JAEA-Conf 2011-002 - 日本原子力研究開発機構

Using the approximated distribution, Eq. (1), the 0.981-MeV γ-ray yield can be represented as a
function of effective temperature Teff and concentration neff of knock-on tritons:
2 nLi
neff
Et
E
C
Y
E
E
t exp
E dEt
mt
T
C
eff
T
eff
2 ITeff
nLi
neff
m T
(2)
t
The γ-ray emission spectrum can be well fitted to a Gaussian distribution:
dY
dE
eff
EE
exp
Here E0 = 0.981 MeV, and represents the broadening of the fitting curve and has dimension of square
energy. The Gaussian distribution with = 96 keV 2 reproduces properly dY /dE in Fig. 6.
It was found that there is the pronounced
correlation between and Teff shown in .
With increasing Teff, the knock- on tritons
reach high energies, resulting in the - ray
emission spectrum with the wider broadening.
Once the parameter is assessed from the
experimental data on dY /dE , then Teff could
be determined by use of the prove curve in Fig. 7.
Equation (2) indicates that once Teff is
determined with a fine accuracy, then we can
assess neff from the experimental γ- ray yield Y .
Fig. 7. Correlation between slope factor of the -ray
emission spectrum and effective temperature Teff of
knock-on tritons.
e
One can also obtain information on the confinement property of fusion-born -particles in burning
DT plasmas. The theoretical curve in Fig. 4, Teff and T derived experimentally should be used for this
purpose. If the experimental plot of (Teff,T) is placed onto the theoretical curve in Fig. 4, then one can
reasonably consider the confinement of the -particles to be classical, i.e., the -particles exhibit the
classical slowing-down behavior described by the Fokker-Planck equation. If not, the -particles
anomalously escape from the plasma core and accordingly their confinement property is deteriorated. In
the latter case, because of losses of the -particles at energy below the average birth energy of E0 = 3.52
MeV, the relative fraction of the -particles with high energy around E0 become larger, resulting in the
effective temperature Teff of the knock-on tritons becoming higher. Accordingly, the experimental
(Teff,T) plot would be placed above the theoretical curve.
JAEA-Conf 2011-002
We showed that the 0.981-MeV γ-rays emitted in the 6 Li (t, p1) 8 Li * reaction have an important
application for diagnostics of the knock-on tritons and -particles in burning plasmas. If these γ-rays
are detected, we can obtain information on key parameters of knock-on triton population (Teff , neff )
0
2
(3)