Plasma and Fusion Research

Volume 17, 2402046 (2022)

Regular Articles

Equilibrium Magnetic Field Requirements during Plasma Initiation and Current Ramp-up Phase in ADITYA/ADITYA-U Tokamak Discharges
Rakesh L. TANNA1,2), Joydeep GHOSH1,3), Chetnarayan GUPTA1), Balakrishnan V. NAIR1), Shivam GUPTA1), Moti N. MAKWANA1), Kunal SHAH1), Supriya NAIR1), Rohit KUMAR1), Suman AICH1), Kumarpalsinh A. JADEJA1,5), Kaushal M. PATEL1), Tanmay MACWAN1,3), Kaushlender SINGH1,3), Suman DOLUI1,3), Ankit KUMAR1,3), Chetna CHAUHAN4), Rajendra P. BHATTACHARYAY1), Prabal K. CHATTOPADHYAY1,3), Malay Bikas CHOWDHURI1), Ranjana MANCHANDA1), Yogesh Chandra SAXENA1) and the ADITYA-U Team1)
1)
Institute for Plasma Research, Nr. Indira Bridge, Bhat, Ghandhinagar, Pin. 382 428, India
2)
Institute of Science, Nirma University, Ahmedabad 382481, Gujarat, India
3)
Homi Bhabha National Institute (HBNI), Mumbai 400085, India
4)
Institute of Technology, Nirma University, Ahmedabad 382 481, Gujarat, India
5)
Department of Physics, Saurashtra University, Rajkot, Gujarat, India
(Received 17 December 2021 / Accepted 28 February 2022 / Published 13 May 2022)

Abstract

Plasma equilibrium in ADITYA/ADITYA-U is provided by two pairs of vertical field coils (BV1 & BV2) placed outside the vessel. A peak loop voltage of ∼20 V is required for successful breakdown and start-up in ADITYA, which leads to a higher IP ramp-rate ∼6 - 8 MA/Sec during the first ∼7 ms of discharge. To hold the plasma column in equilibrium, the vertical field should also be ramped-up at the same rate. Series connections of vertical field (BV) coils do not provide the required ramp rate due to the high L/R time-constant of the coils and 12 pulse converter firing. Therefore, additional arrangements are made to achieve it. The addition of a pre-charged capacitor of 500 μF/3 kV with VF converter based power supply allows successful start-up but causes concern about a slight dip that is observed in the plasma current. To obtain proper stabilization, two techniques are used. One is the paralleling of BV coils, and second is using the combination of another capacitor bank of 19.5 mF/1.2 kV and IGBT based power supply have improved the plasma performance and raised the IP ∼150 kA with dIP/dt ∼ 3.0 - 3.5 MA/s in ADITYA. In this paper, the effect of the equilibrium field in accordance with plasma performance is discussed in detail.

Keywords

plasma, tokamak, equilibrium, start-up, BV series configuration, BV parallel configuration

DOI: 10.1585/pfr.17.2402046

Full Text

PDF format (2.8Mbytes) PDF Download

References

  • [1] R.L. Tanna et al., Nucl. Fusion 57, 102008 (2017).
  • [2] R.L. Tanna et al., Plasma Sci. Technol. 20, 074002 (2018).
  • [3] R.L. Tanna et al., Nucl. Fusion 59, 112006 (2019).
  • [4] R.L. Tanna et al., Nucl. Fusion 62, 042017 (2022).
  • [5] S.B. Bhatt et al., ADITYA: the first Indian tokamak, Indian J. Pure Appl. Phys. 27, 710 (1989).
  • [6] C.N. Gupta et al., IEEE 26th Symp. on Fusion Engineering (SOFE) (2015), doi:10.1109/SOFE.2015.7482398
  • [7] Rohit Kumar et al., Fusion Eng. Des. 165, 112218 (2021).
  • [8] D. Kumawat et al., Indian J. Phys. 95(3), 523 (2021).
  • [9] E.J. Strait et al., Nucl. Fusion 59, 112012 (2019).
  • [10] A. Agarwal et al., Plasma Phys. Control. Fusion 63, 115004 (2021).