A cathode (1) includes a substrate (10), a resistive layer (11) disposed on the substrate (10); at least one cathode conductor (13), and microtips (2) disposed on the resistive layer (11), wherein the cathode conductor (13) has circular wells (17) in the middle of each of which a microtip (2) is disposed, whereby the microtips (2) are electrically isolated from the cathode (13) by a constant access resistance.