Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [$n_e$(0)≃${10}^{19}$ ${\mathrm{m}}^{\mathrm{-}3}$] were characterized by $T_e$(0)=6.5 keV, $T_i$(0)=20 keV, $n_e$(0)=7×${10}^{19}$ ${\mathrm{m}}^{\mathrm{-}3}$, ${\tau }_E$=170 msec, ${\beta }_{\mathrm{theta}}$=2, and a d(d,n${)}^3$He neutron emission rate of ${10}^{16}$ ${\sec }^{\mathrm{-}1}$. The ion temperature and the deuterium-fusion neutron yields were significantly higher than for previous tokamak experiments. The low initial densities were achieved by operation of the Tokamak Fusion Test Reactor with low plasma currents (≤1 MA) and by extensive limiter conditioning.

• Received 26 November 1986

DOI:https://doi.org/10.1103/PhysRevLett.58.1004