Chapter 2
Discharges in Current Large Tokamaks
2.1 Introduction
In Table 2.1 are summarized main plasma parameters of large- or medium-sized
tokamaks operated, in operation, and into operation soon. The plasma–surface interaction (PSI) studied in these machines are referred in this book. Most of the tokamaks
were initially operated with Carbon (C) as plasma-facing surface (PFS) and some
have changed from C to Tungsten (W). Hence, the accumulation of data on plasma–
surface interactions (PSI) and experiences of tokamaks operation with C-wall have
made significant improvement in plasma confinement. After finding that high Z
plasma-facing wall could sustain high-temperature plasma and accordingly ITER
decided to use W as the plasma-facing material (PFM) of divertor, many tokamaks
given in the table have employed W as PFM. Hence plasma–material interactions
(PMI) data useful for its understanding are mostly given for the C-wall, and those
for the W-wall are still limited.
When the temperature of plasma was not high enough to give power load to
increase the temperature of plasma-facing surface (PFS), observed radiation was
mostly from plasma in the wavelength region of ultraviolet to visible light. However,
as described in Chap. 1, with the increasing power load to PFS, radiation from PFS
became appreciable, and accordingly, PMI interactions became appreciable. In the
early days, PFS was considered passive against plasma with little influence on it.
Nowadays, owing to high-power load, PFS actively responds to plasma exposure
giving a significant impact on it. In particular, PMI phenomena in divertor area play
a significant role in plasma confinement through fuel recycling, He pumping, power
exhaust, impurity production, and so on.
© 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_2
17
Discharges in Current Large Tokamaks
2.1 Introduction
In Table 2.1 are summarized main plasma parameters of large- or medium-sized
tokamaks operated, in operation, and into operation soon. The plasma–surface interaction (PSI) studied in these machines are referred in this book. Most of the tokamaks
were initially operated with Carbon (C) as plasma-facing surface (PFS) and some
have changed from C to Tungsten (W). Hence, the accumulation of data on plasma–
surface interactions (PSI) and experiences of tokamaks operation with C-wall have
made significant improvement in plasma confinement. After finding that high Z
plasma-facing wall could sustain high-temperature plasma and accordingly ITER
decided to use W as the plasma-facing material (PFM) of divertor, many tokamaks
given in the table have employed W as PFM. Hence plasma–material interactions
(PMI) data useful for its understanding are mostly given for the C-wall, and those
for the W-wall are still limited.
When the temperature of plasma was not high enough to give power load to
increase the temperature of plasma-facing surface (PFS), observed radiation was
mostly from plasma in the wavelength region of ultraviolet to visible light. However,
as described in Chap. 1, with the increasing power load to PFS, radiation from PFS
became appreciable, and accordingly, PMI interactions became appreciable. In the
early days, PFS was considered passive against plasma with little influence on it.
Nowadays, owing to high-power load, PFS actively responds to plasma exposure
giving a significant impact on it. In particular, PMI phenomena in divertor area play
a significant role in plasma confinement through fuel recycling, He pumping, power
exhaust, impurity production, and so on.
© 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_2
17