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The effect (earlier discovered) of penetration of an electromagnetic-field power flux into a wall exhibiting perfect mixed anisotropic conductivity is considered in more detail. It is shown that the power transmitted into the screen through the nodes of conductivity lines and through resonance-length closed contours can be regarded as the limit value of the power absorbed in a wall characterized by an anisotropic impedance when the absorbing impedance approaches the values corresponding to the case of perfect mixed conductivity.

This article theoretically studies the conditions for existence of longitudinal or flexural waves in nonlinear, isotropic rods and presents numerical simulations corroborating the theoretical results. It has been known that the existence of guided waves at nonlinearity induced double harmonics is subject to constraints which arise from the potential of power flux transfer from the primary generating mode to the generated higher order modes. The knowledge about the behavior of waves in rods at harmonics higher than double is still limited. This gap was addressed here by the method of perturbation coupled with wavemode orthogonality and forced response. This reduces the nonlinear problem to a forced linear problem which was subsequently investigated to formulate an angular order-based constraint as the condition of existence/nonexistence of nonlinearity-driven higher harmonics of longitudinal and flexural waves in rods.

Divertor plasma properties for lower single-null (LSN) configuration in EAST, under a water-cooling graphite wall condition, are presented. A typical shot is selected for analyzing electron temperature, density and power flux at targets. Both higher electron density and lower electron temperature are found at the inboard target, compared to those at the outboard target. A higher power flux is also found to be at the outboard target because of in-out asymmetries for LSN-shaped discharge.

The far-field radiation of a virtual-cathode triode is studied experimentally. The dependences of the power flux density and frequency on the direction of radiation are obtained for various instants of the generation pulse. The radiation of the virtual-cathode triode is characterized by an intricate directional pattern and variable frequency spectrum.

Équipe 107 : Physique des plasmas chauds; International audience; A series of experiments has been performed on JET to investigate the dynamics of transient melting due to edge localized modes (ELMs). The experiment employs a deliberately misaligned lamella in one module of the JET bulk tungsten outer divertor, allowing the combination of stationary power flux and ELMs to transiently melt the misaligned edge. During the design of the experiment a number of calculations were performed using 2D particle-in-cell simulations and a heat transfer code to investigate the influence on the deposited power flux of finite Larmor radius effects associated with the energetic ELM ions. This has been performed using parameter scans inside a range of pedestal temperatures and densities to scope different experimentally expected ELM energies. On the one hand, we observe optimistic results, with smoothing of the heat flux due to the Larmor gyration on the protruding side of the lamella which sees the direct parallel flux-the deposited power tends to be lower than the nominal value expected from geometric magnetic field line impact over a distance smaller than 2 Larmor radii, a finding which is always valid during ELMs for such a geometry. On the other hand, the fraction of the flux not reaching the directly wetted side is transferred and spread to the top surface of the lamella. The hottest point of the lamella (corner side/top) does not always benefit from the gain from the Larmor smoothing effect because of an enhanced power deposition from the second contribution.

Models for the calculation of edge temperature gradients, of growth rates of edge thermal instabilities, and of the enhancement of edge transport coefficients due to thermal instability growth rates have been coupled. The composite model predicts the existence of threshold values of the edge power flux at which the edge transport coefficients sharply decrease and the edge temperature gradients sharply increase; i.e., an edge transport barrier forms. Predicted consequences of this transport barrier formation are found to be qualitatively consistent with phenomena observed experimentally in conjunction with the L–H (low-to-high) transition. It is suggested that this spontaneous formation of an edge transport barrier due to suppression of an edge thermal instability could be a trigger mechanism for the L–H transition in tokamaks.

