The nonstationary model for formation of the anode spot

Physical and mathematical models are suggested to describe anode heating and formation of the anode spot. At increasing current of the vacuum discharge there occurs a crisis in the cathode ion flow leading to a specific (critical) current value at which it is impossible for the ions to reach the anode. It is known that in this case a negative space charge layer with a positive anode voltage drop comes into existence and an electron beam is formed. The value of the anode drop depends on the size of the space charge layer and type of the electrical circuit.