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

Proposed actions:
• Prioritize burning plasma measurement needs, including those for demo.
• Perform phased developments targeted to high-priority needs, including prototyping on
operating devices.
• evaluate the success of these developments, and where appropriate, work to transfer
techniques to iteR or other burning plasma devices.
Scientific and technical Research
measurements are key to scientific understanding. There are many examples of important strides
in fusion science that were triggered by new measurements. new phenomena appear whenever
measurement resolution is enhanced or an additional parameter is measured. The richness of
plasma phenomena means that optimization of fusion performance is a complex process, which
often draws on unexpected parts of the measurement tool kit. While the tool kit planned for iteR
is similar, in many ways, to that for existing tokamaks, the applicability of many of these tools to
a long-pulse, nuclear environment has yet to be established. designs are not mature, and tradeoffs
between capability and reliability have not been made. Finding robust alternate techniques
for at-risk iteR measurements may be pivotal in achieving optimal iteR performance. For example,
moving away from reliance on optical techniques, vulnerable due to degradation of plasma
facing mirrors, toward more compatible microwave methods or X-ray techniques would be appropriate
strategies. as currently envisioned, maintenance for many iteR diagnostic signal-gathering
components involves robotic replacement of port plugs weighing up to 50 tons. These plugs
(Figure 1) house the diagnostic “front-end” components (such as optical elements like mirrors)
and shield the magnets and other subsystems from the fusion core. to deploy these components,
innovative engineering strategies are required that more easily accommodate maintenance and
thus improve overall reliability. For burning plasmas beyond iteR, the significantly harsher environment,
the decreased diagnostic access, and the requirements of increased reliability make
measurements on demo-like plasmas even more difficult and uncertain.
Figure 1. ITER port plugs (red) showing “front-end” diagnostic components.
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