[en] The possible scope of a new CRP on atomic data relevant for neutral beam injection (NBI) should be to constrain and focus on the data issues to all processes relevant when the beam particles have left the sources, which include beam interacting Maxwellian electrons as penetrating plasma edge. The special attention is needed for cross-sections at high energy regions and asymptotic behaviors. Currently available data sets of some relevant processes such as heavy particle collisions involving He and metastable He are lacking the correct asymptotic behaviors at low and high energies.

[en] Any selfonsistent modeling of the plasma in a Tokamak boundary-layer must include neutral particle effects. Important processes involving these particles are dissociation, ionization and charge-exchange. Interactions with the walls must include (ballistic) backscattering, absorption, desorption and reemission. In general, numerical simulation and detailed analytical treatments require strong simplifying assumptions. On the other hand stochastic simulation (''Monte-Carlo''-simulation) can be done without any major approximations in the physical models, but usually at the expense of long computation times. Following the lead of neutron-transport-codes, this work takes advantage of both types of simulations by making use of ''smoothing effects'' on random-variables when conditional expectation values are calculated. In this approach, a Monte-Carlo code, which keeps the dimensionality optional, has been developed, so that, depending on symmetry, one-, two- or threedimensional profiles can be computed for up to nine different neutral particle species. The code is applied to same models, which are designed to describe the neutral gas behaviour in the Tokamaks: UNITOR (Duesseldorf), ASDEX (Garching), TEXTOR (Juelich) and JET (Culham, England). (orig./GG)

[en] Cross sections and rate coefficients are provided for collision processes of CH_y and CH_y⁺ (1≤y≤4) hydrocarbon species with electrons and protons in a wide range of collision energy and temperature. The considered processes include: electron-impact ionisation and dissociation of CH_y, dissociative excitation, ionisation and recombination of CH_y⁺ with electrons, and charge- and atom exchange in proton collisions with CH_y. In dissociative processes all important reaction channels are considered separately. Information is also provided about the energetics for each individual reaction channel. The cross sections and rate coefficients are represented in analytic fit forms. (orig.)

[en] Removal of helium, the ash from the D-T-fusion reaction, from a burning plasma flame, is one of the critical issues for future thermonuclear burning plasma. Even in plasmas driven by additional heating to large Q-values this is a severe problem. Recombination of fuel and ash ions at plasma exposed surfaces, re-emission as neutral particles and subsequent pumping (''recycling'') provides, at least in principle, the mechanism to flush the plasma from its ash. However, plasma surface interaction has to be limited in order to protect vessel components from excessive thermal load, often a conflicting requirement

[en] It has been shown that conventional 2D edge plasma transport models, which are used routinely since more than 20 years for axially symmetric limiter or divertor edge plasmas, have been extended successfully now to a complex 3D magnetic field topology. This is largely due to progress in computing power. Consequently, it has now become possible to employ this detailed numerical bookkeeping tool in future applications on TEXTOR-DED scenarios. By comparison with experimental results, it is now possible to distinguish by numerical calculations, between possible new phenomenons in ergodic edge plasmas on the one hand, and merely complex geometrical effects on the other hand. The future task of edge plasma science with the DED will be to constrain the numerical model as much as possible by experimental data, and then to identify and document those mismatches between calculation and experiment which survive despite the still large number of free model parameters. (orig.)

No abstract available

[en] Modelling of kinetic transport effects in magnetic fusion devices is of great importance for understanding the physical processes in both the core and and the scrape off layer (SOL) plasma. For SOL simulation the EIRENE code is a well established tool for modelling of neutral, impurities and radiation transport. Recently a new trace ion transport module (tim), has been developed and incorporated into EIRENE. The tim essentially consists of two parts: 1) A trajectory integrator tracing the deterministic motion of a guiding centre particle in general 3D electric and magnetic fields. 2) A stochastic representation of the Fokker Planck collision operator in suitable guiding centre coordinates treating Coulomb collisions with the plasma background species. The TIM enables integrated SOL simulation packages such as B2-EIRENE, EDGE2D-EIRENE (2D) or EMC3-EIRENE (3D) to treat the physical and chemical processes near the divertor targets and in the bulk of the SOL in greater detail than before, and in particular on a kinetic rather than a fluid level. One of the physics applications is the formation and transport of hydrocarbon molecules and ions in the divertor in tokamaks, where the tritium co deposition via hydrocarbons remains a serious issue for next generation fusion devices like ITER. Real tokamak modelling scenarios will be discussed with the code packages B2-EIRENE (2D) and EMC3-EIRENE (3D). A brief overview of the theoretical basis of the tim will be given including code verification studies of the basic physics properties. Applications to hydrocarbon transport studies in TEXTOR and ITER, comparing present (fluid) approximations in edge modelling with the new extended kinetic model, will be presented. (Author)

