Positron and thermal desorption studies on He ion implanted nuclear graphite

13th International Workshop on Slow Positron Beam Techniques and Applications

Hu, Z.^1 ; Li, Z.^1 ; Zhou, Z.^2 ; Shi, C.^1 ; Schut, H.^2 ; Pappas, K.^2

State Key Lab of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China^1

Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands^2

关键词: Implantation dose;    Implanted samples;    Nuclear graphite;    Positron implantation;    Radiation-induced;    Reference values;    Temperature intervals;    Vacancy-type defects;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/505/1/012014/pdf
DOI  :  10.1088/1742-6596/505/1/012014

来源: IOP

【 摘 要 】

The positron beam Doppler Broadening (DB) and Thermal Helium Desorption Spectroscopy (THDS) techniques are applied to study the behavior of radiation induced point defects in IG-110 nuclear graphite. The defects are introduced by irradiation at room temperature with 200keV He+at doses ranging from 1015to 1017He/cm2. In the thermal desorption spectroscopy, the release of He+is observed between 500K and 800K. With increasing He+implantation dose, the fraction of He+desorbed decreases from 27% to 3%. In the DB-curves showing the S parameter values versus positron implantation depth, the derived vacancy type defect distribution are in accordance with those obtained by SRIM calculations. Subsequent annealing of the implanted samples in steps of 100K for 5 minutes up to 1200K shows a distinct decrease of the S parameter value to its reference value between 500K and 700K. This temperature interval corresponds to the literature values for single vacancy migration energy of 1-2eV.