Columbia University

Columbia University

The Jerome L. Greene Science Center has acquired a state-of-the-art cryo-tomography transmission electron microscope, capable of revealing the structure of the smallest biological specimens down to the molecular level. However, achieving this level of detail demands rigorous environmental stability, including control over noise, vibration, air currents, temperature fluctuations, and most critically, magnetic field variations.

Challenges with Proximity to NYC Subway

Located directly outside the building is the elevated New York City red line subway service, which operates on 625V DC to power the subway cars. This relatively low voltage necessitates high currents in the tracks and catenary system, resulting in significant ambient magnetic field fluctuations as trains passes. Similar to how a compass reacts to a wire carrying high currents, this system creates swings in the ambient magnetic field as trains go up and down the tracks.

Innovative Magnetic Shielding Solutions

From our experience, we understood that a magnetic Active Compensation System (ACS) alone would not suffice to reduce the magnetic flux density swings from 40mG P-P (4000nT) to the required 0.2mG P-P (20nT)—a reduction of over 200 times or -46dB over a 12ft column height. To address this, Vitatech engineered an innovative hybrid shield combining passive and active elements. This system includes an independent coil system and ACS controller, enabling precision control of magnetic fields around this critical apparatus.

Posted in: ACS Mitigation Scientific
Tags: electronmicroscopy,