Elastic backscattering as a method for the measurement of the integral lithium content in thin films on fusion-relevant substrates

Krat, S.; Mayer, M.; Vasina, Ya. A.; Prishvitsyn, A. S.; Gasparyan, Yu. M.; Писарев, А. А.

doi:10.1016/j.nimb.2019.06.025

Cited by 4 publications

(3 citation statements)

References 61 publications

(107 reference statements)

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“…However, both require an experimentally obtained cross-section and such cross-sections are not always available. The EBS cross-section for H-Li has been recently measured at a similar angle as in our setup, [21], and it is widely used [22][23][24]. A drawback for EBS however is that, due to the low mass number of deuterium, the backscattered protons have low energy.…”

Section: Ebs Analysis and Nra Analysismentioning

confidence: 97%

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

Morbey,

Gonzalez,

Arnoldbik

et al. 2024

Nucl. Fusion

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The vapor-box is a liquid metal based design to cope with the demanding conditions of the divertor. This design relies on the recirculation of lithium by evaporation and condensation. An issue to this approach is the safety risks of Li-D/T formation and co-deposition on both the vapor-box walls - leading to possible recirculation impedance- and on the first wall leading to unacceptable tritium retention. Additively manufactured tungsten Capillary Porous Structure (CPS) samples filled with Li were exposed to high heat flux D plasmas in the linear plasma device Magnum-PSI and Li-D co-deposition was measured as a function of substrate temperature, estimated to be in the range 200-428 ${^\circ}$C and distance between 25-85 mm to the plasma beam center. The D:Li ratio was determined via in-situ ion beam diagnostics (NRA and EBS) and the spectra analyzed simultaneously to maximise the precision of the measurement. The experimental results approach close to the theoretical maximum at 40:60 D:Li ratio and the thickness of the deposited films was 0.02 - 3.2 $\mu$m. For witness plate temperatures above 400 ${^\circ}$C Li films under 150 nm in thickness were deposited and show lower D:Li ratios, as low as 5:95 D:Li ratio. At these temperatures the evaporation rate from the WPs is close to the deposition rate, and the decomposition pressure for LiD becomes comparable to the operational pressure in the vessel during the discharge. SOLPS-ITER simulations were also conducted to complement the experimental data. The results were used to narrow the range of CPS surface temperature to between $650-700$^{\circ}$C and determined that the D$^{+}$ plasma is largely replaced by Li$^{+}$ plasma close to the target surface. Further, the redeposition ratio of the lithium on the CPS surface is determined to be around 80$\%$, which matches well with the value determined from a quartz crystal microbalance. Due to limitations in the modeling of neutral interactions with Li coated surfaces, the SOLPS-ITER modeling does not well recreate the observed Li and D deposition layers on the WPs, indicating that this aspect of the modeling in Eirene needs improvement to accurately model plasmas containing significant quantities of Li. However, SOLPS-ITER simulations should be extended to include LiD molecules and improve the accuracy of heat flux towards the target to improve the comparison with experimental data.

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Section: Ebs Analysis and Nra Analysismentioning

confidence: 97%

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

Morbey,

Gonzalez,

Arnoldbik

et al. 2024

Nucl. Fusion

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“…To measure small amounts of deposited material, Rutherford backscattering spectroscopy (RBS) was used [28]. The amount of material deposited on the experimental sample was about twice the amount of material deposited on the QMB crystal (1.90 ± 0.08 for Li).…”

Section: Qmb Calibrationmentioning

confidence: 99%

“…The amount of material deposited on the experimental sample was about twice the amount of material deposited on the QMB crystal (1.90 ± 0.08 for Li). It was shown also that the lateral distribution of W film was very uniform over the surface, while Li films became inhomogeneous after contact with air due to chemical reactions with atmospheric gases [28]. The calibration was repeated several times over a period of three years, and the ratio between the amount of material deposited on the experimental sample and the QMB crystal remained constant over that period of time.…”

Section: Qmb Calibrationmentioning

confidence: 99%

A setup for study of co-deposited films

et al. 2020

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A setup for investigation of thermal desorption spectra of gases accumulated in thin films deposited by plasma sputtering of solid targets is described. Deposition and thermal desorption spectroscopy (TDS) are performed in two different vacuum chambers separated by a gate valve with the sample transferred between the chambers in-vacuo. The temperature of the substrate for deposited films can be varied in the range of 300-800 K; and the deposition rate is controlled by a quartz microbalance. Thermal desorption of co-deposited gases is analyzed by a quadrupole mass spectrometer. Sputtering rate and evaporation of the film during TDS are measured by quartz microbalances. Three experiments are described 1) trapping of deuterium by the growing chemically active Li film with subsequent decomposition and evaporation of the film, 2) temperature dependent deuterium trapping in the growing W film resulting in trapping with several binding energies, and 3) chemical interaction of D-Li layer with water vapor leading to isotopic H-D exchange and chemical transformation of the deposited film.

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