in a cyclotron, charge moves from one dee to another but both dees being metallic have no electric field in them. Since charge is moved by electric field but if the electric field is present it might enter the dee and thus it would contradict the statement.
Please resolve my query.
So how does charge move
As i understand your query,.... The dees are metallic conductors and don't have electric field inside; In case of a conductor, the charges get equally distributed on the surface leaving zero electric field inside it. ou can understand it better as potential(v) inside a conductor is constant, E= -dv/dr = 0 inside. Hope it clears your doubt... feel free to express if it doesn't.