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

fusion advanced studies torus (cont’d.)
progress report
2010
049
ω/ωA0
1
0.5
1
0.8
0.6
0.4
ω/ω A0
1
0.5
1
0.8
0.6
0.4
0.008
β hot⊥
0.004
Equil.
n=8
n=16
0.2
0.2
0
0 0
0 0
0 0.4 0.8 0 0.4 0.8 0
ρ pol
ρ pol
0.4 0.8
ρ pol
Figure 2.3 – a) Intensity contour plot (of the electrostatic component of the fluctuating em field) of the n=8 Alfvénic mode in
the space of normalized frequency and radial position. The shear Alfvén continuous spectrum for n=8 is indicated by the black
solid line; b) Intensity contour plot of the n=16 Alfvénic mode in the space of normalized frequency and radial position. The
shear Alfvén continuous spectrum for n=16 is indicated by the black solid line; c) Effect of n=8 and n=16 saturated EPM on the
β hot⊥ radial profile
Figure 2.4 – One of the divertor geometries
used for the SOL/edge simulations with
EDGE2D/EIRENE
modes by means of a recently extended version of the hybrid
-1.30
Pump B
FAST divertor n. 4
magnetohydrodynamic gyrokinetic code (HMGC) [2.4],
which is able to simultaneously handle two generic initial
-1.40
particle distribution functions in the space of particle
1.1 1.3 1.5 1.7
constants of motion. The crucial role played by radial
Major radius R (m)
non–uniformities and by the shear Alfvén continuous
spectrum, shown as solid lines in figures 2.3a and 2.3b, is
consistent with the theoretical framework discussed in [2.5,2.6]. The effect of n=8 and n=16 saturated EPM
on the β hot⊥
radial profile, shown in figure 2.3c, suggests that significant radial redistributions of energetic
particle are expected with limited global losses.
Heights z(m)
-1
-1.10
-1.20
Pump A
Plasma–wall interaction activities and optimization of the divertor geometry
The modelling of the FAST scrape–off layer (SOL)/edge plasma with the software package EDGE2D +
EIRENE was carried out in 2010. Simulations have been run for the basic H–mode scenario: different
preliminary divertor designs (fig. 2.4) have been examined by varying the density at the separatrix over the
range n sep
=0.7–1.0×10 20 m –3 [2.7]. The input power into the SOL has been set to 20 or 16 MW and no
impurity seeding was allowed. Besides the importance of an as shallow as allowed strike angle of the separatrix
on the divertor target, simulations highlight that significant detachment is attained only if the divertor
geometry and pump location are optimized to allow the formation of a consistent neutral cloud close to the
strike point. At the lower separatrix densities the help of strongly radiating impurities would appear to be
unavoidable.
Diagnostics
A first assessment of the extent to which the 3 He fast ion population can be diagnosed in FAST with a set of
dedicated diagnostics has been performed [2.8], in order to show the capabilities of FAST in studying fast ion
physics in conditions relevant to a burning plasma. These energetic confined fast particles, with dimensionless
parameters (normalized Larmor radius and plasma pressure) close to those of fusion-born alphas in ITER,
will be produced in deuterium FAST plasmas by means of 30 MW ICRH minority heating. Neutron emission
spectroscopy (NES), gamma ray spectroscopy (GRS) and collective Thomson scattering (CTS) diagnostics have
been reviewed with a description of the state–of–the–art hardware and a preliminary analysis of the required
lines of sight.
Taking as an input the spatially resolved numerical simulations of the energy distribution of ICRH accelerated
particles, the corresponding spectra observed by the set of diagnostics have been simulated for specified lines