The Design Of Drive And Control System For Multi-beam Field Emission X-ray Sources

Field emission have a lot of advantage,such as the low operating temperature,have no time to delay and low power consumption,so it become a very effective way ofelectron emission. the research of its theory and technology in recent years becomemore and more deep, its application field is becoming more and more widely. Carbonnanotube materials because of its unique physical and chemical properties, hasexcellent field emission properties.Multi-beam X-ray source with carbon nanotubes asfield emission cathodes developed with launch control, zero response time and otheradvantages.Field emission need larger electric field intensity to suppress the cathodesurface barrier, this requires a driving power on the one hand have a high output voltage,on the other hand,multiple beam X-ray sources to achieve static emission, drivingvoltage need to have a high repetition frequency.therefore, multiple beamfield-emission X-ray sources requiring a high frequency pulse voltage, and carries onthe drive control, so as to realize the X-ray source in time and space on theprogrammable launch.At present, The Light source of carbon nanotubes and the massive carbonnanotube light source array system for CT is the forefront of research on theinternational.The domestic CT enterprise did not have ability to carry on the researchand development of carbon nanotube X-ray source,especially launches the research ofX-ray source completely to be at the blank condition in the X-ray CT domain to themulti-light beam field, research of the corresponding carbon nanotube field emissionnegative pole X-ray source-based also waits for developing.Research on multi-beamfield emission X-ray source drive control system did not have much shelf technologycan refer to.This paper attempts to develope the drive control system of multi-beamfield emission X-ray source,through the theoretical analysis of field-emission x-raysources and field emission study on switching devices,on the basis of current peopleresearch on carbon nanotube field emission cold cathode X-ray source and its pulsedrive control.This article in view of the carbon nanotube field emission and characteristic ofmultiple beam X-ray source, selected the better switch characteristics of IGBT tube as the drive control circuit of switching devices, and designed a pulse drive control system.This system adopts LabVIEW man-machine interface to set the parameters of the pulsesignal,I.e., the time pulse width and the pulse interval between each channel.FPGA isused to generate various pulse signal,and through the switch circuit to control eachfield emission electron source launch sequence and length. The experimental resultsshow that the system for multiple beam field emission electron source has played agood programmable launch control.