Ideal magnetohydrodynamic turbulence is treated using more realistic boundary conditions than rectangular periodic conditions. The dynamical equations of incompressible magnetohydrodynamics and the associated fields are expanded in a set vector eigenfunctions curl. individual represent force-free fields, but superpositions them do not. Three integral invariants have simple quadratic expressions expansion coefficients: total energy, magnetic helicity, cross helicity. remain temporally...

Renormalization-group theory is applied to incompressible three-dimensional Navier-Stokes turbulence so as eliminate unresolvable small scales. The renormalized equation now includes a triple nonlinearity with the eddy viscosity exhibiting mild cusp behavior, in qualitative agreement test-field model results of Kraichnan. For behavior arise, not only necessary but effects pressure must be incorporated term. will exhibit if it assumed that spectral gap exists between large and

A novel unitary quantum lattice gas algorithm is used to simulate turbulence of a BEC described by the Gross-Pitaevskii equation on grids up 5760^3. For first time, an accurate power law scaling for Kelvin wave cascade determined: k^{-3}. The incompressible kinetic energy spectrum exhibits very distinct spectra in 3 ranges k-space: classical Kolmogorov k^{-5/3} at scales much greater than individual vortex cores, and k^{-3} order cores. In semiclassical regime between these two there...

The propagation and scattering of electromagnetic waves in dielectric media is theoretical experimental interest a wide variety fields. An understanding observational results generally requires numerical solution Maxwell equations---usually implemented on conventional computers using sophisticated algorithms. In recent years, advances quantum information science the development have piqued curiosity about taking advantage these resources for an alternate approach to equations. This...

We discuss the possible magnetohydrodynamic configurations that can be realized as ‘most probable’ states compatible with existence of certain constraints. These constraints either experimentally imposed such constant total electric current or magnetic flux, constants motion, both.

Several features of the equilibrium and non-equilibrium statistical mechanics a two-dimensional plasma in uniform d.c. magnetic field are investigated. The calculations have been motivated by recent derivation Bohm's diffusion coefficient given Taylor & McNamara for this system. charges interact only through electrostatic (logarithmic) potentials. problem is considered both with without guidiiig-centre approximation. With guiding centre approximation, an appropriate Liouville equation...

The thermal equilibrium coefficient of spatial diffusion transverse to a strong uniform dc magnetic field is calculated for fully ionized plasma. particles are assumed move the only as consequence E × B drift, but freely parallel it. interact electrostatically. calculation done at large, fixed and finite, plasma volume. It shown that, B→∞, leading term falls off O(1/B), contains multiplicative factor which goes zero volume becomes infinite. method fails unbounded plasmas.

The consequences of the quasilinear equations are explored. Particular attention is paid to differences between one-dimensional and two- three-dimensional cases, cases discrete continuous wave-number spectra. possibilities problems associated with including damped waves treated. relation conservation laws ‘resonance approximation’, in which limit zero growth rate for unstable taken at finite times, clarified. Numerical solutions case presented.

There are two disparate formulations of the entropic lattice Boltzmann scheme: one these theories revolves around analog discrete H function standard extensive statistical mechanics, while other nonextensive Tsallis entropy. It is shown here that it nonenforcement pressure tensor moment constraints lead to extremizations entropy resulting in Tsallis-like forms. However, with imposition constraint, as fundamentally necessary for recovery Navier-Stokes equations, proved must be form....

A calculation describing the parametric amplification of Alfvén waves in a uniform, perfectly conducting, magnetohydrodynamic fluid is reported. The has been motivated by recent experiment Lehane and Paoloni. magnetically supported uniform column imagined to be subjected an externally imposed, sinusoidally varying, magnetic field which can idealized as spatially uniform. It shown that certain class have axial wavelength long compared with radius parametrically amplified case where their...

The advection of a passive scalar by incompressible turbulence is considered using recursive renormalization-group procedures in the differential subgrid shell thickness limit. It shown explicitly that higher-order nonlinearities induced procedure preserve Galilean invariance. Differential equations, valid for entire resolvable wave-number k range, are determined eddy viscosity and diffusivity coefficients. these do not contribute as k\ensuremath{\rightarrow}0, but play an essential role...

