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Deuterium neutral beams with energies up to 110 keV were injected into TFTR (Tokamak Fusion Test Reactor) plasmas at low magnetic field such that the beam injection velocities were comparable to the Alfven velocity. Excitation of toroidal Alfven eigenmodes was observed by Mirnov coils and beam emission spectroscopy. 10 refs., 4 figs.

A suprathermal electron beam is injected parallel to vector B in a low-..beta.. plasma. The sharp space-potential drop across the surface of the beam generates a strong cross-field current which in turn drives a modified two-stream instability at the lower hybrid frequency. Intense stochastic ion heating is observed with the onset of the instability, and the heating rate is found to be proportional to the wave energy.

Initial operation of the tokamak fusion test reactor has concentrated upon confinement studies of Ohmically heated hydrogen and deuterium plasmas. Total energy confinement times (${\ensuremath{\tau}}_{E}$) are 0.1-0.2 s for a line-average density range (${\overline{n}}_{e}$) of (1-2.5)\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{m}}^{\ensuremath{-}3}$ with electron temperatures of ${T}_{e}(0)\ensuremath{\sim}1.2\ensuremath{-}2.2$ keV, ion temperatures of ${T}_{i}(0)\ensuremath{\sim}0.9\ensuremath{-}1.5$ keV, and ${Z}_{\mathrm{eff}}\ensuremath{\sim}3$. A comparison of Princeton large torus, poloidal divertor experiment, and tokamak fusion test reactor plasma confinement supports a dimension-cubed scaling law.