Cantor fibers having a multilayered cladding structured according to the Cantor fractal scheme are introduced. In each layer the radial field distribution is determined solving a boundary value problem. The mode propagation constant is calculated minimizing the outgoing power flux. Such fibers suffer from low losses even for few cladding layers. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2726–2728, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24716

Effective control of the particle and power flux distributions between the upper and lower divertors has been demonstrated on TdeV, using biasing of the divertor plates, in ohmic discharges with a double null magnetic configuration. Negative biasing of the divertor plates with respect to the walls significantly increases the pressure and the emitted power from the plasma in the active divertor into which E*B drift is directed, but it has little influence on the opposite divertor. This enhanced power dissipation is the result of improved particle retention in the active divertor. The incident power on the plates in the active divertor also increases with biasing, but at a slower rate. The Franck-Condon and charge exchange neutrals contribute significantly to the power loss in the divertors of TdeV in the present operating mode. Positive biasing of the divertor plates has little influence on the total losses from the divertor regions

The H-mode obtained in ASDEX Upgrade by three heating methods (Ohmic, NBI, ICRF) is analysed. The power threshold is shown to be relatively low compared with other tokamaks and to be independent of the heating method. The operational window for the different types of H-phases, (dithering, ELMing with type-III and I ELMs, ELM-free) is given and discussed. The features of the H-mode discharges, in particular quasi-stationary ELMing phases with type I ELMs, are described and discussed. Finally, it is shown that the power flux through the plasma edge is a key parameter for H-mode operation and control.

The formal procedure for the formulation of the relation between displacement and electric fields in operator form is suggested for a smoothly inhomogeneous media with spatial dispersion. This procedure allows one to estimate and consequently reduce errors caused by a lack of information about microscopic processes. Expressions for power flux, power density and power deposition are derived for these media.

Millimeter waves at 60 GHz are suitable for discreet radio contact in restricted area, especially for indoor high rate communications. Such wave exposures have not been reported. That is the reason why a study of possible biological effects upon living beings was required. An experimental irradiation device was calibrated and used to irradiate mice. Specific absorption rate and internal fields have been computed for a mouse irradiated at 60 GHz. The measured power flux in free space at the irradiation area is close to 0.5 mW/cm/sup 2/, this probably produces some subtle biological effects. To look for possible biological effects, the authors exposed DBA2 mice grafted either with L1210 cells or with Lewis tumor cells and healthy Swiss mice. There were four obvious observations: there is an individual sensitiveness to 60 GHz waves; the survival of mice grafted with L1210 cells could be increased; the growth of Lewis tumor was enhanced; and the activity of Swiss mice was increased. In any way, those effects have to be taken into account, and the authors suggest prudence before using a 60-GHz waves for indoor communications.

The ITER divertor design is the culmination of years of physics and engineering effort, building confidence that this critical component will satisfy the requirements and meet the challenge of burning plasma operation. With 54 cassette assemblies, each weighing ~9 tonnes, nearly 3900 actively cooled high heat flux elements rated to steady-state surface power flux densities of 10 MW m−2 and a total of ~60 000 carbon fibre composite monoblocks and ~260 000 tungsten monoblocks/flat tiles, the ITER divertor will be the largest and most advanced of its kind ever constructed. Both the ITER Design Review and subsequent follow-up activities have led to a number of modifications to the device, including the divertor design, significantly improving ITER's operational flexibility. This paper outlines the salient features of the final divertor design, with emphasis on the physics rationale that has defined the design choices and on the performance of the resulting configuration.

During the past four years, experiments using high power, high frequency transmitters have demonstrated that significant modification of the F region of the ionosphere can be effected. This paper illustrates that relatively low power, creating power flux densities in the F region of the order of 1 μw m−2, can also produce significant modification in the ionosphere. Such low power illuminations create field-aligned ionization irregularities that produce a significant scattering cross section in the modified ionosphere. It permits propagation of VHF signals over selected long distance paths that could not be used by natural means.

The antiplane strain problem of the scattering of an incident Love wave by the edge of a thin surface layer is solved. The effect of the layer is represented by a boundary condition applied at the surface of the substrate. In addition, the condition of vanishing traction on the edge of the layer is explicitly enforced. At large distances from the layer’s edge the scattered field is found to consist of a reflected Love wave and a radiated wave. The power flux identity for the problem is derived, and values of the power reflection coefficient are computed. The power flux identity is verified numerically, and the discrepancy which would arise from a failure to satisfy the condition of vanishing traction on the layer’s edge is evaluated.

An electron beam is described as a magnetoelectric medium. Expressions for the energy and power flux densities are deduced and applied to the plane waves propagating in the direction of the beam.