A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D

Nagy, Alex; Bortolon, A.; Brown, W.; Fisher, Peter; Lunsford, R.; Maingi, R.; Mansfield, D.; Mauzey, D.; Nguyen, R.; Vorenkamp, Madeline

doi:10.1109/TPS.2018.2810129

Title: A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D

Abstract

Injection of solid nonfuel pellets has been actively used as a tool for pacing and mitigation of edge localized modes (ELMs). In DIII-D, effective ELM pacing has been demonstrated by the high-frequency injection of lithium and carbon submillimeter spheres, using the impurity granule injector (IGI). This device injects granules into the plasma at speeds up to 150 m/s, through impact with a rotating impeller. In the IGI, high-frequency granule delivery was accomplished through a vibrational granule dropper, in which high time-average rates are obtained at the cost of lack of period control. Here, we present a new in-line granule feeder, capable of delivering granules of size 0.2-2 mm with no restriction of material properties, at quasi-periodic rates of up to 150 Hz, for 0.7-mm diameter lithium granules (600 Hz using 0.3-mm granules). The new dropper mechanism combines two piezo-in-line units; one which feeds the impeller and one which circulates granules that are filtered out of the feeder path. A remotely adjustable filter eliminates granules that are stacked, oversized, or side by side allowing the formation of a single moving granule injection line. The granules fall off the in-line feeder exit one at a time, achieving a quasi-periodic delivery rate proportionalmore »« less

Authors:

^[1]; Bortolon, A. ^[1]; Brown, W. ^[1]; Fisher, Peter ^[1]; Lunsford, R. ^[1]; Maingi, R. ^[1]; Mansfield, D. ^[1]; Mauzey, D. ^[1]; Nguyen, R. ^[2]; Vorenkamp, Madeline ^[1]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
General Atomics, San Diego, CA (United States)

Publication Date:: Tue Apr 10 00:00:00 EDT 2018

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

Sponsoring Org.:: USDOE

OSTI Identifier:: 1440898

Grant/Contract Number:: AC02-09C11466; FC02-04ER54698

Resource Type:: Accepted Manuscript

Journal Name:: IEEE Transactions on Plasma Science

Additional Journal Information:: Journal Volume: 46; Journal Issue: 5; Journal ID: ISSN 0093-3813

Publisher:: IEEE

Country of Publication:: United States

Language:: English

Subject:: 42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Reservoirs; Electron tubes; Bridges; Plasmas; Impurities; Lithium; Impellers; edge localized mode (ELM) trigger; impurity; injector

Citation Formats


                    Nagy, Alex, Bortolon, A., Brown, W., Fisher, Peter, Lunsford, R., Maingi, R., Mansfield, D., Mauzey, D., Nguyen, R., and Vorenkamp, Madeline. A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D.  United States: N. p., 2018. 
Web.  doi:10.1109/TPS.2018.2810129.

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                    Nagy, Alex, Bortolon, A., Brown, W., Fisher, Peter, Lunsford, R., Maingi, R., Mansfield, D., Mauzey, D., Nguyen, R., & Vorenkamp, Madeline. A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D.  United States.  https://doi.org/10.1109/TPS.2018.2810129

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                    Nagy, Alex, Bortolon, A., Brown, W., Fisher, Peter, Lunsford, R., Maingi, R., Mansfield, D., Mauzey, D., Nguyen, R., and Vorenkamp, Madeline. Tue .  
"A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D".  United States.  https://doi.org/10.1109/TPS.2018.2810129.  https://www.osti.gov/servlets/purl/1440898.

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@article{osti_1440898,

  title        = {A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D},

  author       = {Nagy, Alex and Bortolon, A. and Brown, W. and Fisher, Peter and Lunsford, R. and Maingi, R. and Mansfield, D. and Mauzey, D. and Nguyen, R. and Vorenkamp, Madeline},

  abstractNote = {Injection of solid nonfuel pellets has been actively used as a tool for pacing and mitigation of edge localized modes (ELMs). In DIII-D, effective ELM pacing has been demonstrated by the high-frequency injection of lithium and carbon submillimeter spheres, using the impurity granule injector (IGI). This device injects granules into the plasma at speeds up to 150 m/s, through impact with a rotating impeller. In the IGI, high-frequency granule delivery was accomplished through a vibrational granule dropper, in which high time-average rates are obtained at the cost of lack of period control. Here, we present a new in-line granule feeder, capable of delivering granules of size 0.2-2 mm with no restriction of material properties, at quasi-periodic rates of up to 150 Hz, for 0.7-mm diameter lithium granules (600 Hz using 0.3-mm granules). The new dropper mechanism combines two piezo-in-line units; one which feeds the impeller and one which circulates granules that are filtered out of the feeder path. A remotely adjustable filter eliminates granules that are stacked, oversized, or side by side allowing the formation of a single moving granule injection line. The granules fall off the in-line feeder exit one at a time, achieving a quasi-periodic delivery rate proportional to the exit speed. At higher rates, the periodicity deteriorates. This behavior was studied using high-speed cameras and electrostatic measurements, and it was found that at drop rates <60 Hz, the granule delivery period has a variation of ±25% which appears to be caused by gaps which develop in the last centimeter of the injection line, as granules exit off the moving track. The linear feeder concept is robust against bridge instabilities and clogging issues, thanks to the simple diverter filter and constant recirculation of granules. Furthermore, the open-top design of the device facilitates refilling the device from separate reservoirs and has easy access for directly monitoring operation and adjustment. This paper describes the details of the in-line feeder design, along with several design iterations. The goal is a robust in-vacuum mechanism that can deliver granule flow ranging from a single particle to a line of particles at 150 per second, using different sizes and materials from the same apparatus.},

  doi          = {10.1109/TPS.2018.2810129},

  journal      = {IEEE Transactions on Plasma Science},

  number       = 5,

  volume       = 46,

  place        = {United States},

  year         = {Tue Apr 10 00:00:00 EDT 2018},

  month        = {Tue Apr 10 00:00:00 EDT 2018}

}

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Journal Article:

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https://doi.org/10.1109/TPS.2018.2810129

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Cited by: 4 works

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Figures / Tables:

Figure 1: Original Impurity Injector created by Mansfield and Roquemore at PPPL used a PZT disk to move granules to the entrance of the drop tube.

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Works referencing / citing this record:

A multi-species powder dropper for magnetic fusion applications
journal, October 2018

Nagy, A.; Bortolon, A.; Mauzey, D. M.
Review of Scientific Instruments, Vol. 89, Issue 10
DOI: 10.1063/1.5039345

Figures / Tables found in this record:

Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.

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Title: A Quasi-Periodic Linear Feeder for the Impurity Granular Injection on DIII-D

Abstract

Citation Formats

Figures / Tables:

A multi-species powder dropper for magnetic fusion applications journal, October 2018

A multi-species powder dropper for magnetic fusion applications
journal, October 2018