Abstract: A superconducting filter apparatus having a refrigerator for cooling the superconducting filter to cryogenic temperatures, a pilot signal generator for generating a pilot signal that is outside the pass band and inputting the pilot signal to the superconducting filter together with an antenna receive signal, and a discriminating unit for discriminating abnormality in the refrigerator. If the refrigerator malfunctions and temperature of the superconducting filter rises, the pass band of the superconducting filter shifts to the low-frequency side and crosses the frequency of the pilot signal. The pilot signal passes through the superconducting filter at this time. The discriminating unit discriminates abnormality in the refrigerator based upon the pilot signal contained in the output of the superconducting filter.

Abstract: A current sensing noise thermometer is described, in which a low noise amplifier is used to measure the noise current in a sensor resistor and the sensor resistor is connected in series with a superconducting coil, or a coil assembly including at least one superconductor. The superconductor of the coil assembly is preferably positioned inside the coil, and the superconducting transition temperature of the superconductor is used to calibrate the thermometer. Preferably, the sensor resistor is grounded to enable particularly low temperatures to be achieved.

Abstract: Various techniques for forming superconductive lines are described whereby superconductive lines can be formed by stamping, etching, polishing, or by rendering selected areas of a superconductive film (layer) non-superconductive. The superconductive material can be "perfected" (or optimized) after it is formed into lines (traces). In one embodiment, trenches are etched in a substrate, the trenches are filled with superconductive material, and any excess superconductive material overfilling the trenches is removed, such as by polishing. In another embodiment, superconductive lines are formed by rendering selected areas of a superconductive layer (i.e., areas other than the desired superconductive lines) non-superconductive by "damaging" the superconductive material by laser beam heating, or by ion implantation. Superconductive lines formed according to the invention can be used to protect semiconductor devices (e.g.

Abstract: Method and arrangement for detecting the level of a liquid cryogen having a predetermined boiling point and which is being held in a container relative to the bottom of the container. The arrangement includes a container which receives the liquid cryogen and a longitudinal extending sensing member having a length extending from the bottom of the container to a level that is greater than any depth experienced for the liquid cryogen. The sensing member is vertically disposed in the container with one end in contact with the bottom of the container and the other end extending out of the liquid cryogen. The sensing member is composed of a high temperature superconductor material having a critical temperature that is higher than the predetermined boiling point of a selected cryogen. An electrical current is passed through the sensing member and the voltage drop across the sensing member is measured.

Abstract: A fiber optic system detects temperature transients in a superconducting magnet. A signal optical fiber is placed in function proximity with the superconducting magnet for responding to a temperature transient condition and a reference optical fiber is remote from the signal optical fiber. A coherent light outputs coherent light for input to the signal and reference optical fiber to provide a phase shift of about 90.degree. to the coherent light in the signal or reference optical fiber. In one embodiment, a low pass filter provides feed back to the phase modulator to stabilize the modulation while a high pass filter passes temperature transient signals to a suitable analyzer, such as a digital storage oscilloscope, or the like.

Abstract: A temperature measuring device comprises a light emitter, a nitrogen-containing diamond sensor, a light receiver, and lengths of fibre optics which connect the light emitter and the light receiver to the diamond sensor. The diamond sensor has a base through which the emitted and reflected light pass and sloping surfaces which lead to an apex. The amount of light which is absorbed by the diamond sensor will vary according to the temperature in which the diamond sensor is placed.

Abstract: A device is provided for measuring radiant energy, the device comprising a substrate; a bolometer formed from a high T.sub.c superconducting material disposed on the substrate in an area that is about 1.times.5 .mu.m.sup.2 and about 0.02 .mu.m in depth; and a planar antenna disposed on the substrate and coupled to receive radiation and to impart the received radiation to the bolometer.

Abstract: A cryogenic level sensor assembly. A sensor assembly includes a continuous length of high temperature ceramic superconductor material, an exterior housing for holding the length of ceramic superconductor material, a support material disposed between the ceramic superconductor material and the exterior housing, and a resilient retention material disposed opposite the ceramic superconductor material for holding the superconductor material while allowing expansion and contraction thereof during thermal cycling.

Abstract: A superconducting transition edge bolometer is constructed using high critical temperature conducting films by stabilizing a substrate of magnesium oxide or sapphire with a silicon base that is bonded to the substrate using a thermally conductive bonding layer. The base is etched away in the region of the desired radiation detecting portion of the superconductor establishing a controlled thermal connection between the detecting portion and the base which base serves as a thermal bath for the bolometer.

Abstract: A level gauge and measurement method are provided using a sensing element comprising a superconductive alloy represented by the formula:Mo.sub.a Ru.sub.b Z.sub.cwherein Z is phosphorous, boron, or a mixture of phosphorous and boron,b has a value of about 20 to about 40,c has a value of about 10 to about 30, anda+b+c=100.The sensing element has a superconductivity critical temperature of at least 4.2K and is useful for measuring the level of liquid helium independently of pressure fluctuations in the reservoir vessel.

Abstract: A superconducting device is disclosed with the device having multiple layers of thin film configured to achieve highly sensitive measurements based upon temperature. The device is implemented, in simplest form, as a stripline having a ground plane layer of superconductor, a configured layer of superconductor, and a dielectric layer between the ground plane layer and the configured layer. The device is operated at a temperature just below the transition temperature of the superconducting materials utilized so that the inductance of the device depends substantially upon temperatures encountered, with highest sensitivity resulting when at least one of the superconducting layers has a thickness that is small relative to the magnetic penetration depth of the superconducting material utilized.