Abstract: In the inductive motion sensor, there are provided magnetic field generating means (4, 5, 7, 8) for generating a magnetic exciting field and a measuring device for measuring a mutually induced measurement magnetic field as a measure of the motion. The measuring device is arranged with an offset from the magnetic field generating means in the motion direction and is thereby no longer subjected to the temperature-dependent variations of the exciting field.

Abstract: An apparatus for controlling the temperature, during testing, of IC devices formed on a wafer includes a chuck for locating the devices during testing and multiple temperature control devices arranged on the chuck to correspond with the arrangement of the devices being tested on the wafer. The chuck itself can be cooled or heated, such as by the flow of a temperature-controlled fluid, and a temperature control device such as a heating element can be associated with each IC device being tested. Alternatively, a separate heat sink can be associated with each temperature control device and its corresponding IC device.

Abstract: A magnetic field measuring device useful for measuring a magnetic field associated with an electric current, including a bus section connectable into the path of the electric current, a first magnetoresistive (MR) bridge oriented to be sensitive to the magnetic field of a current in the bus section, a second MR bridge oriented to be substantially insensitive to the magnetic field of a current in the bus section, a biasing coil configured and positioned to apply a magnetic field to the first and second MR bridges, whereby the sensitivity of the first MR bridge can be controlled; and a signal processing device responsive to a voltage output of the second MR bridge to control the current through the biasing coil. The device exhibits good rejection of stray magnetic and electric fields, is convenient to use, and can be fabricated in a single chip, with or without associated signal processing and conditioning circuitry, using conventional IC processing techniques.

Abstract: A self-adjusting assembly and method are disclosed. In the disclosed embodiments, a support assembly for supporting a device comprises a pair of support members for supporting the device. One of the members is adapted to help support the device from a ground, and another of the members is adapted to provide lateral support for the device and to permit free longitudinal movement of the device as it expands or contracts due to temperature variations.

Abstract: A position sensor for a medical device comprises a core made of a high permeable material such as Wiegand effect material comprising a mixture of cobalt, vanadium, and iron. The position sensor has an outer diameter of approximately 0.4 mm and is used in a medical device having an outer diameter of approximately 0.67 mm.

Abstract: A head testing apparatus is provided for testing a data recording head. The apparatus includes a test volume, a magnetic field source, a holder and a thermoelectric source. The test volume is adapted to receive the head, and the magnetic field source is positioned to generate a magnetic field within the test volume. The holder is adapted to hold the head and position the head within the test volume. The thermoelectric source is positioned to contact the head when the head is positioned within the test volume by the holder.

Abstract: The sheet resistance meter has: a coil which produces a magnetic field; a sensor head provided to enable the magnetic field to induce eddy currents in a thin film formed on a substrate so that the lines of a magnetic force exerted by the magnetic field extend on one side of the substrate; a control device for detecting the sheet resistance of the thin film according to a variation of the magnetic field caused by the eddy currents; a capacitor for achieving resonance with the coil; and a groove section, a primary air port, an auxiliary air port, and a side air port, provided in the sensor head, for controlling the temperature of the coil. The arrangement stabilizes results of the measurement of a sheet resistance by a sheet resistance meter of a one-sided eddy current detection type when it is used continuously.

Abstract: A bicycle computer includes a base member structured to mount to a structural member of a bicycle. A cover having an inner surface is swingably coupled to the base so that the inner surface may be moved from a closed position where the inner surface faces the base member to an open position where the inner surface may be viewed or accessed by a user.

Abstract: The design of an electro-magnetic radiation suppression shield and cooling housing for a computer, server or other electronic device having a computer processor may be greatly enhanced and expedited by a test apparatus that permits the placement of electro-magnetic radiation suppression plates at differing locations, spacings and alignments, which allows a variance in positioning the electro-magnetic radiation source. The test apparatus not only has an air flow cooling opening in which an electro-magnetic radiation suppression panel forms cooling air flow holes but also a fixture for disposing a second similar electromagnetic radiation suppression panel at a distance from the first electro-magnetic radiation suppression panel. Each of the panels may be substituted to test various designs.

Abstract: The invention relates to an MR device with means for localizing and/or visualizing a medical instrument (2) inserted into an object (1) to be examined. In order to construct such a device in a more economical and more reliable manner, according to the invention the medical instrument (2) is provided with a magnet device (3) which is controllable by means of a control unit (4, 5) in such a manner that information concerning the position of the magnet device (3) in MR data sets can be specifically changed. The invention also relates to a corresponding MR method.

