Plasma confinement by a picket-fence

A current produced line cusp field is shown to confine both plasma and primary ionizing electrons.     

Enhanced confinement and stability of a field-reversed configuration with rotating magnetic field current drive

A new experiment has been constructed to study the sustainment of a field-reversed configuration (FRC) with a rotating magnetic field (RMF). FRCs were formed with cold, unmagnetized ions and thus without a kinetic ion component that was believed to provide stability to internal tilt modes. No destructive instabilities were observed for the RMF FRC. Only peripheral radial penetration of the RMF was observed. The radially inward flow arising from axial screening currents at the FRC edge reduced convective and conductive losses to the measurement limit of the diagnostics.     

反场构型等离子体靶压缩过程中强磁场对α粒子能量的约束效应

基于一维弹塑性磁流体力学程序（SSS-MHD）,研究了反场构型（FRC）等离子体靶在磁驱动固体套筒压缩过程中强磁场对α粒子能量约束效应,分析了α粒子的非局域和局域自加热对FRC等离子靶压缩峰值温度的影响,以及α粒子能量在整个压缩过程中端部损失效应。等离子体部分采用多温单流体的模型,能量的计算中引入了DT离子、电子及α粒子多成分温度的能量方程,同时考虑了等离子体压缩过程热平衡下的核反应和非局域自加热问题。研究结果表明,磁化靶聚变等离子体在压缩过程中具有较好的稳定性,能够保持刚性转子的靶结构,压缩过程形成的强磁场能够将α粒子的能量约束在O点附近的区域,有利于等离子体靶的点火及燃烧;α粒子对等离子体的自加热效应主要集中在等离子体电流中心区,而非等离子体中心轴处;α粒子对DT等离子体局域和非局域自加热过程存在差异,局域自加热过程的功率大于非局域自加热过程的功率,FRC等离子靶压缩峰值状态温度相差0.5倍。在反场构型的刮离层区,α粒子的能量端部损失在FRC等离子体靶的压缩和膨胀过程中逐渐增大。     

Radial magnetic field in magnetic confinement device

The intrinsic radial magnetic field(B r) in a tokamak is explored by the solution of the Grad–Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement.     

The stationary confinement of plasma by a magnetic field at anisotropic pressure

The method of moments of the Boltzmann-Vlasov equation is used to derive relations between the macroscopic quantities of high-temperature plasma (i.e. the density of particles, the mass velocity and the generally anisotropic tensor of the kinetic pressure of particles) and the static electromagnetic field by which the plasma is stationarily confined. The well-known relation between the isotropic pressure of particles and the pressure of the magnetic field is then obtained from this as a special case. Plane geometric configuration of the plasma boundary and negligible collision interaction of the particles are assumed. The results are verified on a simple kinetic model of plasma with known trajectories of the particles.     

Electric confinement and magnetic superconductors

Reinterpretation of the pioneering work of Nielsen and Olesen and others on magnetic confinement in (electric) superconductors leads to simple models which exhibit electric confinement of the type hoped for in quantum chromodynamics. “Electric” flux tubes joining “quarks” arise at a semi-classical level as a result of the existence of (pseudo) particles. The theory can be described in terms of a classical action principle only upon suitable modification of the action; this modification has profound topological significance as it is intimately related to the quantization condition for (pseudo) particles.     

On a magnetic confinement of femtosecond laser pulse plasmas

Perspectives of magnetic confinement for the increase of life times of laser plasmas generated by femtosecond laser pulses are considered. Possibilities that are provided by miniature magnetic cusp configurations with magnetic fields of moderate intensities (of order of Teslas) are investigated. The construction of micro-traps with permanent magnets, making it possible to increase neutron yield, seems to be very simple and possible for most modern “table top" laser experiments.     

Ion confinement by electrostatic potential well in magnetic multipole device

An effective confinement of fast ions is achieved by a negative electrostatic potential well produced by injection of electrons into a surface magnetic multipole device.     

Observations of improved stability and confinement in a high-beta self-organized spherical-torus-like field-reversed configuration

An extremely high-beta (over 85%) self-organized field-reversed configuration (FRC) with a spherical-torus- (ST-)like core is produced in the translation, confinement, and sustainment experiment by highly super-Alfvénic translation of a spheromaklike plasmoid. Substantial flux conversion from toroidal into poloidal occurs during the capture process, resulting in the ST-like core. This plasma state exhibits a remarkable stabilizing property for the ubiquitous centrifugally driven interchange modes present in theta-pinch formed FRCs. This is explained, for the first time, by a simple model taking into account magnetic shear and centrifugal effects. The FRC-ST configuration has up to 4 times improvement in flux confinement times over the scaling of conventional theta-pinch formed FRCs and, thus, a significant improvement in the resistivity and transport.     

