User Manual
Contents
1. the applied current The magnetic field direction is controlled by the polarity of the applied current a 4 Terminal Color Function Brown X coil ee 2 Connect the sensor cable to the external voltmeters The sensor cable s connector has five pins as shown below However only 4 pins are used Pin 1 to red wire is ground Pin 2 yellow is to be connected to DC 3 Volt power supply Pin 3 blue is X axis field sensor voltage output Vx Pin 4 black is Y axis field sensor voltage output Vy Ng Terminal Color Function og Pa asa Yellow J om k J d 3 Magnetic Sensor Readings The magnetic field sensor outputs are ratiometric Zero magnetic field output corresponds to 50 of the voltage supplied to S 2 V supply A positive field increases the output voltage and a negative field reduces the output voltage from this 50 of S 2 value To obtain best sensor performance DC 3V should be applied to S 2 Do not exceed 3 5VDC The sensitivity is 10mV G but a calibrated correction factor needs to be used to determine actual field at the location of the device under test Calibration parameters taken at the center of the test area and in the plane of the mounting PCB are given below With 3VDC supplied to S 2 zero magnetic field corresponds to Vx 1 5 V and Vy 1 5V Positive field corresponds to an output of gt 1 5 to 2 9 V and negative field SpinField 2D Manual 3 Micro Magnetics Inc corresponds to an out2. Micro Magnetics Inc Micro Magnetics Sensible Solutions SpinField 2D Two Dimensional Magnetic Field Platform User Manual www directvacuum com www micromagnetics com SpinField 2D Manual Micro Magnetics Inc Overview SpinField 2D Two Dimensional Magnetic Field Platform The SpinField 2D Two Dimensional Magnetic Field Platform is used to generate a two dimensional magnetic field of arbitrary direction and strength The platform consists of a pair of orthogonal electromagnets capable of generating two magnetic fields along the X and Y axis Sample space is a square approximately1 5 by 1 5 inch Magnetic field strength is measured by a pair of magnetic sensors located below the sample mounting surface There is one sensor each for the X and Y axis magnetic fields Each sensor outputs a voltage proportional to the magnetic field along its sensing axis Applications Magnetic sensor characterization Research on magnetic properties of thin films crystals devices Research on spintronics Bio magnetic applications in magnetic immunoassay magnetic separation Magneto optics Magnetic hysteresis loop measurement Ordinary and extraordinary Hall effect measurement Magnetic biasing for sensors and other devices Non destructive evaluation based on eddy current sensing Using rotating field to remotely control magnetic particles Ferromagnetic resonance EPR NMR spectroscopy Electromagnet Specifications Pole Dia
3. erheat the magnets During higher current or long maximum current operation make sure the region near the magnetic field platform is well ventilated If needed use an electric fan to remove heat generated by the platform Keep the magnetic field platform in a dry environment SpinField 2D Application Note Generating AC Magnetic Field Frequency Dependence of Maximum Magnetic Field Generated by SpinField Magnetic Field Platform SpinField 2D Manual 5 Frequency Dependence of Maximum H Field in RL Circuit Micro Magnetics Inc Fall River MA USA I Introduction In any scientific experiment it is important to document the physical limits of the apparatus used It would be counterproductive to attempt data collection in a regime where the equipment cannot function properly or at all In our laboratory constant use of magnetic fields produced by alternating currents running through magnetic coils is needed and it is very valuable to know the extent to which these coils can produce various field strengths We wish to find the maximum magnetic field strength a given set of coils can produce at a range of different frequencies The circuit used is essentially a RL circuit consisting of a resistor and an inductor in series The AC source can be assumed to be a purely sinusoidally oscillating potential difference V t Vosin wt In a series circuit consisting of a resistor and an inductor the potential difference across t
