Abstract: An apparatus and method for measuring local heat transfer distribution of an object surface. The apparatus includes a heater element for providing heat flux, a member disposed on a surface of the heater element for receiving impinging cooling air. A liquid crystal element is provided on a side of the heater element remote from the surface, and an insulating material is disposed adjacent to the liquid crystal element and remote from the heater element. The apparatus further includes means for determining heat transfer distribution coefficients from the liquid crystal element.

Abstract: An apparatus and method for measuring local heat transfer distribution of an object surface. The apparatus includes a heater element for providing heat flux, a member disposed on a surface of the heater element for receiving impinging cooling air. A liquid crystal element is provided on a side of the heater element remote from the surface, and an insulating material is disposed adjacent to the liquid crystal element and remote from the heater element. The apparatus further includes means for determining heat transfer distribution coefficients from the liquid crystal element.

Abstract: Demountable cryocoller cold heads must make reliable contacts having low thermal resistance at cryogenic temperatures for cooling such devices as radiation shields used in superconducting magnets. Cryostat vacuum and a bellows is utilized in order to engage the cold head second stage interface, while the first stage interface is independently engaged by means of a bolted flange and a bellows. A soft metal such as indium is employed at the contact surfaces of the heat stations.

Abstract: A precooler with a geometry that permits it to be mounted in a cryocooler interface and to use the same thermal connections at the heat stations is provided. The precooler has two stages each with its own heat exchanger, thermally isolated from the other. The latent heat of evaporation of cryogenic liquids is used to remove the sensible heat of superconductive magnet. The different stages can be cooled at a controlled rate resulting in reduced temperature gradients and therefore lower thermal stresses.

Abstract: Retractable cryogenic leads for superconducting magnets are provided for making low resistance contacts at liquid helium temperature reliably in the presence of heavy frost. A tube defining a bayonet socket on one end extends through a vertical stack cover of a cryostat insert to engage and disengage a vertical terminal rod having a transverse pin. A copper rod is slidable mounted inside the tube and is vertically displaced relative to the tube by a hydraulic actuator having a housing secured on the other end of the tube. A piston is slidably mounted in the housing. After the bayonet socket engages the pin of the vertical terminal rod, the piston when extended from the housing can force the copper rod against the top of the vertical terminal rod.

Abstract: An axial disconnect is provided for use with refrigerator systems in which the valve motor and displacer drive are not on the same axis as the displacer (cold end) or for situations where the stresses transmitted to the plug shields are to be minimized. The axial refrigeration connection allows field interruption of the refrigerator-cryostat conduction path to prevent excessive heat leak to the cryostat in the event of a refrigerator failure or scheduled service.

Abstract: A rotating refrigerator connection is provided which allows field interruption of the heat conduction path between a one, two or three stage cryogenic refrigerator and a cryostat in the event of a refrigerator failure or scheduled service.

Abstract: A protection device for interrupting power to a load connected to a pair of terminals when the temperature of a terminal exceeds a predetermined threshold comprises an alloy having a eutectic at the predetermined threshold and a neon gas-filled glow tube electrically coupled in parallel with the thermal fuse. The thermal fuse is electrically serially connected between the terminal and the load and thermally coupled to the terminal so that an excessive temperature rise at the terminal causes the fuse to melt, thereby removing power from the load and causing the glow tube to be lit.

Abstract: Temperature indicating apparatus for sensing overheating at a pair of terminals on an electrical power line comprises a pair of thermocouples, each thermally coupled to and electrically isolated from a different one of the terminals, and a light emitting diode (LED) coupled to the output of the thermocouples through a conditioning circuit. An excessive temperature rise at either terminal causes the output voltage of the thermocouple coupled thereto to increase, thus causing the LED +o to be lit and to provide a visual indication of overheating. A meter display may be provided to show the actual temperature of the terminals in response to thermocouple voltage output. A method for determining heating at a termination without physical intervention comprises determining the rate of temperature rise of the termination for a known current therethrough and comparing the rate to a predetermined rate threshold.