Electron beam deflection appts. for computer tomography

摘要

An electron beam is deflected from a circular path to a circular path parallel to the original without changing its charge distribution. The deflection arrangement includes two pairs of deflection dipoles and a compensation dipole for the stray fields. The electron beam is deflected by 45 deg. in each pair. Each dipole can be composed of magnetic coils. The compensation dipole is supplied with a current greater than the deflection dipoles. The stray fields of the compensation dipoles are polarised opposite to the deflection dipoles so that the overlap of the fields leads to extinguishing.