The influence of high magnetic flux densities on electromagnetic focusing of electrons

The resolution of "magnetically focused" image tubes is shown to be relatively constant with increasing magnetic flux density (B) until B exceeds (2/ηΔt), where η is the Electron charge-to-mass ratio and Δt is the transit-time, difference between focused and unfocused electrons. Magnetic flux densities higher than this value give rise to increased electron-optic resolutions, in proportion to B.