Control-Oriented Core-SOL-Divertor Model to Address Inte- grated Burn and Divertor Control Challenges in ITER
V. Graber and E. Schuster
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Remote, November 9-13, 2020
Abstract
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Burn control in ITER will require careful regulation of the core-plasma’s
density and temperature while guaranteeing safe operation of the divertor.
Satisfying performance objectives in the plasma core is challenging due
to the core’s sensitivity to both the conditions and the requirements
in the scrape-off-layer (SOL) and divertor regions. First, SOL-divertor
conditions determine the strength to which deuterium-tritium recycling
fuels the core. This could be particularly important in ITER where there
might be limits on the level of tritium that can be supplied externally.
Second, the SOL-divertor conditions prescribe the intensity to which
intrinsic impurities (W and He) and puffed impurities (needed to achieve
detachment) pollute the plasma core. Third, the ability to maintain
some level of detachment depends strongly on the separatrix density and
the power flowing into the SOL from the core. Clearly, core-control
objectives will need to be balanced with divertor-control objectives.
In this work, the phenomena outlined above are described by using a
control-oriented core-SOL- divertor model. The model consists of three
components: (1) the energy and density transport equations of the
core-plasma, (2) neutral particle balances in the diver- tor region,
and (3) a two-point model that relates the plasma conditions at some
upstream separatrix position to that at the divertor target. Using this
core-SOL- divertor model, the coupled burn and divertor control challenges
faced by ITER can be investigated.