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Integrated plasma facing component calorimetry for measurement of shot integrated deposited energy in the NSTX-U

Publication Type
Journal Name
Review of Scientific Instruments
Publication Date

The upgrade to the National Spherical Torus eXperiment (NSTX-U)1
power and enables plasmas to be sustained for up to 5 seconds. The graphite plasma facing
components (PFCs) have been re-designed to handle greater heat and energy fluxes than were
seen in NSTX using a castellated design. Some scenarios will produce divertor heat fluxes well
above the 6-7 MW/m2
the PFCs are designed to withstand, and means of intra and inter-shot
control are under investigation Select castellations in divertor regions will be instrumented
with thermocouples designed to measure the shot-integrated energy deposited in each
castellation. The thermocouples are located away ~25mm from the plasma facing surface to
prevent stress concentrations in the castellations. The deposited energy is therefore
determined by finite element analysis of the thermal behavior of the tile consistent with the
thermal wave propagation in the castellations. We present experimental testing and validation
of a castellated graphite target instrumented with thermocouples at various depths in the
castellation. During testing, incident heat flux is provided by a programmed, electron beam
system and surface temperatures are measured via infrared thermography directly viewing the
target surface.

1J. Menard et al 2012 Nucl. Fusion 52 083015