Near-surface investigation of positron diffusion length in helium-implanted Fe9Cr and its ODS variant

A new approach to near-surface positron annihilation analysis of ion irradiated ferritic alloys

“…This paper demonstrates the feasibility of using the lifetime spectra obtained at PLEPS or any other pulsed low-energy positron beam to determine positron diffusion length. The obtained results are compared to previous DBS measurements on the same helium-implanted materials [16]. The present study complements and concludes decade-long research aimed at applying PAS techniques to improve the fundamental understanding of radiation tolerance of nano-oxide dispersion-strengthened steels.…”

“…The obtained positron lifetime results were compared to our earlier study of these materials using Doppler broadening spectroscopy (DBS). The DBS experiments, performed at the Aalto university's DBS facility, were reported in details in [16,25]. Although the DBS results were obtained for positron energies ranging between 0.5 keV -36 keV, in this work, we use reference data for the same energy range that was used for PALS.…”

“…The investigation of positron diffusion in ion-irradiated Fe-based alloys has been previously published in a few research studies [9,16]. The experimental values of the positron diffusion length are commonly obtained using one-dimensional Doppler broadening spectra, which were collected as a function of the positron energy.…”

Comparison between Subsequent Irradiation and Co-Irradiation into SIMP Steel

“…The irradiation temperature was well controlled at 300 ± 5 ℃ detected by an infrared thermometer. The Monte-Carlo code Stopping and Range of Ions in Matter (SRIM-2008) quick cascade simulations was used to simulate depth profiles of the displacement damage induced by 6.4 MeV Fe 3+ irradiation and the helium deposition (using the threshold displacement energy of 40 eV and the density of 7.86 g·cm −3 ) [ 9 ]. The simulated result is illustrated in Figure 1 a.…”

“…We can use Fe ion irradiation to simulate neutron irradiation-induced lattice displacement. The production of transmutation helium in the material can be effectively simulated by He ion implantation [ 8 , 9 , 10 ]. Due to the simultaneous occurrence of lattice disorder and helium accumulation, simultaneous dual-beam implantation of Fe and He seems to be an optimal procedure for an experimental simulation of realistic radiation condition.…”