Focus on Magnetics

GMW Associates has introduced two new magnetic-field-to-analog voltage transducers from Sentron AG, designed for measuring, controlling, and mapping magnetic fields. The transducers consist of a measuring probe incorporating a tiny Hall element(s) connected to an analog electronics module with a differential output voltage of ± 10.000 V full scale. The single-axis model YM12-3-2 provides an accuracy to 0.1% and a 3-dB bandwidth of 5 kHz over a linear magnetic-field range of ±2 tesla (model suffix 2.0 T). The model 3M12-2-2 is a three-axis device with an accuracy to 1% and a 3-dB bandwidth of >1 kHz in the 2-T range (suffix 2.0 T); both models have a sensitivity of 5 V/T. For a higher field sensitivity of 50 V/T, both models are available in the field range of 0.2 T (suffix 0.2 T). Optional accessories include a ±12-V power supply and a zero-gauss chamber. GMW Associates, 955 Industrial Road, San Carlos, California 94070, http://www.gmw.com

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The Lake Shore Cryotronics model 7400 VSM (vibrating sample magnetometer) is well suited for the characterization of intrinsically low magnetic-moment materials such as ultrathin magnetic films and heterostructures. Compared to the company’s earlier model 7300 VSM, the 7400 features a 10-fold improvement in moment sensitivity, achieving a value of better than 0.5 µemu. This is attained via improvements in electronic sensitivity, vibration isolation of the head assembly from the electromagnet and VSM sense coils, and increased amplitude of the mechanical drive. Like the 7300, the 7400 systems include three different versions based on variable-gap 4-in, 7-in, or 10-in electromagnets. Vector/torque and automated sample rotation options further extend the capability of the 7400 for anisotropy studies. Lake Shore Cryotronics Inc, 575 McCorkle Boulevard, Westerville, Ohio 43082, http://www.lakeshore.com

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Astronautics Corporation of America has announced a permanent-magnet, room-temperature magnetic refrigerator that uses a material based on gadolinium, a metallic element that exhibits a large magnetocaloric effect. Unlike previously demonstrated magnetic refrigerators using superconducting magnets, the Astronautics version incorporates a permanent magnet, resulting in a compact package that runs virtually silent and vibration free. The gadolinium-based material is alternately magnetized and demagnetized by rotating a wheel on which it is mounted through a magnetic field. The refrigerator provides a cooling range similar to a household air conditioner, but is more energy efficient than conventional vapor-cycle units. The heat-transfer fluid used in the prototype is water. Astronautics Corporation of America, P.O. Box 523, Milwaukee, Wisconsin 53201, http://www.astronautics.com

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HYPRES has developed a high-resolution, low-temperature SQUID (superconducting quantum interference device) microscope system for rock magnetometry (see figure for image of Martian meteorite), and imaging of the magnetic fields produced by action currents, injury and developmental currents, remanent magnetization, and magnetic susceptibility in isolated living tissue and experimental animal preparations. The instrument is capable of making measurements that could lead to new insights into cellular biology and electro- and magneto-physiology. The sample, either in air or an aqueous solution, is scanned beneath the tail of the Dewar with a retractable sensor, enabling a sample-to-sensor spacing of 50 µm. The liquid-helium-based system has a spatial resolution of 250–1000 µm and a field sensitivity of 50–1000 fT/root Hz. HYPRES Inc, 175 Clearbrook Road, Elmsford, New York 10523, http://www.hypres.com

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Oxford Instruments has introduced what is reportedly the world’s first operational superconducting magnet designed for nuclear magnetic resonance at 900 MHz (protons). The magnet operates at a temperature of 2.2 K, has a field strength of 21.1 tesla, a field stability of ≥ 10 Hz/hr (protons), and a 45-mm bore access inside the magnet’s room-temperature shims. The magnet incorporates the company’s new superconducting materials and joint technology, new developments to manage the megajoules of stored energy, and a new approach to restraining forces present in the magnet coils. As the NMR frequencies become higher due to the higher magnetic fields, they should make possible an increased understanding of proteomics and related biomolecular research. Oxford Instruments, Superconductivity, Tubney Woods, Abingdon, Oxon OX13 5QX, England, http://www.oxford-instruments.com

