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We were able to form a channel of microcracks in the transparent dielectric using the passively mode-locked pulsed wave of Nd:YAG radiation. The channel of microcracks started on the back side of a planar specimen; then it grew from pulse to pulse in the direction inside and ended on the face side.

The usual demonstration that neoclassical transport is automatically ambipolar, and independent of the radial electric field (E,), is shown to be valid only in an equilibrium axisymmetric plasma in which there is no other source or damping of toroidal momentum. If it were generally true, it would be difficult to explain the measured current drawn from a biased internal probe, as used to induce H modes. However, this current and its variation with applied voltage are consistent with the alternative analysis by Galeev and Sagdeev, in which the ion and electron fluxes depend on E, -B&. The behaviour of E, and impurity pump-out during enhanced MHD activity can also be explained using this analysis.