Effect of Magnetic Fields on SEMs/TEMs
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The following examples demonstrate the impact of magnetic fields on SEMs/TEMs and how various magnetic field sources can predictably manifest in site surveys. (Images are courtesy of Spicer Consulting.) These real-life instances can offer guidance to mitigate similar situations in your facility.
Elevators create strong DC fields, producing a gradient within an SEM/TEM lab that can disrupt measurements. The following survey data from Spicer highlights the field strength as the elevator rises and lowers over time.
Lighting within a room can have a severe impact on the ambient magnetic fields, which is why it is important to measure these fields under different circumstances.
Close proximity to a transformer or substation creates a significant field for SEMs/TEMs, highlighting the importance of identifying field sources and creating sufficient distance to optimize SEM/TEM operation in the lab.
Large magnets can create substantial fields affecting sensitive electron microscopes. The predictable behavior of magnetic fields in the following measurement shows the 6T magnet powering on and off.
SEMs/TEMs can experience field disruptions at DC, 16.7, 50, or 60 Hz as a result of trams and trains passing nearby. Currents flowing along the power lines create large fields.
Nearby vehicle traffic generates sporadic, yet influential magnetic fields for SEMs/TEMs, creating intermittent disturbances throughout the day.
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