Upgraded space and time resolved visible spectroscopic diagnostic on ADITYA-U tokamak.

Abstract

Poloidal asymmetries in neutral and impurity ion temperatures and particle and impurity transports have been observed in many tokamaks. To investigate these asymmetries, space-resolved visible spectroscopic diagnostic of the ADTIYA-U tokamak has been upgraded to measure the spatial profile of Hα and impurities spectral line profile, ion temperature, and plasma rotation from both low and high field sides of the plasma, simultaneously with a better spatial resolution. This has been done by developing a linear array of 15 optical fibers as compared to the present linear array of nine fibers having a core diameter of 400 μm and coupling it to the entrance slit of a 1 m long high-resolution spectrometer of the existing diagnostic. A sCMOS detector with a larger height has also been employed to record 15 tracks as compared to the nine tracks when the spectrometer was coupled to a CCD detector having a size of 26.6 × 6.6 mm. The spatial profile of the Hα spectral line from the low and high field sides of the ADITYA-U plasma has been now recorded at every 20 ms to investigate neutral particle dynamics.