The transport properties of injected impurities were examined in the TEXTOR tokamak to determine the influence of the limiter configuration. Using laser blow-off and the decay of the centrally located charge states of iron, transport scaling studies were performed in which plasmas bounded by standard poloidal limiters and plasmas bounded by the ALT II toroidal limiter were compared. The results presented show the appearance of the long impurity confinement regime in both limiter configurations which was coincident with the detachment of the plasma. Shifts in the critical density for the onset of this regime were seen. Possible plasma conditions responsible for these differences are addressed. The absence of significant accumulation of intrinsic impurities during the long confinement regime indicates a different generation/transport mechanism in detached plasmas.
Plasma initiation and preliminary magnetic control in the HL-2M tokamak