Review on simulation methods of micro focal spot x-ray tubes´ electron emission system

The micro focal spot x-ray tube is an x-ray source with 1~100μm x-ray focal spot´s nominal size. Since its high space resolution, this source is the kernel in such scientific researches and applications as biomedicine, biochemical dynamics, industrial nondestructive examination and detection x-ray microscopy and micro-CT. The electron emission system is the key part of the x-ray tube, it includes the thermal cathode and the focusing system. The cathode provides free electrons and the focusing system helps to constitute the focusing field. Upon the deep understanding on the structure and the working principle of the emission system, in this paper we summarize several methods to simulate the working process of the emission system.