GB868061A - Improvements relating to regulating arrangements for gaseous electric discharge devices - Google Patents

Abstract

868,061. Temperature control of discharge devices. COMPAGNIE FRANCAISE THOMSON-HOUSTON. Dec. 19, 1957 [Jan. 22, 1957], No. 39521/57. Class 40 (1). [Also in Group XL (a)] The source of heating current for the heater element of a gaseous electric discharge device contains means responsive to variations in ambient temperature to modify the heating current accordingly. The heater element is in heatexchange relationship with material containing absorbed gas so that variations in ambient temperature cause this material to liberate or absorb gas from the atmosphere within the envelope of the discharge device and thus nullify variations of pressure due to the ambient temperature changes. In Fig. 1 the heater is supplied from a constant-current source 8 (or a voltage source with series resistor). The heater element 3 is surrounded by a hollow member 4 having walls of a material capable of absorbing hydrogen, e.g. titanium, zirconium, cerium, thorium, vanadium or tantalum, and is connected to the source via a thermistor 2. Outside the envelope are a further thermistor 9 and (optional) series resistor 10. When the ambient temperature varies, the thermistor 9 takes more or less current and the heating current through 2 or 3 therefore decreases or increases respectively. The walls of the hollow member 4 then absorb or liberate hydrogen to maintain constant the pressure in the envelope. In a modification (Fig. 3, not shown) the circuit outside the envelope comprises only a voltage source in series with a resistor having a high positive temperature coefficient.