Counter injection into ASDEX leads to good particle, momentum, and also energy confinement with XE -80 ms at 1 MW (43 ms for co-injection). The improved confinement develops gradually during the heating phase and correlates with a simultaneous peaking of the density profile. The ion heat transport has to be reduced for a consistent transport analysis, in agreement with theoretical expectations. The sawtooth instability flattens the density profile and transiently reduces the energy content.PACS numbers: 52.55.Fa, 52.50.Gj An important goal of tokamak research is the development of plasma regimes with good confinement under auxiliary heating conditions to provide well established scenarios for the upcoming deuterium-tritium experiments. An important and challenging task is the understanding of the energy and particle transport in a tokamak plasma. In particular, it is the electron transport which is much higher than neoclassical theory predicts and which shows an unexplained variation with plasma parameters. But there is also accumulating experimental evidence that the ion heat transport is enhanced as well above the neoclassical expectation. 1 The effort to increase the plasma temperatures by auxiliary heating generally causes the electron transport to increase even further, resulting in the degraded confinement properties of the L mode. An alternative to the L-mode confinement is the H mode which shows good confinement properties even at high heating power 2 (L denotes low and H high confinement properties).In this paper we report on another operational regime characterized by good confinement properties. It develops when neutral injection as an auxiliary heating method is applied in the counter direction (against the direction of the plasma current). The injection of energetic neutral atoms into the plasma is presently the most successful and reliable auxiliary heating method. The orbits of the energetic ions after ionization depend strongly on the injection geometry. In case of counter injection (ctr-NI) the power and particle deposition profiles are broader and the fraction of ions which is lost during the slowing down phase is somewhat larger. There have been many attempts in the past to study ctr-NI heated plasmas and to compare their characteristics with those under co-injection (co-NI). 3,4 The main results were that particle confinement improves and remarkable differences in impurity transport have been noted. While co-NI reduces the impurity concentration, ctr-NI causes the impurities to accumulate in the plasma center. The different transport behavior was explained on the basis of neoclassical impurity transport in a situa-tion with momentum input and plasma rotation. 5 The energy confinement time T£, however, was found to degrade like that of L-mode plasmas heated with co-NI.On ASDEX we observe improved particle confinement with ctr-NI both affecting the bulk plasma (leading to a density increase without any external gas puffing only fueled by the beam) and giving rise to low-Z and high-Z impurity acc...

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