CONFINEMENT TRANSITIONS WITH RADIATION COOLING IN TEXTOR-94

New experiments performed at high power with radiation cooling on TEXT OR-94, upgraded for long pulses, have shown the following. (i) Improve d confinement conditions at high density (for which the plasma is main ly thermal) lasting for several seconds up to the present maximum flat top time of the upgraded machine with a low and stationary central im purity content. Note that the radiation occurs near the plasma edge, m ainly inside the last closed magnetic flux surface. (ii) The existence of confinement transitions during the radiatively cooled phase of the discharge: the already observed transitions from higher to lower conf inement regimes have been confirmed but, remarkably, transitions from lower to higher confinement are now also present, leading to an improv ement of the confinement time of up to a factor of three.