Magnetron

Magnetron is a vacuum tube consisting of a cylindrical cathode and a coaxial anode, between which a direct current potential creates an electric field. A magnetic field is applied longitudinally by an external magnet. The magnetic field of external magnets affects on the electrons which follow arcing paths towards the anode. When they strike the anode, they cause it to become negatively charged in that region. Some areas will become more or less charged than the areas around them. These differences cause currents to appear. Since the current has to flow around the outside of the cavity, this process takes time. During that time additional electrons will avoid the hot spots and be deposited further along the anode, as the additional current flowing around it arrives too. This causes an oscillating current to form as the current tries to equalize one spot, then another.The oscillating currents flowing around the cavities causes large amounts of microwave radiofrequency energy to be generated in the cavities. Magnetrons are an important source of power in radar systems and in microwave ovens.