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Title: First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges

Abstract

A critical challenge facing the basic long-pulse H-mode for ITER is to control edge-localized modes (ELMs). A new method using a multichamber lithium (Li) granule injector (LGI) for ELM triggering experiments has been developed in Experimental Advanced Superconducting Tokamak (EAST). First experimental results of the control of ELMs are obtained in EAST with a tungsten divertor. It is found that the injector has good capacities, i.e., allowing good flexibilities in granule size selection, injection rate, and injection velocity. In conclusion, LGI has successfully triggered ELMs during the H-mode. These results indicate the LGI would be a promising method to control ELMs in long-pulse steady-state tokamaks.

Authors:
ORCiD logo [1];  [2];  [2];  [3];  [2];  [2];  [4]; ORCiD logo [5];  [6]; ORCiD logo [7];  [1];  [1];  [1];  [1];  [1]
  1. Chinese Academy of Sciences, Hefei (China)
  2. Princeton Univ., Princeton, NJ (United States). Princeton Plasma Physics Lab.
  3. Chinese Academy of Sciences, Hefei (China); CAS key Lab. of Photovoltaic and Energy Conservation Materials, Hefei (China)
  4. Johns Hopkins Univ., Baltimore, MD (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  7. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1415985
Grant/Contract Number:
2017YFA0402500; 11625524; 11605246; 11775261; AC02-09CH11466
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
IEEE Transactions on Plasma Science
Additional Journal Information:
Journal Name: IEEE Transactions on Plasma Science; Journal ID: ISSN 0093-3813
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Edge localized modes (ELM); Experimental Advanced Superconducting Tokamak (EAST); lithium (Li) granule injection (LGI)

