Design Of Pulse Neutron Generator Control System Based On DSP/BIOS

The small neutron generator is a device that can generate neutrons.It has the advantages of easy portability,good monochromaticity,high neutron energy,safe use and convenient maintenance.It has a wide range of applications in oil logging,coal quality analysis,explosives and drug testing.The small neutron generator developed by the project team in the past has insufficient real-time performance,low communication rate,easy error in custom protocol frame,hysteresis of control interface display,and no pulse working mode.In the ion source ionization experiment,the ion source current in the neutron tube lags behind the reservoir current,resulting in low regulation speed and low stability of the ion source current,thus affecting the stability of the neutron yield.Based on the above problems,this paper designs a DSP/BIOS based pulse neutron generator control system.The pulse neutron generator control system is divided into two parts:hardware design and software design.In terms of hardware:It mainly includes core board,drive sampling board,storage power supply,ion source power supply,accelerating power supply and He-3detector.The control chip on the core board selects the 32-bit digital signal controller TMS320F2812 with flash memory to realize six-channel AD sampling,three-way power control PWM output,two-way pulse PWM signal output and serial communication.The driving sampling board filters the three PWM signals into a DC signal,realizes the control of the power voltage through the DC signal,and collects the voltage and current of the three power sources.The power control circuit includes an isolation circuit and a filter circuit.The power supply voltage and current collecting circuit is composed of a voltage follower circuit,an isolation circuit and a filter circuit.When the accelerating pole voltage is operated at 100 kV,it is prone to discharge,which may interfere with or damage other electronic devices.In order to ensure the safe and reliable operation of the core board and the driving sampling board,an optocoupler isolation chip,a fuse and a Zener diode are added.In terms of software:It mainly includes the core board DSP/BIOS program and the industrial computer LabVIEW control program.In the core board DSP/BIOS program,AD sampling program,sampling filter program,PWM output program and serial communication program are completed by DSP/BIOS configuration file hardware resource on-chip and DSP/BIOS resources,Modbus communication protocol is used to communicate with LabVIEW contro programl.In the LabVIEW program,the Modbus communication protocol in the LabVIEW DSC component is used to communicates with the core board.The program is designed into a multi-threaded structure,which mainly includes an event triggering thread and an event processing thread.The two threads use message queue structure to communication.The LabVIEW control program mainly realizes three-way power supply parameters,the power supply voltage control,the data monitoring and storage.The control of the trigger pulse and the synchronous pulse signal in the ion source pulse working mode is realized,and the working mode of the ion source power source can be switched online.This article tests the console:the storage supply voltage,the ion source supply voltage and the accelerating power supply voltage.The three-way power supply output is approximately linear with the control signal.The storage voltage adjustment accuracy is 1.7mV,the adjustment range is 0-5 V;the ion source voltage adjustment accuracy is 1.7 V,the adjustment range is 0-3000 V;the acceleration pole voltage adjustment accuracy is 0.023 kV,and the adjustment range is 0-130kV.D-T neutron generator meets the design requirements.The neutron yield can reach 1.0×10~8n/s,the life span reaches 8000 hours,and the neutron yield stability is within ±2%.