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Time-resolved high-resolution soft x-ray spectra from gas-puff injected Ar impurity ions have been investigated for neutral beam heated and ohmically heated discharges in the TEXTOR tokamak. The experimental spectra show systematic deviations from corona model calculations for the line intensities of the forbidden He-like lines x, y, z and the Li-and Be-like dielectronic satellite spectra: theoretical corona model calculations predict intensities significantly too low. High-intensity Li-like inner-shell excited satellites correlate with the neutral beam injection. The discrepancies could also be observed in the stationary phase of an inductively heated discharge. In the heating phase the discrepancies are even larger. We propose charge-exchange processes between the neutral atoms and the impurity ions as an explanation of the experimental findings. Good agreement with the experimental observations can then be obtained without the need for invoking large (anomalous) diffusion coefficients. A self-consistent coupling of the population kinetics of the neutrals and the impurity ions, also taking into account charge-exchange processes from excited states of hydrogen/deuterium permit the determination of the neutral fraction and of the electron lifetime on the sole basis of impurity spectra analysis. Independent Monte Carlo simulations of neutral gas transport also provides the ionization degree in the centre and the electron lifetime. These calculations are also in good agreement with the spectroscopic results.

Thin pure aluminum wires which are rapidly vaporized in small glass capillaries by means of a short pulse current from an electrical discharge convert into a nonideal plasma near solid density. For a short period of time, the inner wall of the rigid glass capillary confines the homogeneous plasma until the induced pressure pulse disintegrates the capillary. During this part of the discharge, no instabilities occur, and the transient plasma covers a range of parameters according to the charge of the capacitors: the particle density ranges from 0.001 to 1.0 g/cm 3 , the temperature from 7000 to 24 000 K and the electron density from 2.0ϫ10 25 to 3.0 ϫ10 26 m Ϫ3 . Plasma conductivity was deduced by simply applying Ohm's law to the measured voltage drop across the wire and to the measured current through the wire. ͓S1063-651X͑98͒14411-2͔PACS number͑s͒: 52.25. Fi, 52.25.Jm, 52.25.Qt, 72.15.Ϫv

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