A braking electric field of intensity E is created between two parallel grids.
A wide electron beam falls along the normal to the front grid, with a charge
density of ρ and a velocity of v . Ignoring the interaction of the electrons
0 0
themselves, find the charge density distribution between the grids if: a) the
speed of electrons is so great that they pass through the grids and do not
return; b) electrons are reflected by the field. Starting from what values of
ρ in the second case should the charge field between the grids be taken into
0
account?