Vacuum enhancing system or non-evaporable getter of the type used en solar-receptor vacuum tubes which comprises a series of non-evaporable getter material pads the geometry of which is that of a prism with rounded corners and said pads are drilled through the centre thereof and linked by means of a cable ending in a quick-fit closure that allows the fitting thereof to be automated. This system is placed downstream of the expansion-compensating device in the form of non-radial bellows in the longitudinal direction and in the void defined by the vessel that is the interface part between the absorber tube and the expansion-compensating device. A getter system is placed in a radial arrangement, at each of the two ends of the receptor tube, resulting in a receptor tube of completely symmetrical geometry.