X-ray imaging crystal spectrometer
An X-ray Imaging Crystal Spectrometer (XICS) has been deployed by the Princeton Plasma Physics Laboratory on W7-X in collaboration with Auburn University and IPP. The diagnostic has been successfully operated for both the OP 1.1 and 1.2 experimental campaigns. The spectrometer is similar to the instrument designed and implemented on LHD, measuring emission from hydrogen and helium-like argon (Ar) ions as well as helium-like iron (Fe) from Laser Blow Off (LBO) injection experiments. The diagnostic yields line-integrated measurements of ion temperature as well as ion poloidal flow velocity requiring an inversion to recover the actual profiles.
The XICS system has become a routine diagnostic on W7-X and is utilized for the analysis of Fe LBO injection experiments with modeling of impurity transport for comparisons to neoclassical transport theory and the effects of varying Electron Cyclotron Resonant Heating (ECRH) from the core to the edge.
In the future, impurity transport analysis and modeling will be extended to include plasmas in turbulence reduced regimes enabled by the new Continuous Fueling Pellet Injector System (CFPS) to be implemented on W7-X. Additionally, new heating capabilities using Neutral Beam Injection (NBI) and Ion Cyclotron Resosant Heating (ICRH) offer the possibility of separately heating the ions allowing for systematic variation of the ion temperature profile and its effect on transport.
Primary Auburn personnel: Tomie Gonda and David Maurer
PPPL collaborator: Novimir Pablant
IPP collaborator: Andreas Langenberg