Plasma and Fusion Research

Volume 16, 2402055 (2021)

Regular Articles

Investigation of Recycling and Impurities Influxes in ADITYA-U Tokamak Plasmas
Nandini YADAVA1,2), Malay Bikas CHOWDHURI3), Joydeep GHOSH3,4), Ranjana MANCHANDA3), Tanmay MACWAN3,4), Nilam RAMAIYA3), Ankur PANDYA5), Sripathi PUNCHITHAYA K.1,6), Ismayil6), Kumarpalsinh A. JADEJA3), Umesh C. NAGORA3), Surya K. PATHAK3), Minsha SHAH3), Pramila GAUTAM3), Rohit KUMAR3), Suman AICH3), Kaushal M. PATEL3), Rakesh L. TANNA3) and ADITYA-U Team3)
1)
The National Institute of Engineering, Mysuru 570 008, Karnataka, India
2)
Institute of Science, Nirma University, Ahmedabad 382 481, Gujarat, India
3)
Institute for Plasma Research, Bhat 382 428, Gandhinagar, India
4)
HBNI, Training School Complex, Anushakti Nagar 400 085, Mumbai, India
5)
Institute of Technology, Nirma University, Ahmedabad 382 481, Gujarat, India
6)
Manipal Institute of Technology (MAHE), Bangalore 560 064, Karnataka, India
(Received 29 November 2020 / Accepted 16 February 2021 / Published 21 April 2021)

Abstract

Fuel particle and impurity influxes have been investigated for ADITYA-U tokamak plasma operated with toroidal belt limiter using PMT based spectroscopic diagnostic system installed on machine. The influxes of hydrogen and impurity ions are estimated using various lines of sight (LoS) terminating on the graphite limiter and stainless steel wall to understand their contributions in recycled particle and impurities into the main plasma. It is found that the influxes of neutral hydrogen and oxygen are around 4 times higher in case of LoS terminating on the limiter than the wall while carbon influxes from the both LoSs are comparable. The comparable integrated particle influxes from both LoSs indicate the important role of the wall in the recycling and presence of the impurities in the plasma. The particle confinement time (τp) and recycling coefficient (R) are also estimated to quantify those from the estimated particle influxes. The τp values vary between 8 to 25 ms when plasma electron density is in the range of 2.0 - 3.2 × 1019 m−3. Analysis of recycling coefficient, R suggests that the Plasma Facing Component (PFC) acts as the particle sink at the beginning of the plasma operational campaign. The R values tend to become more than one as the campaign progresses suggesting that the PFC acting as the particle source.

Keywords

ADITYA-U tokamak, spectroscopy, recycling, impurity influx, particle outflux, particle confinement time

DOI: 10.1585/pfr.16.2402055

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