The Challenge
To provide a shielding solution for the new FEI TEM Microscope installed at Cambridge University. The shielded enclosure was designed to enable the microscope to perform at its maximum resolution without interference from magnetic fields. The shielded enclosure would need to be able to provide a “quietness” zone around the microscope of less than 10nT p-p.
The Solution
Global EMC provided a multi-layer high permeability Faraday cage to line the walls, ceiling and floor of the host building. This enabled the user to maximize the internal space of the room, whilst not enclosing the microscope to permit ease of maintenance and workspace around the microscope.
Shielded doors, waveguides and honeycomb vents completed the installation to allow penetrations and services to be brought into the room.
The shield effectiveness was stringently tested by putting adjoining electrical cables under full load condition whilst performing the “quietness” commissioning certification tests.
Benefits To The Customer
The client received a shielded enclosure that exceeded the required magnetic field shielding required. The room post mitigation achieved a <5nT p-p in magnetic field perturbations as measured over the allotted time.
Product Information
Location – Materials science, Cambridge University
Machine – FEI Transmission Electron-Microscopy
Room Dimensions – 7m x 7m x 7m
Quasi-DC slow moving field disturbance sources – local delivery vehicles/lifts/pallet trucks etc.
Mains power magnetic field disturbance – 400A feeder cable close to room.
Magnetic field ‘quietness’ target - <10nT p-p
Resultant worst case magnetic field VLF/ELF/DC perturbations (post mitigation) – 5nTp-p as measured over time.
Mitigation methods:
• Active cancellation system – None
• Passive shield – Multi-layer high permeability Faraday cage