Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System

Ghiozzi, Adriana G.; Velez, Danah A.; Gebhart III, Trey E.; Gehrig, Monica L.; Ericson, Milton N.; Baylor, Larry R.; Rasmussen, David A.

doi:10.1080/15361055.2021.1906149

Title: Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System

Abstract

One technique for mitigating disruptions in a tokamak is shattered pellet injection (SPI). SPI is a process in which a large solid pellet consisting of deuterium, neon, or argon is desublimated in a pipe gun barsrel and launched downstream. Pellets are shattered just before entering the plasma by an impact with an angled tube. Injection of these materials into the plasma radiates stored thermal energy, limits current decay rates, suppresses the generation of runaway electrons, and dissipates runaway electrons if necessary. A critical element of the SPI system is a fast-acting valve that releases high-pressure gas to dislodge and accelerate pellets directly, or indirectly via a mechanical punch. A prototype valve sized for the ITER SPI system has been designed and fabricated. A pulsed high-voltage power supply energizes the valve’s internal magnetic coil, which induces eddy currents in the adjacent flyer plate resulting in a repulsive force between the flyer plate and the coil. The flyer plate action lifts a valve seat, allowing high-pressure gas to flow from the valve plenum to the downstream (breech) location of the pellet or mechanical punch. All of the valve’s internal components are designed to operate in ITER-level static background magnetic fields. Here, amore »« less

Authors:

^[1]; Velez, Danah A. ^[1]; Gebhart III, Trey E. ^[1];

^[1];

^[1]; Rasmussen, David A. ^[1]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: Tue Aug 17 00:00:00 EDT 2021

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1818726

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Fusion Science and Technology

Additional Journal Information:: Journal Volume: 77; Journal Issue: 7-8; Journal ID: ISSN 1536-1055

Publisher:: American Nuclear Society

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; shattered pellet injection; flyer plate valve; computational fluid dynamics

Citation Formats


                    Ghiozzi, Adriana G., Velez, Danah A., Gebhart III, Trey E., Gehrig, Monica L., Ericson, Milton N., Baylor, Larry R., and Rasmussen, David A. Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System.  United States: N. p., 2021. 
Web.  doi:10.1080/15361055.2021.1906149.

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                    Ghiozzi, Adriana G., Velez, Danah A., Gebhart III, Trey E., Gehrig, Monica L., Ericson, Milton N., Baylor, Larry R., & Rasmussen, David A. Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System.  United States.  https://doi.org/10.1080/15361055.2021.1906149

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                    Ghiozzi, Adriana G., Velez, Danah A., Gebhart III, Trey E., Gehrig, Monica L., Ericson, Milton N., Baylor, Larry R., and Rasmussen, David A. Tue .  
"Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System".  United States.  https://doi.org/10.1080/15361055.2021.1906149.  https://www.osti.gov/servlets/purl/1818726.

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@article{osti_1818726,

  title        = {Pressure Response Optimization of an Eddy Current-Driven Flyer Plate Valve for the ITER Shattered Pellet Injection System},

  author       = {Ghiozzi, Adriana G. and Velez, Danah A. and Gebhart III, Trey E. and Gehrig, Monica L. and Ericson, Milton N. and Baylor, Larry R. and Rasmussen, David A.},

  abstractNote = {One technique for mitigating disruptions in a tokamak is shattered pellet injection (SPI). SPI is a process in which a large solid pellet consisting of deuterium, neon, or argon is desublimated in a pipe gun barsrel and launched downstream. Pellets are shattered just before entering the plasma by an impact with an angled tube. Injection of these materials into the plasma radiates stored thermal energy, limits current decay rates, suppresses the generation of runaway electrons, and dissipates runaway electrons if necessary. A critical element of the SPI system is a fast-acting valve that releases high-pressure gas to dislodge and accelerate pellets directly, or indirectly via a mechanical punch. A prototype valve sized for the ITER SPI system has been designed and fabricated. A pulsed high-voltage power supply energizes the valve’s internal magnetic coil, which induces eddy currents in the adjacent flyer plate resulting in a repulsive force between the flyer plate and the coil. The flyer plate action lifts a valve seat, allowing high-pressure gas to flow from the valve plenum to the downstream (breech) location of the pellet or mechanical punch. All of the valve’s internal components are designed to operate in ITER-level static background magnetic fields. Here, a study was conducted to optimize the downstream pressure response for a range of valve sizes and operating pressures. In particular, the study analyzes the breech pressure response associated with varying plenum pressures as well as varying breech volumes. A computational fluid dynamics simulation was built in STAR-CCM+ and validated against data from laboratory experiments. The resulting simulation outputs, in the form of downstream responses for a variety of initial plenum pressures and breech volumes, will be used as a complement to experimental data to ensure the pressure pulse is suitable for pellet survivability. These data, combined with studies on pellet shear strength and shock response, will be applied to optimization of overall operating parameters of the ITER SPI system.},

  doi          = {10.1080/15361055.2021.1906149},

  journal      = {Fusion Science and Technology},

  number       = 7-8,

  volume       = 77,

  place        = {United States},

  year         = {Tue Aug 17 00:00:00 EDT 2021},

  month        = {Tue Aug 17 00:00:00 EDT 2021}

}

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Works referenced in this record:

A new Disruption Mitigation System for deuterium–tritium operation at JET
journal, October 2015

Kruezi, Uron; Jachmich, Stefan; Koslowski, Hans Rudolf
Fusion Engineering and Design, Vol. 96-97
DOI: 10.1016/j.fusengdes.2015.06.109

Fast acting eddy current driven valve for massive gas injection on ITER
conference, May 2015

Lyttle, M. S.; Baylor, L. R.; Carmichael, J. R.
2015 IEEE 26th Symposium on Fusion Engineering (SOFE)
DOI: 10.1109/SOFE.2015.7482379

Disruptions in ITER and strategies for their control and mitigation
journal, August 2015

Lehnen, M.; Aleynikova, K.; Aleynikov, P. B.
Journal of Nuclear Materials, Vol. 463
DOI: 10.1016/j.jnucmat.2014.10.075

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Abstract

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