MAGNETIC FIELD COMPENSATION SYSTEMS
Manufacturing and Marketing Licensee ETS-Lindgren

MV-EMFC Systems
Active-Feedback Magnetic Shielding for Electron Microscopy and MRI
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Performance: Linear Research Associates' unique EMFC-series active-feedback magnetic shielding technology (U.S. Pattent 5,465,012) provides instantaneous, high-level protection at any frequency or combination of frequencies within a wide passband. No other commercially-available compensation system attains this uniformly high level of magnetic field suppression at all frequencies which can interfere with EM operation. Superior perfomance and reliability are guaranteed!


Ambient field reduction with extended-range EMFC-QDC-3 system.

MV-EMFC System Components

1) Field Sensors/Preamplifiers: Alternating current magnetic fields radiating from nearby a.c. power wiring, ground loops, transformers and related sources are detected via pickup sensors mounted on the EM column. These proprietary (U.S. Patent 5,469058) devices are physically small yet highly responsive to interfering magnetic fields. Column-mounted a.c. sensors and the co-located preamplifier module assure maximum transverse a.c. field attenuation at the beam location. Extended-range EMFC-QDC systems substitute a calibrated fluxgate probe to suppress lower-frequency magnetic field fluctuations caused by trucks, subway trains, and elevators or nearby analytical equipment such as mass spectrometers or MRI scanners.

2) Signal Processor/System Controller: High-level signals from the magnetic field sensor preamplifiers are conditioned and amplified by a phase-correcting signal processor and power driver in the controller chassis. Signal levels throughout the processing chain are supervised by an internal controller with front-panel programmable setpoints for warning and tripoff. The controller also implements a setup algorithm for easy initial adjustment and provides continuous fail-safe fault monitoring for the internal power supplies and power amplifiers.

3) Driven Coils: Compensation flux for reduction of interfering magnetic fields throughout the room is generated by driven coils which are mounted along or near the room vertices. Coil sets for each axis are placed on opposing walls and consist of single 0.5 inch [1.3 cm] o.d. cables installed in plastic raceway. Cable installation is fast and noncritical.

4) Performance: Linear Research Associates' unique EMFC-series active -feedback magnetic shielding technology provides instantaneous, high-level protection at any frequency or combination of frequencies within a wide passband. No other commercially-available compensation system attains this uniformly high level of magnetic field suppression at all frequencies which can interfere with EM operation. {Char: ambient field reduction with extended-range EMFC-QDC-3 system.]

MV-EMFC System Types

Specifications

MODEL EMFC-AC-3
FOR AC INTERFERENCE
MODEL EMFC-QDC-3
FOR AC AND LOW FREQUENCY INTERFERENCE
  • 3 axis
  • 2m3 minimum protected volume
  • 15uTavg (150mGavg) max. compensation
  • 10Hz - 1.5KHz bandwidth
  • 32 dB (factor of 40) typical a.c.-mains magnetic field attenuation
  • 1nTavg (10µGavg) noise floor
  • 3 axis
  • 5m3 minimum protected volume
  • 3uTavg (30mGavg) max. compensation
  • .001Hz - 1.0kHz bandwidth
  • >30 dB (factor of 32) attenuation of magnetic field variation
  • 1nTavg (10µGavg) noise floor


Sales, quotes, and site specific questions contact

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5244 Perry City Road Trumansburg, NY, USA 14886
Phone: (607) 387-3411

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