Molybdenum (Mo) thin films have been deposited on soda-lime glass substrates using a DC magnetron sputtering system. Their electrical resistivity, and their morphological, structural and adhesive properties have been examined with respect to the deposition power, deposition time and substrate temperature. The electrical resistivity of the Mo films could be reduced by increasing any of the above parameters. Within the range of the investigated deposition parameters, the films showed a mono-crystalline nature with a preferred orientation along the (1 1 0) plane. The Mo films adhesion to the soda-lime glass could be improved by increasing the substrate temperature. At a deposition power of 200 W, deposition time of 20 min and substrate temperature of 450°C, Mo thin film exhibiting mono-crystalline structure with thickness equal to 450 nm and electrical resistivity equal to 1.85 · 10 À4 X cm was obtained.ª 2011 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V.All rights reserved.

The transport of neutral helium atoms near divertor or limiter target plates in fusion devices has been studied using Monte Carlo simulation techniques. The atomic processes of ionization of helium atoms by electron impact and elastic scattering with plasma ions are included as well as the thermal motion and the streaming of the ions along the magnetic field. The results obtained show significant effects of elastic collisions below about 10 eV, causing a substantial fraction of the helium atoms to be reflected back to the target plate. This effect can be beneficial for the pumping of helium from the discharge chamber. A two-dimensional Monte Carlo code has been used to study helium recycling near a vented target plate. It is found that a substantial pumping efficiency can be obtained if the transparency of the vented plate is high (≥30%) and the ports are aligned nearly parallel to the magnetic field.

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