Study On Injection Of Tracer Element ¹³C Into ITER Wall Material Graphite

Carbon walls in the International Thermonuclear Experimental Reactor(ITER)will suffer from some damages such as irradiation,activation,evaporation,sputtering,bubbles because it contacts with high energy plasma beam bombardment directly,the transient and steady-state heat load and the electromagnetic effect,so it is necessary to be detected carbon wall corrosion extent in order to ensure the safety security of ITER.Compared with other elements,the carbon isotope 13C,as the original component of carbon wall,is not only a stable isotope in common use,but also will not cause adverse effects on the safe use of ITER.Therefore,13C is considered to be the best tracer element for carbon wall injection.(4)In this paper,the isotopic 13C ion was injected into graphite to obtain the concentration gradient of 13C ion,and the relationship between the injection depth and the concentration of the tracer element 13C was calculated by numerical simulation,so as to achieve the purpose of calibrating the corrosion depth of carbon wall according to the measured concentration of the tracer element 13C on the surface of the sample after corrosion.The main content of this paper includes the following three aspects:(1)By simulating the injection behavior of tracer element 13C into graphite,we determined the injection parameters and injecting tracer element 13C into graphite successfully,the injection energy is E=9MeV,the injection dose is Φ=5.5×1015 atoms/cm2.(2)The laser-induced Breakdown Spectroscopy(LIBS)and time-of-flight secondary ion mass spectrometer(TOFSIMS)are used to detect the concentration distribution of 13C.The results showed that 13C was successfully injected into the graphite and the concentration distribution was Gaussian normal distribution with the peak value in the range of 6-8 μm.Matlab is used to process the data,and the error of the smooth curve is only 0.56%.(3)Compared with the actual detection curve,the 13C concentration distribution curve simulated by TRIM program in SRIM-2013 software has a big difference in the range of maximum concentration and depth,with an error ΔT=2.70%.Through the Monte Carlo(M-C)method combined with the modified LSS theory,the obtained 13C concentration distribution is in good agreement with the actual detection curve,but the result is discontinuous and no error can be calculated.According to the new concentration distribution calculation formula N(X),the simulation curve is very similar to the experimental test curve and the error of the three methods is only ΔHigh=0.67%,which is suitable for the simulation of the concentration-depth relationship after 13C ion implantation in graphite samples under various conditions.This paper can combine the calibration of 13C tracer element and laser-induced plasma etching wall material to detect and remove the carbon co-deposition layer,also provide a theoretical basis for online detection of carbon wall corrosion.