The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas

Rice, J. E.; Sciortino, F.; Gu, M.; Cao, N.; Hughes, J. W.; Irby, J. H.; Marmar, E. S.; Mordijck, S.; Reinke, M. L.; Reksoatmodjo, R.

doi:10.7910/DVN/YJXA00

Title: The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas

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Abstract

X-ray transitions of the very high-n Rydberg series in Ar^16+ have been observed from Alcator C-Mod tokamak plasmas. Individual emission lines up to 1s16p - 1s^2 have been resolved and the central chord line brightnesses with principal quantum number n between 7 and 16 are generally found to decay as 1/n^alpha, with alpha slightly larger than 3. In the plasma periphery, emission from 1s9p - 1s^2 and 1s10p - 1s^2 are found to be significantly enhanced relative to this decrease, indicative of selected population of these levels through charge exchange between background neutral deuterium in the ground state and Ar^17+. An unresolved feature between the wavelengths of 1s27p - 1s^2 and 1s30p - 1s^2 is also present, which arises through charge exchange with neutral deuterium in the n^* = 3 excited state. The brightnesses of transitions populated by charge exchange are spatially up/down asymmetric, with an excess on the side of the magnetic surface X-point. The relative brightness of the unresolved very high-n feature compared to 1s7p - 1s^2 is found to increase with electron temperature and decrease with electron density. Simulations of line emission just on the long wavelength side of the Ar^16$ ionization limit indicate that the principalmore »« less

Authors:

Rice, J. E.; Sciortino, F.; Gu, M.; Cao, N.; Hughes, J. W.; Irby, J. H.; Marmar, E. S.; Mordijck, S.; Reinke, M. L.; Reksoatmodjo, R.

OSTI

Publication Date:: Thu Nov 04 04:00:00 UTC 2021

DOE Contract Number:: FC02-99ER54512; SC0014264

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

OSTI Identifier:: 1886675

DOI:: https://doi.org/10.7910/DVN/YJXA00

Citation Formats


                    Rice, J. E., Sciortino, F., Gu, M., Cao, N., Hughes, J. W., Irby, J. H., Marmar, E. S., Mordijck, S., Reinke, M. L., and Reksoatmodjo, R. The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas.  United States: N. p., 2021. 
        Web.  doi:10.7910/DVN/YJXA00.

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                    Rice, J. E., Sciortino, F., Gu, M., Cao, N., Hughes, J. W., Irby, J. H., Marmar, E. S., Mordijck, S., Reinke, M. L., & Reksoatmodjo, R. The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas.  United States.  doi:https://doi.org/10.7910/DVN/YJXA00

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                    Rice, J. E., Sciortino, F., Gu, M., Cao, N., Hughes, J. W., Irby, J. H., Marmar, E. S., Mordijck, S., Reinke, M. L., and Reksoatmodjo, R. 2021.  
"The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas".  United States.  doi:https://doi.org/10.7910/DVN/YJXA00.  https://www.osti.gov/servlets/purl/1886675. Pub date:Thu Nov 04 04:00:00 UTC 2021

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@article{osti_1886675,

  title        = {The Very High n Rydberg Series of Ar^16+ in Alcator C-Mod Tokamak Plasmas},

  author       = {Rice, J. E. and Sciortino, F. and Gu, M. and Cao, N. and Hughes, J. W. and Irby, J. H. and Marmar, E. S. and Mordijck, S. and Reinke, M. L. and Reksoatmodjo, R.},

  abstractNote = {X-ray transitions of the very high-n Rydberg series in Ar^16+ have been observed from Alcator C-Mod tokamak plasmas. Individual emission lines up to 1s16p - 1s^2 have been resolved and the central chord line brightnesses with principal quantum number n between 7 and 16 are generally found to decay as 1/n^alpha, with alpha slightly larger than 3. In the plasma periphery, emission from 1s9p - 1s^2 and 1s10p - 1s^2 are found to be significantly enhanced relative to this decrease, indicative of selected population of these levels through charge exchange between background neutral deuterium in the ground state and Ar^17+. An unresolved feature between the wavelengths of 1s27p - 1s^2 and 1s30p - 1s^2 is also present, which arises through charge exchange with neutral deuterium in the n^* = 3 excited state. The brightnesses of transitions populated by charge exchange are spatially up/down asymmetric, with an excess on the side of the magnetic surface X-point. The relative brightness of the unresolved very high-n feature compared to 1s7p - 1s^2 is found to increase with electron temperature and decrease with electron density. Simulations of line emission just on the long wavelength side of the Ar^16$ ionization limit indicate that the principal quantum number decay exponent is closer to alpha = 4 at very high n. The brightness dependence on n below 16 is in excellent agreement with calculations from the Flexible Atomic Code package.},

  doi          = {10.7910/DVN/YJXA00},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {Thu Nov 04 04:00:00 UTC 2021},

  month        = {Thu Nov 04 04:00:00 UTC 2021}

}

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DOI: https://doi.org/10.7910/DVN/YJXA00

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