Research On Key Technologies Of Ultra Fast Pulsed X-ray Source

X-rays have the characteristics of high energy,strong penetrating ability,and no attenuation in vacuum environment.It plays an increasingly important role in the fields of industry and scientific research such as non-destructive testing,security inspection,X-ray communication and pulsar navigation.The application of pulsed X-rays to accurately determine the time response and sensitivity of the detector or scintillator is of great significance for the performance evaluation of the actual application scenarios of related equipment.As the performance of scintillators and detectors improve,ultrashort pulse X-ray sources with pulse widths ranging from a few nanoseconds to hundreds of picoseconds are needed.The traditional thermionic cathode X-ray source has large volume,low energy efficiency,high energy consumption,large heat generation,and slow response time.It cannot achieve instantaneous emission and shutdown of X-rays,so it is difficult to achieve ultra-short pulse width X-ray emission.In addition,the traditional thermionic cathode X-ray source uses tungsten wire as the electron emission structure.Due to the characteristics of the tungsten wire in a hightemperature working environment,it is easy to rupture in a complex external environment,thereby affecting the life of the X-ray source.In view of the various problems faced by the application of thermionic cathode Xray sources in industry,scientific research and other fields,this thesis innovatively studies the light-controlled ultra-fast pulsed X-ray source based on photocathode.The X-ray source is more adaptable in various use environments by using photocathode instead of traditional thermionic cathode structure.And the photocathode does not need to be heated when working,while the heat dissipation requirements of the system are reduced;through the external modulation of the light source,the intensity of the photocathode input light is controlled to realize the intensity modulation of the emitted X-ray.Due to the instantaneous response characteristics of the photocathode,no preheating step is required,and compared to the thermionic cathode X-ray source,better modulation performance can be achieved.In this paper,an X-ray tube based on a photocathode is designed,a sample tube is developed,and a pulsed X-ray source performance characterization experimental system is constructed.Through the reasonable design and parameter matching of the test system,the blue LED with a wavelength of 460 nm is used as the light source to illuminate the S20 cathode;the MOSFET-based LED light modulation circuit is used to achieve the intensity control of the emitted X-ray.The maximum tube current is 2.37 m A,and the output energy is adjustable from 0-25 k V.At the same time,based on this system,the X-ray digital signal transmission verification is tested,and the static simulation experiment of the X-ray pulsar profile is realized.A simulation experiment result with a pulse profile similarity better than 99% is obtained,which verifies the excellent X-ray modulation performance of the developed ultra-fast pulsed X-ray source.