A soft X ray imaging system consisting of three arrays of silicon surface barrier diodes is applied to the tomographic analysis of internal plasma perturbations in the T-10 tokamak (R, = 1.5 m, a = 0.32 m). It is found that density limit disruptions in a plasma with a high safety factor at the edge (qa = 3.5-4.5) are associated with joint rotation of the m = 2, n = 1 and m = 1, n = 1 modes, overlapping at the energy quench stage. Electron cyclotron resonance heating is used to prevent density limit disruptions or to recover stable operation of the discharge after the energy quench at the density limit,

This paperpresents an overview of results of the 1994/95 experimental campaign on JET with the new pumped divertor and draws implications for ITERin the areas of detached and radiative divertorplasmas, theuseofberyllium as a divertor target tile malerial, the confmement properties of discharges with the same dimensionless parameters (exceptforthedimensionless Larmorradius) as lT!3R and the effect of varying the toroidal magnetic field ripple in the FTER relevant range.Discbarges withhigh fusionpe~ormance athighcurrentjn steadystate with ELMS and in the ELM-free hot -ion H-mode, are also reported. Limits to operations are discussed and projections to D-T performance are made.

JET was extensively modified in the 1992/93 shutdown. The new pumped divertor and many new systems were brought into operation early in 1994. Operations have progressed to 4 MA plasma current and, with substantial additional heating, H-mode confinement results confirm the expected scaling. The high power handling capability of the pumped divertor with sweeping is estimated at 20 MW for 20 s. H-mode plasmas have large Type I ELMs. With lower hybrid heating alone, 2 MA full current drive has been achieved with good efficiency, and with ICRF power, effective heating and direct electron heating have been demonstrated.

Different types of sawtooth oscillations in T-10 tokamak plasmas (a = 0.3 m, R0 = 1.5 m) have been studied with a two-dimensional soft X-ray tomographic reconstruction method. The analysis of the experimental data indicates that a variety of mechanisms of the sawtooth crash can be realized in T-10. The realization of the mechanisms depends on the electron temperature profile (current density profile) in the central region of the plasma.