1 - Nuclear Sciences and Applications - IAEA

292 KAWAHATA et al.
0 6 12 18 24
radius(cm)
FIG. 5. Time evolution of density profile ne(r,t) with injection of a small pellet and profile shape factor,
k, defined by ne = ne(O)(l-(r/af) k .
fitting of the profile as n,.(r,t) = ne(0,t)(l-(r/a) 2 ) k(t) . We try to estimate the diffusion
coefficient D and the inward velocity v in the following two ways: First, by comparing
the profiles and k-values at two different times, t[ and t2, in Fig. 5, we estimate
D and v roughly, assuming that D and v do not change during density relaxation.
Secondly, we also estimate D and v by using a 1-D transport code, assuming
D(r) = D(0)/(n(r)/n(0)) and v(r) = v(a)(r/a) p . Good agreement with the experimental
data has been obtained for D(0) = 0.4 m 2 -s -1 , v(a) = 20 m-s" 1 and p = 2. The
values D and v as calculated by the two methods agree with each other within a factor
of two.
REFERENCES
[1] DUCHS, D.F., et al., in Plasma Physics and Controlled Nuclear Fusion Research 1986 (Proc.
11th Int. Conf. Kyoto, 1986), Vol. 1, IAEA, Vienna (1987) 325.
[2] TANG, W.M., et al., ibid., p. 337.
[3] WALTZ, R.E., et al., ibid., p. 345.
[4] BROWER, D.L., et al., Phys. Rev. Lett. 59 (1987) 48.
[5] WATARI, T., et al., in Plasma Physics and Controlled Nuclear Fusion Research 1986 (Proc.
11th Int. Conf. Kyoto, 1986), Vol. 1, IAEA, Vienna (1987) 495.
[6] KADOMTSEV, B.B., POGUTSE, O.P., Rev. Plasma Phys. (Engl. Transl.) 5 (1970) 308.
[7] CHANG, C.J., HINTON, F.L., Phys. Fluids 25 (1982) 1493.