GB901218A - Electrical signal transmission apparatus - Google Patents

Abstract

901,218. Capacitors. STANDARD TELEPHONES & CABLES Ltd. Sept. 13, 1960, No. 31507/60. Class 37. A capacitative connector for conductors entering a low temperature apparatus presenting a barrier to heat flow along each conductor by breaks in the conductors across which capacitance couplings exist, comprises (Fig. 1) concentric cylinders 1, 2, 3, 4 of which 1 and 4 are copper and 2 and 3 are of e.g. stainless steel having low thermal conductivity. Cylinder 1 is connectible by a threaded ring 6 to a Dewar vessel (not shown) containing, e.g. a computer memory comprising superconductive storage elements immersed in liquid helium, and is sealed to cylinder 2 by ring 7 supported by thin rods 13 attached to cylinder 3. Cylinders 3, 4 are sealed by ring 10 and supported by plate 14 screwed to rubber seal 15 by clamping ring 16. Cylinder 4 is closed at its lower end by aper. tured plate 18, below which is an apertured plate 20 closing cylinder 3, and an apertured plate 22 closing cylinders 2, 3; the plates being of silver-plated brass. The spaces between cylinders 1 and 2, 3 and 4, and within 4 are evacuated by a vacuum pump attached to side tube 9 and jacket 12 is open to the atmosphere and contains e.g. liquid nitrogen. Coaxial cables 24 connecting apparatus at room temperature to the apparatus in the Dewar vessel are soldered into apertures of plate 14 and traverse the interior of cylinder 4 to pass through apertures of plates 18, 20, 22 within the thickness of each of which there is a break in each of the inner conductors (Fig. 2), the outer conductor being soldered to the upper surface of each plate and each aperture being internally coated with a layer 26 of electrical and thermal insulation, e.g. silicon monoxide. The inner conductors terminate respectively in a cup end 31 and an engaging head 33 separated therefrom by a layer 32 of e.g. silicon monoxide, permitting large capacitance coupling with minimal thermal conductivity. Plates 18, 20, 22 are earthed over a thin wire (not shown). In a modification (not shown), plate 18 is unapertured, to close cylinder 4, and the conductors 24 pass loosely through apertures of plate 14 lined with e.g. silicon monoxide, and the interior of cylinder 4 is filled with e.g. liquid helium.