Chapter 1
Introduction
1.1 The Organization of This Book
There is one significant difference between plasma–material interactions (PMI) and
other interactions between gas and solid or liquid, and liquid and solid. For the latter
cases, one can think of chemical or thermo-dynamical equilibrium where no energy
transfer occurs, while in PMI there is always energy or power flow from plasma to
materials under a steep gradient of (potential) energy. The higher energy state of
plasma than that of plasma-facing materials causes energy release or power flow
from the plasma to the materials by radiation and kinetic energy of plasma particles
(ions of fuels, He and impurities, and electrons motivated by the energy gradient).
Such power release by the radiation and the kinetic energy of the particles results in
PMI which includes so many different physical and chemical phenomena that it is
hardly possible to introduce PMI phenomena in an orderly sequence but to introduce
important subjects separately. (Please refer Fig. 1.3, which describes various physical
and chemical phenomena occurring in a wide range of energy states together with
energy ranges corresponding to fusion reaction, burning plasma, plasma–surface
interactions, material responses to the power exhaust in a fusion reactor).
In addition, fuel losses by burning and flow-out from fusion plasma must be
compensated by fueling, which is another important subject of PMI in a reactor.
Different from most of the plasma apparatus, tritium (T) is used as a fuel of the
reactor. Since T is hazardous due to its radioactivity and its resources are scarce,
special care is required for safety handling and fuel self-sufficiency. Fuel recycling
at plasma-facing surface (PFS) has often been discussed separately with the power
load. However, as described above, the power is carried by fuel particles. Hence, the
fuel recycling should be discussed considering the power flow.
This book tried to describe PMI phenomena referring basic physics and chemistry
in them and their roles in the construction of a fusion reactor. To realize this, the
total of 11 chapters are grouped into three parts which correlate with each other as
shown in Fig. 1.1. Part I consists of three chapters. Following the present chapter
(Chap. 1) which describes the concept of PMI, brief introduction of a D-T fusion
© 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_1
3
Introduction
1.1 The Organization of This Book
There is one significant difference between plasma–material interactions (PMI) and
other interactions between gas and solid or liquid, and liquid and solid. For the latter
cases, one can think of chemical or thermo-dynamical equilibrium where no energy
transfer occurs, while in PMI there is always energy or power flow from plasma to
materials under a steep gradient of (potential) energy. The higher energy state of
plasma than that of plasma-facing materials causes energy release or power flow
from the plasma to the materials by radiation and kinetic energy of plasma particles
(ions of fuels, He and impurities, and electrons motivated by the energy gradient).
Such power release by the radiation and the kinetic energy of the particles results in
PMI which includes so many different physical and chemical phenomena that it is
hardly possible to introduce PMI phenomena in an orderly sequence but to introduce
important subjects separately. (Please refer Fig. 1.3, which describes various physical
and chemical phenomena occurring in a wide range of energy states together with
energy ranges corresponding to fusion reaction, burning plasma, plasma–surface
interactions, material responses to the power exhaust in a fusion reactor).
In addition, fuel losses by burning and flow-out from fusion plasma must be
compensated by fueling, which is another important subject of PMI in a reactor.
Different from most of the plasma apparatus, tritium (T) is used as a fuel of the
reactor. Since T is hazardous due to its radioactivity and its resources are scarce,
special care is required for safety handling and fuel self-sufficiency. Fuel recycling
at plasma-facing surface (PFS) has often been discussed separately with the power
load. However, as described above, the power is carried by fuel particles. Hence, the
fuel recycling should be discussed considering the power flow.
This book tried to describe PMI phenomena referring basic physics and chemistry
in them and their roles in the construction of a fusion reactor. To realize this, the
total of 11 chapters are grouped into three parts which correlate with each other as
shown in Fig. 1.1. Part I consists of three chapters. Following the present chapter
(Chap. 1) which describes the concept of PMI, brief introduction of a D-T fusion
© 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_1
3