| Summary: | <p>This thesis, presents results from the Joint European Torus (JET), beryllium
ITER-like wall. Isotopic hydrogen retention is investigated at three
microstructurally unique sites: erosion zones, co-deposition zones, and
melted material, found across the reactor at the inner and outer wall
limiters and dump plate tiles. The techniques applied to these novel inservice
materials were: Scanning Electron Microscopy with Energy Dispersive
X-Ray (SEM-EDX), Raman Spectroscopy; Focused Ion Beam (FIB)
3D milling; Scanning Transmission Electron Microscopy (STEM) with
Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive X-Ray
(EDX); Atom Probe Tomography and Thermal Desorption Spectroscopy
(TDS).</p>
<p>Clustering of deuterium (D) with beryllium deuteride (BeD2) was found
at the outer eroded material, whilst not at the inner. BeD2 was present
at the core of D clusters up to 8 at%. Co-deposition at the outer limiter
tile was governed by beryllium oxide (BeO), whilst at the inner it was
governed by Be with D. EUROFusion samples produced from High Power
Impulse Magnetron Sputtering (HiPIMS) returned similar EELS results to
JET samples; presenting a reasonable model. Melted material produced
highly oxidised zones devoid of metallic impurities from marker layers in
spatially optimum sites, surrounded by grains produced via high temperature
material mixing. Several types of beryllium deuteroxide (BeOD)
with varying stoichiometries were presented</p>
<p>Retention is lowest at the inner wall eroded zone, increasing at the outer
wall eroded zone, and increasing further between inner to outer wall codeposits.
Melted material, remains an outlier. Overall total retention,
in melted materials was similar to outer wall co-deposit, however composed
of over 77% H. Material mixing was suggested the cause due to
beryllium/nickel alloying seen in melted materials.</p>
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