In this letter, a comprehensive mechanism for the nucleation and growth of bubbles on dislocations under plasma exposure of tungsten is proposed. The mechanism reconciles long-standing experimental observations of hydrogen isotopes retention, essentially defined by material microstructure, and so far not fully explained. Hence, this work provides an important link to unify material's modelling with experimental assessment of W and W-based alloys as candidates for plasma facing components.

Reaction rate theory in solids is modified taking into account intrinsic localized modes or discrete breathers (DBs) that can appear in crystals with sufficient anharmonicity, resulting in violation of Arrhenius' law. Largeamplitude oscillations of atoms about their equilibrium positions in the lattice cause local potentials of alternating sign, which are described in terms of time-periodic modulations of the potential barriers for chemical reactions taking place in the vicinity of DBs. The reaction rate averaged over large macroscopic volumes and times including many DBs is increased by a factor that depends on the DB statistics. The breather statistics in thermal equilibrium and in thermal spikes in solids under irradiation with swift particles is considered, and the corresponding reaction rate amplification factors are derived.

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Recent results on heavily irradiated natural and synthetic NaCl crystals give evidence for the formation of large vacancy voids, which were not addressed by the conventional Jain±Lidiard model of radiation damage in alkali halides. This model was constructed to describe metal colloids and dislocation loops formed in alkali halides during earlier stages of irradiation. We present a theory based on a new mechanism of dislocation climb, which involves the production of V F centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of excess H centers. Voids are shown to arise due to the reaction between F and V F centers at the surface of halogen bubbles. Critical parameters associated with the bubble-to-void transition are evaluated. Voids can grow to sizes exceeding the mean distance between colloids and bubbles, eventually absorbing them, and, hence, igniting a back reaction between the halogen gas and metal. The amount of radiation damage in alkali halides should be evaluated with account of void formation, which strongly aects the radiation stability of material.

Ions arriving at a semiconductor surface with very low energy (2 -8 eV) are interacting with defects deep inside the semiconductor. Several different defects were removed or modified in Sb-doped germanium, of which the E-center has the highest concentration. The low fluence and low energy of the plasma ions implies that the energy has to be able to travel in a localized way to be able to interact with defects up to a few microns below the semiconductor surface. After eliminating other possibilities (electric field, light, heat) we now conclude that moving intrinsic localized modes (ILMs), as a mechanism of longdistance energy transport, are the most likely cause. This would be striking evidence of the importance of ILMs in crystals and opens the way to further experiments to probe ILM properties both in semiconductors and in the metals used for contacts. Although most of the measurements have been performed on germanium, similar effects have been found in silicon.