Negative electron affinity cold cathode X-ray tube

Abstract

The invention discloses a negative electron affinity cold cathode X-ray tube. The negative electron affinity cold cathode X-ray tube is characterized in that the cold cathode consists of an electrical emission type negative electron affinity cold cathode, wherein the cold cathode material contains a P-N knot, and can be used for generating vacuum electron emission without additionally arranging a light source; an X-ray tube target material is positioned in a tube anode; the cold cathode and the anode target material are in sealed connection through cold indium, and the vacuum degree of the whole tube is E-8Pa. The negative electron affinity cold cathode X-ray tube has the advantages that the defect that a conventional photoelectric cathode X-ray source needs an external light source is solved, the X-ray tube is compact in structure, convenient to use and stable in beam. Compared with a field emission cathode X-ray tube, the X-ray tube cold cathode is a large-area semiconductor epitaxial wafer without a plurality of micro tips of the field cathode, and therefore, the X-ray is high in resolution and good in uniformity. The negative electron affinity cold cathode X-ray tube is suitable for all semiconductor materials, surfaces of which can form negative electrode affinity, suitable for GaAs, and also suitable for various photoelectric cathode materials of GaAsP, InGaAs, AlGaN and GaN.

Description

technical field [0001] The invention relates to a negative electron affinity cold cathode X-ray tube, which is characterized in that the negative electron affinity cathode in the vacuum photocathode is used in the X-ray tube, and the cathode can emit high-energy electrons without an external light source. Compared with the traditional field emission cold cathode X-ray tube, the X-ray tube of the present invention has the characteristics of compact volume, uniform X-ray, high resolution and the like. The invention belongs to the technical field of photoelectric emission materials and the application field of cold cathode electron guns. Background technique [0002] X-ray tubes are widely used in special equipment fields such as security inspection and medical treatment, and their cathodes are mainly hot cathodes or field emission cold cathodes. Based on existing cathodes, X-ray tubes still have many disadvantages in terms of miniaturization and high resolution. Hot cathodes...

AI Technical Summary

Problems solved by technology

Based on existing cathodes, X-ray tubes still have many shortcomings in terms of miniaturization and high resolution

Hot cathodes have major defects in practical applications: (1) Hot cathodes are generally large in size and are not suitable for miniaturized cathodes (2) Thermionic beams have poor directionality and difficult focusing, which limits the high resolution of X-ray imaging

Since the basic physics of the vacuum photocathode is the photoemission effect, its inherent disadvantage is that when using the vacuum photocathode as the cold cathode of the X-ray tube, an external light source must be provided, so whether it is the existing domestic patents CN201210563112, CN201210563539 and the United States Patent US8,837,678 B2 has complex external incident light generating device and light coupling system

[0005] 1. X-rays with constant brightness are required in some applications, and the uncertainty of ambient light intensity directly affects the beam current of GaAs cold cathode photoemission, which in turn affects the intensity of outgoing X-rays

[0006] 2. The external light source and cold cathode are independent components. In order to eliminate the influence of ambient light, a complex optical fiber coupling system is required, which is difficult to meet the application requirements of miniaturized X-ray tubes, and also increases product costs and reduces product reliability.

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