Gyrokinetic simulations of electromagnetic turbulence in magnetically confined torus plasmas including tokamak and heliotron/stellarator are reviewed. Numerical simulation of turbulence in finite beta plasmas is an important task for predicting the performance of fusion reactors and a great challenge in computational science due to multiple spatio-temporal scales related to electromagnetic ion and electron dynamics. The simulation becomes further challenging in non-axisymmetric plasmas. In finite beta plasmas, magnetic perturbation appears and influences some key mechanisms of turbulent transport, which include linear instability and zonal flow production. Linear analysis shows that the ion-temperature gradient (ITG) instability, which is essentially an electrostatic instability, is unstable at low beta and its growth rate is reduced by magnetic field line bending at finite beta. On the other hand, the kinetic ballooning mode (KBM), which is an electromagnetic instability, is destabilized at high beta. In addition, trapped electron modes (TEMs), electron temperature gradient (ETG) modes, and micro-tearing modes (MTMs) can be destabilized. These instabilities are classified into two categories: ballooning parity and tearing parity modes. These parities are mixed by nonlinear interactions, so that, for instance, the ITG mode excites tearing parity modes. In the nonlinear evolution, the zonal flow shear acts to regulate the ITG driven turbulence at low beta. On the other hand, at finite beta, interplay between the turbulence and zonal flows becomes complicated because the production of zonal flow is influenced by the finite beta effects. When the zonal flows are too weak, turbulence continues to grow beyond a physically relevant level of saturation in finite-beta tokamaks. Nonlinear mode coupling to stable modes can play a role in the saturation of finite beta ITG mode and KBM. Since there is a quadratic conserved quantity, evaluating nonlinear transfer of the conserved quantity from unstable modes to stable modes is useful for understanding the saturation mechanism of turbulence.

The Lorentzian renormalization plasma shielding effects on the elastic electron–atom collision are investigated in generalized Lorentzian semiclassical plasmas. The eikonal analysis and the effective interaction potential are employed to obtain the eikonal scattering phase shift, differential eikonal collision cross section, and total eikonal collision cross section as functions of the collision energy, impact parameter, nonthermal renormalization parameter, and spectral index of the Lorentzian plasma. It is found that the influence of Lorentzian renormalization shielding suppresses the eikonal scattering phase shift and, however, enhances the eikonal collision cross section in Lorentzian semiclassical plasmas. Additionally, the energy dependence on the total collision cross section in nonthermal plasmas is found to be more significant than that in thermal plasmas.

In collisional fluids, a number of key processes rely on the frequency of binary collisions. Collisions seem necessary to generate a shock wave when two fluids collide fast enough, to fulfill the Rankine–Hugoniot (RH) relations, to establish an equation of state or a Maxwellian distribution. Yet, these seemingly collisional features are routinely either observed or assumed, in relation with collisionless astrophysical plasmas. This article will review our current answers to the following questions: How do colliding collisionless plasmas end-up generating a shock as if they were fluids? To which extent are the RH relations fulfilled in this case? Do collisionless shocks propagate like fluid ones? Can we use an equation of state to describe collisionless plasmas, like MHD codes for astrophysics do? Why are Maxwellian distributions ubiquitous in particle-in-cell simulations of collisionless shocks? Time and length scales defining the border between the collisional and the collisionless behavior will be given when relevant. In general, when the time and length scales involved in the collisionless processes responsible for the fluid-like behavior may be neglected, the system may be treated like a fluid.

