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Ion beam coating techniques like ion implantation (II), ion beam mixing (IBM), and ion beam assisted deposition (IBAD) offer the possibility of protecting target windows against corrosion by very high quality thin layers of inert materials. 11:Ion implantation consisted of the preparation of thin surface layers by implanting ions with energies from 50 to 600 keV preferably into metallic substrates to form alloys.IBM: Ion beam mixing was used for preparation of thin layers from materials which were previously coated galvanical-ly or by evaporation techniques. Deposits were interfacially mixed with the support material through bombardment with rare gas ions. IBAD:Ion beam assisted deposition consisted of the deposition of a substrate vapor under simultaneous bombardment of the support preferably with a rare gas ion beam of 1-30 keV.The latter two techniques led to excellent adhesion of the coating by interlocking layer and support. No spattering, tearing or rubbing of the layer was observed even under extreme conditions of high heat and pressure load. Thin layers prepared through IBM or IBAD procedures usually had a thickness of 0.01-1 pm and were homogeneous. They showed very low mechanical stress and low microporosity. The I1 technique generally produced stable and metastable surface alloys by a low temperature non equilibrium process without influencing significantly the bulk properties of the support. The layer thickness usually was in the range of 0.02-1 pm. Auger electron spectroscopy was used for the investigation of layer quality. Inconel 600 , nickel/chromium (80%Ni/20%Cr) , copper, and copper/beryllium (98%Cu/2%Be) were used to date as support materials. The foils had a thickness of 10 and 20 pm and were coated by IBAD under simultaneous bombardment with 6 keV argon ions with layers of pure Ni ranging from 0.1-1.2 pm, and with layers of car on ranging from 0.1-0.7 pm. These preparations were tested in [ l ' F ] F productions as target windows of a Ne/F2 gas target system witi deuteron beam currents ranging from 10-20 pA at fluorine concentrations of 0.5-5%. Results of these experiments and further examples will be presented.

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