Confinement loss in JET ELMy H-modes

The concentration of unspent zinc-based hydrogen sulfide scavenger in an oil-based drilling fluid is controlled by selectively dissolving and extracting the unspent scavenger in a solvent, such as glacial acetic acid, separating the aqueous solution, measuring the concentration of dissolved zinc in the aqueous solution, for example, with an X-ray fluorescence spectrograph, and utilizing the results of the measurements to proportion the extent of changes in concentration of the scavenger in the drilling fluid.