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Stabilization of sawtooth instability by short gas pulse injection in ADITYA-U tokamak

Suman Dolui1,2,*, Kaushlender Singh1,2, Bharat Hegde1,2, T. Macwan3, SK Injamul Hoque1,2, Umesh Nagora1,2, Jaya Kumar A.4, S. Purohit1, A. N. Adhiya1 et al.

K. A. Jadeja1, Harshita Raj1,2, Ankit Kumar1,2, Ashok K. Kumawat1,2, Suman Aich1,2, Rohit Kumar1, K. M. Patel1, P. Gautam1, Sharvil Patel1, N. Yadava5, N. Ramaiya1, M. K. Gupta1, S. K. Pathak1,2, M. B. Chowdhuri1, S. Sharma1,2, A. Kuley4, R. L. Tanna1, P. K. Chattopadhyay1,2, A. Sen1,2, Y. C. Saxena1,2, R. Pal6, and Joydeep Ghosh1,2,†

  • *Contact author: suman.dolui@ipr.res.in
  • †Contact author: jghosh@ipr.res.in
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Phys. Rev. Research 7, 033161 – Published 15 August, 2025

DOI: https://doi.org/10.1103/wbkn-kz71

Abstract

Experiments on ADITYA-U tokamak show a marked enhancement in the sawtooth period by application of short gas puffs of fuel that cause a modification of the radial density profile. A consequent suppression of the trapped electron modes then leads to an increase in the core electron temperature. This slows down the heat propagation following a sawtooth crash causing a delay in achieving the critical temperature gradient inside the q=1 surface required for the next sawtooth crash to happen. The overall scenario has strong similarities with the behavior of sawtooth under electron cyclotron resonance heating (ECRH). Our findings suggest an alternate technique for sawtooth control that may be usefully employed in small- and/or medium-sized tokamaks that do not have an ECRH or any other auxiliary heating facility.

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Phys. Rev. Research 7, 033161– Published 15 August, 2025
  • Received 31 December 2024
  • Accepted 26 June 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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