicomponent plasma with an infinitely large number of ion species. The criterion has the form of a set of inequalities one of which coincides with the Bohm criterion for a two-component plasma.     

Complete spectrum of kinetic eigenmodes for plasma oscillations in a weakly collisional plasma

Kinetic eigenmodes of plasma oscillations in a weakly collisional plasma, described by a collision operator of the Fokker-Planck type, are obtained in closed form for initial-value as well as for boundary-value problems. These eigenmodes, which are smooth and compose a complete discrete spectrum, play the same role for weakly collisional plasmas as the Case-Van Kampen modes do for collisionless plasmas.     

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给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。     

Ignition regime for fusion in a degenerate plasma

We identify relevant parameter regimes in which aneutronic fuels can undergo fusion ignition in hot-ion degenerate plasma. Because of relativistic effects and partial degeneracy, the self-sustained burning regime is considerably larger than previously calculated. Inverse bremsstrahlung plays a major role in containing the reactor energy. We solve the radiation transfer equation and obtain the contribution to the heat conductivity from inverse bremsstrahlung.     

小孔等离子体运动实验方法

在间接驱动惯性约束聚变的黑腔中,辐射烧蚀的高Z等离子体的流体力学运动过程对激光注入黑腔的效率、辐射场均匀性和通过诊断口的黑腔辐射温度诊断都有显著影响。为研究诊断口在黑腔辐射场中的等离子体缩口过程,用激光产生X光辐射加热低Z泡沫填充的金黑腔诊断口,以激光辐照钛平面靶产生的2～5 keV高能段窄能区X光作为背光源,用X光分幅相机获得了源靶和小孔靶两种靶型的小孔等离子体运动过程图像,研究了X光烧蚀的小孔等离子体的流体力学运动过程,探索了定量测量小孔等离子体面密度的空间分布与时间演化过程的实验诊断方法,初步给出小孔等离子体的面密度。     

Possible schemes of producing a plasma for a shortwave laser

The required energy input to the target material, needed to obtain lasing in the 25–200-Å band, is estimated. It is shown that in the case of a solid target consisting of a single chemical element, the energy-input requirements are unrealistically high. If the plasma is initially ionized beforehand, a pumping energy of 10 J is sufficient for lasing in the 100–200-Å band. For lasing in the 25–50-Å band one can use a hydrogen matrix with a small content of working element. The needed energy input is then several kilojoules.Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 120, pp. 68–75, 1980.     

The Bohm criterion for a dusty plasma sheath

The formation of the sheath in a dusty plasma is investigated. The Bohm criterion is derived for two different cases: (a) when electrons are in thermodynamic equilibrium and dust grains provide the immobile, stationary background and (b) when both electrons and ions are in thermodynamic equilibrium and dust grains are moving. In the first case, Bohm criterion gets modified due to the fluctuation of the charge on the grain surface. In the second case, the collisional and Coulombic drag play important role in determining the Bohm criterion.     

Compton transport cross section for a hot plasma

The equation for diffusion transport of photons in a hot, Compton-scattering-dominated plasma is derived and a transport cross section is identified. Using a reasonable assumption for the frequency dependence of the flux, this relativistically—correct cross section is numerically evaluated for a set of photon energies and electron temperatures. A simple but accurate fit to the calculation is also presented.     

The Landau singularities for a double-stream instability plasma

Dispersion relation roots in a double stream instability plasma are given: the pole responsible for this instability is not the Maxwellian Landau pole. Then, we determine the analytic value of the Landau pole in a quasi-linear theory.     

磁化冷等离子体球的瑞利散射

给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。