Macroscopic resonances in planar geometry

Resonating response is a characteristic feature of free-particle system contained between two vibrating planar surfaces. Resonance frequencies and widths are determined by a mean period of motion of particles reflected from the walls. Resonances due to quasiperiodic macroscopic motion appear when the interaction among quasi-particles by means of perturbations of the common self-consistent field is included. They have finite widths corresponding to collisionless Landau dissipation. Possible relationship of this phenomenon to nuclear giant resonances is discussed.     

The gyrokinetic water-bag modeling in toroidal geometry

The present paper addresses the gyrokinetic water-bag model in toroidal geometry. The previous works were focused on the water-bag concept in magnetized cylindrical plasmas. Here we report on the possibility to improve the water-bag model by taking into account the curvature and gradient drifts. After a presentation of the model, a local linear analysis with some approximations is performed. Interchange and ion temperature gradient instabilities are examined with this new gyro-water-bag model in order to show its ability and its theoretical interest in describing kinetic instabilities in toroidal geometry.     

组合几何蒙特卡罗粒子输运支撑软件框架JCOGIN介绍

介绍了JCOGIN支撑软件框架层次式、模块化的体系结构及其核心数据结构。这些使得JCOGIN软件框架能够支撑大规模复杂几何的蒙特卡罗（MC）粒子输运并行计算。同时介绍了在JCOGIN支撑软件框架下研发的JMCT程序,并进行了性能测试,在2万处理器核上模拟20亿粒子,并行效率达到70%。     

Macroscopic states induced in superconducting media by a transport current under flux creep

The physical features of the formation of macroscopic states of superconducting composites consisting of a superconductor and a coating under flux creep are discussed. It is demonstrated that there exist characteristic electric field strengths depending on the properties of the superconductor, cooling conditions, and characteristics of the stabilizing coating, which affect the intensity of the E-I characteristics of the superconducting composites. Analysis shows that the measurements of the critical properties of superconductors can be accompanied by a nonuniform electric field distribution over the composite cross section and high stable superheating of the superconductor, which do not lead to superconductivity breaking.     

Anomalous bootstrap current estimates from experimentally found values of the radial electron transport

A method of computation of anomalous bootstrap current is suggested which uses calculated or experimentally found values of the radial transport velocity. The underlying theory is the drift kinetic equation approach of Shaing to anomalous plasma transport in a toroidal configuration and/or the MHD approach of Klíma and Petrílka to convection and diffusion in a plasma cylinder under the influence of RF fields.The author thanks R. Klíma and the referee for valuable comments.     

Boundary conditions of the RGE flow in the noncommutative geometry approach to particle physics and cosmology

We investigate the effect of varying boundary conditions on the renormalization group flow in a recently developed noncommutative geometry model of particle physics and cosmology. We first show that there is a sensitive dependence on the initial conditions at unification, so that, varying a parameter even slightly can be shown to have drastic effects on the running of the model parameters. We compare the running in the case of the default and the maximal mixing conditions at unification. We then exhibit explicitly a particular choice of initial conditions at the unification scale, in the form of modified maximal mixing conditions, which have the property that they satisfy all the geometric constraints imposed by the noncommutative geometry of the model at unification, and at the same time, after running them down to lower energies with the renormalization group flow, they still agree in order of magnitude with the predictions at the electroweak scale.     

New approach to transport improvement in a helical magnetic axis system by introduction of effective toroidal curvature

A new approach to transport improvement in a helical magnetic axis stellarator is proposed. First of all, the proposal is presented for the L = 1 system. The effective toroidal curvature term epsilon(T), defined as the sum of the usual toroidal curvature and one of the nearest satellite harmonics of the helical field, determines confinement conditions of localized trapped particles. There exists a certain correlation between the smallness of epsilon(T) and the omnigeneity. This approach would give rise to the possibility of a stellarator design study in a wider parameter domain than quasisymmetry approaches.     

Self-reversal phenomena of toroidal current by reversing the external toroidal field in helicity-driven toroidal plasmas

In order to understand self-organization in helicity-driven systems, we have investigated the dynamics of low-aspect-ratio toroidal plasmas by decreasing the external toroidal field and reversing its sign in time. Consequently, we have discovered that the helicity-driven toroidal plasma relaxes towards the flipped state. Surprisingly, it has been observed that not only toroidal flux but also poloidal flux reverses sign spontaneously during the relaxation process. The self-reversal of the magnetic fields is attributed to the nonlinear growth of the n=1 kink instability of the central open flux.     

