Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

Lunsford, R.; Bortolon, A.; Roquemore, A. L.; Mansfield, D. K.; Jaworski, M. A.; Kaita, R.; Maingi, R.; Nagy, A.

doi:10.1088/1741-4326/aa6cd3

Title: Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

Abstract

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 discharges 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.

Authors:

Lunsford, R. ^[1]; Bortolon, A. ^[1]; Roquemore, A. L. ^[1]; Mansfield, D. K. ^[1]; Jaworski, M. A. ^[1]; Kaita, R. ^[1]; Maingi, R. ^[1]; Nagy, A. ^[1]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Publication Date:: Tue May 16 00:00:00 EDT 2017

Research Org.:: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1362046

Grant/Contract Number:: AC02-09CH11466

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Fusion

Additional Journal Information:: Journal Volume: 57; 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; granule injection; ELM pacing; neutral gas shielding

Citation Formats


                    Lunsford, R., Bortolon, A., Roquemore, A. L., Mansfield, D. K., Jaworski, M. A., Kaita, R., Maingi, R., and Nagy, A. Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges.  United States: N. p., 2017. 
Web.  doi:10.1088/1741-4326/aa6cd3.

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                    Lunsford, R., Bortolon, A., Roquemore, A. L., Mansfield, D. K., Jaworski, M. A., Kaita, R., Maingi, R., & Nagy, A. Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges.  United States.  https://doi.org/10.1088/1741-4326/aa6cd3

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                    Lunsford, R., Bortolon, A., Roquemore, A. L., Mansfield, D. K., Jaworski, M. A., Kaita, R., Maingi, R., and Nagy, A. Tue .  
"Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges".  United States.  https://doi.org/10.1088/1741-4326/aa6cd3.  https://www.osti.gov/servlets/purl/1362046.

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@article{osti_1362046,

  title        = {Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges},

  author       = {Lunsford, R. and Bortolon, A. and Roquemore, A. L. and Mansfield, D. K. and Jaworski, M. A. and Kaita, R. and Maingi, R. and Nagy, A.},

  abstractNote = {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 discharges 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.},

  doi          = {10.1088/1741-4326/aa6cd3},

  journal      = {Nuclear Fusion},

  number       = 7,

  volume       = 57,

  place        = {United States},

  year         = {Tue May 16 00:00:00 EDT 2017},

  month        = {Tue May 16 00:00:00 EDT 2017}

}

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Works referenced in this record:

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Works referencing / citing this record:

Modeling of Ablatant Deposition from Electromagnetically Driven Radiative Pellets for Disruption Mitigation Studies
journal, July 2019

Lunsford, Robert; Raman, Roger; Brooks, A.
Fusion Science and Technology, Vol. 75, Issue 8
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Carbon impurities behavior and its impact on ion thermal confinement in high-ion-temperature deuterium discharges on the Large Helical Device
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Title: Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

Abstract

Citation Formats

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Long-pulse stability limits of the ITER baseline scenario journal, January 2015

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Observation of ablation and acceleration of impurity pellets in the presence of energetic ions in the CHS heliotron/torsatron journal, July 2002

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Lithium pellet deposition and penetration in TFTR journal, October 1992

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Reduction of Edge-Localized Mode Intensity Using High-Repetition-Rate Pellet Injection in Tokamak $H$ -Mode Plasmas
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First Observation of Edge Localized Modes Mitigation with Resonant and Nonresonant Magnetic Perturbations in ASDEX Upgrade
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Model of ablation flow near light-atom pellets with surface boundary conditions
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Non-linear MHD modelling of ELM triggering by pellet injection in DIII-D and implications for ITER
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ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER
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First observations of ELM triggering by injected lithium granules in EAST
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Analysis of low Z _a impurity pellet ablation for fusion diagnostic studies
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Techniques for injection of pre-characterized dust into the scrape-off layer of fusion plasma
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Fullerene-related structure of commercial glassy carbons
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