Field emission cold cathode soft X-ray tube using carbon nanotubes

Abstract

The invention discloses a field emission cold cathode soft X-ray tube using a carbon nano tube. The soft X-ray tube provided with a field emission type cold cathode and taking the carbon nano tube asan electron emission material takes a foil film plated with gold (Au) at the inner side of a beryllium window as a target electrode, and the electron emission surface of the carbon nano tube on the cold cathode is parallel to the front surface of a gold-plated target electrode surface, so that X-rays generated on the target electrode are emitted forwards. The soft X-ray tube provided by the invention is equipped with the cold cathode, so that the filaments can be heated without power, and the related power consumption may be saved. The tube current is uniformly distributed on the gold-plated target pole surface to prolong the damage of the target pole, so that the long service life of the soft X-ray tube can be maintained. By means of the mode, the irradiation angle is increased, and the uniformity of the X-ray intensity in an X-ray irradiation area is improved. At the aspect of the manufacturing process, as an assembly type process capable of producing a large number of low-cost smallsoft X-ray tubes, vacuum exhausting and sealing can be performed on the plurality of soft X-ray tubes at the same time by establishing a vacuum packaging process.

Description

technical field [0001] The invention relates to the technical field of carbon nanotubes, in particular to field emission cold cathode soft X-ray tubes utilizing carbon nanotubes. Background technique [0002] When the free electrons on the metal surface receive energy beyond the work function, they will escape from the metal surface, and every metal has its inherent work function. In addition, the phenomenon that electrons escape from metal surfaces also occurs when high electromagnetic fields are applied and light rays exceeding a certain energy are irradiated. Thermionic emission is a phenomenon in which a large number of electrons in a metal are heated to escape by overcoming a surface barrier (work function). Photoelectron emission is a phenomenon in which electrons get enough energy to overcome the surface potential barrier (work function) when a substance is irradiated by light. Field emission is a phenomenon in which electrons overcome the surface barrier tunneling ...

AI Technical Summary

Problems solved by technology

[0012] (1) With repeated heating, the characteristics of electron emission after the filament is heated will change, and will limit the life of the X-ray tube;

[0013] (2) In the process of heating the filament to emit thermal electrons, gas will be generated and the vacuum degree will be reduced due to internal heating;

[0014] (3) The power supply for heating the filament is required;

[0015] (4) In cases where X-rays of special wavelengths are required (such as research or material analysis), tungsten evaporated when the filament is heated can contaminate the target surface, thereby reducing the quality of X-rays

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