In this paper, the properties of photonic band gap (PBG) and surface plasmon modes in the three-dimensional (3D) magnetized plasma photonic crystals (MPPCs) with face-centered-cubic (fcc) lattices are theoretically investigated based on the plane wave expansion (PWE) method, in which the homogeneous magnetized plasma spheres are immersed in the homogeneous dielectric background, as the Voigt effects of magnetized plasma are considered (the incidence electromagnetic wave vector is perpendicular to the external magnetic field at any time). The dispersive properties of all of the EM modes are studied because the PBG is not only for the extraordinary and ordinary modes but also for the mixed polarized modes. The equations for PBGs also are theoretically deduced. The numerical results show that the PBG and a flatbands region can be observed. The effects of the dielectric constant of dielectric background, filling factor, plasma frequency and plasma cyclotron frequency (the external magnetic field) on the dispersive properties of all of the EM modes in such 3D MPPCs are investigated in detail, respectively. Theoretical simulations show that the PBG can be manipulated by the parameters as mentioned above. Compared to the conventional dielectric-air PCs with similar structure, the larger PBG can be obtained in such 3D MPPCs. It is also shown that the upper edge of flatbands region cannot be tuned by the filling factor and dielectric constant of dielectric background, but it can be manipulated by the plasma frequency and plasma cyclotron frequency.

This paper is devoted to study the dynamics of a discharge lamp in different position. As an example of application, we chose the mercury lamp. For this, we realized a three-dimensional model, steady state. After the validation of this model, we used it to reproduce the influence of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp operating in different positions. Indeed, the pressure and the orientation of the lamp are modified. The effect of convective transport and the accumulation of mercury behind the electrodes are studied.

Superbanana and superbanana plateau transport processes are critical to plasma confinement in tokamaks with broken symmetry. The transport is caused by the superbanana resonance, which occurs at a pitch angle that makes the toroidal drift speed vanish, i.e. the tips of the superbananas. The physics consequences of the resonance on the symmetry breaking induced toroidal momentum damping and on the energetic alpha particle transport have been demonstrated using large aspect ratio expansion. Here, the existing theory for the superbanana and superbanana plateau transport is extended for finite aspect ratio tokamaks with broken symmetry. The effects of finite plasma β, and magnetic field shear are naturally included. Here, β is the ratio of the thermal plasma pressure to the magnetic field pressure. The explicit expressions for the transport fluxes in these regimes in terms of the equilibrium quantities are presented. It is shown that the main effects are to modify the resonance function G(k) and the expression for the pitch angle parameter k in the existing theory.

The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

A theory of electrodeless electric propulsion systems (EEPS) based on the use of the solenoid magnetic field and the rotating electromagnetic field produced by antennas is developed, which includes a study of the plasma acceleration by the Radio Frequency (RF) field and the concomitant thrust. It was assumed that the frequency of the RF field exceeds the lower hybrid frequency but is much less than the electron gyrofrequency. Relations for the thrust are obtained and analyzed. It is shown that thrust gain is significant only when the RF-induced drift velocity well exceeds the fluid velocity of the injected plasma. It is revealed that the curvature of the magnetic field lines and the plasma acceleration in the region outside the solenoid are the factors which can considerably increase the thrust. On the other hand, it is found that the axial inhomogeneity of the plasma and some other factors are unfavorable for the thrust. The obtained results can be used for the optimization of particular experiments aimed to create a new thruster for long-time space missions.

We consider the limits of validity of ray tracing and ray diffusion equations, for short wavelength waves propagating in a turbulent plasma background. We derive an improved transport equation for the electric field autocorrelation function, where first order diffraction effects associated with these waves are included. We apply this description to the case of lower hybrid (LH) waves propagating in non-stationary plasma where density perturbations can occur due to drift wave turbulence, as well as magnetic field perturbations due to MHD turbulence. This is relevant to the problem of LH current drive.

We investigate the transformation process of longitudinal Langmuir wave into the transverse electromagnetic wave in turbulent plasma subjected to an upper hybrid pump. The case, when upper hybrid pump wave decays into daughter and ion – sound waves is considered. The transformation of the Langmuir wave into electromagnetic one is considered as the possible mechanism of energy radiation from the plasma. It is shown that the frequency of such radiation is chosen to be near double electron Langmuir frequency 2ωpe. These results give us the possibility to explain the nature of radiation from the laboratory and cosmic plasmas (particularly, from the solar crown).