[en] The burn condition for D-T plasmas is derived in a form which acounts for the stationary helium concentration being selfconsistently determined by the coupling of the fusion power and helium production. The ratio of the global α-particle confinement time τ_α^* (definition in the text) to the energy confinement time τ_E is taken as a qunatity characterizing the prevailing confinement and exhaust regime. It is shown that for an ignited and stationary burning D-T plasma this ratio needs to remain sufficiently below 15 (or below 10 for typical impurity concentrations). This poses a lower limit to the required helium exhaust efficiency and indicates that operational regimes might be desirable where the internal particle confinement time does not diverge too far from and in excess of the energy confinement time, and where the boundary layer - e.g. through high particle density and outward flow - acts as a sufficient shield against recycled α-particles. It is further demonstrated that for any given temperature (and for otherwise equal overall exhaust and recycling conditions) either burning can be achieved at two quite different values of the fusion parameter (triple product nxTxτ_E) and ash concentrations (one at low concentrations in the range 5-20%, the other in the range of 20-35%) or not at all. A similar evaluation applied to the D-³He fusion reaction leads to even more stringent limits on the ratio τ_α^*/τ_E, which must be smaller by a factor 3 to 4 compared to the D-T case. (orig.)

[en] Atomic, molecular and plasma surface interaction data (AMS data) are key ingredients in fusion edge plasma transport codes. These codes are indispensible tools both for interpretation of current magnetic fusion experiments, in particular for the plasma domain near exposed components of the furnace chamber. But they are also used to guide reactor design of particle (ash) and heat removal components (so called divertors) from future fusion power plants. In magnetic fusion research the issue of atomic, molecular and PMI data used in transport codes is often regarded as being largely 'in hand', and the focus is often on transport terms rather than on the collision integrals in the kinetic equations. However, in particular the favorable plasma states of so called 'divertor detachment', which are currently regarded as the divertor operational regime for the ITER fusion reactor and possible also for the first fusion power plants, show a chemical richness and sometimes even dominance over transport issues not otherwise encountered in magnetic fusion. In order to allow evaluation of AMS data in fusion edge transport codes (and their further improvements) the only way seems to be via public exposure of AMS data as activated in any particular code application. For this puropse the online data analysis tool HYDKIN (www.hydkin.de) is developed and maintained at FZJ. The goal of this online 'toolbox' is threefold: a) processing of the ''as unprocessed as possible'' raw atomic data (typically: cross sections vs. collision energy) into condensed data as needed in transport codes (e.g.: rate coefficients, or collisional radiative ''effective'' rate coefficients based on quasi steady state assumptions for some of the species, etc. b) public exposure of atomic and molecular data as finally active in particular code applications, including also their extrapolation beyond the tabulated or fitted range, as encountered during the code runs, c) spectral analysis of the collision-radiative rate matrix of the system, providing both identification of possibly underlying reduced chemistry models as well as closed form sensitivity coefficients for all rates and species. The status of the HYDKIN toolbox, its underlying cross section database, its interface to the EIRENE kinetic (Monte Carlo) Boltzmann solver, and results from a sensitivity analysis for the example of hydrocarbon fragmentation in fusion divertor plasmas is discussed. (author)

[en] This paper deals with two, on first sight only loosely related topics: Firstly, with the issue of helium removal from a stationary burning D-T fusion device, and secondly, with the so called 'recycling process' in the plasma near exposed first wall components. The strong interrelation of these two issues will be a major point in the discussion. It is observed that the helium removal for steady plasma burn is apparently very closely connected with the details of plasma recycling via the neutral particle channel. Firstly because only neutral ash particles can be channeled into pumping stations, but secondly also because of the effects of neutral particle recycling on the edge plasma flow, and thus on the forces acting on the ionized helium particles. Various conflicting requirements have to be met simultaneously such as: good confinement (for energy balance); poor confinement (for particle throughput); strong pumping (for ash removal); and weak pumping (for favorable high recycling conditions). The search for a plasma edge configuration compatible with all these constraints, both experimentally and by computer simulations, is one of the key design issues to be solved before a reliable plasma surface interaction concept for ITER (and a future reactor) can be developed. 9 refs., 5 figs