with the dynamics of millions of particles (e.g. the formation of the helium nanobubbles in tungsten, see Fig. 3.4), and the reaction-diffusion-based codes are used to
simulate such macroscopic features as hydrogen and helium transport and trapping
in the fusion-related materials and to interpret the TDS data.
However, in practice, application of even MD simulations to the study of many
important practical problems (e.g. nucleation and growth of the fuzz shown in
Fig. 3.2b) is beyond both the present and near-future computer capabilities. In
addition, interatomic potentials used in the MD simulations do not always result in
the physically meaningful outcomes (e.g. see [16]). On the other hand, the reactiondiffusion-based codes, which can be used for the long-time, large-scale simulations,
rely on the transport properties of the species of interest (e.g. hydrogen and helium)
and the rate constants of different “reactions”.
These hydrogen and helium transport models, as well as the rate constants, which
are either taken from some ad hoc assumptions or deduced from the MD simulations,
in most cases, do not allow for the effects of lattice stress, which can play an
important role in many different phenomena.
As a result, understanding of the physics involved in the fusion plasma-materialrelated phenomena in many cases is still rather poor. Therefore, in this chapter, we
will consider only the most generic features of the plasma interactions with the PFC
materials in a magnetic fusion environment and give short reviews of some interesting phenomena, even though their physics might be not entirely clear yet. Further
details of the current research activities, considering both solids (beryllium and
tungsten) and liquids (lithium, tin) as potential materials for the PFCs, can be
found in relevant review papers (e.g. see [6, 17–25]) and original journal
publications.
Fig. 3.4 MD simulations of
growing helium nanobubble in tungsten emitting
dislocation loops. Helium
atoms are in red and
displaced tungsten atoms are
in grey colors. (Reproduced
with permission from [15],
© Elsevier 2015)
52
3 Plasma-Material Interactions in Magnetic Fusion Devices
simulate such macroscopic features as hydrogen and helium transport and trapping
in the fusion-related materials and to interpret the TDS data.
However, in practice, application of even MD simulations to the study of many
important practical problems (e.g. nucleation and growth of the fuzz shown in
Fig. 3.2b) is beyond both the present and near-future computer capabilities. In
addition, interatomic potentials used in the MD simulations do not always result in
the physically meaningful outcomes (e.g. see [16]). On the other hand, the reactiondiffusion-based codes, which can be used for the long-time, large-scale simulations,
rely on the transport properties of the species of interest (e.g. hydrogen and helium)
and the rate constants of different “reactions”.
These hydrogen and helium transport models, as well as the rate constants, which
are either taken from some ad hoc assumptions or deduced from the MD simulations,
in most cases, do not allow for the effects of lattice stress, which can play an
important role in many different phenomena.
As a result, understanding of the physics involved in the fusion plasma-materialrelated phenomena in many cases is still rather poor. Therefore, in this chapter, we
will consider only the most generic features of the plasma interactions with the PFC
materials in a magnetic fusion environment and give short reviews of some interesting phenomena, even though their physics might be not entirely clear yet. Further
details of the current research activities, considering both solids (beryllium and
tungsten) and liquids (lithium, tin) as potential materials for the PFCs, can be
found in relevant review papers (e.g. see [6, 17–25]) and original journal
publications.
Fig. 3.4 MD simulations of
growing helium nanobubble in tungsten emitting
dislocation loops. Helium
atoms are in red and
displaced tungsten atoms are
in grey colors. (Reproduced
with permission from [15],
© Elsevier 2015)
52
3 Plasma-Material Interactions in Magnetic Fusion Devices