The alpha particles are coupled to the hydrogen/deuterium background plasma via charge exchange processes. Population kinetics calculations show that in the framework of standard models, the charge transfer from hydrogen/deuterium excited states to helium leads to a strong divergence of the atomic populations and to a critical dependence on the number of quantum states retained in the simulations. The divergence is related with the large crosssections for charge transfer from excited states of the background atoms. For typical parameter conditions (e.g., ITER) the charge-exchange-induced population flow may even reach the level of flow typically induced by turbulent diffusion. A self-consistent excited-states coupling approach of atomic kinetics is proposed, which avoids divergences and critical dependence on the number of states. This approach also removes free parameters from the system and provides therefore the ideal basis for a pure diffusion analysis in space which is requested to test global effects of turbulent transport theories.The confinement of the fusion plasma is one of the most important issues in the magnetic fusion research and intensive efforts have therefore been devoted to the understanding of the particle transport. However, the physical processes that underlie plasma transport in torodially confined plasmas are not so well understood. The plasma transport induced by Coulomb collisions (the so-called classical or neo-classical transport) is often much less than what is actually observed [1, 2] and thus the transport is called anomalous.Methods which determine the particle transport independent of theoretical plasma models are therefore of extraordinary and fundamental importance in the magnetic fusion research. Spectroscopic methods have turned out to be very effective. One of the most powerful spectroscopic methods is based on the space-and time-resolved observation of line emission from impurity ions [1][2][3]. This emission is simulated from an atomic physics model with given temperature and density profiles [1,4] and contrasted with the experimental data. Diffusion and convective velocity parameters, D and V , respectively are then determined by matching best the experimental observations [1-3].

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The variation of the energy interval between the intercombination line (1s2p(3P1)→1s2) and the resonance line (1s2p(1P1)→1s2) of He-like aluminium with plasma density and temperature is investigated. Since such energy interval is equivalent to the exchange energy of the state 1s2p(3P1), we consider the dependence of this energy shift on the plasma environment. It was found that the shifts of exchange energy increase (decrease) with the increase of electron density (electron temperature), and the shifts of exchange energy become more sensitive to the electron density as the electron temperature decreases, i.e. in the strongly coupled plasma regime. An approximately linear relation is found between the shifts of exchange energy and the electron density. The results show that dense plasma effects are very important for the simulation of the spectral fine structure. The relative shifts between the intercombination (1s2p(3P1)→1s2) and the resonance line (1s2p(1P1)→1s2) are discussed for diagnostic applications.

The radial dependence of the free electron density within the ion sphere radius in finite temperature dense plasmas shows characteristic scaling laws that permit us to derive analytical plasma screening potentials. A generalized analytical approach is developed which shows good agreement with self-consistent quantum mechanical calculations. It is empirically discovered that anomalous strong scaling in the analytical model provides agreement with data obtained in a regime where the lattice structure still prevails.

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Here, we report results of an experiment creating a transient, highly correlated carbon state using a combination of optical and x-ray lasers. Scattered x-rays reveal a highly ordered state with an electrostatic energy significantly exceeding the thermal energy of the ions. Strong Coulomb forces are predicted to induce nucleation into a crystalline ion structure within a few picoseconds. However, we observe no evidence of such phase transition after several tens of picoseconds but strong indications for an over-correlated fluid state. The experiment suggests a much slower nucleation and points to an intermediate glassy state where the ions are frozen close to their original positions in the fluid.

a b s t r a c tThe FLASH XUV-free electron laser has been used to irradiate solid samples at intensities of the order 10 16 W cm À2 at a wavelength of 13.5 nm. The subsequent time integrated XUV emission was observed with a grating spectrometer. The electron temperature inferred from plasma line ratios was in the range 5-8 eV with electron density in the range 10 21 -10 22 cm À3 . These results are consistent with the saturation of absorption through bleaching of the L-edge by intense photo-absorption reported in an earlier publication.

An analytical expression for the Lyman α line profile is proposed, for the purpose of radiation transport studies in divertor plasmas. It is shown that the coupling between Zeeman and Stark broadening has to be retained so as to describe accurately the line shape. This is confirmed by comparison to numerical simulations. The latter furthermore allow to quantify the accuracy of the Stark broadening model for the whole range of conditions encountered in divertors. Lyman α and Lyman β lines are investigated in details.