1 - Nuclear Sciences and Applications - IAEA

4.5
-.4..
?3.
POLOIDAL PLANE
IAEA-CN-S0/A-IV-5 261
T
2.6 3.6
RADIUS
Sawtooth Craah
1.4 MA. 12 MW NBI ' b '
/ft
Detected Triton Orbits
q-l Surface (1.4 MA)
Triton Detector
I msec 10 niaac
m/n = 2/1 Mode
FIG. 3. (a) Poloidal cross section of TFTR with an escaping 1 MeV triton orbit that reaches one of
the lost alpha detectors. The bottom two traces indicate some of the 1 MeV triton losses correlated with
MHD activity, including (b) a sawtooth crash and (c) an m/n = 2/1 oscillation. The neutron flux signal
indicates a reduction of the 2.45 MeV neutron emission with sawtooth and m = 2/1 MHD.
and, if all the measured DD neutrons were created by beam-target
reactions [13]. The projected alpha heating is only 2.5% of the
total at the end of the neutral beam injection (3.95 sec in Fig.
4a) but is about 25% of the total at 4.4 sec (or 0.4 sec after the
beams). The energy content in the alphas would have risen from 7%
of the total at 3.95 sec to 35% of the total at 4.4 -• 4.6 sec.
This energy content and its anisotropy (if any) should be
detectable with the magnetic diagnostics. The alpha density (Fig.
4e) would have risen from 0.25% at 4.4 sec to 1.1% at 4.6 sec,
primarily due to the decay of the central electron density. The
average alpha energy would fall from 2.2 MeV at 4.0 sec to 0.8 MeV
at 4.4 sec, which emphasizes the transient nature of the alpha
population. For all TFTR supershot plasmas, the calculated alpha
slowing down duration is 2 to 5 times the bulk plasma energy
confinement time (Fig. 4c).