| 摘要 |
The invention provides a device for producing and focussing an electron beam; the device comprising an evacuated chamber (4), a source of electrons (2), a target (6), means for creating an electric field to accelerate a stream of the electrons constituting the electron beam through the chamber towards the target, and means (12) for providing a magnetic field crossing the electron beam; characterised in that the magnetic flux of the magnetic field progressively reduces in the direction of the target. |
