Compatibility of the Zr-Al alloy with a tokamak plasma environment

We have investigated the compatibility of the Zr-Al alloy bulk getter with a tokamak plasma environment, where the hydrogenic fluxes are sufficient to cause embrittlement in relatively short times. Under normal operating conditions with the getters activated, it is necessary to regenerate the absorbed hydrogenic species before the embrittlement limit is reached. We present a method for determining the loading under tokamak conditions where the Zr-Al surface characteristics can change. During glow discharge cleaning and pulse discharge cleaning, it is not convenient to regenerate. We find, however, that during the cleaning operations the getter self-inerts, thus limitng the loading. We present data and a model which accounts for this behavior in terms of impurity adsorption on the room temperature getter surface during the cleaning operations. (orig.)