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The EFNMR1-A from TeachSpin is a hands-on classroom instrument that offers a conceptually transparent way to introduce nuclear magnetic resonance at an intermediate level. A high-Q sample coil surrounds a 125-ml plastic bottle containing a liquid rich in either hydrogen or fluorine nuclei. The sample is placed in a uniform part of Earth’s magnetic field with the coil’s axis aligned perpendicular to this field. A DC power supply is connected to the sample coil to produce a DC magnetic field for polarizing the nuclei. When the polarizing field is switched off, the nuclei’s magnetization vector precesses in Earth’s field. The resulting AC (1.9–2.7 kHz) dipole field is then detected. This Earth’s field NMR apparatus reportedly can lead students to an understanding of precession, Curie’s law of paramagnetism, spin-lattice relaxation, and even spin–spin coupling. TeachSpin Inc, 45 Penhurst Park, Buffalo, New York 14222-1013, http://www.teachspin.com

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Electro Standards Laboratories has announced the model 3850 Motor Control Development Station (MCDS) for those who are developing and improving AC- and DC-motor control systems and electronics in laboratories, plants, and classroom experimentation stations. The unit incorporates a fixed point digital signal processor, A/D and D/A channels, 1 megabit/s serial ports, digital I/O, encoder input, and a three-phase pulse-width-modulated output power stage compatible with induction motors, DC motors, permanent magnet motors, and linear motors. MCDS models are available with output powers of 2–20 kW. Software modules provide real-time vector-current control, speed control, and position control; graphical user interface software expedites the adjustment of tuning parameters. Electro Standards Laboratories, 36 Western Industrial Drive, Cranston, Rhode Island 02921, http://www.electrostandards.com

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ADE’s X9 magnetic properties analysis system can characterize thin-film magnetic materials without operator involvement. It is said that, in a single step, the X9 can automatically calibrate and run both hysteresis and magnetoresistance loops at low and high magnetic fields, allowing the determination of pinned-layer exchange and thickness, free-layer exchange and thickness, free-layer coercivity, and transport properties. The X9 can measure thin films with repeatability equivalent to 0.025 nm of nickel-iron, important in the process control required for the fabrication of advanced magnetic memory materials; it combines a field resolution of 0.001 Oe with a maximum field of 20 kOe. The tool can automatically load, measure, and unload samples from cassettes and features software to measure and analyze complex magnetic structures. ADE Corporation, 80 Wilson Way, Westwood, Massachusetts 02090-1806, http://www.ade.com

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Intelligent Motion Systems has introduced the IB462S and IB463S miniature bipolar stepping motor drivers. Their sinking inputs eliminate the need for additional circuitry when interfacing to control devices with sinking outputs. The 462 model provides 160 W of output power (2 A per phase), while 230 W is obtainable from the 463 (3.5 A per phase). Both models feature optically isolated inputs, half- and full-step operation, a chopping rate of more than 20 kHz that eliminates audible noise, and a requirement of only a single power supply of 12–40 V. The high voltage allows for greater speeds at higher torque without resorting to larger motors or drivers. The small size of both models makes them suitable for either printed-circuit board or frame/chassis mounting. Intelligent Motion Systems Inc, 370 North Main Street, P.O. Box 457, Marlborough, Connecticut 06447, http://www.imshome.com

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Compumotor Division of Parker Hannifin Corp has introduced MotionPanel, a PC-based graphical user interface that is designed to be paired with the company’s 6K Motion Controller. The GUI provides highspeed Ethernet communications, upload/download capabilities, and built-in intelligence without the need for programming. The 6K instrument can control 2-8 axes (cascadable to 40 axes), which serve both servo and stepper motor drives. The MotionPanel comes with more than 70 preconfigured motion control panels; the software automatically knows if the controller is set up as a 2-, 4-, 6-, or 8-axis system and operates accordingly. The software can also determine if and what expansion analog or digital I/O modules are connected to the system. Compumotor Division, Parker Hannifin Corporation, 5500 Business Park Drive, Rohnert Park, California 94928, http://www.compumotor.com

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A CD from Data Device contains data sheets, product brochures, application notes, and designers’ guides for the company’s motor drivers/controllers, motion feedback technologies (synchros and resolvers), data bus interfaces, and solid-state power controllers. Data Device Corporation, 105 Wilbur Place, Bohemia, New York 11716-2482, http://www.ddc-web.com

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A 48-page color catalog from Kinetic Systems provides technical information on the company’s vibration isolation workstations and mounts, vibration-free platforms, optical tables, islands, breadboards, and accessories. Vibration isolation technology is explained in basic terms. Kinetic Systems Inc, 20 Arboretum Road, Boston, Massachusetts 02131, http://www.kineticsystems.com

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