4. he entire circuit can be defined purely in terms of the resistance R the inductance L and the alternating current V RI L gio t RI t Fa After assuming the current flowing through the circuit is a superposition of sine and cosine functions the differential equation can be solved yielding an Electromagnet Figure 1 Experimental apparatus expression for the current in the circuit as well as its maximum R sin wt Lw cos wt NO E Vo imax TRIE Za Since the current flowing through the inductor is directly proportional to the magnetic field produced by it the Maximum Field A U o Co 0 5 0 50 100 150 200 250 Frequency Hz Figure 2 Maximum field as a function of AC frequency with fit curve maximum field is related to the maximum current by a constant factor C Ka a Il Experimental Setup and Procedure A function generator was set to output a sine wave with a peak to peak voltage of 1 000 V and an offset of 0 000 V A resistor of known resistance was placed in series with the magnetic coils and a voltmeter was placed in parallel to the resistor to measure the potential difference across the resistor Figure 1 Potential differences were measured across the resistor for a time equivalent to 10 periods of AC current at a given frequency A range of frequencies from 0010 Hz to 200 0 Hz was tested Using previous calibration the calculated current flowing through the coils
5. meter 1 06 inches 27 mm Pole Gap 1 8 inches Dimensions Diameter 8 5 inches 8 without cover H 6 5 inches Weight 21 Ibs 9 5 kg Resistance of coils 48 ohms nominal Maximum current 1 Amp sustained Magnetic field per amp X Axis 343G Y Ax1s 337G Cooling ambient SpinField 2D Manual l Micro Magnetics Inc X Y Magnetic Field Sensors Specifications Supply Voltage Vcc 3 VDC 2 5 3 5V Supply Current 6mA Output Saturation Vcc 0 1V Sensitivity 10 mV G Quiescent Output 0 50 x Vcc Noise 80 mV peak to peak 1 Electromagnet Pole Fixture 2 Housing 3 Removable Cover Use of the Two Dimensional Field Platform The field platform comes with two cables a power cable and a sensor cable each having a unique connector These cables plug into the matching sockets of the field platform DOWER 1 Connect the field platform to the external current sources The power cable s connector has four pins as shown below Terminal 1 brown wire and 2 yellow are used for X axis electromagnet Terminal 3 green and 4 white are used for the Y axis electromagnet Connect these four colored electrical wires to two external power supplies that supply the currents to the X and Y axis electromagnets SpinField 2D Manual 2 Micro Magnetics Inc When applying currents to the electromagnets do not exceed the maximum current as specified The magnetic field strength is linearly proportional to the amplitude of
6. put of x1 5V to 0 1V Therefore the magnetic field strength can be computed using the following formula B Gauss V 0 5 V supply 159 Vy 0 5 V supply 233 40 302 By Gauss Vy 0 5 V supply 233 Vx 0 5 V supply 159 40 302 Calibration Parameters Sensor output to field strength X axis 6 3mV G off axis 1 9 mV B G Y axis 4 3 mV G off axis 1 3 mV ByG Applied current to magnetic field output X Ax s 343 G Amp Y Axis 337 G Amp Y Field Directions 4 Mounting a Sample The SpinField 2D Two Dimensional Magnetic Field Platform can be used with or without the aluminum cover The cover is removed by loosening the hex head screw SpinField 2D Manual 4 Micro Magnetics Inc located on the outer lip of the cover rotating the cover counter clockwise and lifting the cover up and off the housing Mount the device under test as close to the surface of the square aluminum stage and to the center of the stage as possible The will ensure the fields sensed by the sensors are the same field applied to the sample The device under test can be mounted onto the platform using the M3 hole pattern see figure below located on the fixture in the plane between the magnet poles Jx M3 5 Ventilation of the Magnetic Field Platform The magnetic field platform is designed to handle 1 amp maximum sustained current However larger currents can be used for short durations if care is taken not to ov
7. was converted to magnetic field strength All parameters were controlled and set up with National Instruments LabVIEW software III Results The maximum magnetic field as a function of AC frequency is shown in Figure 2 As can be seen the highest maximum fields are seen with the lowest frequencies decreasing rapidly until an inflection point After this point the maximum field approaches zero slowly as the frequency increases After fitting the predicted maximum field frequency relationship to the data it is apparent that the theory matches the experimental results quite well The data shown in figure 2 differs from the value of the maximum magnetic field by just a constant A simple calibration routine relating current flow in the circuit to the produced magnetic field would yield the correct values
Download Pdf Manuals
Related Search