Characterization of the plasma current quench during disruptions in ADITYA tokamak. (29th October 2020)

• Record Type: Journal Article
• Authors: Purohit, S.; Chowdhuri, M.B.; Ghosh, J.; Joisa, Y.S.; Raval, J.V.; Jha, S.K.; Raju, D.; Jadeja, K.A.; Manchanda, R.; Gupta, M.K.; Pathak, S.K.; Gupta, C.N.; Bhat, S.B.; Tanna, R.L.; Chattopadhyay, P.K.; Saxena, Y.C.; Sen, A.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 60:Number 12(2020)
• Publication Date: 2020-10-29
• Subjects: ADITYA tokamak -- disruption -- current quench time -- edge safety factor -- MHD -- magnetic islands; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/abb79c
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: The rate of plasma current-quench during tokamak plasma disruptions determines the electromagnetic forces on the in-vessel components/vacuum vessel. Also halo currents and rapid changes of poloidal field due to the plasma vertical displacement contribute to loads on vessel and in-vessel components and hence needs to be studied thoroughly to safeguard these tokamak peripherals. The plasma current quench occurrence during the spontaneous major disruption has been investigated for a set of ADITYA tokamak disrupted discharges and average plasma current quench and instantaneous current quench rates have been estimated. The fastest area-normalized plasma current ( IP ) quench time is observed to be ∼5 ms m −2 . The estimated post disruption plasma electron temperatures (PDET) are observed to be ∼15–35 eV and proportional to area-normalized plasma current quench time. Further analysis of several disruptive discharges of ADITYA tokamak reveal that the current quench time is inversely proportional to the pre-disruptive values of edge safety factor, qa, and the current quench properties are strongly correlated with the prevailing pre-disruptive plasma magnetohydrodynamic (MHD) activities. For larger values of pre-disruptive qa, the larger island widths of m = 2 and m = 3 MHD modes leads to a significant overlap of these islands. Such an overlap along with the deeper locations of the islands inside the plasma column, as compared to discharges having smaller values of pre-disruptive qa, seems to facilitate the faster current quench.