The performance of electron beam devices is negatively influenced by external magnetic fields. For this reason, especially in cities with many sources of interference, measures must be taken to be able to operate such devices. Four reference projects are described below.
The Research Institute for Molecular Pathology (IMP) intended to build a new research laboratory where the high-end TEM microscope Krios G4 from ThermoFisher will be installed.
As the magnetic field fluctuations in the Vienna BioCenter are very high due to the nearby metro / tram lines and internal sources, and the required specifications are very low at <10nT, the IMP decided to shield the space with Systron’s LabShield® passive concept and an additional active cancellation system.
Systron planned, designed and installed the passive and active shielding including a facing shell to protect the sensitive shielding material and the profiles to fix the lab internal installations.
With the shielding concept implemented, the magnetic field levels in the sensitive area of the microscope column could be reduced to well below the target value of 10 nTpp, while the magnetic field level in the unshielded neighbouring room was up to 1400 nTpp.
The University of Stuttgart is building a new laboratory complex for the Centre for Applied Quantum Technology (ZAQuant). One of the four high-precision laboratories must meet the highest requirements for vibration and noise protection as well as protection against electromagnetic fields.
The room was constructed as a free-standing cuboid, which was placed on top of the floor-side shielding. Subsequently, the shielding had to be attached to the other five sides on the outer surface of the cuboid.
Systron EMV GmbH shielded the laboratory with two passive shielding layers based on Systron LabShield® to reduce the magnetic field levels in the frequency range from 0 Hz to 625 Hz.
The acceptance measurements carried out showed that the shielding reduced the magnetic fields to < 14 nTpp according to the requirements.
ETH Zurich and its Scientific Centre for Optical and Electron Microscopy (ScopeM) intended to build two new microscopy rooms. At the time of construction, the specific microscope types had not yet been defined. The target values for the variable magnetic fields were set at 20 nTpp in the centre of the room.
As there was a power line and two lifts close to the room, ETH decided to passively shield the rooms with Systron LabShield®.
Systron planned, designed and installed the passive shielding, including a facing shell to protect the sensitive shielding material and the profiles for fixing the internal laboratory installations.
The control measurements after the installation of the shielding showed that the magnetic field values were below 20 nTpp even over a longer period of time, in all field directions.
At the TU-Dresden, two laboratory rooms for TEM electron microscopes at the Dresden Center for Nanoanalysis (DCN) have to meet the highest requirements regarding magnetic interference fields. Measures are necessary because the nearby tram line caused massive DC shifts. Since transmission electron microscopes (TEM) are used, there are particularly high requirements for the residual magnetic variable fields in the slow DC frequency range (<1Hz). A target value of <20nT is specified.
To achieve the required target values, Systron developed a shielding concept based on Systron LabShield®.
In this project, the two microscopy rooms were completely shielded on all sides with thermally treated nickel iron (Mu metal).
Measurements after installation of the shielding confirmed that the required target values were achieved.