Damage studies on irradiated tungsten by helium ions in a plasma focus device

Seyyedhabashy, Mir mohammadreza; Tafreshi, M. A.; Bidabadi, Babak Shirani; Shafiei, S.; Nasiri, Ali

doi:10.1016/j.net.2019.10.003

Cited by 16 publications

(2 citation statements)

References 28 publications

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“…In this study, we focused on the damage by neutron irradiation in the vicinity of the surface in W, and would like to leave the comment that the behavior of He is also important topic in order to understand the surface effect especially in the context of nuclear fusion. Irradiation damage near the surface of tungsten is known to be mainly caused by blistering by He ions generated by the D-T reaction, and many studies have been conducted to understand this phenomenon [36,[57][58][59][60]. Although our study did not analyze the direct surface irradiation damage by He ion, still the knowledge obtained in this study can be extended and applied to understand the irradiation damage in any nonsymmetrically structured systems such as micro-voids, cracks and even grain boundaries, which affect the mechanical behavior of PFM [12][13][14][15][16][17][18][19] and hence has vast implications in PFM design.…”

Section: Discussionmentioning

confidence: 99%

Free-surface effect on displacement cascades in BCC W: molecular dynamics study

et al. 2020

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We investigated the free-surface effect on displacement cascades in bcc tungsten using molecular dynamics simulations. Primary knock-on atom (PKA) is projected at different initial depths with two different projectile directions, inward and outward, to the surface. Compared to the bulk system, a simulation system with free surface contains increased number of remaining point defects and clustered defects at equilibrium. This pronounced defect production near the free surface is caused by the suppression of defect recombination events. The interstitials energetically favor the formation of adatoms at the free surface, and the nonsymmetric feature of interstitial mobility is responsible for active vacancy clustering at the sub-surface. The free surface effect extends to 8 and 4 nm in depth when the PKA projectile direction is outward and inward, respectively, with PKA energy of 30 keV at 400 K. Beyond this characteristic depth, the defect population and clustered fraction become similar to those in bulk system. Clustered vacancy develops into extended defects such as ⟨100⟩ and ⟨111⟩/2 vacancy loops. For the first time, immobile ⟨111⟩/2 dislocation is observed in PKA simulation, which is consistent with the experimental reports of both stable ⟨100⟩ and ⟨111⟩/2 dislocations of Mason et al (2014 J. Phys.: Condens. Matter. 26 375701).

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Section: Discussionmentioning

confidence: 99%

Free-surface effect on displacement cascades in BCC W: molecular dynamics study

et al. 2020

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“…Extensive studies have been performed to characterize ion emission in PFDs in order to determine ion uence, ion energies, ion emission distribution and energy spatial distribution. Such studies have been commonly by others at one point on or around the z-axis above the anode by applying ion detectors like activation detectors for deuterium and nitrogen ions 2,11 , Faraday cups for hydrogen, helium, neon, argon and nitrogen ions [12][13][14][15][16][17][18][19][20][21][22] , Thomson spectrometer for hydrogen, deuterium, helium and nitrogen ions [23][24][25][26] , other methods used time of ight (TOF) technique for hydrogen and carbon 27,28 , CR-39 for hydrogen, deuterium, neon and nitrogen 23,[29][30][31][32][33] , PM-355 for deuterium ions 32 , LR-115 for hydrogen ions 34 and polycarbonate detectors by using extra aluminum lter as attenuators for nitrogen 35 .…”

Section: Introductionmentioning

confidence: 99%

Breakthrough 4π helium ion energy spatial distribution determination in plasma focus space by Sohrabi mega-size panorama cylindrical ion image detector

Zarinshad,

Sohrabi,

Amrollahi

et al. 2024

Preprint

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Recently Sohrabi theorized and discovered that ions in plasma focus devices (PFD) are emitted in 4π ion space instead of within small solid angle above anode, as commonly believed. Ion energies are commonly determined by others at single points above or around anode top. In this study, He ion energy distributions were determined in 4π PFD space applying Sohrabi mega-size panorama cylindrical polycarbonate ion image detectors pre-etched by surface layer removal (SLR) process before electrochemical etching. The SLR is pre-etching process which remove certain thickness of detector surface. Results show that track density versus layer thickness removed has saturation plateau corresponding to countable track density which is equal to penetration range of “minimum detected energy” in the detector. Also, thickness in which track density approaches zero is equal to penetration range of “maximum detected energy” in detector. At different cylindrical detector heights studied, corresponding minimum ion energies (7.0 to 328 keV) and maximum ion energies (70 to 640 keV) and for top cylinder base at different angles minimum energies (57 to 535 keV) and maximum energies (135 to 640 keV) were determined. The novel methods applied proved quite efficient for determination of He ion energies in 4π PFD ion space.

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