[en] It is established, that three principally different types of the plasma stationary states may be realized in tokamaks: 1) the discharges, wherein the electron and ion channels are subjected to the neoclassical theory; 2) the charges, wherein the longitudinal conductivity is the Spitzer one the ions are neoclassical and the electron channel is anomalous; 3) the discharges, wherein the ion and electron channels are anomalous. The nondimensional parameters, responsible for realizing each of three types of charges are determined. It follows from the realization criteria for the various types of states, that the second-type discharges are most typical for the tokamaks with modern parameters. The physical cause of originating various-type discharges consists in the principally different role of turbulent fluctuations in the dynamics of the ion and electron components of the finite-size magnetized plasma. The problem on the profiles self-congruence is considered. The law of the temperature conductivity coefficient growth by approaching the plasma string periphery is determined

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[en] The features of reversed shear configuration and current research status are discussed. The relations from trade-off consideration between MHD stabilities and bootstrap current fraction, and the operational contours of advanced tokamak are obtained. The operational regime and corresponding density and temperature profiles for appropriate FEB reversed shear configuration (FEB-RS) are found. The physical parameters of FEB-RS fusion reactor core are calculated. Studies show the plasma performances of reactor core are much improved compared with the same size FEB designed earlier

[en] A framework is developed for investigating complex multivariate relationships in a dataset. This is based on using the universal approximation abilities of a multi-layer perceptron (MLP) neural network to predict a quantity of interest from a large set of parameters. A measure of redundancy is derived, and used in such a way that the average influence on the predicted quantity from any parameter can be estimated. Input parameters can be ordered in terms of increasing redundancy and therefore assist in finding the most important parameters a phenomenon of interest depends upon. In spite of the problem being multi-dimensional, the functional form of the one-to-one relationship between a parameter and a quantity of interest can be visualized. This framework is then used together with sensitivity analysis to investigate the dependence of the total radiated power of JET plasmas on a large number of parameters, leading to the identification of a much smaller set of parameters to be used in an effective MLP predictor of total radiated power. (author)

[en] This paper reports a comparative experimental study of large-scale coherent structures which are embedded in the turbulent fluctuations observed in a magnetized plasma device. The confining magnetic field is purely toroidal and has no rotational transform. Turbulent density fluctuations of two different plasma discharges are compared: thermionic discharge and inductive resonant wave heating. It turns out that fundamental features of spatiotemporal structures depend primarily on the plasma source and not on the magnetic field configuration. In the thermionic discharge plasma double-vortex structures and in the wave-heated plasma single-vortex structures are found. This can be attributed to the injection of mass and negative space charge in the case of thermionic discharge. The phase coherency is determined by the large-scale coherent structures. Phase shift of approx. π/2 between plasma potential and density structures changes in sign for the two different plasma sources. (author)

[en] A theoretical investigation of the dynamics of plasma discharge, excited by the fast 6 ns full width at half maximum current pulse with 4.5 kA peak in a 0.8 mm diameter channel inside an alumina capillary filled with Ar, is performed by computer simulation. A one-dimensional two-temperature magnetohydrodynamic model that takes into account plasma dynamics as well as the ablation of the wall material under the heat flux from the plasma has been explored. Simulations for Ar initial pressures of 100-500 mTorr show that a hot dense uniform plasma core is formed at the centre of the discharge channel. The parameters of this core are favourable for soft x-ray lasing at 46.9 nm due to the generation of population inversion in the plasma by the collisional electron excitation of Ne-like Ar IX ions. (author)

[en] The Full Scale Sector Model Project, which was initiated in 1995 as one of the Seven Large Projects for ITER R and D, has been continued with the joint effort of the ITER Joint Central Team and the Japanese, Russian Federation and United States Home Teams. The fabrication of a full scale 18 deg. toroidal sector, which is composed of two 9 deg. sectors spliced at the port centre, was successfully completed in September 1997 with a dimensional accuracy of ±3 mm for the total height and total width. Both sectors were shipped to the test site at the Japan Atomic Energy Research Institute and the integration test of the sectors was begun in October 1997. The integration test involves the adjustment of field joints, automatic narrow gap tungsten inert gas welding of field joints with splice plates and inspection of the joints by ultrasonic testing, as required for the initial assembly of the ITER vacuum vessel. This first demonstration of field joint welding and the performance test of the mechanical characteristics were completed in May 1998, and all the results obtained have satisfied the ITER design. In addition to these tests, integration with the midplane port extension fabricated by the Russian Home Team by using a fully remotized welding and cutting system developed by the US Home Team was completed in March 2000. The article describes the progress, achievements and latest status of the R and D activities for the ITER vacuum vessel. (author)

[en] A recent article (details in the title) reported a generalized scaling law for the ignition energy of inertial confinement fusion targets in terms of the in-flight fuel adiabat, the peak implosion velocity, and the peak drive pressure. Previous scaling laws had not taken into account the scaling with the peak drive pressure. The key point of the analysis was the realization that the adiabat of the stagnated fuel is not simply given by the in-flight adiabat, as previously assumed implicitly, but instead depends on implosion history, and involves the drive pressure. In these comments it is pointed out that, while the simulations in said recent article account for complicated transport and equations of state, a simpler physical model based on ideal gas dynamics without heat conduction or any other transport physics advanced previously by one of the authors of these comments (for instance, Meyer-ter-Vehn, J. and Schalk, C., Z. Nat. forsch. 37A, 955 (1982)) yields quite similar scaling. This observation leads to a form of the scaling laws in terms of only the drive pressure and the Mach number, indicating the central importance of these variables, rather than the complicated transport and equations of state, for the determination of the ignition temperature