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

• to establish reliable steady-state diagnostic operations.
• to address calibration issues.
experience with measurement systems on iteR will be extremely valuable, but incomplete.
iNtEgRatioN oF high-pERFoRMaNcE StEady-StatE BuRNiNg plaSMaS:
RESEaRch REquiREMENtS
Overall goal: Create and conduct research, on a routine basis, of high-performance core, edge and
SOL plasmas in steady state with the combined performance characteristics required for DEMO.
The elements identified in the Priorities, Gaps and opportunities Report as requiring integration
to meet this goal were the high-performance burning plasma core, the edge and scrape-off layer
plasmas, sustainment of the magnetic configuration and plasma, and optimization of the plasma
configuration.
The ReneW integration panel has identified the core plasma dynamics and the coupling of the
plasma edge to the core in a self-consistent high-performance fusion plasma regime as areas for
focusing scientific exploration and development. two supporting elements have emerged as important
for achieving these integrated regimes experimentally and providing confidence that the
high fusion power regime can be reached: developing high confidence predictive theory and simulation,
and a substantial focus on plasma material interactions and material evolution under plasma
and neutron loads.
The demonstration of a high-performance plasma core suitable for fusion power generation is a
significant integration step in itself. The core plasma issues associated with reaching these parameters
are generally broken up along topical plasma physics areas. key issues and requirements for
each are discussed, and must be integrated.
Self-consistent transport and current profiles in alpha-dominated plasmas
The plasma transport of energy, particles, momentum, and current become strongly interdependent as
the core plasma reaches large bootstrap current fraction, high beta, and high ratio of alpha power to
input power. Under these conditions, what are the plasma configurations that emerge from
these self-consistent internal physics processes?
The fusion reactions will generate high-energy alpha particles, which heat the thermal ions and
electrons in the plasma as they slow down. The magnitude and profile of this heating in the plasma
is determined by the density and temperature of the ions. The profiles of the temperature and
density of the ions and electrons are determined both by the heating source and the transport
processes for energy, particles, and momentum. The transport is driven by turbulence, which is
dependent on the gradients of temperature and density, as well as the profiles of magnetic and
electric fields. The plasma generates its own “bootstrap” current that will strongly influence the
profile of the magnetic field; it is determined by the profiles of the temperature and density of
ions and electrons. as the high fusion power regime is approached, the plasma’s own processes
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