4.7 Interaction of Released Particles with Photons …
71
As such, atomic and molecular processes in boundary plasma have been the main
subjects in PMI studies and various reviews and textbooks have been published,
for example, see references [5, 35–37]. In this book, details of these atomic and
molecular processes in boundary plasma are not discussed.
4.8 Summary
Released particles from PFM into boundary plasma include three different ones, i.e.
fuels or H, sputtered particles and other impurities released from PFM, and electrons.
In addition, photons are directly emitted from PFS. Since plasma discharge prefers
wall pumping, H recycling was not systematically studied except Hα measurement
which has been used to determine hydrogen influx. However, the amount of retained
fuel in PFM must be far larger than that in the burning plasma, some changes in the
fuel retention caused by temperature rise given by localized or transient power load
would influence plasma confinement. Therefore, the dynamic behavior of hydrogen
in PFM should play a quite important role. This chapter is devoted to foresee it
in a reactor based on fundamental physics and chemistry of hydrogen behavior in
candidate PFM.
Erosion is also quite important in respect of lifetime of PFM and H retention in
deposited materials. Since the incident fluence of fuels in present tokamaks is still
far less compared to that of a reactor, no PFM was changed owing to erosion, and H
retention in deposited layers in plasma shadowed area gave no significant influence
on plasma. Therefore, little attention has been paid to erosion and deposition and
accompanied lifetime of PFM in present tokamaks. However, the lifetime of PFM in
a reactor should be estimated prior to use. In addition, usage of T as a fuel requires
strict control in its inventory for both T safety and fuel self-sufficiency. The subjects
written here would help for both.
Most of the PMI studies up to now are relating the interaction of released particles
from PFM and boundary plasmas, and analysis of photons from the boundary plasma
has been the main target in PMI studies. Because spectroscopy has been the most
important diagnostic, we have to continue to rely on it. In a fusion reactor, available
ports for diagnostics would be limited, spectroscopy and other diagnostic techniques
shall be selected appropriately to be useful for controlling the burning plasma. For
that, this chapter would give important information.
References
1. B.D. Wirth, K.D. Hammond, S.I. Krasheninnikov, D. Maroudas, Challenges and opportunities
of modeling plasma–surface interactions in tungsten using high-performance computing. J.
Nucl. Mater. 463, 30–38 (2015)
2. Radiation effects on Solid surfaces, Ed. M. Kaminsky, American Chemical Soc., Washington
(1976). ISBN: 0-8412-0331-8
71
As such, atomic and molecular processes in boundary plasma have been the main
subjects in PMI studies and various reviews and textbooks have been published,
for example, see references [5, 35–37]. In this book, details of these atomic and
molecular processes in boundary plasma are not discussed.
4.8 Summary
Released particles from PFM into boundary plasma include three different ones, i.e.
fuels or H, sputtered particles and other impurities released from PFM, and electrons.
In addition, photons are directly emitted from PFS. Since plasma discharge prefers
wall pumping, H recycling was not systematically studied except Hα measurement
which has been used to determine hydrogen influx. However, the amount of retained
fuel in PFM must be far larger than that in the burning plasma, some changes in the
fuel retention caused by temperature rise given by localized or transient power load
would influence plasma confinement. Therefore, the dynamic behavior of hydrogen
in PFM should play a quite important role. This chapter is devoted to foresee it
in a reactor based on fundamental physics and chemistry of hydrogen behavior in
candidate PFM.
Erosion is also quite important in respect of lifetime of PFM and H retention in
deposited materials. Since the incident fluence of fuels in present tokamaks is still
far less compared to that of a reactor, no PFM was changed owing to erosion, and H
retention in deposited layers in plasma shadowed area gave no significant influence
on plasma. Therefore, little attention has been paid to erosion and deposition and
accompanied lifetime of PFM in present tokamaks. However, the lifetime of PFM in
a reactor should be estimated prior to use. In addition, usage of T as a fuel requires
strict control in its inventory for both T safety and fuel self-sufficiency. The subjects
written here would help for both.
Most of the PMI studies up to now are relating the interaction of released particles
from PFM and boundary plasmas, and analysis of photons from the boundary plasma
has been the main target in PMI studies. Because spectroscopy has been the most
important diagnostic, we have to continue to rely on it. In a fusion reactor, available
ports for diagnostics would be limited, spectroscopy and other diagnostic techniques
shall be selected appropriately to be useful for controlling the burning plasma. For
that, this chapter would give important information.
References
1. B.D. Wirth, K.D. Hammond, S.I. Krasheninnikov, D. Maroudas, Challenges and opportunities
of modeling plasma–surface interactions in tungsten using high-performance computing. J.
Nucl. Mater. 463, 30–38 (2015)
2. Radiation effects on Solid surfaces, Ed. M. Kaminsky, American Chemical Soc., Washington
(1976). ISBN: 0-8412-0331-8