Spectroscopic diagnostics on low aspect-ratio tokamaks

Low aspect-ratio tokamaks (LARTs) have intrinsic features which require specific diagnostics for particle transport and confinement studies. Such spectroscopic diagnostics are developed in collaboration between the CDX-U group at Princeton Plasma Physics Laboratory and the Plasma Spectroscopy group at Johns Hopkins University. This paper presents results obtained from the low aspect-ratio CDX-U tokamak, as well as future diagnostic developments for CDX-U and other LARTs. These results are based on spectroscopy in the VUV (500 Å - 2000 Å) using a multiple grating normal incidence spectrometer equipped with an optical multichannel analyzer, and in the XUV range on emission recorded using multilayer mirror devices.