Citation Formats

Sun, Z., Lunsford, R., Maingi, R., Hu, J. S., Mansfield, D. K., Diallo, A., Tritz, K., Canik, J., Wang, Z., Andruczyk, D., Wang, Y. M., Zuo, G. Z., Huang, M., Xu, W., and Meng, X. C. First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges. United States: N. p., 2017. Web. doi:10.1109/TPS.2017.2773095.
Sun, Z., Lunsford, R., Maingi, R., Hu, J. S., Mansfield, D. K., Diallo, A., Tritz, K., Canik, J., Wang, Z., Andruczyk, D., Wang, Y. M., Zuo, G. Z., Huang, M., Xu, W., & Meng, X. C. First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges. United States. doi:10.1109/TPS.2017.2773095.
Sun, Z., Lunsford, R., Maingi, R., Hu, J. S., Mansfield, D. K., Diallo, A., Tritz, K., Canik, J., Wang, Z., Andruczyk, D., Wang, Y. M., Zuo, G. Z., Huang, M., Xu, W., and Meng, X. C. 2017. "First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges". United States. doi:10.1109/TPS.2017.2773095.
@article{osti_1415985,
title = {First Results of ELM Triggering With a Multichamber Lithium Granule Injector Into EAST Discharges},
author = {Sun, Z. and Lunsford, R. and Maingi, R. and Hu, J. S. and Mansfield, D. K. and Diallo, A. and Tritz, K. and Canik, J. and Wang, Z. and Andruczyk, D. and Wang, Y. M. and Zuo, G. Z. and Huang, M. and Xu, W. and Meng, X. C.},
abstractNote = {A critical challenge facing the basic long-pulse H-mode for ITER is to control edge-localized modes (ELMs). A new method using a multichamber lithium (Li) granule injector (LGI) for ELM triggering experiments has been developed in Experimental Advanced Superconducting Tokamak (EAST). First experimental results of the control of ELMs are obtained in EAST with a tungsten divertor. It is found that the injector has good capacities, i.e., allowing good flexibilities in granule size selection, injection rate, and injection velocity. In conclusion, LGI has successfully triggered ELMs during the H-mode. These results indicate the LGI would be a promising method to control ELMs in long-pulse steady-state tokamaks.},
doi = {10.1109/TPS.2017.2773095},
journal = {IEEE Transactions on Plasma Science},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
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  • The ability of an injected lithium granule to promptly trigger an edge localized mode (ELM) has been established in multiple experiments. By horizontally injecting granules ranging in diameter from 200 microns to 1mm in diameter into the low field side of EAST H-mode discharges we have determined that granules with diameter > 600 microns are successful in triggering ELMs more than 95% of the time. Granules were radially injected from the outer midplane with velocities ~ 80 m/s into EAST upper-single null discharges with an ITER like tungsten monoblock divertor. ELM triggering was a prompt response to granule injection, andmore » for granules of a sufficient size there was no evidence of a "trigger lag" phenomenon as observed in full metal machines. We also demonstrated that the triggering efficiency decreased with granule size during dynamic size scans. These granules were individually tracked throughout their injection cycle in order to determine their efficacy at triggering an ELM. Furthermore, by simulating the granule injection with an experimentally benchmarked neutral gas shielding (NGS) model, the ablatant mass deposition required to promptly trigger an ELM is calculated and the fractional mass deposition is determined. Simulated 900 micron granules capable of triggering an ELM show a peaked mass deposition of 3.9 x 10 17 atoms per mm of penetration at a depth of approximately 5 cm past the separatrix.« less
  • The secretory pro-hormone chromogranin A (CHGA) is densely packed into storage granules along with catecholamines, playing a catalytic role in granule biogenesis. 3-Dimensional structural data on CHGA are lacking. We found a superfamily structural homology for CHGA in the tropomyosin family of alpha-helical coiled-coils, even in mid-molecule regions where primary sequence identity is only modest. The assignment was confirmed by an independent algorithm, suggesting approximately 6-7 such domains spanning CHGA. We provide additional physiochemical evidence (chromatographic, spectral, microscopic) consistent with this unusual structure. Alpha-helical secondary structure (at up to approximately 45%) was confirmed by circular dichroism. CHGA molecular mass wasmore » estimated by MALDI-TOF mass spectrometry at approximately 50 kDa and by denaturing gel filtration at approximately 50-61 kDa, while its native Stokes radius was approximately 84.8 A, as compared to an expected approximately 30 A; the increase gave rise to an apparent native molecular weight of approximately 578 kDa, also consistent with the extended conformation of a coiled-coil. Small-angle X-ray scattering (SAXS) on CHGA in solution best fit an elongated cylindrical conformation in the monodisperse region with a radius of gyration of the rod cross-section (Rt) of approximately 52 A, compatible with a coiled-coil in the hydrated, aqueous state, or a multimeric coiled-coil. Electron microscopy with negative staining revealed an extended, filamentous CHGA structure with a diameter of approximately 94 +/- 4.5 A. Extended, coiled-coil conformation is likely to permit protein 'packing' in the secretory granule at approximately 50% higher density than a globular/spherical conformation. Natural allelic variation in the catestatin region was predicted to disrupt the coiled-coil. Chromaffin granule ultrastructure revealed a approximately 108 +/- 6.3 A periodicity of electron density, suggesting nucleation of a binding complex by the CHGA core. Inhibition of CHGA expression, by siRNA, disrupted regulated secretory protein traffic by approximately 65%, while targeted ablation of the CHGA gene in the mouse reduced chromaffin granule cotransmitter concentrations by approximately 40-80%. These results suggest new roles for secretory protein tertiary structure in hormone and transmitter storage, with implications for secretory cargo condensation (or dense core 'packing' structure) within the regulated pathway.« less
  • Here, by employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s –1 are presented for NSTX-U L-mode type plasmas, as well as H-mode dischargesmore » with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s –1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.« less
  • Here, energy transport analyses of DIII-D high-β P EAST-demonstration discharges have been performed using the TGYRO transport package with TGLF turbulent and NEO neoclassical transport models under the OMFIT integrated modeling framework. Ion energy transport is shown to be dominated by neoclassical transport and ion temperature profiles predicted by TGYRO agree closely with the experimental measured profiles for these high-β P discharges. Ion energy transport is largely insensitive to reductions in the E × B flow shear stabilization. The Shafranov shift is shown to play a role in the suppression of the ion turbulent energy transport below the neoclassical level.more » Electron turbulent energy transport is under-predicted by TGLF and a significant shortfall in the electron energy transport over the whole core plasma is found with TGLF predictions for these high-β P discharges. TGYRO can successfully predict the experimental ion and electron temperature profiles by artificially increasing the saturated turbulence level for ETG driven modes used in TGLF.« less
    Cited by 1
  • Here, energy transport analyses of DIII-D high-β P EAST-demonstration discharges have been performed using the TGYRO transport package with TGLF turbulent and NEO neoclassical transport models under the OMFIT integrated modeling framework. Ion energy transport is shown to be dominated by neoclassical transport and ion temperature profiles predicted by TGYRO agree closely with the experimental measured profiles for these high-β P discharges. Ion energy transport is largely insensitive to reductions in the E × B flow shear stabilization. The Shafranov shift is shown to play a role in the suppression of the ion turbulent energy transport below the neoclassical level.more » Electron turbulent energy transport is under-predicted by TGLF and a significant shortfall in the electron energy transport over the whole core plasma is found with TGLF predictions for these high-β P discharges. TGYRO can successfully predict the experimental ion and electron temperature profiles by artificially increasing the saturated turbulence level for ETG driven modes used in TGLF.« less