Fast ion confinement in negative triangularity plasmas on the TCV tokamak

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SULTAN (acronym for SUpraLeiter TestANlage) is the major facility for testing and evaluating high current superconductors for the next generation of fusion magnets. Located at Paul Scherrer Institut PSI in Villigen, Switzerland, the facility was constructed in the late seventies as a common venture of three European Laboratories: ENEA (Italy), ECN (Netherlands), and SIN (Switzerland). Since 1994 SULTAN is operated by EPFL-CRPP and is offered by the European Commission as contribution to the worldwide cooper

Current profile tailoring by electron cyclotron heating (ECH) and current drive (ECCD) is used to improve central electron energy confinement in the TCV tokamak. Counter-ECCD on axis alone achieves this goal in a transient manner only. A stable scenario is obtained by a two-step sequence of err-axis ECH, which stabilizes magnetohydrodynamics modes, and on-axis counter-ECCD, which generates a flat or inverted current profile. This high-confinement regime, with central temperatures up to 9 keV (at a. normaliz

A high temperature superconducting current lead for application in fusion magnets was developed in collaboration of three laboratories. Bi-2223 Ag/Au tapes were selected to be used in the current lead and two industrial fabricated 10 kA modules were extensively tested. Both modules were used in the 20 kA current lead which was successfully tested in continous operation at 20 kA and over short time up to 40 kA. (C) 2001 Elsevier Science B.V. All rights reserved.

Alfven eigenmodes (AEs) with intermediate toroidal mode numbers are modelled using the global gyrokinetic PENN code to determine the stability of high performance tokamak discharges in the presence of energetic particles. A large plasma pressure and a weak magnetic shear in the core give rise to radially extended kinetic AEs, which are stabilized by the high shear at the edge of a divertor (X point) configuration. Large values for the safety factor and the ion Larmor radius in reversed shear operation may h

Recent stability results of external kink modes and vertical modes in compact stellarators are presented. The vertical mode is found to be stabilized by externally generated poloidal flux. A simple stability criterion is derived in the limit of large aspect ratio and constant current density. For a wall at infinite distance from the plasma, the amount of external flux needed for stabilization is given by F-i = (kappa(2) - kappa)/(kappa(2) + 1), where kappa is the axisymmetric elongation and F-i is the fract

In Se.C.R.E.T.S. (Segregated Copper Ratio Experiments on Transient Stability), the stability performance under transverse field transient is compared for two Nb3Sn cable-in-conduit conductors which differ only because of the different distribution of the stabilizing copper, either included in the Nb3Sn strand cross section or segregated as bundled copper wires. If the segregated copper is found to be effective for stability purposes, the copper fraction in the Nb3Sn strands can be Substantially reduced, wit

The energy confinement time of TCV Ohmic, L-mode discharges is observed to depend strongly on the plasma shape, improving slightly with elongation and degrading strongly as triangularity is increased from zero to positive values. The thermal conductivity of these plasmas is found to be independent of the shape. This observation, combined with geometrical effects on the temperature gradient and a degradation with increasing input energy flux, can explain the observed variation in the energy confinement time.

Electron cyclotron resonance heating (ECRH) experiments at 39 GHz with power levels similar to those of Ohmic heating have been conducted in the TCA tokamak, in either the X-mode or the O-mode. ECRH was observed to be more efficiently absorbed in low density and low q(a) discharges. At low density the central electron temperature increased by a factor of two over Ohmic values and the stored energy increased by 40% when up to 80% of the plasma energy was supplied by ECRH. During low density ECRH operation, t

The paper describes measurements of the sawtooth instability in JET, in which the instability wave function is shown to extend to the edge where it is measured using magnetic coils. The numerous magnetic probes in JET allow the time evolution of the (n = 0, 1, 2, 3) toroidal Fourier components to be analysed. The n = 1 magnetic component is similar to the m = 1 soft X-ray centroid motion. This fact indicates the potential of edge signals in retrieving the poloidal mode spectrum of the q = m/n = 1 surface. T

Fast ion confinement in negative triangularity plasmas on the TCV tokamak

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User specifications for conductor samples to be tested in the SULTAN facility

Long-pulse improved central electron confinement in the TCV tokamak with electron cyclotron heating and current drive

Development program of a 60 kA high temperature superconductor current lead for the ITER toroidal field coils

Stability of Alfven eigenmodes in optimized tokamaks

Magnetohydrodynamics stability of compact stellarators

Se.CRETTS : A stability experiment on the role of segregated copper in Nb3Sn cable-in-conduit conductors

Influence of plasma shape on transport in the TCV Tokamak

Electron-Cyclotron Resonance Heating on the Tca Tokamak

Global Sawtooth Instability Measured by Magnetic Coils in the Jet Tokamak