Chapter 3
Plasma-Material Interactions in Magnetic
Fusion Devices
Abstract Diverse plasma interactions with the materials of the plasma facing
components (PFCs) are very important in magnetic fusion devices. They determine
the PFC erosion and, therefore, the PFC’s lifetime, plasma contamination with
unwanted impurities, retention of radioactive tritium, and often result in a strong
degradation of the material properties. Unfortunately, this area of research is still
underdeveloped and our understanding of complex processes involving plasmamaterial interactions is still far from completeness. Here the current status of our
knowledge of plasma interactions with the PFC materials is presented.
The choice of material for a fusion reactor is a complex problem, which concerns
both the structural and PFC materials facing different requirements such as material
resilience to high heat fluxes and neutron fluence (e.g. see [1] and the references
therein). Here we only consider the PFC materials. The plasma-material interaction
for fusion-relevant conditions is a relatively young area of research where our
understanding of the physics involved is still incomplete. Therefore, in this chapter,
we will focus on the issues that, we believe, are the most important for the
description of the edge plasma processes on the one hand and, on the other hand,
the physics of which is reasonably well understood and verified. In addition, we will
also discuss some gaps in our understanding/description of plasma material interactions in magnetic fusion devices.
Usually, it is assumed that the major issues of plasma interaction with the
materials of the PFCs are related to the PFC erosion (determining the PFC’s lifetime)
and tritium retention. For example, carbon had been dismissed as the PFC material
for ITER based on the assessment of tritium retention [2], which was later, to some
extent, confirmed experimentally [3]. However, there is still a need for both better
assessment of tritium retention in the materials potentially suitable for the PFCs and
understanding of other phenomena related to plasma-material interaction in future
reactors.
The processes occuring at the surface and within some depth beneath the surface
of the PFCs in fusion devices are very complex and diverse. They determine a wide
spectrum of different phenomena including erosion of the PFC material, plasma
contamination with impurity, plasma recycling and tritium retention, dust formation,
© Springer Nature Switzerland AG 2020
S. Krasheninnikov et al., On the Edge of Magnetic Fusion Devices, Springer Series in
Plasma Science and Technology, https://doi.org/10.1007/978-3-030-49594-7_3
49
Plasma-Material Interactions in Magnetic
Fusion Devices
Abstract Diverse plasma interactions with the materials of the plasma facing
components (PFCs) are very important in magnetic fusion devices. They determine
the PFC erosion and, therefore, the PFC’s lifetime, plasma contamination with
unwanted impurities, retention of radioactive tritium, and often result in a strong
degradation of the material properties. Unfortunately, this area of research is still
underdeveloped and our understanding of complex processes involving plasmamaterial interactions is still far from completeness. Here the current status of our
knowledge of plasma interactions with the PFC materials is presented.
The choice of material for a fusion reactor is a complex problem, which concerns
both the structural and PFC materials facing different requirements such as material
resilience to high heat fluxes and neutron fluence (e.g. see [1] and the references
therein). Here we only consider the PFC materials. The plasma-material interaction
for fusion-relevant conditions is a relatively young area of research where our
understanding of the physics involved is still incomplete. Therefore, in this chapter,
we will focus on the issues that, we believe, are the most important for the
description of the edge plasma processes on the one hand and, on the other hand,
the physics of which is reasonably well understood and verified. In addition, we will
also discuss some gaps in our understanding/description of plasma material interactions in magnetic fusion devices.
Usually, it is assumed that the major issues of plasma interaction with the
materials of the PFCs are related to the PFC erosion (determining the PFC’s lifetime)
and tritium retention. For example, carbon had been dismissed as the PFC material
for ITER based on the assessment of tritium retention [2], which was later, to some
extent, confirmed experimentally [3]. However, there is still a need for both better
assessment of tritium retention in the materials potentially suitable for the PFCs and
understanding of other phenomena related to plasma-material interaction in future
reactors.
The processes occuring at the surface and within some depth beneath the surface
of the PFCs in fusion devices are very complex and diverse. They determine a wide
spectrum of different phenomena including erosion of the PFC material, plasma
contamination with impurity, plasma recycling and tritium retention, dust formation,
© Springer Nature Switzerland AG 2020
S. Krasheninnikov et al., On the Edge of Magnetic Fusion Devices, Springer Series in
Plasma Science and Technology, https://doi.org/10.1007/978-3-030-49594-7_3
49