An ideal diode sh

Vacuum diode consists of two electrodes- a cathode and an anode. The cathode emits free electrons while the anode collects the free electrons. Thus the current only flows from the anode to the cathode. A large current flows in forward biased p-n junction diode while a small current flows in reverse-biased p-n junction diode. Therefore, vacuum diode is close to an ideal diode which passes current only in one direction.