Control Technology Of Beam Intensity For The Coupled System In CiADS Facility

China initiative Accelerator Driven System(Ci ADS)has been built in Guangdong province.The Ci ADS facility consists of a proton accelerator,a spallation target cooled with Lead-Bismuth Eutectic(LBE)and a sub-critical reactor cooled also with LBE.Without any control rod inside the reactor,the control of the reactor power is controlled by adjusting the proton beam intensity.It is very important to control the beam intensity of the accelerator,when the accelerator,spallation target and reactor are coupled.This thesis studies the control of the beam intensity of the proton accelerator.The following three research works have been described in the thesis.Firstly,the control technology of beam intensity based on adjustable aperture is studied,and the influence of beam’s parameters on the beam intensity is simulated in detail.The beam intensity is controlled by using an aperture device at the Low Energy Beam Transport(LEBT)line of the accelerator to block the outer particles of the beam.Since the circular aperture size is adjustable,the beam intensity can be adjusted by changing the diameter of the circular aperture.In order to observe the variation of beam intensity with both the size and center of beam spot,the beam intensity is calculated by assuming that the proton beam is a Gaussian distribution with various FWHMs(Full Width at Half Maximum).The simulation results show that the beam intensity decreases with the increasing FWHM,when the diameter of the circular aperture is fixed.On the other hand,if the beam center deviates from the center of the circular aperture,the beam intensity will also decrease,where both the diameter of the circular aperture and beam’s FWHM remains unchanged.Secondly,the automatic control of beam intensity based on proportional-integraldifferential(PID)controller is studied,where the three parameters of the PID controller are determined with a genetic algorithm.In order to decrease the time for searching the three control parameters of the PID controller,the optimized genetic algorithm is developed as follows.Because each control parameter is represented in a binary number,it is very important to extract the most significant bits(MSB).During the initialization of populations,the optimized genetic algorithm fully considers all possibilities of the most significant bits,ensuring that the best value of the three control parameters can be found as soon as possible.The simulation results show that the genetic algorithm can find the parameters very quickly and the PID controller can perfectly adjust the beam intensity to the setting value.In addition,even if the beam intensity changes due to the change of either the beam’s FWHM or the beam center,PID automatic control technology can be used to restore the beam intensity to the set value.Finally,based on the proposed control technology of beam intensity and the simulation results,the control system of beam intensity is implemented in the distributed control system(DCS).The devices for adjusting the beam intensity include a Beckhoff controller,a Beckhoff servo driver,a Beckhoff servo motor,all three from Beckhoff company in Germany,and a domestic aperture device.The data exchange between the Beckhoff controller and the DCS system is taken with the Modbus / TCP communication protocol.The deviations between the setting value and the measured value of the rotation angle in the aperture device have been measured,where the setting value of the angle is given at the operation interface of DCS system.The measurement results showed that the deviation of the angle adjustment of the aperture is less than0.002 degree.According to the relationship between beam intensity and aperture rotation angle,the adjustment accuracy of the beam intensity is 0.00005。...