Abstract: An IC device temperature control system is provided which includes a magnetometric sensor that detects a magnetic field generated around an IC device received in a chamber for inspection when electric current is supplied to the IC device, and a converter that converts an output signal from the magnetometric sensor to information indicative of an amount of heat generated by the IC device. A temperature control device controls a temperature of the IC device, and a control unit controls the temperature control device to maintain the temperature of the IC device within a predetermined range based on the information indicative of the amount of heat generated by the IC device.

Abstract: The sheet resistance meter has: a coil which produces a magnetic field; a sensor head provided to enable the magnetic field to induce eddy currents in a thin film formed on a substrate so that the lines of a magnetic force exerted by the magnetic field extend on one side of the substrate; a control device for detecting the sheet resistance of the thin film according to a variation of the magnetic field caused by the eddy currents; a capacitor for achieving resonance with the coil; and a groove section, a primary air port, an auxiliary air port, and a side air port, provided in the sensor head, for controlling the temperature of the coil. The arrangement stabilizes results of the measurement of a sheet resistance by a sheet resistance meter of a one-sided eddy current detection type when it is used continuously.

Abstract: Temperature sensing through observable, temperature-dependent effects on an interrogating magnetic field is facilitating by a sensing module having, first, a signal element that interacts with the interrogation field to produce a remotely readable magnetic response; and disposed proximate to the signal element, a temperature-sensitive component. This latter component may include a modulation element having a magnetic permeability varying with temperature in the operating range and/or a bias element comprising a magnet having a Curie temperature in the operating range. The temperature-sensitive component interacts magnetically with the signal element such that the remotely readable magnetic response is indicative of a temperature in the operating range.

Abstract: An electronic autoclave cycle passively records the number of thermal cycles to which an instrument has been subjected in a steam autoclave. When a sterilization cycle has been completed, and the instrument is next energized in use, a microprocessor is employed to read the sensor and record the occurrence of a sterilization cycle. Information as to the cumulative number of cycles through which the instrument has been subjected is stored in a non-volatile memory. This data is suitably displayed on a display panel. The sensor employed uses either the Curie temperature or a temperature near but below the Curie temperature of a ferromagnetic material by first magnetizing the material and then, later, checking its flux density to determine whether a thermal cycle has occurred. In a first embodiment, a Hall effect sensor is used to directly measure the magnetic field strength of the magnetizable material.

Abstract: Method and apparatus for detecting or analyzing chemical reactions, such as an enzyme reaction, and other events in which electron translation is accompanied by photon emission utilizing a magnetometer probe to detect a change in electromagnetic field strength as a characterization of the event. The event may be of unknown cause and a recorded time course of the change in electromagnetic field strength may be compared with known events to determine the cause of the unknown cause event.

Abstract: The present invention provides a detector system for access control, the system comprising: transmitter coils; associated receiver coils; transponders suitable for generating identifiable signatures; and processor circuits adapted firstly to detect a weapon passing between the transmitter and receiver coils by analyzing variations in the signal received by the receiver coil, and secondly to detect the identifiable signature of a transponder on the basis of the signal received by the receiver coils; wherein: the transmitter coils are adapted to generate respective frequencies, firstly for exciting and detecting any weapons passing between the transmitter and receiver coils, and secondly for activating transponders; the transponders have means suitable for powering their internal circuits electrically from the signal received at the "activation" frequency; each weapon excitation and detection frequency is very different from each frequency used for activating transponders and for transponder signatures; and the

Abstract: A device and process for determining the uniformity of a superconducting film's critical current density and transition temperature over a large area uses an array of ac coils placed in close proximity to a superconducting film. A variable ac current is passed through each coil which induces a proportional current in the superconducting film. A lock-in amplifier set to the third harmonic of the ac current is put in parallel with the ac current source. When the current in the film exceeds the critical density of the film then the third harmonic is picked up by the lock-in amplifier. In this way one can measure the critical current density of the film at each of the coils. The above coils are mounted within a flat plate (the film side of the substrate is placed against the plate). The entire assembly is cooled within a cryostat so that the temperature can be precisely controlled.

