Plasma and Fusion Research

Volume 17, 2402011 (2022)

Regular Articles

Impurity Behavior in High Performance ADITYA Tokamak Plasmas

Malay B. CHOWDHURI¹⁾, Ranjana MANCHANDA¹⁾, Joydeep GHOSH^1,2), Nandini YADAVA³⁾, Sharvil PATEL⁴⁾, Nilam RAMAIYA¹⁾, Anand K. SRIVASTAVA⁵⁾, Kumudni TAHILIANI¹⁾, Meduri V. GOPALAKRISHNA¹⁾, Umesh C. NAGORA¹⁾, Praveen K. ATREY¹⁾, Surya K. PATHAK^1,2), Shishir PUROHIT¹⁾, Joisa SHANKARA¹⁾, Kumarpalsinh A. JADEJA¹⁾, Rakesh L. TANNA¹⁾, Chet N. GUPTA¹⁾, Prabal K. CHATTOPADHYAY^1,2) and ADITYA Team¹⁾

1): Institute for Plasma Research, Bhat, Gandhinagar 382 428, India
2): Homi Bhaba National Institute, Training School Complex, Anushaktinagar, Mumbai 400 094, India
3): Institute of Science, Nirma University, Ahmedabad 382 481, Gujarat, India
4): Pandit Deendayal Energy University, Raisan, Gandhinagar, 382 007, Gujarat, India
5): Birla Institute of Technology-Mesra, Jaipur Campus, Jaipur 302 017, India

(Received 31 December 2021 / Accepted 3 February 2022 / Published 30 March 2022)

Abstract

Impurity behavior has been studied for the high performance Ohmically heated ADITYA tokamak plasmas operated with higher toroidal magnetic field and multiple gas puffs. The neutral hydrogen and impurity emissions in the visible range were monitored by photo multiplier tube (PMT) based system in which interference filter used for wavelength selection. The VUV spectral line emissions from impurities, such as C⁴⁺, O⁵⁺ and Fe¹⁴⁺, were also recorded by a VUV survey spectrometer operated in the 10 - 180 nm. It has been found that H_α, O¹⁺, and C²⁺ emissions normalized with electron density (n_e), and visible continuum normalized with n_e² show a gradual decrease with increase in density indicating lower impurity concentration in these discharges. The VUV emission also shows the similar trend with increasing n_e. Indeed, the impurity transport study using iron emissions confirms that the iron concentration reduces with increasing n_e. This is also corroborated by the observed reduction in plasma effective charge, Z_eff and radiation power loss with the increase in n_e. These results clearly indicate that the improved confinement for ADITYA plasma are correlated with reduction of impurities concentration in those discharges.

Keywords

impurity, visible, VUV, spectroscopy, plasma, ADITYA tokamak

DOI: 10.1585/pfr.17.2402011

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