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Next: VII. Pellet Displacement Up: MHD Effects on Previous: V. Inboard Injection

VI. Intermediate Injection

In the case of intermediate injection, the initial density blob is located at the top, shown in in Fig.14(a). The density enhancement tex2html_wrap_inline963 The density at tex2html_wrap_inline899 , tex2html_wrap_inline1013 is shown in Fig.8(b). The pellet material is relatively uniformly spread around its initial magnetic surfaces.

The density peak, as it spreads along the magnetic field, also rotates, moving towards the outboard side. But by the time the peak reaches the outboard side, it is no longer big enough to cause outward displacement.

Incidentally, the motion of the peak around the magnetic surfaces is related to a mechanism of poloidal rotation spinup. To achieve a spinup, the density perturbation must be maintained against the smoothing effect of sound waves, either by a spatially dependent diffusion, or by injection of beams or pellets.

The flux surface averages of tex2html_wrap_inline937 are shown in Fig.10(a,b). In intermediate cases, the pellet's motion is more tangent to the magnetic field, and there is relatively less motion of the averaged density peak. The initial averaged density profile is shown in Fig.10(a). At t =150, the profile is given by Fig.10(b), with very little shift of the peak, although there is significant diffusive loss, with tex2html_wrap_inline945

Hank Strauss
Wed Jan 7 14:23:34 EST 1998