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

corporation of a sol wave-sheath code is necessary for quantitative work. edge physics transport
and turbulence codes are available in which radiofrequency effects can be included.
The action items are as follows: (1) Use improved diagnostic coverage to verify the strength and
location of radiofrequency sheaths, confirming connection along b to the antenna. The associated
sputtering should be quantified by spectroscopic measurements. (2) compare and verify existing
radiofrequency sheath models; aid inclusion in boundary codes. (3) improve or develop models
for parasitic power loss from radiofrequency antennas and launchers; develop methods for reducing
the loss. (4) incorporate radiofrequency models in boundary codes and validate with diagnostic
data. (5) incorporate radiofrequency sheath and loss models in antenna and propagation
codes. (6) integrate boundary transport and turbulence, wall codes, and radiofrequency antenna
and propagation codes to understand the interdependence (e.g., gas puffing to enhance radiofrequency
coupling to the main plasma).
4. Integrated experimental tests and development of innovative divertors
While this section is brief, it nevertheless involves a major effort in testing and utilizing the building
blocks of sections 1-3. complete physics understanding and validation of models in all boundary
areas discussed will require significant operational time on confinement experiments. While
dedicated test stands can better address validation of certain elements of the models (see Thrust
10), more dedicated run time will be needed on existing machines to properly test integrated performance
in a realistic environment.
innovative divertor magnetic configurations such as the super-X and/or snowflake for reducing
peak heat fluxes offer high payoff and should be tested. These configurations can be formed in
existing devices without new magnetic coils. some snowflake configurations have already been
made. The super-X may require installation of some extended divertor surfaces at larger major radius
to accept the heat flux. Promising results of such tests should be followed by extensive analysis
to optimize their implementation in future devices, and to ensure that all the functions of
a divertor — power exhaust, acceptable impurities, and helium exhaust — can be performed simultaneously
in the very challenging environment of future fusion plasmas. other innovations
related to divertor materials are given in Thrust 11.
all operational scenarios and new device designs discussed in ReneW will require substantial input
from the knowledge gained in this Thrust, to ensure that the boundary layer plasma will satisfactorily
perform the many functions required for high-power fusion devices. While the emphasis
here has been on tokamak boundary plasma, every effort should be made to understand the range
of device types where the data and models are applicable and how to extend them where needed.
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