Abstract: The invention relates to a cold cathode pressure sensor comprising a gastight housing having a test gas inlet, an anode and a cathode arranged in said housing, and a radiation source directed to said cathode for igniting a cold cathode discharge. Said housing is at least partly made of glass. Said radiation source is arranged outside said housing and irradiates said cathode through the housing glass. Said radiation source substantially emits a radiation of a wavelength of more than 350 nm and less than 1,400 nm.

Abstract: In a leak detector with a sniffer probe, the invention provides that the sniffer tube (12), which is provided in the form of a throttling capillary line and which leads from the sniffer probe (10) to a vacuum chamber (13), has an inner cross-sectional area that varies in the longitudinal direction. The cross-sectional area enlarges in the direction of flow of the drawn-in gas, thus from the inlet (11) to the vacuum chamber. This reduces the dead time, i.e. the transit time of the gas through the sniffer tube (12).

Abstract: The invention relates to a gas transmitter (1) with selective gas permeable surfaces (4), comprising a support disc (3), provided with a number of through openings (2), made from a semiconductor material, a membrane (5), covering the openings (2) in the support disc (3) which forms the selective gas permeable surfaces (4) and means for controlling the temperature of the membrane (5). According to the invention, the temperature control means may be simplified whereby the support disc (3) itself serves as a means for controlling the temperature of the membrane (5).