Chapter 3
Power Load on Plasma-Facing Materials
3.1 Introduction
In the early days of research on plasma–material interactions (PMI), the main research
targets were the spontaneous response of material surface or surface phenomena
induced by the collision of incident energetic particles, such as reflection, secondary
particles emission, photon emission, and reemission of incident particles, which are
discussed in Chap. 4. In the progress of plasma confinement with higher temperature
and density, power load to plasma-facing materials (PFM) becomes so high to cause
materials melting, erosion, and degradation of materials properties. Consequently,
the lifetime of PFM becomes concern. Influences of power load to the materials
appear as sublimation, melting, or re-solidification which sometimes accompanies
material cracking or flaking, and heat-influenced zone in near surface such as recrystallization. In reverse, melting and evaporation influence plasma confinement by
plasma contamination and melt layer motion. Ironically, extremely high-power load
accompanying a significant amount of material sublimation could protect further
power load by vapor shielding which is a new topic.
This chapter is devoted to describe how power is loaded to PFM and what carries
the power. In Sect. 3.2, the distribution of power load to various locations in a fusion
reactor is briefly introduced. Since the power load is divided into two categories,
i.e. steady state and transient or off-normal event like disruption, they are separately
introduced in Sects. 3.3 and 3.4, respectively. Power load by a neutron is also separately discussed in Sect. 3.5. The detailed material responses to the power loads are
described in Chap. 5.
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
T. Tanabe, Plasma-Material Interactions in a Controlled Fusion Reactor, Springer Series
in Plasma Science and Technology, https://doi.org/10.1007/978-981-16-0328-0_3
37
Power Load on Plasma-Facing Materials
3.1 Introduction
In the early days of research on plasma–material interactions (PMI), the main research
targets were the spontaneous response of material surface or surface phenomena
induced by the collision of incident energetic particles, such as reflection, secondary
particles emission, photon emission, and reemission of incident particles, which are
discussed in Chap. 4. In the progress of plasma confinement with higher temperature
and density, power load to plasma-facing materials (PFM) becomes so high to cause
materials melting, erosion, and degradation of materials properties. Consequently,
the lifetime of PFM becomes concern. Influences of power load to the materials
appear as sublimation, melting, or re-solidification which sometimes accompanies
material cracking or flaking, and heat-influenced zone in near surface such as recrystallization. In reverse, melting and evaporation influence plasma confinement by
plasma contamination and melt layer motion. Ironically, extremely high-power load
accompanying a significant amount of material sublimation could protect further
power load by vapor shielding which is a new topic.
This chapter is devoted to describe how power is loaded to PFM and what carries
the power. In Sect. 3.2, the distribution of power load to various locations in a fusion
reactor is briefly introduced. Since the power load is divided into two categories,
i.e. steady state and transient or off-normal event like disruption, they are separately
introduced in Sects. 3.3 and 3.4, respectively. Power load by a neutron is also separately discussed in Sect. 3.5. The detailed material responses to the power loads are
described in Chap. 5.
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
T. Tanabe, Plasma-Material Interactions in a Controlled Fusion Reactor, Springer Series
in Plasma Science and Technology, https://doi.org/10.1007/978-981-16-0328-0_3
37