Detached divertor plasmas in JET

During 1991/92 a series of experiments was performed in which the divertor density was raised to the point where a sudden reduction of the particle flux to the target plates occurred. The radiation from these detached plasmas can be as high as 90% of the input power, thus making it possible to run discharges with input energies far above what would otherwise be the limit of the target tiles. The primary diagnostics for assessing the radiation from these plasmas are, of course, the bolometer arrays. During 1991/92 there were three such arrays, two spanning the entire plasma as viewed from a main horizontal port (R = 5.8 m, Z = ± 0.5 m), and one vertical camera which viewed virtually the entire plasma except the divertor. In addition, there is data available from a CCD camera and from several discrete visible spectroscopy views. (author) 6 refs., 2 figs., 1 tab