Abstract: To provide a nondestructive inspection apparatus with a reduced distance between a superconducting magnetic sensor and an object under inspection, a cryostat for cooling the sensor to a superconducting state is provided with inner and outer vessels. The inner vessel has a baseplate on which the magnetic sensor is disposed, and has an inner wall defining a central chamber for containing a refrigerant for cooling the magnetic sensor. The outer vessel has an inner wall defining a central chamber for containing the inner vessel, the magnetic sensor and the stage. A gap between the inner and outer vessels is evacuated to insulate the inner chamber from the ambient atmosphere. To facilitate ease of transferring an object to and from the stage for inspection, a load lock area is provided adjoining the outer vessel.

Abstract: A coil arrangement having a primary and two balanced secondaries is used to measure ac susceptibility and, using sample movement, also to perform absolute dc moment measurements. Since the same coil arrangement is used for both AC and DC measurements, the measurements can be made successively within a cryogenic chamber without removing the sample. This is a big advantage, because the changed conditions associated with removing and replacing a sample between measurements can cause confusing, uncorrelated results. A high speed voltmeter is used to perform the signal analysis for the moment measurement. The system can be configured to yield high resolution dc moment measurements to 25 ppm and sensitivities to better than 5.times.10.sup.-5 emu.

Abstract: A magnetic flux microscope that measures the magnetic field about a sample surface. The apparatus uses a thin-film superconducting quantum interference device (SQUID) as the scanning device. Magnetic shielding is provided about the SQUID and is held stationary relative to the SQUID. The apparatus and method provides a very high magnetic image of the sample with a very high spatial and field resolution.

Abstract: An apparatus and method for detecting a magnetic field has been described incorporating a material which switches from an antiferromagnetic order to a ferromagnetic order upon the application of a magnetic field and wherein the material is FeRh, FeRu, FePd or MnPt, a heating element for controlling the temperature of the material and a current source for sensing the change of resistance of the material to determine when the material is ferromagnetically ordered. The invention overcomes the problem of small changes in resistance of magnetoresistive sensors operating in only the ferromagnetic order.

Abstract: An electronic component is conditioned to remove distortion in a temperature response characteristic due to a temperature hysteresis effect, by subjecting the component to a controlled temperature variation prior to operation of the component at a given temperature. A circuit is disclosed wherein the component is a zener reference element and a bias voltage of cyclical waveform and of reducing magnitude is applied to a control transistor to cause corresponding variation of the temperature of the zener via an on-chip heater. The zener is subsequently operated at a normal bias voltage corresponding to the mean value of the cyclic waveform.

Abstract: A stochastic excitation, SQUID detection system for determining the frequency response of a sample. A pair of counterwound detection coils are adjacent to an excitation coil. The sample is selectively placed in one of the detection coils for taking measurements. The SQUID sensor is a broadband, high sensitivity device which enables the frequency response of the sample to be determined over a wide bandwidth with a single measurement.

Abstract: An improved AC susceptometer and methodology for its use which is particularly suitable for the characterization of the properties of superconducting materials. Added to the circuitry of a conventional AC susceptometer is frequency domain analytical equipment for measuring the induced magnetic response. The addition of frequency domain measuring equipment permits the determination of the harmonic components of the induced magnetic response. The measurement of the harmonic components of the response also provides novel methodology for studying the phenomena of flux penetration, flux pinning and movement and permits the measurement of parameters such as lower critical field, critical temperatures, and the irreversibility line.

Abstract: An improved AC susceptometer and methodology for its use which is particularly suitable for the characterization of the properties of superconducting materials. Added to the circuitry of a conventional AC susceptometer is frequency domain analytical equipment for measuring the induced magnetic response. The addition of frequency domain measuring equipment permits the determination of the harmonic components of the induced magnetic response. The measurement of the harmonic components of the response also provides novel methodology for studying the phenomena of flux penetration, flux pinning and movement and permits the measurement of parameters such as lower critical field, critical temperatures, and the irreversibility line.

Abstract: This invention relates to an apparatus and method for measuring the resistance of superconductors. Structures of this type, generally, allow the resistance of the superconductor to be accurately measured in a non-destructive manner by using a bifilar coil which includes an integrated loop/switch formed from the bifilar coil.

