Real Time Operation of MAST Thomson Scattering Diagnostic

The MAST (Mega-Amp Spherical Tokamak) Thomson scattering diagnostic provides measurements of electron temperature and density at 130 spatial points with similar to 10 mm resolution across the plasma. Eight 30 Hz 1.6J Nd:YAG lasers have been combined to produce an average sampling rate of 240 Hz with minimum interval >1 mu s. The scattered light signals are registered as polychromator outputs at 1 GHz rate in a short interval around each laser pulse. There are two tasks when real-time system capability is needed: 1) triggering of lasers and acquisition on plasma events to provide higher time resolution; 2) output physical data, electron temperature and density, in real-time for plasma control and other applications. In a standard mode the system works with postshot data acquisition; the physical data are produced as a result of intensive processing including results from other diagnostics. The real-time mode requires a fast processing algorithm and a fast way for gathering and dispatching data. This paper presents the implementation of real-time capabilities and first results of their usage.