[en] The situation of the nuclear power plants in the World is commented, making emphasis on the Spanish case. It is also pointed the difficulty of the nuclear industry to overcome the main caveats of this energy source: To guarantee the safety of the reactors, the management of the high radioactive level waste, and high investments necessary to build a nuclear power plant. These caveats have made that the public opinion is against the nuclear energy in Europe, and especially in Spain. It is difficult that a re launching of nuclear energy without the economical support of the governments, which guarantees the return of the investments. (Author) 7 refs

[en] Preliminary studies for ion Cyclotron Resonance Heating (ICRH) in the frequency range f=3-150 MHz are presented for TJ-IU torsatron. This wide range implies the use of two different theoretical models. The first valid for high frequency, where the WKB approximation is applicable, and the second one which solves the full wave equation in one dimension. The high frequency calculations have been made using a ray tracing code and taking into account the magnetic field and plasma 3-D inhomogeneity. The results obtained in this case are presented in the first paper of this report, being the most important the criterion to avoid Fast Wave (FW)-Slow Wave (SW) coupling at Lower Hybrid Resonance, near the plasma edge, and the existence of so called Localized Modes. For the low frequency range wave-length is of the size of the plasma radius, there fore, the WKB approximation cannot be used. In this case a 1-D model is used which disregards toroidal effects, to study the main available heating scenarios which are presented in the second work of this report. The studies are made for hydrogen, deuterium and mixed plasmas with and without He3 majority. Finally, the antenna designs to reach these several scenarios are presented in the third paper. Two different antenna models are provided for SW excitation, one of the current type and the other one of potential type. A third antenna is designed to excite FW which is similar to the current type antenna for SW, but rotated 90 degree centigree. (Author)11 refs

[en] A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs

[en] This work is devoted to introduce new optimization criterion in the DAB (Distributed Asynchronous Bees) code. With this new criterion, we have now in DAB the equilibrium and Mercier stability criteria, the minimization of Bxgrad(B) criterion, which ensures the reduction of neoclassical transport and the improvement of the confinement of fast particles, and the reduction of bootstrap current. We have started from a neoclassically optimised configuration of the helias type and imposed the reduction of bootstrap current. The obtained configuration only presents a modest reduction of total bootstrap current, but the local current density is reduced along the minor radii. Further investigations are developed to understand the reason of this modest improvement.

[en] Plasma dispersion functions for complex wave propagation frequency in the weak relativistic regime for arbitrary longitudinal refractive index are estimated and presented in this work. These functions, that are know as Shkarofsky functions in the case of real frequency, are estimated using a new method that avoids the singularities that appear in previous calculations shown in the preceding literature. These results can be used to obtain the properties of plasma instabilities in the weakly relativistic regime. (Author) 14 refs

[en] Langevin equations for quasi-linear wave particle interaction are obtained taking advantage of the unique vocal equivalence between Fokker-Plank equation and the former ones. Langevin equations are solved numerically and, hence, the evolution of a single particle embedded in an electromagnetic field in momentum space is obtained. The equations are relativistic and valid for any wave. It is also shown that the stochastic part of the equations is negligible in comparison with the deterministic term, except for the momentum to the resonance condition for the main parallel refractive index. (Author) 24 refs

[en] Researchers deal with increasingly difficult, complex issues that require more resources and tools. In addition to strictly technical problems, they are also required to produce research that is understood, at least in part, by the public and to be able to convey what are almost always difficult ideas and concepts the frontiers of knowledge. It rarely happens, but sometimes it is possible to solve several problems at the same time. As we will see throughout the article, Volunteer Computing, when properly handled, is able to supply computing power the scientific community and also serve as a window to science in the homes of citizens. (Author) 5 refs

[en] In this paper we propose a method to estimate the induced current by electron cyclotron waves fast enough, from the numerical point of view, to be included in a ray-tracing code, and yet accounting for the complicated geometry of stellarators. Since trapped particle effects are particularly important in this Current Drive method and in stellarator magnetic configuration, they are considered by the modification they introduce in the current drive efficiency. Basically, the method consists of integrating the Fisch and Boozer relativistic efficiency, corrected with the effect of trapped particles, times the absorbed power per momentum interval. This one is calculated for a Maxwellian distribution function, assuming a nearly linear regime. The influence of impurities and of species which are not protons is studies, calculating the efficiency for plasmas with Zeff non = 1. Finally, a numerical analysis particularized to TJ-II stellarator is presented. The absorbed power density is calculated by the ray tracing code RAYS, taking into account the actual microwave beam structure. (author) 17 fig. 23 ref

[en] Transport calculations for the Reference Configuration under Neutral Beam Injection in TJ-II are discussed. For all these analysis the Transport Code PROCTR has been used but, in reason of the complex geometry of TJ-II, some modifications to the code have been needed, not only for the absorption, losses and deposition radial profile evaluations, but also for the treatment of the transition between ECRH and NBI or the fit of Transport Coefficients to the different Scaling Laws. The attained centralβ values for high density ( central value around 11 x 10''13 cm''3), in steady, range between a minimum of 1.9% for the GRB law up to 3.6% or 4.2% for those laws that show an explicit dependence with the rotational transform (ISS and LGS), with an intermediate value of 2.8% for the LHD case. Global energy confinement times range between 3.9 and 8.8 ms for the two extreme cases and 5.6 ms for LHD. As well ions as electrons are clearly in the plateau regime, in contrast to the ECRH phase where the electrons are well inside the 1/ν regime, dominated by helical ripple effects. The effect of impurities is to decrease slightly the absorption and the attainable β levels, but only for Zeff values higher than 4 this degradation becomes important. For the stationary state the density remains always below the semiempirical limit, independently of the Zeff value. Even along the first stages of injection, where absorption can be rather low, the limit is not reached, at least for Zeff < 4, so that radioactive collapse along this critical phase should not to be expected. (Author) 14 refs

[en] One of the most exploited features of the TJ-II Heliac, a facility in the Laboratorio Nacional de Fusion (CIEMAT, Madrid), is its ability to explore plasmas in different magnetic configurations. For this reason, there are available libraries that provide the metrics and associated magnitudes for many among all possible configurations. On the other hand, the transport codes that can normally be used to perform transport calculations cannot dea properly with these geometries, which is especially delicate when there are induced plasma currents. In the present work we adopt ASTRA, a transport analysis shell, to study the approximations performed when calculations that impose axi-symmetry (as ASTRA does) are performed on magnetic configurations that are not really axi-symmetric. After describing how we obtain those TJ-II metric averages that must be set in ASTRA, we perform two comparisons: (i) we obtain the vacuum rotational transform as deduced from the metric coefficients but imposing axisymmetry, and compare the results with the rotational transform yielded by the existing libraries; and (ii) we build a ID transport code with TJ-II metrics so its results can be compared with those of ASTRA. In both cases, the differences found indicate that evaluating the evolution of the rotational transform under ohmic induction and transport evolution is acceptable assuming that the geometry itself does not evolve. (Author) 11 refs