Surface conditioning of fusion devices by carbonization: Hydrogen recycling and wall pumping

摘要: Measurements made in the tokamak Torus Experiment for Technology Oriented Research (TEXTOR) with carbonized graphite limiters and Inconel liner (‘‘all carbon machine’’) from a simulation vessel are presented discussed particular emphasis on hydrogen recycling phenomena. The during discharges is strongly affected by wall temperature. Slow loading or deloading of occurs at low (150 °C) temperatures, whereas stationary conditions reached rapidly 350 °C. At 350 °C, coefficients smaller than 1 can be achieved. Active density control demonstrated using pumping effect combination shifts plasma position. No tendency saturation as function discharge number found when temperature A model explanation observed effects. It involves particle induced desorption, thermal outgassing, implantation hydrogen. Particle desorption dominates temperatures high concentrations films, outgassing becomes increasingly important higher temperatures. Hydrocarbon formation release areas exposed to fluxes codeposition C:H possible additional sink, which could effective phenomenon.