Let us assume we have a very strong electron microscope. One that would need multiple electro-static and electro-magnetic lenses.
The electrostatic lens is used to accelerate the electrons to a desired energy.
The electro-magnetic lens is used to change the path of the beam.
Now I'd assume that especially the electro-magnetic lenses, created by running high currents through a coil, can create significant magnetic fields.
On one hand I'd expect that:
- These magnetic fields interact with each other if we have more than 1 electro-magnetic lens.
- That the magnetic fields generated could cause problems outside of the E-microscope machine, like pulling metal objects towards it. Just like the MRIs in hospitals.
But neither seems to be the case. Why? When I was there, I asked about that but got only a very short answer:
'We use Helmholtz coils to stabilize the magnetic field'
What exactly does that mean? Can anyone help?