An electron emitter includes an emitter section having a plate shape, a cathode electrode formed on a front surface of the emitter section, and an anode electrode formed on a back surface of the emitter section. A flexible sheath is coupled at one end to the cover member. The focus volume defined in free space away from the lens can be very small, providing excellent resolution for magnetic resonance imaging, for example. The development system further includes a non-magnetic, cylindrical shell for transporting the developer between the supply and the development zone, wherein the shell can be rotatable or stationary.