Preliminary Study On The Reliability Of Julong No. 1 Device

The Primary Test Stand(PTS)built at the China Academy of Engineering Physics is a typical pulsed power driver,which can deliver an 8?10 MA,90ns rise-time(10%?90%)current to a load.PTS is an important platform for the experimental researches such as Z-pinch driven inertial confinement fusion,hyper-velocity flyer launch and the research of pulsed power technology.The purposes of PTS reliability study based on the reliability theory and method include preventing the occurrence of fault,eliminating the consequence of failure and improving the facility reliability.This method could guide the design of system and components,find out the regular pattern of faults which occur and develop in the lifetime of important components,gain the experience of fault prevention and control.This paper discusses the reliability design of key components of PTS,analyzes the failure mode effects and criticality,and validates the reliability data of key components.The facility reliability is obtained from the reliability model,and the operation and maintenances strategy is proposed.The main contents and conclusions of this paper are organized as below.Based on the technical characteristics of PTS,the key components of Marx generator and main switch play an important role in achieving the technical goals of the facility.Stable and reliable Marx generator is the basis to generate a single low-jitter ultra-high power pulse.High-performance main switch is the key of a single low-jitter ultra-high power pulse control.Both of them are the key components of the whole multi-channel parallel ultra-high power pulse facility.This paper discusses the design of key components from two aspects:performance design and reliability design.The reliability design mainly includes simplified design,derating design,margin design,parts selection and control et al.There are three steps for the experimental process of PTS:charging,triggering,pulse forming and transmission.The main failure modes,which are common and have a great influence in the experiment,are Marx generator prefire,main switch prefire,magnetic insulation transmission line flashover between cathode and anode et al.The fault criterion is defined,the cause and influence are analyzed,and the improvement measures are put forward.According to occurrence probability,effect severity and detection difficulty,the method of risk priority number is used to analyze the criticality of failure mode.The components are sorted by risk priority,and corresponding sequence from high to low is Marx generator,main switch and magnetic insulation transmission line.Based on the self-breakdown voltage data of the key components such as field distortion gas switch,Marx generator and main switch,the voltage distribution approximately fits to the Gauss distribution.The distribution parameters are solved by a parameter estimating method.The self-breakdown probability is calculated under different working ratio.Under Marx generator's working ratio of 65%and main switch's working ratio of 85%,the calculated self-breakdown probability is in good agreement with the statistical result of experiment.Under field distortion gas switch's working ratio of 65%,the calculated self-breakdown probability is different from the statistical result of experiment.Because of the "bucket effect",the self-breakdown probability of Marx generator is largely determined by the switch who has high self-breakdown probability.The calculated self-breakdown probability is an average value therefore lower than the statistical result.The comparison between the calculations and statistical results shows that under the working ratio of 65%the self-breakdown probability of field distortion gas switch and Marx generator is about 10-4 and 6×10-3 respectively,under the working ratio of 85%the self-breakdown probability of main switch is about 3×10-3 to 4x 10-3.According to the different criterion of successful PTS experiments,three reliability model have been built including starting from charging,starting from triggering and starting from triggering with a main switch prefire allowed.Under Marx generator's working ratio of 65%and main switch's working ratio of 85%,the reliability of three models is 81.3%,88.8%and 97.7%respectively.The operation and maintenance strategies are obtained through theoretical analysis.These strategies include reducing the working ratio of Marx generator and main switch and maintaining the Marx generators first which have higher self-breakdown probability than the average.With these strategies,the reliability of the three models can be increased to 91.9%,97.6%and 98%respectively.Through the research work of this paper,the reliability theory and method is applied in the designing and operating the pulsed power facility,and the reliability data processing and analysis method is verified.This paper is meaningful for both existing and newly built facility to improve their reliability.