Research On Transient Signal Front-end Recording System In ICF Experiment

Controlled nuclear fusion is a theoretically important method for mankind to obtain clean and cheap energy.Among the methods to achieve nuclear fusion,Inertial Confinement Fusion(ICF)is one of the most likely technological routes to achieve controlled nuclear fusion.In order to study fast transient experiments in fusion,it is necessary to diagnose the transient processes of neutrons,X-rays,and gamma ray s produced in the fusion reaction.In ICF diagnostic experiments,transient recording of each key physical signal is a crucial element in the diagnosis of fusion processes.The signal recording scheme in ICF has the problem of signal distortion due to long distance transmission.The fusion process generates complex strong radiation,including strong ionizing radiation and strong electromagnetic radiation,in the experimental area of the firing range.The strong radiation can reduce the measurement accuracy of the diagnostic equipment in the target room and even directly cause irreversible damage.Therefore,the current signal recording scheme is to transmit transient signals through tens or even hundreds of meters of UHF analog cables to commercial equipment in the control room behind the shielding wall for measurement and recording.The problem with this scheme is the amplitude attenuation and signal-to-noise ratio degradation that occurs in analog signals over long distances.the signal bandwidth generated in the ICF can reach up to 1.5 GHz or more,and decreases to less than 1 GHz after long distance transmission in non-specialized cables.Meanwhile,when there are more diagnostic channels,the long distance and large number of analog cables can make the installation,maintenance and upgrade of the diagnostic system more difficult.How to solve this problem is the main research of this thesis,in which the method of front-loading the signal recording module is used to successfully realize the development of a fast transient signal front-loading recording system(TSFRS).Instead of using long cables for signal transmission,the TSFRS is installed directly at the back end of the detector for high-quality recording of diagnostic signals,thus circumventing the impact of loss effects on signal quality.In achieving this goal,the main difficulties to be solved in the research are the fast transient signal recording challenge,the gamma radiation interference problem and the need for radiation resistant reinforcement of the TSFRS.The ICF experiment duration is in the nanosecond range,and the rise time and duration of the diagnostic signal are correspondingly only in the nanosecond or even picosecond range,which puts high demands on the performance of the signal recording system.Based on the characteristics of the diagnostic signal and related parameters,the electronic requirements for fast transient signal recording are a bandwidth of 1.5 GHz and a sampling rate of 10 Gsps.Under the restriction of technology blockage and high-speed ADC chip procurement,the parallel alternate sampling(TIADC)technology is used in the design of TSFRS,and the hybrid phase measurement method is proposed to solve the key problems in this technology.The TSFRS design uses the parallel alternate sampling(TIADC)technique and proposes a mixed-phase measurement method to solve the key problems in this technique,and successfully achieves high-fidelity recording of fast transients.While solving the problem of long cable transmission,the imported high-end equipment was replaced by localization,which greatly reduced the cost of experimental platform construction.In the neutron diagnosis experiments of ICF,the neutron-accompanying gamma rays introduce interference signals,which affect the accuracy of neutron diagnosis.The solution to this problem is to use neutron-gamma signal screening to eliminate the influence of interfering signals and obtain a high-fidelity signal.In the study of neutron screening methods,this thesis proposes a local charge comparison method based on the theory of fast and slow neutron-gamma components.The method has strong screening performance,small demand on system resources and short dead time,and realizes real-time neutron-gamma screening in neutron diagnostic experiments and solves the interference problem of gamma signals.Ionizing radiation and electromagnetic radiation in ICF experiments can degrade the performance of electronics equipment and even damage the equipment.The effects of ionizing radiation on the equipment include single particle effect and total dose effect;electromagnetic radiation will enter the system through electromagnetic coupling,introducing electromagnetic noise as well as current pulse interference.In response to the above effects of strong radiation environment,the system design has taken targeted anti-radiation reinforcement measures.In the ICF field test,the radiation-resistant reinforced TSFRS successfully completed the fast transient signal recording work.After fully investigating the above key issues,a TSFRS prototype with a bandwidth of 2 GHz and a sampling rate of 10 Gsps was designed and implemented.The system was field tested in the ICF range area,and the test results showed that the system could not only achieve high quality fast transient signal recording,but also operate normally under high radiation environment,which solved the problem of fast transient signal recording in current diagnostic experiments.