Real-time plasma control at JET using an ATM network

At JET, the Plasma Shape Control System (PPCC-SC) drives fast power amplifiers connected to the poloidal field coils. It determines the plasma boundary using the XLOC algorithm and data from the Magnetics Measurement System, KC1D. The additional heating systems, NB (Neutral Beam), ICRH (Ion Cyclotron Resonance Heating), and LHCD (Lower Hybrid Current Drive) can be controlled by real-time algorithms on the RTSS (Real-Time Signal Server). The Wall Load Limit System limits the power applied to the vessel. Also, experimental systems analyze data in real-time, e.g. RT-BETA-LI calculates Wdia, Beta, Li, etc., and RT-EFIT calculates the current profiles and flux-surfaces. These systems are hosted on a variety of hardware/software platforms, including - VME/VxWorks, TMS320C40 DSP/native code, and PC/WindowsNT. They communicate using ethernet, fibre-optic point-to-point links, or with reflective memory. To improve reliability and flexibility, a new real-time data network (RTDN) is being developed, using standard ATM components. Simple tests on ATM connections indicate that, for packets of a few hundred bytes, point-to-point transfers take less then 250#mu#s, which is adequate. ATM links for the DSP systems have been developed, based on a PowerPC VME card. A simple message protocol, application programmer interface, and data presentation tools have also been developed. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:4672.262(99/27) / BLDSC - British Library Document Supply CentreGBUnited Kingdo