The Jeans self-gravitational instability is studied for dense quantum viscous plasma with Hall term and intrinsic magnetization generated by collective electron spin. The quantum magnetohydrodynamic model is employed to formulate the basic equations of the problem. The dispersion relation is obtained using the normal mode analysis, and further reduced for both transverse and longitudinal modes of propagation. The transverse mode of propagation is found to be unaffected by the Hall term but affected by quantum effect, viscosity, and magnetization parameters. The Jeans criterion of instability in the transverse direction is modified by Alfven velocity, magnetization parameter, and quantum effect. The non-gravitating magnetized mode is obtained in the longitudinal direction, which is modified by Hall parameter and is not affected by quantum term, whereas the gravitational mode is unaffected by the magnetization parameter but affected by viscosity and quantum parameters. It is observed that the Jeans condition of instability is affected by the quantum term. The growth rate of Jeans instability is plotted for various values of magnetization, quantum, and viscosity parameters of the quantum plasma medium.

In this research, the effect of inserting deuterated solid target in plasma focus device ‘SBUMTPF1’ on neutron yield has been investigated. The deuterated target with the diameter of 2.5 cm was placed at different heights relative to the anode tip. In each height, the best place of target (where the ion density is highest) was found from observing the effects of ions struck on the aluminum samples. Also for each height, 20 shots were performed at the optimum pressure of deuterium working gas and operating voltage, which are equal to 1.5 mbar and 24 kV, respectively. The neutron production was measured with two activation counters, which placed in 0○ and 90○ relative to the anode axis. Neutron scattering from two activation counters was calculated with MCNP4C code and the results showed that this effect is negligible. In this article, the probability of implanting deuterium ions into the titanium target was also investigated. Deviation angle of the ion emission relative to the anode axis was measured experimentally in this research and it was about 3.1○.

Alborz tokamak is an educational system for studying plasma phenomena in many physics and engineering experiments. A hot filament and a reverse discharge loop are used in the tokamak as the pre-ionization system. The hot cathode prepares a local initial electron density, then the reverse discharge loop trigger the ionization avalanche by means of inducing a toroidal electric field. The parameters of the hot filament are determined in order to produce the desired electron source. Filament temperature is simulated by using three-dimensional finite element method. The average values of filament temperature and electron density at the plasma core (at the end of pre-ionization process) were calculated and are about 2750 K and 1019 m−3, respectively. The resultant electron density and equivalent plasma resistivity due to reverse discharge loop are also calculated. In this paper, the simulation results, optimum structural style, the obtained parameters, the temperature of different parts of the filament and produced electron density are presented and discussed.

The interaction between incident transverse magnetic (TM) waves and nonuniform plasma cylinder is investigated. The forward and backscattering fields of incident TM microwave are calculated and analyzed by using the scattering matrix model. The dependences of the scattering field on plasma electron density, collision frequency, and incident frequency are analyzed, respectively. The electric field distribution across the section of the plasma cylinder is deduced, visually shown, and discussed.

The theory for the two-stream free-electron laser with the whistler wave as a slow electromagnetic wave wiggler is studied theoretically. The results show that for small values of plasma density, there are seven groups of orbits and the plasma density enhancement leads to increase in the number of trajectories. Also, increasing the plasma density causes growth in the axial velocity for groups (1–4) of orbits and a reduction for groups (6–7). It is shown that for groups (6–7), the effect of plasma is to increase the gain, and for groups (1–4) the effect of plasma is to decrease the gain. For group (1) the effect of plasma is to decrease the maximum frequency and for group (3) it is to increase the maximum frequency.

In this paper, the effect of the electron collision frequency with background ions on TMmr mode field components, the trajectory and the electron energy gain is studied. The field components of the TMmr mode in the elliptical waveguides are calculated. The ohmic heating for three different value of collision frequency calculated and the power losses is obtained. The deflection angle and acceleration gradient of an electron in the fields associated with a transverse magnetic (TM) wave propagating inside a elliptical waveguide for TMmr mode is studied. The relativistic momentum and energy equations for an electron are solved, which was injected initially along the propagation direction of the microwave. The results for TMmr mode are graphically represented. Finally, the optimum point of acceleration for the even mode TM11 is obtained and it is shown that in a cross section of elliptical waveguide optimum point is center of ellipse.

The authors would like to correct several misprints in the original article (Sulem and Passot 2014).