Abstract: On the basis of a finding that a magnetic hysteresis of a metal material, among magnetization characteristics changing with secular degradation of the metal material, shows a clear correspondence with the degree of degradation of the metal material, a change in such a magnetization characteristic is measured to estimate the degree of secular degradation of the metal material. In a typical embodiment, a superconducting quantum interference device is used to detect the magnetization characteristic of a measuring object. According to the present invention, the degree of embrittlement of a metal material used in an environment of high temperatures can be quickly detected in a non-destructive fashion so that the danger of brittle fracture of the metal material can be reliably prevented.

Abstract: An improved NDE method utilizes a laser source with modulator and scanning mirror, a pancake shape eddy current detecting coil, a lock-in amplifier, a system controller, and an impedance gain/phase analyzer. The laser is directed by the scanning mirror to a specimen to be analyzed. A very localized or small area of the specimen is impacted directly by the laser beam creating a thermal and stress wave in the specimen. An impedance gain/phase analyzer is connected to the eddy current detecting coil and to a lock-in amplifier through the system controller. The lock-in amplifier is also synchronized to the laser modulator. The system controller is used to control the lock-in amplifier, scanning mirror, and to process data from the analyzer. Raster scanning of the laser beam across the speciment allows the detection by the coil of the laser generated thermal and elastic strains induced in the specimen by the laser. The rastering of the laser beam is controlled by the controller by positioning the mirror.

Abstract: A hot flaw detector is equipped with a sensor holding member that has a circular opening through which the material to be inspected will pass and that holds a flaw detecting sensor. Provision is made of an annular cooling liquid injection port that is open at an end of the sensor holding member adjacent to the inner peripheral wall of the circular opening, and provision is further made of an annular cooling liquid introduction port that is open at the other end of the sensor holding member adjacent to the inner peripheral wall of the circular opening. The cooling liquid is injected from the annular cooling liquid injection port, and forms a liquid film along the inner peripheral wall of the circular opening, and is recovered through the annular cooling liquid introduction port. The inner peripheral wall of the sensor holding member is effectively cooled by the liquid film which drips little onto the material to be inspected.

Abstract: A non-contact level measurement system for monitoring distances with very high accuracy between a sensor coil and a metallic object such as a molten liquid level over either very narrow or extended distances. Controllers coupler with heaters, thermocouples, coolant air are provided for maintaining the sensor coil at a operating temperatures within the range of 400.degree. F. and 1200.degree. F. to eliminate variations to the operation of the sensor coil. The system incorporates an L-C resonant circuit connected between the output of an oscillator and the input of an operational amplifier. A variable inductor parallel with the capacitor of the L-C resonant circuit is used to obtain a precise offset operating frequency of the resonant circuit from the frequency of the oscillator.

Abstract: A system for nondestructive analysis of barrier coatings on electrically conductive materials includes imposition of a controlled known heat load to a localized area of the coating and measuring electrical conductivity of the underlying material at or near the localized area of the coating. The electrical conductivity of the material is affected by changes in temperature related to thermal conduction into the material through the coating. Thermal resistance of the coating and defects between the coating and the material can therefore be detected.

Abstract: A system for photoinductive imaging for flaw detection of materials and for calibrating eddy-current probes includes positioning an eddy-current probe adjacent to a specimen to be analyzed or to be used as a calibration fixture. A source of thermal energy is modulated and focused to a localized area on the specimen. Thermal energy is then scanned across at least a portion of the detection area of the eddy-probe. The resulting signal from the eddy-current probe is recorded and can depict either thermal-influenced components of the specimen or the response pattern of the eddy-current probe. The record can therefore be used to image flaws or physical holes or shapes of the specimen or calibrate the eddy-current probe.

Abstract: A fluxgate magnetometer having wide temperature range accuracy, without adding temperature compensating components, is obtained by: (1) a fluxgate adjusted by aligning a permeable magnetic tape core relative to the secondary winding of the fluxgate so as to substantially equalize each of the pulses induced in the secondary winding by the transition from core saturation to unsaturation in both directions, and (2) increasing the fluxgate magnetometer primary drive current above what is normally considered saturation current to reduce sensitivity of the output to temperature and primary drive changes.

Abstract: A compressed-air cooled transducer coil assembly for slag detector apparatus includes a refractory shield, top and bottom end blocks, a coil winding, and at least two spaced-apart guide bars. The shield may be positioned to coaxially surround the pour tube of a continuous steel caster so as to leave a space therebetween. The end pieces are connected to the shield. The coil winding is connected to the end blocks and is positioned so as to coaxially surround the shield leaving an air gap therebetween. The guide bars each have a bore whose lower end is attached to the bottom end block and whose middle portion projects into the space between the shield and the pour tube. The top and bottom end blocks have conduits which communicate with the air gap and the bores.

