Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak

Baek, S. G.; Wallace, G. M.; Bonoli, P. T.; Brunner, D.; Faust, I. C.; Hubbard, A. E.; Hughes, J. W.; LaBombard, B.; Parker, R. R.; Porkolab, M.; Shiraiwa, S.; Wukitch, S.

doi:10.7910/DVN/PZOMOI

Title: Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak

Abstract

Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to ne≈1.5×10^20 m^-3 in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current - and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at ne≈1.0×10^20 m^-3 reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor.

Authors:: Baek, S. G.; Wallace, G. M.; Bonoli, P. T.; Brunner, D.; Faust, I. C.; Hubbard, A. E.; Hughes, J. W.; LaBombard, B.; Parker, R. R.; Porkolab, M.; Shiraiwa, S.; Wukitch, S.

Publication Date:: 2019-01-18

DOE Contract Number:: FC02-99ER54512

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:: 1881223

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

Citation Formats


                    Baek, S. G., Wallace, G. M., Bonoli, P. T., Brunner, D., Faust, I. C., Hubbard, A. E., Hughes, J. W., LaBombard, B., Parker, R. R., Porkolab, M., Shiraiwa, S., and Wukitch, S. Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak.  United States: N. p., 2019. 
        Web.  doi:10.7910/DVN/PZOMOI.

Copy to clipboard


                    Baek, S. G., Wallace, G. M., Bonoli, P. T., Brunner, D., Faust, I. C., Hubbard, A. E., Hughes, J. W., LaBombard, B., Parker, R. R., Porkolab, M., Shiraiwa, S., & Wukitch, S. Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak.  United States.  doi:https://doi.org/10.7910/DVN/PZOMOI

Copy to clipboard


                    Baek, S. G., Wallace, G. M., Bonoli, P. T., Brunner, D., Faust, I. C., Hubbard, A. E., Hughes, J. W., LaBombard, B., Parker, R. R., Porkolab, M., Shiraiwa, S., and Wukitch, S. 2019.  
"Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak".  United States.  doi:https://doi.org/10.7910/DVN/PZOMOI.  https://www.osti.gov/servlets/purl/1881223. Pub date:Fri Jan 18 00:00:00 EST 2019

Copy to clipboard


                    
@article{osti_1881223,

  title        = {Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak},

  author       = {Baek, S. G. and Wallace, G. M. and Bonoli, P. T. and Brunner, D. and Faust, I. C. and Hubbard, A. E. and Hughes, J. W. and LaBombard, B. and Parker, R. R. and Porkolab, M. and Shiraiwa, S. and Wukitch, S.},

  abstractNote = {Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to ne≈1.5×10^20 m^-3 in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current - and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at ne≈1.0×10^20 m^-3 reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor.},

  doi          = {10.7910/DVN/PZOMOI},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {2019},

  month        = {1}

}

Copy to clipboard

Dataset:

View Dataset

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

Save / Share:

Export Metadata

Save to My Library

Works referencing / citing this record: