Observation of poloidal asymmetry in measured neutral temperatures in the Aditya-U tokamak plasma

The neutral particle temperature in the edge region of the Adiya-U tokamak has been measured by recording the hydrogen Balmer alpha emission spectra at 656.28 run from different lines of sight in both the high and low field sides. The spatial profile of the H-alpha emission has been recorded using a 1 m multi-track spectrometer. The neutral temperature is estimated from the Doppler broadening of the measured H-alpha spectrum by appropriately removing the contribution from the Zeeman splitting of the spectral lines. A computer simulation code was developed to estimate the neutral temperature by including the broadening mechanisms such as Doppler broadening and the Zeeman effect to simulate the H-alpha emission spectrum along with the proper convolution of the instrumental width of the diagnostic system. It has been observed that the high field side neutral temperature (similar to 4-6 eV) during plasma flat top is almost twice that of the low field side (similar to 2-3 eV) suggesting poloidal asymmetry in the neutral temperature.