组合几何蒙特卡罗粒子输运支撑软件框架JCOGIN介绍

介绍了JCOGIN支撑软件框架层次式、模块化的体系结构及其核心数据结构。这些使得JCOGIN软件框架能够支撑大规模复杂几何的蒙特卡罗（MC）粒子输运并行计算。同时介绍了在JCOGIN支撑软件框架下研发的JMCT程序,并进行了性能测试,在2万处理器核上模拟20亿粒子,并行效率达到70%。     

Tokamak中自举电流的剖面准直性

利用Harris模型,通过求解等离子体平衡方程,计算俘获粒子份额,分别对常规剪切和中心负剪切下tokamak中的自举电流的大小和剖面准直性进行了计算和分析.自举电流分布与等离子体平衡电流分布之间的剖面准直性可以通过调整等离子体的密度、温度和电流分布参数,以及描述等离子体形状的拉长度k和三角变形因子d来获得.中心负剪切位形有利于自举电流产生,并有好的剖面准直性.通过计算比较,分别在常规剪切位形下和中心负剪切位形下获得了一组优化的等离子体参数,在这组参数下,自举电流有较大的份额和好的剖面准直性 关键词： tokamak 自举电流 剖面准直性     

Losses and nonlinear steady-state particle distribution functions for fully ionized tokamak-plasmas in the collisional transport regimes

Fully ionized L-mode tokamak plasmas in the fully collisional (Pfirsch-Schlüter) and in the low-collisional (banana) nonlinear transport regimes are analyzed. We derive the expressions for particles and heat losses together with the steady-state particle distribution functions in the several collisional transport regimes. The validity of the nonlinear closure equations, previously derived, has been indirectly tested by checking that the obtained particle distribution functions are indeed solutions of the nonlinear, steady-state, Vlasov-Landau gyro-kinetic equations. A quite encouraging result is the fact that, for L-mode tokamak plasmas a dissymmetry appears between the ion and electron transport coefficients: the latter submits to a nonlinear correction, which makes the radial electron coefficients much larger than the former. In particular we show that when the L-mode JET plasma is out of the linear region, the Pfirsch-Schlüter electron transport coefficients are corrected by an amplification factor, which may reach values of order 10². Such a correction is absent for ions. On the contrary, in the banana regime, the ion transport coefficients are increased by a factor 2 and the nonlinear corrections for electrons are negligible. These results are in line with experiments.     

Electrostatic ion cyclotron wave dispersion relation in a steady-state toroidal plasma

Summary Electrostatic ion cyclotron wave dispersion relation has been studied in the experiment THORELLO, a steady-state magnetized toroidal plasma, produced in different neutral gases by hot-filament electron emission and acceleration by a bias voltage. Electron temperature and density, evaluated by Langmuir probes, are of the order of 5eV and 10¹⁰ cm⁻³, respectively. The maximum toroidal magnetic field on the axis is about 2kG. The waves are excited by a pair of thin metallic blades, fed with opposite phase by a low power (<10 W) RF signal, and detected by a movable RF probe. An interferometric method allows the evaluation of the perpendicular wave number, for any given frequency. The fit of experimental data with theoretical curves gives the possibility to evaluate the order of magnitude of the ion temperature. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Macroscopic approach to the Casimir friction force

The general formula is derived for the vacuum friction force between two parallel perfectly flat planes bounding two material media separated by a vacuum gap and moving relative to each other with a constant velocity v. The material media are described in the framework of macroscopic electrodynamics whereas the nonzero temperature and dissipation are taken into account by making use of the Kubo formulas from non-equilibrium statistical thermodynamics. The formula obtained provides a rigorous basis for calculation of the vacuum friction force within the quantum field theory methods in the condensed matter physics. The revealed v dependence of the vacuum friction force proves to be the following: for zero temperature (T = 0) it is proportional to (v/c)³ and for T > 0 this force is linear in v/c.     

Macroscopic spin and charge transport theory

According to the general principle of non-equilibrium thermodynamics, we propose a set of macroscopic transport equations for the spin transport and the charge transport. In particular, the spin torque is introduced as a generalized `current density' to describe the phenomena associated with the spin non-conservation in a unified framework. The Einstein relations and the Onsager relations between different transport phenomena are established. Specifically, the spin transport properties of the isotropic non-magnetic and the isotropic magnetic two-dimensional electron gases are fully described by using this theory, in which only the macroscopic-spin-related transport phenomena allowed by the symmetry of the system are taken into account.     

Effect of local toroidal flow on double-tearing modes in cylindrical geometry

The effect of local toroidal flow (LTF) on double-tearing modes (DTMs) is investigated in cylindrical geometry using the reduced magnetohydrodynamics (RMHD) model. The results indicate that the LTF between the two rational surfaces is the dominant suppression effect on DTMs. The suppression effect is enhanced with the flow width increasing, and the DTMs become more stable with the increase of the shear of the LTF between the two rational surfaces. So, in the reversed shear magnetic field configuration, the local flow is driven between the two rational surfaces, which can effectively suppress the development of DTMs and maintain the high-performance state.