EFD-C(13)05/07 Toroidal Alfven Eigenmode Amplifier Control at JET Using Commercial FPGA and PXI Platform to Study Plasma Instabilities

At JET a unique 8-coil antenna system has been implemented to study the plasma instabilities due to fast-ion interactions with Alfven Eigenmodes in support of ITER. The present system has a single amplifier with a power of 5kW that is controlled by ageing electronic modules. This single amplifier was driving all eight different in-vessel antennas, with only +/­ (0o or 180o) control of relative phase between the antennas, and with only a common single frequency sweep. The new system is comprised of eight individual 4kW amplifiers to drive the antennas, increasing the total system power to 32kW. The existing function generator and control electronics are replaced by National Instruments FPGA-based cards and PXI Express platform. This unit will control all eight amplifiers in real-time and is also synchronized with the JET system-wide 1MHz reference clock. The different functions of the digital control unit are to generate the amplifier drive signals with the desired frequency and phase, and to control the gain of all eight amplifiers. This paper will cover the system architecture, the initial test results and the advantages of this new system compared to the older system.