A series of measurements has been carried out on ETA-BETA II at various plasma currents between 100 and 180 kA to study the time evolution of the electron temperature Te and density ne. It is for the first time that such a study has been performed under the quasi-steady conditions of the current flat-top phase. The temperatures were found to rise from below 100 eV at current peak to more than 200 eV towards the end of the discharge with all currents. The increase of Te is closely related with the decrease of ne and hence with the increase of the ratio I/N. Linear scaling of Te with current is found only when the evaluation is performed at constant I/N. The poloidal beta varies little over a wide range of plasma parameters and shows a negative dependence on I/N. The resistance anomaly factor is found to rise from below 3 soon after current peak to as high as 15 in some cases at the end of the discharge. A universal and almost linear dependence of the increase of on I/N is apparent in the range of currents investigated.
Enhanced performance of high current discharges in JET produced by ICRF heating during the current rise