Extended Schottky Thermal Emission Theory Research

Cathode is the source of the electron gun when the electron gun is emitting electrons in the microwave vacuum devices. It is one of the most important components that can affect the performance of the electron gun. It plays?a decisive role in launch capability and life of the electron gun, while the launch capability of the electron gun has a great influence on many parameters of the microwave vacuum devices such as the output power, bandwidth and life and so on. As the heart of the information equipment in modern military, the microwave vacuum devices have to improve and increase the properties of the cathode emission and improve the overall technological level of the cathode in order to maintain a high frequency, power and other advantages relative to the semiconductor devices. The cathode emission of electron gun has a great relationship with the cathode material, cathode temperature and the structure of the electron gun and the three aspects must be considered completely in order to achieve accurate simulation of electron gun. The performance parameters of the electron gun directly affect the key performance indicators such as the efficiency of microwave electron tube, life, gain, linearity and so on; therefore the rational design of electron gun is an important link in the overall design of microwave tubes.The thermal electron emission of the cathode is a very complex mechanism affected by many factors, each of which plays a very important role on whether the cathode is emitting stably. First of all, the impact of the temperature of the cathode, because the temperature directly affects the size of electron kinetic energy at the micro level, which directly shows that the energy that their escape from the cathode. The second is the distance between the cathode and anode. The size of the distance will largely determine the number of electrons the anode receives from the cathode emission, which will affect the anodic current. Besides, the position and the size of the voltage of the virtual cathode produced by space charge, which affects the number of electrons emitting from the cathode to the anode because the virtual cathode is the last obstacle that the electron can reach the anode. At the same time, the initial velocity of the cathode emitting electrons is also a factor that can not be ignored. It indirectly affects the electron emission of cathode by directly affecting the position and the Strength of the voltage of the virtual cathode. Moreover, there is also the potential difference between the cathode and anode, because it is the most important promotion factor that the electronic breakthrough the virtual cathode barrier, it is directly related to the number of electrons that emission from the cathode and received to the anode. Theory, the Schottky effect should be considered when the electric field strength between the anode and cathode is greater than 10~2V cm , and the relativistic effect to be considered when the electric field strength greater than 5×10~4V cm.The innovation of the paper: Analysis the effecting from electron tunnel effect to electron escape from the cathode, In the condition field emission electron wave effect when the premise of re-solving the Schrodinger equation, the micro analysis of electric field between the anode and cathode between 10~2～10~5V cm, the extended Schottky is a more accurate expansion emission model. And demonstrate the continuity between the models. Finally, by analyzing the changing nature of law of the periodic table of elements in the paper, focusing on the microscopic properties of electrons and composite materials, the role of electric dipole moment between the cathode work function of the impact, in theory, provide the relative right direction for the selection of cathode materials, identified new materials comply with emission cathode emission characteristics and potential for further experimental work to determine a certain basis.