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Title: Investigation of atomic and molecular processes in H α emission through modelling of measured H α emissivity profile using DEGAS2 in the ADITYA tokamak

Abstract

In order to understand the atomic and molecular processes involved in the emission of the hydrogen Balmer alpha (H α) spectral line from tokamak plasmas, the measured radial profile of H α emissivity in ADITYA tokamak discharges has been modeled using the DEGAS2 neutral particle transport code. The radial profile of emissivity has been measured using a 1.0 m multi-track spectrometer and with PMT array based space-resolved visible spectroscopic diagnostics involving interference filters. The radial profile of the neutral hydrogen density has been obtained using the DEGAS2 code by reproducing the experimentally observed H α emissivity profile. It has been found that the neutral density falls by 80–200 times at the plasma center compared to its maximum value at the plasma edge near the limiter (ρ = 0.92). Detailed investigation of the contributions of atomic and molecular processes involved in H α emission reveals the significant presence of hydrogen molecules and molecular ions within ~4 cm of the limiter radius. Here, the contributions from processes involving H + 2 ions are found to be higher than those from the molecular hydrogen dissociation with H + 2 dissociative recombination dominating over H + 2 dissociation at the extreme edge of themore » plasma.« less

Authors:
 [1];  [1];  [2];  [1];  [3];  [1]; ORCiD logo [2];  [2];  [1];  [1];  [1];  [1]; ORCiD logo [4]
  1. Inst. for Plasma Research, Gandhinagar (India)
  2. Inst. for Plasma Research, Gandhinagar (India); Homi Bhaba National Inst., Mumbai (India)
  3. Gujarat Univ., Ahmedabad (India)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
ADITYA Team
OSTI Identifier:
1558755
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 7; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ADITYA tokamak; DEGAS2; atomic and molecular processes; Hα emissivity

Citation Formats

Dey, Ritu, Chowdhuri, M. B., Ghosh, Joydeep, Manchanda, R., Yadava, Nandini, Ramaiya, N., Banerjee, S., Nagora, U. C., Atrey, P. K., Raval, J. V., Shankar Joisa, Y., Tanna, R. L., and Stotler, D. P. Investigation of atomic and molecular processes in Hα emission through modelling of measured Hα emissivity profile using DEGAS2 in the ADITYA tokamak. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab0f01.
Dey, Ritu, Chowdhuri, M. B., Ghosh, Joydeep, Manchanda, R., Yadava, Nandini, Ramaiya, N., Banerjee, S., Nagora, U. C., Atrey, P. K., Raval, J. V., Shankar Joisa, Y., Tanna, R. L., & Stotler, D. P. Investigation of atomic and molecular processes in Hα emission through modelling of measured Hα emissivity profile using DEGAS2 in the ADITYA tokamak. United States. doi:10.1088/1741-4326/ab0f01.
Dey, Ritu, Chowdhuri, M. B., Ghosh, Joydeep, Manchanda, R., Yadava, Nandini, Ramaiya, N., Banerjee, S., Nagora, U. C., Atrey, P. K., Raval, J. V., Shankar Joisa, Y., Tanna, R. L., and Stotler, D. P. Thu . "Investigation of atomic and molecular processes in Hα emission through modelling of measured Hα emissivity profile using DEGAS2 in the ADITYA tokamak". United States. doi:10.1088/1741-4326/ab0f01.
@article{osti_1558755,
title = {Investigation of atomic and molecular processes in Hα emission through modelling of measured Hα emissivity profile using DEGAS2 in the ADITYA tokamak},
author = {Dey, Ritu and Chowdhuri, M. B. and Ghosh, Joydeep and Manchanda, R. and Yadava, Nandini and Ramaiya, N. and Banerjee, S. and Nagora, U. C. and Atrey, P. K. and Raval, J. V. and Shankar Joisa, Y. and Tanna, R. L. and Stotler, D. P.},
abstractNote = {In order to understand the atomic and molecular processes involved in the emission of the hydrogen Balmer alpha (Hα) spectral line from tokamak plasmas, the measured radial profile of Hα emissivity in ADITYA tokamak discharges has been modeled using the DEGAS2 neutral particle transport code. The radial profile of emissivity has been measured using a 1.0 m multi-track spectrometer and with PMT array based space-resolved visible spectroscopic diagnostics involving interference filters. The radial profile of the neutral hydrogen density has been obtained using the DEGAS2 code by reproducing the experimentally observed Hα emissivity profile. It has been found that the neutral density falls by 80–200 times at the plasma center compared to its maximum value at the plasma edge near the limiter (ρ = 0.92). Detailed investigation of the contributions of atomic and molecular processes involved in Hα emission reveals the significant presence of hydrogen molecules and molecular ions within ~4 cm of the limiter radius. Here, the contributions from processes involving H+2 ions are found to be higher than those from the molecular hydrogen dissociation with H+2 dissociative recombination dominating over H+2 dissociation at the extreme edge of the plasma.},
doi = {10.1088/1741-4326/ab0f01},
journal = {Nuclear Fusion},
number = 7,
volume = 59,
place = {United States},
year = {2019},
month = {5}
}

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