Neutral beam injection on the Tokamak fusion test reactor

The neutral beam injection experiment on TFTR has now been underway for over two years, during which time we have injected as much as about 20 MW of beam power at energies up to 110 keV. We have obtained qualitative evidence of direct current drive by the injected beam ions. Recently we have produced plasmas in which the energy confinement time, β p , neutron emission, stored energy (both total and electron), and ion temperature exhibit a pronounced enhancement over previous behavior. Under these conditions we have obtained preliminary indications that significant bootstrap current is being driven. Operation will continue with new sources with which we should be able to increase the beam pulse length fourfold.