Design And Experimental Of Micro-structure Transmission Anode X-ray Source

Since Pfeiffer proposed the grating phase contrast imaging based on ordinary X-ray sources in 2006,phase contrast imaging method has been widely researched and most likely to be used in practical applications.The advantage of the imaging method is that high coherence X-ray photons can be obtained in ordinary X-ray sources,which will reduces the requirement for X-ray sources.However,phase contrast imaging requires the analyser gratings with large area and small period structure,and the fabrication of large area and small period gratings has always been a worldwide problem.Swiss scholar Tilman Donath was proposed an inverse Talbot-Lau grating phase contrast imaging method in 2009.This method enlarges the period of analyser grating and reduces the difficulty of making analyser grating,but it needs a source grating with small period.In this paper,in order to solve the problem of source grating fabrication based on inverse Talbot-Lau grating phase contrast imaging method,the source grating located behind the X-ray source is fabricated directly in the ordinary X-ray source by micro-nano processing methods.In this way,the inverse Talbot-Lau grating phase contrast imaging system reduces a source grating,not only reduces the difficulty of grating fabrication,but also simplifies the structure of the imaging system.It has played an important role in promoting the practical application of inverse Talbot-Lau grating phase contrast imaging.This paper is about the development of microstructure transmission anode X-ray source and fabricated one kind of planar X-ray cathode,and fabricated the tungsten arrays with micron size on pyrolytic graphite and conductive diamond substrates.The specific work is as follows:1.From the point of view of electron emission,this paper analysed the helical emission cathode shortcoming and designed a planar structure of cathode.The actual electronic focal spot size of planar cathode structure was 0.4mm x 0.4mm on the open vacuum device test platform,which meets the requirements of transmission X-ray source for focal spot size.2.Analysis of the advantages of transmission structure in phase contrast imaging system,through the formula to calculate when 30 KV X-ray can through the tungsten metal film thickness was 1.07 ?m.Analyse and select low atomic number,high melting point,high thermal conductivity and good electrical conductivity of carbon materials as anode substrate.3.The tungsten arrays structure with a period of 24?m and a line width of 3.5?m was fabricated on pyrolytic graphite and conductive diamond substrates by photolithography,magnetron sputtering and Lift-off technology.The tungsten film thickness on various substrates was about 1?m,comparing with the difference between the various substrate processing parameters.Finally,pyrolytic graphite and conductive diamond cathode substrates with tungsten arrays were bombarded on an open vacuum device test platform.