Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

Research Requirements
in this section, a brief review of major issues and gaps, identified by the Priorities, Gaps and opportunities
Panel and by ReneW panels, is given for each panel. most importantly, the research
required to address these challenges is assessed, both in terms of the quantitative targets that
should be met, and the set of priority activities and tools – theory, computational, experimental
and technological – that will be needed. These requirements form the basis of ReneW Thrusts, as
briefly outlined later in this chapter and described in more detail in Part ii of the Report.
MEaSuREMENt: additioNal RESEaRch REquiREMENtS
Overall goal: Make advances in sensor hardware, procedures and algorithms for measurements of
all necessary plasma quantities with sufficient coverage and accuracy needed for the scientific mission,
especially plasma control.
The ability to make accurate measurements on hot magnetically confined plasmas has driven
much of the understanding and progress to date in this field. accurate measurements are presently
routinely used both for improving our basic understanding of plasma behavior and for facilitating
control of those plasma quantities for which control “actuators” exist. as we proceed beyond
iteR, toward creating steady-state high-performance burning plasmas, there are additional major
challenges for making the necessary measurements. (Please refer to the extended discussion of
research opportunities for measurements in chapter 1. since the motivations for measurement
capability are the same for these two Themes in many cases, we will not repeat the shared motivations
here.) beyond iteR, the environmental hazards for diagnostics close to steady-state burning
plasmas are much greater and more daunting than for the iteR plasmas, e.g.,
• two orders of magnitude higher fluence than iteR; flux 3-4 x that of iteR.
• higher wall temperature: up to 650° c vs 240° c.
• Possibility of liquid metal walls.
We can better appreciate the increased challenges when we estimate the lifetimes of various components
and diagnostics in such an environment. if we consider only the radiation-induced effects
on components, place them in the equivalent locations as in iteR, and use present-day technology,
then we find that the component lifetimes in a full-power demo-like environment are
predicted to be:
• ~ 13 weeks for magnetic sensors.
• ~ 1 week for bolometers.
• ~ a few hours for vacuum ultraviolet (vUv) windows.
• ~ a few hours for pressure gauges.
These lifetimes are unacceptable, and significant development and careful design are required so
that the necessary measurement capability is maintained for these steady-state, more self-organized,
burning plasmas. additionally, we must at present judge the use of optical diagnostics as
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