Research On Physics And Technology Of Pulse X-ray Machine Driven By Explosive Power Supply

X-ray pulse generators have been applied in many researches such as non-destructive testing,biomedicine,plasma physics,and hydrodynamic experiments.Especially,at certain conditions portable X-ray pulse generators with a small bulk are demanded.Explosive-driven ferroelectric generators(EDFEGs)have high energy density and storage stability.They can generate autonomously pulsed voltage and pulsed currents without primary external energy and provide primary high voltages to capacitance devices or high currents to inductors.An innovative pulsed power source could be exploited by use of EDFEGs and reasonable pulse modulation technologies.This dissertation has proposed a portable X-ray pulse generator,of which an EDFEG is used as primary power supply,inductive energy storage and opening switch for generation of high voltage pulse with fast rising time,and X-ray diode to emit flash X-ray.Physics and technology of the portable X-ray pulse generator have been investigated.Dielectric properties and leaking resistance of Pb(Zr0.95Ti0.05)O3,i.e.PZT 95/5,ferroelectric ceramic under shock compression and high electric field have been studied.These works help us to understand the dielectric properties of PZT 95/5 ferroelectric ceramic and provide important parameters for the design of EDFEGs.On the basis of EDFEGs and inductive energy storage technology,we have accomplished successfully high voltage pulse with fast rising time on an X-ray diode.Demonstratively,a prototype of portable X-ray pulse generator driven by an EDFEG was tested,and a flash X-ray photo of Richtmyer-Meshkov instablity of Sn disk's freedom surface disturbed by shock stress has been obtained in nanosecond time duration.The main achievements and conclusions of this thesis are as follows.1)A full-circuit simulation model of EDFEGs,which concerns dielectric properties,leaking conductance and equivalent resistance in serial of PZT 95/5 ferroelectric ceramic,was developed for EDFEGs on the basis of the analysis of working process and physical models of EDFEGs.Discharge properties of EDFEGs for three conditions of circuit loads,resistance,capacitance and inductance,were discussed.Effects of model parameters such as dielectric properties,leak conductance and equivalent resistance in serial of ferroelectric ceramic on load currents or output energy were analyzed.2)Dielectric properties and leaking resistivities of PZT 95/5 ferroelectrics under shock compression and high electric field were investigated.The results of displacement charges tests under pulse electric fields show that poled PZT 95/5 has intense non-linear dielectric property,and that the permittivity of depoled PZT 95/5 has a little change.A new method was proposed to test realtime,in-site,and online permittivity of PZT 95/5 ferroelectrics during shock compression.For the first time,dynamic permittivity and damping resistance of PZT 95/5 ferroelectrics were captured effectively.Serial experiments were designed to test the leaking currents of PZT 95/5 ferroeletcrics during the discharge process of EDFEGs.The realtime leaking currents were obtained under shock compression and high electric fields.These experimental results provided important material's parameters for the full-circuit simulation model of EDFEGs.3)On the basis of full-circuit simulation model,resistivity vs specific action model,and material's parameters,theoretical designs and calculations of EDFEGs for two output patterns,i.e.high voltage output and high current output,were carried out.The feasibility for the technology combined EDFEGs and inductive energy storing was expounded and proved.High voltage output pattern for EDFEGs was selected,and all related technologies were verified,such as charging capacitors upto 90 kV by EDFEGs,controlling accurately discharge sequence,and producing a fast voltage pulse with peak of 150 kV,rising time of about 5 ns on a resistor load of 45 ?.4)An X-ray diode for a portable X-ray pulse generator was designed and tested.In experiments,the diode voltages were about 130 kV with rising time of about 3.0 ns and half width of about 30 ns,and the diode currents were about 3.4 kA.The half width of X-ray pulse produced by the diode was between 15 ns and 20 ns.Its radiation dose was beyond 2.2 mR at 1 m distance,and its focal spot was a hollow ring with a diameter of about 1.0 mm.5)The design and experiments of a prototype of portable X-ray pulse generator driven by an EDFEG were accomplished.The prototype was composed of an EDFEG with high voltage output and a main X-ray machine.In detonation experiments the voltage of the capacitor charged by the EDFEG was 74.5 kV.The voltage of X-ray diode was 132 kV with rising time of 3.0 ns and half width of 30 ns,and the current was 3.4 kA.The X-ray produced by the diode was used at the same time to take an X-ray photo of Richtmyer-Meshkov instablity of Sn disk's free surface disturbed by shock stress.In result,an instant image of the development of Richtmyer-Meshkov instablity of Sn metal's free surface was obtained successfully.Compared with other X-ray machines with a certain voltage level and radiation dose,the pulsed X-ray machine developed in this paper has a volume reduction of more than 50%,a weight reduction of more than 70%,and no power supply is required.