Abstract: A meter for sheet conductance measurements does not touch the conductive surface of a sample. A probe having a resonant tank coil is positioned against a parallel supporting surface of the sample, which may be flat or curved and of unrestricted area. An oscillator incorporating the tank coil is controlled to stabilize oscillator amplitude in response to eddy current loading by the sample. An electrostatic shield in a finger configuration prevents capacitive coupling between the tank coil and the sample without hindering magnetic coupling. A readout of sheet conductance is driven by the oscillator control. Direct current can be coupled to the tank coil for temperature control preventing undesired resistance changes in the tank coil. The oscillator can be controlled by an optically coupled variable gain element. Measurements can be made with the tank coil up to at least 0.75 inch from the conductive surface of the sample.

Abstract: A device for quality testing hot test objects, comprises at least one coolant-cooled rotatable body, and at least one transducer (for example a surface transducer coil) eccentrically mounted in or on the body to move along an endless path in close proximity to a surface of the test object. The transducer is conncted directly or indirectly to an associated sensing circuit. A device according to the invention is characterized in that the flow of coolant is adapted to take place via an inlet channel and an outlet channel, both of which are disposed close to the axis of rotation of the body, and at least one further channel extending between the inlet and outlet channel to convey coolant at least close to the transducer(s).

Abstract: An azimuth calculation apparatus includes an azimuth sensor mounted on a moving body for detecting a direction of the moving body, the azimuth sensor having an excitation winding wound on an annular magnetic core and a pair of output windings wound on the core perpendicularly relative to one another to produce first and second output signals therefrom in response to energization of the excitation winding. The calculation apparatus is arranged to detect a temperature of the azimuth sensor and to determine a pair of correction values based on the detected temperature of the azimuth sensor so as to correct each value of the first and second output signals from the output windings to an optimal value for calculating the direction of the moving body in dependence upon the corrected output signals from the output windings.

Abstract: A thermoregulated magnetic susceptibility sensor assembly for well-logging or the like is disclosed. The assembly includes a sensing solenoid and a non-metallic container for the sensing solenoid. Located in the container and spaced from the sensing solenoid are a plurality of heaters. These heaters are uniformly positioned about the sensing solenoid and a heat transfer material is located between the heaters and the sensing solenoid. The heat transfer material conducts the heat from the heaters to the sensing solenoid in a substantially uniform manner so that the sensing solenoid is maintained at a uniform temperature. Preferably, temperature sensors are provided to control the heat output of the heaters to maintain the sensing solenoid at the desired uniform temperature. To minimize heat transfer to the heaters from the external environment, a layer of insulation is provided around the heaters.

Abstract: According to the process, a toroidal sample of ferrimagnetic material to be analyzed is placed in a thermostatically-controlled enclosure fitted with temperature regulation and detection means. The toroidal sample is submitted to an electro-magnetic magnetizing field of given frequency and the flux induced in the sample is measured directly using a measuring loop, around the sample and which is connected to a vectorial voltmeter.

Abstract: A Hall effect magnetic field sensing circuit provides an operation amplif which is connected to a signal voltage terminal of the Hall effect sensor with a negative temperature coefficient (TK) of the resistance of the drive current path whose drive current path is provided with an input resistor such that a portion of the Hall effect sensor responds to the change in temperature thereof to vary the drive current and provide temperature compensation of the Hall voltage. A differential amplifier can be provided to eliminate the zero residual voltage effect and a summing circuit connected to the operational amplifier rectifies nonlinearity.

Abstract: Blood flow in human limbs is measured non-invasively by a nuclear magnetic resonance blood flowmeter which includes a pair of polarizing magnets whose fields are stabilized by electromagnets in each pole piece that are energized in accordance with the magnetic flux of the magnets as sensed by a Hall effect sensor. Blood molecules are either self-tagged by the polarizing field or are separately tagged by a tag coil whose field is orthogonal to the polarizing field. Once tagged, the variation in the magnetic moment of the molecule due to the tagging is detected by the variation in voltage in the receiver coil which is located orthogonally to the transmitter coil so as to reduce crosscoupling therebetween.

