[en] It is shown that plasma waves need not have an asymmetric spectrum in order to produce an electric current in a plasma embedded in a curved magnetic field. For instance, in a toroidal plasma, up-down asymmetric electron-cyclotron heating drives a toroidal current even if there is no net wave-particle momentum transfer and the wave field does not interact preferentially with electrons travelling in any one direction. The resulting current drive efficiency is calculated and is found to be smaller than that of the conventional current drive mechanism in the banana regime, but not insignificant in the plateau regime. (author)

No abstract available

[en] A general expression for the parallel friction is straightforwardly derived by using only the fact that the Fokker-Planck operator conserves momentum. Assuming the Galilean invariance of the F.P. operator, a simplified operator is obtained for unlike particle collisions, which gives the correct expression for the friction force. The study of the influence of the shape of the distribution function on the friction shows that the fluid description of the Pfirsch-Schluter regime fails out when temperature gradients are taken into account. In the case of banana regime the results obtained differ from those previously derived for multi species

No abstract available

[en] A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ϕ₁(r) cos(kz) cos(ωt−lθ), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ω matches the azimuthal rotation frequency ω_R, is usually dominant at low collision frequency ν but becomes negligible at higher ν. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ν (banana) regime, the radial oscillations have amplitude Δr ≈ v_r/ω_T, so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ν increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ν values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles

[en] Neoclassical transport coefficients are derived for a multi-species plasma in a mixed regime, with several banana-plateau species, a, and several Pfirsch--Schlueter species, z. It is assumed that m/sub a/very-much-less-thanm/sub z/, but the masses are otherwise arbitrary

No abstract available

[en] This paper will discuss the energy savings of steam traps and present the energy, economic, and environmental reasons why an active steam trap maintenance program is good for the company's bottom line. Each topic will be reviewed in addition to some new services, products, practices and technology available to help maintain or improve the efficiency of steam systems

[en] The neoclassical diffusion of a plasma in traps with a helical magnetic axis is investigated theoretically in the regime where the effective trapped-particle collision frequency is of the order of the frequency of trapped-particle oscillations between the magnetic mirrors. It is shown that in the case considered a formal analogy with the neoclassical transport theory of axisymmetric systems exists. It allows particle and heat fluxes to be obtained, without special calculations, by a modification of the corresponding expressions for the transport coefficients in axisymmetric systems. Expressions for the transport coefficients in the plateau and banana diffusion regimes are obtained. - Studies of this kind are important for the problem of plasma containment in stellarator-type traps. (author)

No abstract available