Plasma confinement in tokamaks with robust torus

We present a non-linear symplectic map that describes the alterations of the magnetic field lines inside the tokamak plasma due to the presence of a robust torus (RT) at the plasma edge. This RT prevents the magnetic field lines from reaching the tokamak wall and reduces, in its vicinity, the islands and invariant curve destruction due to resonant perturbations. The map describes the equilibrium magnetic field lines perturbed by resonances created by ergodic magnetic limiters (EMLs). We present the results obtained for twist and non-twist mappings derived for monotonic and non-monotonic plasma current density radial profiles, respectively. Our results indicate that the RT implementation would decrease the field line transport at the tokamak plasma edge.     

Fano resonance in electronic transport induced by the magnetic confinement in a graphene nanoribbon

Based on the Floquet scattering theory, a model of graphene-based electronic device is presented, in which electrical transport is controlled by adjusting Dirac fermions energy near resonance conditions. The presence of an oscillating field leads to the Fano resonance in transport through a magnetic structure in an armchair graphene nanoribbon (AGNR). The Fano resonance originates from bound states of the magnetic confinement, according to subband indices in the AGNR. The ballistic conductance is markedly affected by the Fano resonance due to the quasi-one-dimensional nature of AGNRs. The results may help realizing graphene electronics with the resonant characteristics in the conductance.     

托卡马克高约束运行模式和磁约束受控核聚变

磁约束受控核聚变是最终解决人类能源问题的有希望的途径之一.托卡马克的高约束运行模式可以大大降低下一代磁约束聚变实验装置和将来的聚变示范反应堆的规模和造价.文章简要介绍了托卡马克高约束模式的特征,实现条件及亟待研究解决的科学技术问题,包括触发高约束模式的物理机理,功率阈值与等离子体参数的关系等,以及在高约束运行模式下观察到的边缘局域模的驱动机制、控制或缓解技术等.     

托卡马克高约束运行模式和磁约束受控核聚变

磁约束受控核聚变是最终解决人类能源问题的有希望的途径之一.托卡马克的高约束运行模式可以大大降低下一代磁约束聚变实验装置和将来的聚变示范反应堆的规模和造价.文章简要介绍了托卡马克高约束模式的特征,实现条件及亟待研究解决的科学技术问题,包括触发高约束模式的物理机理,功率阈值与等离子体参数的关系等,以及在高约束运行模式下观察到的边缘局域模的驱动机制、控制或缓解技术等.     

Screening of a low-frequency magnetic field by an open thin-wall spherical shell

The solution to the problem of penetration of a low-frequency magnetic field through a semitransparent open spherical shell is reduced to solving the system of second-order Fredholm integral equations. The effect of the opening angle of the open shell and of some geometrical parameters of the screen as well as electrophysical properties of the spherical shell material on the attenuation of the field in the spherical shell is analyzed numerically.     

Plasma fluctuations and confinement of fusion reaction products

The interaction between the fluctuations that can be excited in a magmetically confined plasma and the high-energy-particle population produced by fusion reactions is analyzed in view of its relevance to the process of thermonuclear ignition. The spectrum of the perturbations that, in the absence of fusion reaction products, would be described by the incompressible ideal magnetohydrodynamic approximation is studied considering finite values of the plasma pressure relative to the magnetic pressure. The combined effects of the magnetic field curvature and shear are taken into account and the relevant spectrum is shown to consist of a continuous portion, that could be identified as a mixture of shear-Alfvén and interchange oscillations, and a discrete unstable part corresponding to the so-called ballooning modes. The rate of diffusion of the fusion reaction products induced by oscillations in the continuous part of the spectrum, as estimated from the appropriate quasi-linear theory, is found to be significantly smaller than could be expected if normal modes (i.e., nonconvective solutions) were excited. However, a relatively wide intermediate region is identified where “opalescent” fluctuations, capable of achieving significant amplitudes and corresponding to a quasi-discrete spectrum, can be excited.     

Plasma diffusion across a magnetic field

Using a simple model of a slowly diffusing plasma across a strong magnetic field, it is demonstrated that plasma mass and energy evolves from an initially given density and temperature distribution into isothermal state with a self-similar diffusion profile that depends only on its initial mass and energy.     

Single-particle magnetic moments in a relativistic shell model

Starting from the original σ + ω model of Walecka, single-particle properties of finite nuclei are derived in the Dirac-Hartree approximation. In such a model, large relativistic corrections are found for the single-particle Dirac magnetic moment, whose origin is found to be closely connected with the effective nucleon mass in nuclei yielding a reasonable value of the spin-orbit splitting. A phenomenological model, which takes into account tensor as well as space-like vector potentials, is found to reduce considerably the amount of relativistic corrections. A possible connection with the Dirac-Hartree-Fock approximation is discussed.     

磁场中等离子体鞘层的结构

采用流体力学理论，研究了斜磁场作用下的等离子体鞘层结构.在不同大小及方向的磁场作用下，对鞘层的离子，电子密度分布，离子流速度分布，电势分布和Bohm判据进行了讨 论.结果显示磁场对鞘层的结构有明显的影响.在静电力和洛仑兹力的作用下，离子流作螺旋进动，离子密度分布产生振荡. 关键词： 磁鞘 等离子体 磁场