Prime pagine RA2010FUS:Copia di Layout 1 - ENEA - Fusione

050
progress report
2010
of observation and the observables related to changes in the tails of the fast ion energy distribution have been
determined and studied. As for NES, the neutron emission (from the fusion reaction) energy spectrum reflects
the energy distribution of the deuteron population with the possible suprathermal components caused, for
instance, by external heating. The GRS measured gamma ray emission spectra, from reactions between fast
ions and impurities, allow different information to be extracted: fast ions exceeding the threshold energies of
the reactions (by the identification of characteristic gamma ray peaks), combined fast ion density, temperature
and impurity concentration (by peak intensities), fast ion temperature (by doppler broadening of the emission
lines observed). At last, in CTS the doppler broadened scattered radiation provides space and time resolved
information on the velocity distribution of the plasma ions, including the fast–ion population generated by
ICRH. The detailed characterization of the fast particles dynamics poses demanding requirements since all
the relevant plasma parameters should be ideally measured with spatial resolution close to the fast particles
Larmor radius (of the order of 6 cm) and time resolution of the order of the interaction time of Alfvén modes
with the fast particles (of the order of 30 ms) in the FAST H–mode reference scenario.
The results of the analysis, based on numerical simulations of the spatial and energetic particle distribution
function of the ICRH accelerated minority 3 He ions, have shown that NES and GRS measurements can
provide information on the anisotropy of the fast 3 He population and a measurement of its effective tail
temperature, with time resolutions in the range 20–100 ms, and that the proposed CTS diagnostics can
measure the fast ion parallel and perpendicular temperature with a spatial resolution of 5–10 cm and a time
resolution of 10 ms.
2.3 Design Description
The FAST project significantly advanced in the year 2010 [2.9] as for load assembly design, vacuum vessel
and plasma facing components (fig. 2.5), with close attention to the remote maintenance issues. Extensive
studies were carried out to investigate several divertor design options.
Divertor design
The divertor optimization of the divertor from the physics and engineering point of view significantly
advanced in 2010; at the same time, a whole divertor design has been completed [2.10], able to withstand a
power load up to 20 MW m –2 by using W monoblocks tiles [2.11,2.12]. Further studies will be carried out to
complete the optimization in the next year.
The divertor, as currently designed, is composed by a cassette body (CB) that supports all the plasma facing
components (PFC). The cassette body routs the water coolant and is mounted onto the vacuum vessel inboard
and outboard rails via a mechanical locking system. Each
divertor module spans over 5 degrees for a total of 72
modules in the whole tokamak and each module is made of
6 rows of W monoblocks, individually cooled by pressurized
water flowing in CuCrZr pipes, 12 mm diameter wide. The
dome geometry is provided with a large opening in front of
the strike zones in order to allow neutrals to flow into the
private flux region and to be removed from there by pumps
located in the divertor port (fig. 2.6). Slots drilled in the
divertor body cassette provide for the needed pumping
conductance. The plasma facing components are expected
to be able to remove the heat load coming from the plasma
via conduction and convection during the normal and
transient operation. The outboard vertical target poloidal
profile has been chosen in order to minimize the impinging
heat loads by assuring ∼20° striking angle.
Figure 2.5 – Complete CATIA5 model showing the
main components of FAST: from outer to inner, the
cryostat, the poloidal and toroidal field coils, the
vessel with the access ports, the first wall with the
divertor and the central solenoid
The hydraulic scheme of the divertor cooling foresees a
manifold which feeds the coolant into each tiles row from
the top of the outer vertical target, the coolant than flows