Status of tokamak plasma physics

The present-day performance of tokamak plasmas is reviewed and compared with reactor requirements. Energy confinement time is found to increase with plasma density and radius, resulting in n tau/sub E/-values between 1012-1013 cm-3s in present large devices. The ion temperature has been raised to almost 2 keV by intense neutral-beam injection. Effective methods for impurity control, plasma fueling, and exhaust must still be developed for long-pulse operation. The maximization of fusion power density required for an economic tokamak reactor seems attainable by a combination of moderately high magnetic field and one or more beta-enhancement schemes such as the use of a noncircular plasma cross section