JET new diagnostic capability on the route to ITER

• The JET scientific programme is directed towards the development of ITER relevant scenarios. In support of this, significant effort has been made to develop diagnostics to better characterise the power deposition on the plasma facing components, to investigate in more detail the radiation losses particularly in the divertor region and to better detect Magneto Hydrodynamic Modes (MHD) instabilities and their effects on fast ion confinement. A new wide-angle infrared camera provides for the first time the opportunity to perform infrared thermography in the JET main chamber, even during fast events like ELMs and disruptions. A completely new bolometric system, with better spatial resolution particularly in the divertor, is now used to investigate the total radiation losses and their influence on the ELM behaviour. A new set of microwave waveguides has improved by 20 dB the signal to noise ratio of the JET X-mode reflectometers, that are now routinely used to detect MHD instabilities and in particular to localise the location of Alfven Eigenmodes. This improved diagnostic capability to monitor MHD instabilities is complemented by two new diagnostics to detect lost fast particles. Both the new scintillator probe and a poloidal array of Faraday cups have already shown clear correlations between MHD activity and ion losses at the edge.

Keyword

plasma diagnostics

ITER

JET

Publication and Content Type

ref (subject category)

art (subject category)