On the effectiveness of SPIDER RF system improvements

The first experimental phase of the novel and complex power supply system of SPIDER revealed some issues requiring deep studies to be understood: the interaction of the RF oscillators due to magnetic coupling among the on board circuits because of large connection loops; frequency instability of the oscillators that prevent the possibility to deliver the rated power; the flow of stray RF currents on the plant components that affects also diagnostic signals due to the adoption of a capacitive voltage divider (CVD) at the output of the RF generators.