A new type of water-vapour replenisher and its application to a t.r. switch

A low-pressure water-vapour replenisher is described for use in a t.r. switch. The water-vapour pressure exerted by the replenisher is sensibly constant over the temperature range ¿20°C to + 120°C. Measurements of the physical properties of the replenisher are discussed with reference to the theory of adsorption advanced by Polanyi. The observed change in these properties when an electrodeless gas discharge is excited in the same vacuum enclosure, but remote from the replenisher, is described, using various rare gases to support the discharge. Release of water vapour from the replenisher under these conditions is attributed to the action of metastable atoms at the adsorbed water-vapour layers. The use of the replenisher in a t.r. switch led to a switch having a long life and short recovery time, once some problems of isolation of the replenisher from the d.c. and r.f. gas discharges had been overcome.