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22-27 October 2018
Mahatma Mandir Conference Centre
Asia/Kolkata timezone
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Effect of multiple periodic gas puff on neutral temperature in Aditya – U tokamak

24 Oct 2018, 14:00
4h 45m
Mahatma Mandir Conference Centre

Mahatma Mandir Conference Centre

Gandhinagar (nearest Airport: Ahmedabad), India
Poster P4 Posters

Speaker

Ms Nandini Yadav (Gujarat University)

Description

The fuel gas injection(s) in measured quantity during the current flat-top region of Aditya-U tokamak discharges has been observed to modify significantly the edge and scape-off-layer (SOL) plasma properties. The effect of these gas puffs on the neutral temperature and their penetration in the edge and SOL region has been studied by measuring the Hydrogen balmer-emission spectra at 656.28 nmfrom different line of sights in the edge and SOL region in both high and low field regions of Aditya-U. The neutral temperature is estimated from the Doppler broadening of the measured H spectrum by appropriately removing the contribution from the Zeeman splitting of the spectral lines. A computer simulation code has been developed in-house whichgenerates synthetic chord-averaged H emission spectra at different radius of the plasma using the electron temperature, density and the magnetic field strength of that radial location measured with other diagnostics. The code includes all the broadening mechanisms such as Doppler, Zeeman, Stark or pressure broadening for simulating the H emission spectrum along with proper convolution of the instrumental width of the measuring system. Depending on the strength of the magnetic field, the code incorporates 7 Zeeman components in case of normal Zeeman splitting, whereas 48 (18 π and 30 ) components are taken in to account in case of Paschan-Back Zeeman splitting. The simulated spectra are used to obtain true values of neutral temperatures by iteratively fitting them to the measured spectrum from the edge and SOL region of Aditya – U tokamak [1]. Furthermore, the developed code has been used to isolate the cold, warm and hot (charge-exchange) components of the hydrogen atoms from the measured H emission spectra from the edge region of Aditya – U tokamak. References: [1] S. Banerjee, J. Ghosh, R. Manchanda, et al., “Observations of Hα emission profiles in Aditya tokamak”, J. Plasma Fusion Res. Series 9, 29 (2010).
Paper Number EX/P4-13
Country or International Organization India

Primary author

Ms Nandini Yadav (Gujarat University)

Co-authors

Mrs Deepti Tripathi (Gujarat University) Ms Harshita Raj (Institute for Plasma Research) Dr Joydeep Ghosh (Institute for Plasma Research) Mr Kaushal Patel (Institute for Plasma Research) Mr Kumarpalsinh Jadeja (Institute for plasma Research) Dr Malay Bikas Chowdhuri (Institute for Plasma Research) Mrs Nilam Nimavat (Institute for Plasma Research) Mrs RANJANA MANCHANDA (INSTITUTE FOR PLASMA RESEARCH) Mr Rakesh Tanna (Institute For Plasma Research) Dr Ritu Dey (Institute for Plasma Research) Dr Santanu Banerjee (Institute for Plasma Research)

Presentation Materials

Paper