Trapping of hydrogen isotopes in radiation defects formed in tungsten by neutron and ion irradiations

Abstract

Retention of D in neutron-irradiated W and desorption were examined after plasma exposure at 773 K. Deuterium was accumulated at a relatively high concentration up to a large depth of 50-100 m due to the trapping effects of defects uniformly induced in the bulk. A

Deuterium retention in tungsten damaged with W ions to various damage levels

“…It has been found that (i) at the damage levels in the range from 0.1 to 50 dpa, the concentration of the W-ion-induced defects demonstrates very weak dependence on the number of displacements per atom, and (ii) the quasi-saturation concentration of the W ion-induced defects decreases twice as the W-ion irradiation temperature increases from 300 to 573 K. were published earlier in Ref. [21].…”

“…It has been experimentally shown [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23] that irradiation of W materials with 0.2-20 MeV H, He, Si, and W ions leads to an enhancement of hydrogen isotope retention in comparison with undamaged materials. However, damage created by ions is concentrated in a narrow region below the surface (in the damaged zone), while neutron-induced damage extends to larger depths.…”

“…The dependence of D concentration trapped in the damage zone at the damage peak, damage C D , on the damage level in W was studied in several works [10,13,14,16,18,21,22]. For W pre-irradiated with 12 MeV Si ions and then exposed to low-energy, high flux D plasmas at 473 and 773 K, Wampler et al [10] observed an increase of the concentration damage C D as the damage level at the damage peak increased from 0.006 to 0.6 dpa (in this work the damage level was calculated with the displacement energy of E d = 40 eV).…”

Deuterium trapping at defects created with neutron and ion irradiations in tungsten

“…A significant increase in D retention with neutron irradiation was observed even at a damage level as low as 0.025 dpa, and the D concentration in n-irradiated W reached values of 0.1-0.2 at% at all temperatures examined [3,7]. The desorption of D from nirradiated specimens continued up to temperatures above 1173 K, while that from nonirradiated specimen was completed at ≈700K after plasma exposure at 473K [2] and at ≈970K after exposure at 773K [6]. The activation energy for D detrapping, E det , from defects that contribute to dominant trapping at 773K was evaluated to be ≈1.8 eV [6,7].…”

“…The desorption of D from nirradiated specimens continued up to temperatures above 1173 K, while that from nonirradiated specimen was completed at ≈700K after plasma exposure at 473K [2] and at ≈970K after exposure at 773K [6]. The activation energy for D detrapping, E det , from defects that contribute to dominant trapping at 773K was evaluated to be ≈1.8 eV [6,7]. However, the retention of hydrogen isotopes at a higher damage level has not been examined.…”