GB738848A - Thermal and like radiation sources - Google Patents

Abstract

738,848. Electric lamps; infra-red heaters &c. DISTILLERS CO., Ltd. Jan. 22, 1954 [Feb. 4, 1953], No. 3123/53. Classes 39 (2) and 39 (3). A source of thermal and like radiation, more particularly of infra-red rays, comprises a metal chamber 1 provided with evacuating tubes 4, 5 and a front opening closed by a window 3 behind which a funnel 2 of thermally conductive material, such as copper or brass, is located with its inner end adjacent to a metal strip 7 which is supported at both ends within the chamber and connected in an electric circuit, the position of the metal strip being such that the extremity of the funnel adjacent to the strip coincides with the portion of the strip at the operating t emperature it is desired to use. The inner end of the funnel opening is preferably of square or rectangular section ; the outer end, which may be circular, is covered by a window 3 of glass, quartz, or sapphire. The metal strip 7 is carried by end members 8 and 9 supported and tensioned by springs 10, 11, the spring 10 being connected by a conducting bar 12 to a head 15 which is engaged by a terminal screw 16 extending through a solid glass bulb 17 sealed within an opening in the chamber. Rotation of the strip 7 during the adjustment of its tension is prevented by providing the bar 12 with an insulated bush 13 of rectangular cross-section which fits slidably within a constriction of corresponding section. A similar bush 19 is provided on the other end connecting bar 18 which passes through a glass bulb 21 sealed within the adjacent end of the chamber 1. The chamber, which is made of metal of high thermal conductivity and high thermal capacity, such as copper or brass, has its interior surface blackened so that it may absorb radiation of all wavelengths, whilst the funnel 2, made of the same metal, has its interior and exterior surfaces polished to reflect radiation falling thereon. The metal strip 7 may consist of any metal, e.g. nichrome or tantalum, which emanates infra-red rays when heated to an - appropriate temperature. Measurement of the temperature of the strip 7 is facilitated by a window 6 at the outer end of the tube 4 to which the evacuating tube 5 is connected.