Determination of the pressure and the released gas flow in a chamber connected through a small conductance with the chamber equipped with gauges

During evacuation of the X-ray tube there are conditions when vacuum gauges cannot be connected directly but only to an auxiliary volume connected to the X-ray tube through a tube of a relatively small conductance. Then the m easured pressure is different from that in the X-ray tube. To determine the pressure and the flow of the released gas in the X-ray tube, it is necessa ry to calculate these from the measured pressure. Under certain assumptions , which, are usually fulfilled on evacuation of sealed-off vacuum systems, formulae enabling this calculation were derived. Experimental data, which w as obtained during extensive study of X-ray tube evacuation, was used to pu t the formulae to the test. (C) 2001 Elsevier Science Ltd. All rights reser ved.