Cross sections are calculated for electromagnetic wave scattering and mode transformation from magnetic density fluctuations in a homogeneous plasma. For the special case of perpendicular to field, scatter ordinary extraordinary modes—but cannot transform these modes. On other hand, field can modes but on single branch. incident frequencies order electron plasma frequency or gyrofrequency, cross due have similar value. Estimates given tokamak with emphasis question how detect localize...

The electron Bernstein wave (EBW) is typically the only in cyclotron (EC) range that can be applied spherical tokamaks for heating and current drive (H&CD). Spherical (STs) operate generally high-β regimes, which usual EC O- X-modes are cut off. In this case, EBWs seem to option provide features similar waves—controllable localized H&CD used core plasma as well accurate stabilization. EBW a quasi-electrostatic excited by mode conversion from suitably launched or X-mode; its...

An alternative development of the recursive-renormalization-group (RNG) theory for subgrid modeling turbulence is presented which now independent order in averaging performed. The relevant approximations, perturbation ordering, and process are explicitly considered. In particular, it shown that, higher-order nonlinearities introduced into RNG Navier-Stokes equation, only third-order nonlinearity appears at desired level expansion. Moreover, these triple-velocity product terms appear same as...

Kinetic lattice methods are a very attractive representation of nonlinear macroscopic systems because their inherent parallelizability on multiple processors and avoidance the convective terms. By uncoupling velocity from spatial grid, one can employ higher order (non-space-filling) isotropic lattices---lattices which greatly enhance stable parameter regions, particularly in thermal problems. In particular, superiority octagonal over previous models used 2D (hexagonal or square) 3D...

The progress and challenges in thermal lattice-Boltzmann modeling are discussed. In particular, momentum energy closures schemes contrasted. Higher order symmetric (but no longer space filling) velocity lattices constructed for both 2D 3D flows shown to have superior stability properties the standard lower) symmetry lattices. While this decouples lattice from spatial grid, interpolation required following free-streaming is just 1D. connection between fixed vectors temperature-dependent...

The free-decay renormalization-group theory for Navier-Stokes turbulence [Zhou, Vahala, and Hossain, Phys. Rev. A 37, 2590 (1988)] is extended to the case of forced turbulence. An eddy-damping function obtained, which nonlocal in time space. Using a multitime scale perturbation analysis, time-local renormalized eddy viscosity determined as fixed point an integro-difference recursion relation. It exhibits mild cusp behavior particular forcing exponent that gives Kolmogorov energy spectrum,...

Electromagnetic waves are an inherent part of all plasmas—laboratory fusion plasmas or astrophysical plasmas. The conventional methods for studying properties electromagnetic rely on discretization Maxwell equations suitable implementing classical, present day, computers. traditional methodology is not efficient quantum computing implementation—a future computational source offering a tantalizing possibility enormous speed up and significant reduction in cost. This paper addresses two topics...

Lattice-based quantum algorithms are developed for vector soliton collisions in the completely integrable Manakov equations, a system of coupled nonlinear Schrödinger (coupled-NLS) equations that describe propagation pulses birefringent fibre unity cross-phase modulation factor. Under appropriate conditions exact 2-soliton solutions yield inelastic collisions, agreement with theoretical predictions Radhakrishnan et al. (1997 Phys. Rev. E56, 2213). For linearly fibres, quasi-elastic...

It is shown that the alpha-particle contribution to scattered power can be dominant in coherent scattering of a CO2 laser Maxwellian plasma. For Ti = Te 10 keV, optimal forward-scattering angle around 1.0°, with detection electron density fluctuation wavenumbers k⊥ >> k|| (relative toroidal magnetic field). A strong resonance occurs at lower hybrid frequency. Because dependence signal on temperature and alpha distribution function, it seems feasible scattering, using heterodyne techniques,...

Thermal lattice Boltzmann (TLBE) models that utilize the single relaxation time scalar Bhatnagar, Gross, and Krook collision operator have an invariant Prandtl number. For flows with arbitrary number, a matrix is introduced. The parameters are generalized so transport coefficients become density independent. TLBE simulations presented for two-dimensional free decaying turbulence induced by strongly perturbed double velocity shear layer various numbers.