Rapid turn-on of shelf-stored tubes: an update

The authors discuss the poisoning during shelf storage, of cathode surfaces as a result of adsorption of ambient gas residuals. The magnitude of the poisoning depends on the type of cathode and residual gas and follows the same order in which these different cathodes adsorbed the various ambient gases (i.e. sticking coefficients). Turn-on consists of several simultaneous processes. These involve the desorption of the poisoning compounds and the regeneration of a new Ba-O surface via the impregnant within the cathode matrix. The effects which various factors have on the reactivation time are also discussed. These include different exposures to poisoning gases, heating time and temperature, Ba impregnant concentration, Ba-O bonding, cathode types, surface composition and pore spacing. In addition, from analysis of low-energy interatomic and valence Auger data, the surface configurations were determined during various stages of poisoning and activation