What could happen when a high speed electron hits a stationary cation?

[martin f]

What 'could' happen when a high speed electron hits a stationary cathion?

 

[mfb]

Cation?

It depends on the energy, and "high speed" is not useful to define this. The electron could get captured or it could do the usual electron/matter-interactions (mainly Bremsstrahlung) without caring about the other electrons. It can get deflected without any significant interaction with the atom.