Abstract: The magnetic susceptibility well-logging unit with single power supply thermoregulation system provides power from a single surface power supply over a well-logging cable to an integrated circuit voltage regulator system downhole. This voltage regulator system supplies regulated voltages to a temperature control system and also to a Maxwell bridge sensing unit which includes the solenoid of a magnetic susceptibility probe. The temperature control system is provided with power from the voltage regulator system and operates to permit one of several predetermined temperatures to be chosen, and then operates to maintain the solenoid of a magnetic susceptibility probe at this chosen temperature. The temperature control system responds to a temperature sensor mounted upon the probe solenoid to cause resistance heaters concentrically spaced from the probe solenoid to maintain the chosen temperature.

Abstract: An eddy current system and method is disclosed for detecting flaws in hot pipe product. The system includes a detector test head (22) having a heat shield (24) defining a generally cylindrical inner wall through which the pipe passes longitudinally. The test head includes structure (50, 62, 64) for spirally directing water onto the inside surface without contacting the hot pipe as it passes through the heat shield. Debris is thereby removed from the space between the shield and the pipe, and the test head is effectively cooled and shielded from the heat of the pipe. Where the pipe is heated above its Curie temperature, such that the pipe is rendered non-magnetic, no normally required saturation coil is needed to magnetically saturate the pipe for eddy current testing, because the coolant flowing over the inner wall cools the test head but does not lower pipe temperature below the Curie point.

Abstract: A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.

Abstract: To test a conductor with superconductive material which is in the superconducting state, the conductor is led through an external magnetic field which comprises at least two magnetic field regions spatially separated from each other and arranged one behind the other in the lengthwise direction of the conductor, the fields of which are angularly displaced from each other in the circumferential direction relative to the longitudinal axis of the conductor permitting disturbances in all superconductivity regions in superconductors of any cross section to be ascertained with certainty.

Abstract: An eddy current flaw detection apparatus which is particularly adapted for inspecting articles at elevated temperatures. A plurality of detectors are supported about at least a portion of a workpiece path of travel to detect and locate flaws in workpieces. A non-magnetic, metallic shield is between the detectors and the workpiece path. A cooling medium is applied to the heat shield to protect the detectors from the heat of a hot workpiece. The cooling medium is also used to purge foreign matter from the assembly.In one embodiment an exciter and detector assembly is disclosed which is constructed as an integral unit encapsulated within moisture-impervious material. In this embodiment, the assembly is movable relative to the workpiece path.In another embodiment, the detectors and the exciter surround the workpiece path.Metallic powder is sprayed on a hot workpiece to mark the location of detected flaws. The heat of the article fuses the marking metal powder in place on the hot workpiece.

Abstract: The invention relates to an apparatus for compensating the output of a pendulous induction compass transmitter to eliminate heading errors during turns due to the vertical component of the Earth's magnetic field as well as those due to the horizontal component of the Earth's magnetic field perpendicular to the axis of tilt. By compensating for the effects of the Earth's vertical field component, instabilities and anomalies such as "Northerly Turning Error" are eliminated or minimized. Compensation for vertical field error is provided by generating a signal proportional to the product of the Earth's magnetic field M, the sine of the magnetic dip angle D at the given latitude and the sine of the aircraft tilt or bank angle .phi.. A compensating signal proportional to cos .phi. is generated and used to compensate for two cycle error.

Abstract: A magnetometer wherein inductance of a resonant circuit is made sensitive changes in magnetic field to vary an oscillator operating frequency. The magnetometer utilizes a ferromagnetic sensor element that is characterized by high permeability in weak magnetic fields when the element is maintained at predetermined elevated temperatures near the Curie point of the element material and also exhibits a hysteresis curve having a steep slope in the region of field strengths on the order of the earth's magnetic field. The preferred embodiment includes resistive heating of the element and use of substantially pure iron as the element material.

Abstract: A device for detecting phase transformations in a magnet material is disclosed. A sample is placed in a coil coupled to a harmonic oscillator and subjected to heat radiation means for simulating predetermined heating and cooling rates which result in phase transformations within the material being tested. The phase transformations are a function of changes in magnetic permeability which vary with temperature changes.

Abstract: An electromagnetic oven is provided with a control system comprising a sensor located within the oven, a detector coupled to the sensor, and control means responsive to signals from the detector. In one embodiment, the control means activate a counter which, upon a predetermined number of operations, signals a condition of the load within the oven and may modify subsequent energy inputs to the load.