Expanding the capability of reaction-diffusion codes using pseudo traps and temperature partitioning: Applied to hydrogen uptake and release from tungsten

Isolating the detrapping of deuterium in heavy ion damaged tungsten via partial thermal desorption

“…For example, the sample with a pTDS peak-and-hold temperature of 467 K (dashed gold) only begins to appreciably release D when the temperature exceeds 510 K during the subsequent final TDS (solid gold). This separation indicates that the underlying assumptions of the PTTP scheme [28] can be used to distinguish and isolate traps with progressively higher release energies. As a result, taken together the NRA and TDS data can be used to quantify the location and concentration of D residing in each trap, as illustrated in the following discussion.…”

“…shown are based on the PTTP scheme that assumes a minimal separation in detrapping energies. For instance, a difference below 0.1 eV for consecutive detrapping energies leads to a significant error as outlined in [28]. Table 2 provides a summary of the resulting trap concentrations and energies found to give the best fit to the NRA and pTDS data with the least number of traps.…”

“…In order to use the verified and validated reaction-diffusion code TMAP7 [32,33,34] to model these results that require more than three types of traps with distinct detrapping energies, we employed a Pseudo Trap and Temperature Partitioning (PTTP) scheme as outlined and applied to TMAP7 [28].…”

“…Reaction-diffusion parameters as outlined in [28,26] were used and detailed in Table 1. During the D 2 plasma exposure phase, the implanted D flux was simulated as a Gaussian with mean depth (r implant ) and standard deviation (σ implant ) with a reflection coefficient (R).…”

“…4. Thus, there are likely at least 6 or 7 unique detrapping energies needed to model this data set obtained with a sample temperature of 373 K during plasma exposure, as seen in previous work[28,13,31].…”