Speaker
Description
See the full abstract here:
http://ocs.ciemat.es/EPS2019ABS/pdf/P1.1017.pdf
A new diagnostic - the imaging heavy ion beam probe (i-HIBP) [1] - for the simultaneous measurement of plasma potential, magnetic field and density fluctuations is being developed at the ASDEX Upgrade tokamak. A neutral beam of heavy atoms is injected into the plasma at energies around 70 keV. As the neutral primary beam penetrates the plasma, it ionizes leading to the generation of a fan of secondary beams which are deflected by the magnetic field of the tokamak and collected by a scintillator plate placed behind the limiter shadow of the machine. The light emitted by the scintillator plate is imaged by a fast-camera which provides high spatial and temporal resolution. The light pattern measured at the scintillator plate contains radially resolved information about the density, potential and magnetic field in the edge and scrape-off layer regions of the plasma. Detailed modelling of the beam trajectories has been carried out in order to find the optimum setup within the machine spatial constraints. The modelling includes the 3D magnetic field of the tokamak, to take into account effects such as the toroidal field ripple, as well as beam attenuation effects for Caesium and Rubidium atoms, in which electron impact ionization and charge exchange processes have been considered. Based on this modelling, a sensitivity study has been carried out to determine which physics phenomena can be investigated with the i-HIBP at ASDEX Upgrade. The hardware design will be presented, including the arrangement of the injector out-vessel and the scintillator and optics in-vessel. The results of laboratory tests for the characterization of the injector will be discussed.
[1] J. Galdon-Quiroga et al, JINST 12 C08023 (2017)
