A new equilibrium reconstruction procedure using magnetic, line integrated electron density and Faraday rotation measurements has been developed. The method has been applied to a number of elongated tokamak equilibria which were computed by using a free-boundary MHD equilibrium code. Typical errors in four global plasma parameters (|3 p , fij, n and qo) are evaluated as functions of the measurement errors and the number of source function parameters. Assuming realistic random perturbations in the measurements, the method allows source functions with up to six independent parameters to be reconstructed. It is shown that, when electron density and Faraday rotation measurements are included, the accuracy in the determination of qo is increased by at least a factor of two, compared with cases without Faraday rotation data. The effects of adding a diamagnetic probe and of varying the plasma elongation are also investigated.

During the first year of operation, the TCV tokamak has produced a large variety of plasma shapes and magnetic configurations, with 1 . O B J1.46T, I <800kA, ~S2.05, -0.7G%0.7. A new shape control algorithm, Eased on a finite element reconstruction of the plasma current in real time, has been implemented. Vertical growth rates of 800 sec-', corresponding to a stability margin f=l.IS, have been stabilized. Ohmic H-modes, with energy confinement times reaching 8 h s , normalized beta (p ,aB/I> of 1.9 and z P R 8 9 -P of 2.4 have been obtained in singlenuB X-point deuterium discharges with the ion grad B drift towards the X-point. Limiter H-modes with maximum line averaged electron densities of 1 . 7~1 0~~m -~ have been observed in D-shaped plasmas with 360kASIp&00kA.

The detailed experimental data obtained on the TCA tokamak [Proceedings of the 11th Symposium on Fusion Technology (CEC, Luxembourg, 1981), Vol. I, p. 601] concerning the antenna loading and wave fields as a function of the Alfvén wave spectrum are presented. The plasma density, plasma current, working gas, toroidal magnetic field, and frequency were varied systematically and the detailed results are compiled and discussed. In addition the phasing of the antenna currents was varied systematically, thereby exciting different combinations of modes, including pure traveling waves. The conclusions relevant to the design of an antenna system have been stressed.

A rotating coil probe for the magnetic field measurement on a long pulsed tokamak Rev.The TCV Tokamak was designed to create a large variety of plasma shapes. Such a large flexibility requires high precision magnetic measurements with a good spatial coverage. This article gives a detailed description of the magnetic sensor geometry, fabrication, calibration, the associated electronics, and the diagnostic operation and monitoring. A substantial effort has been made to quantify the precision in the measurements and a novel method has been developed to derive corrections in the sensor position and calibration which optimise the consistency of the entire measurement set. Accuracy of 0.5 mWb in the poloidal flux and 1 mT in the magnetic field with a position error of a few mm have been achieved.

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 off-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 normalized beta(N) approximately 0.6), has been sustained for the entire duration of the heating pulse, or over 200 electron energy confinement times and 5 current redistribution times.