Title: Design and Testing of a Prototype Eddy Current Actuated Valve for the ITER Shattered Pellet Injection System

Abstract

Reliably mitigating disruptions is essential for ITER to meet its long-term operational research plan without damage to the in-vessel components. Currently, the shattered pellet injection (SPI) technique is the most effective radiator of thermal energy and has been chosen for the baseline disruption mitigation system (DMS) for ITER. The SPI process uses cryogenic temperatures to desublimate material into the barrel of a pipe gun forming a solid cylindrical pellet. Pellets for ITER will initially be hydrogen and hydrogen-neon mixtures. Once formed, pellets are dislodged and accelerated using high-pressure gas (40-60 bar) delivered by a fast-opening valve. The solenoid valves currently used for SPI experiments will not operate in an ITER environment due to the large background magnetic field. An ITER prototype fast-opening valve, called a flyer plate valve (FPV), has been designed and has undergone a wide range of testing. The FPV operates by pulsing current through a pancake coil that is closely coupled with a ``flyer plate.'' The flyer plate is an aluminum plate in which eddy currents are generated creating a repulsive force from the pancake coil. The force generated in the flyer plate rapidly lifts the valve tip off the seat and delivers a pulse of gasmore » to the rear of the pellet, breaking it free from the barrel and accelerating the pellet downstream to its intended target. The design of the valve has been iterated on over the lifetime of this project, as the DMS for ITER shifted from massive gas injection (MGI) to SPI. The most recent design has been tested, and operational ranges have been mapped. The valve must survive 3000+ cycles in an ITER-like magnetic field. The principal functional requirement of this valve is to reliably dislodge and accelerate hydrogen (or H-Ne mixture) pellets into ITER. The valve was mated with an ITER SPI test stand and has been shown to be capable of launching pellets reliably. The valve and power supply design will be discussed in this article, along with the various testing setups used to determine the feasibility of this valve for use on ITER.« less

Authors:

Gebhart III, Trey  ^[1];

• Search DOE PAGES for author "Gebhart III, Trey"
• Search DOE PAGES for ORCID "0000-0001-8259-6095"

Ericson, Nance  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6628-4865"

Meitner, Steven  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-7751-7716"

Baylor, Larry  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-0325-7771"

Gardner, Walter ^[1]; Bigelow, Tim S.  ^[1];

• Search DOE PAGES for author "Bigelow, Tim S."
• Search DOE PAGES for ORCID "0000-0002-2014-4090"

Rasmussen, David ^[1]

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+ Show Author Affiliations

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

Publication Date:

Wed Apr 20 00:00:00 EDT 2022

Research Org.:

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

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1865743

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

IEEE Transactions on Plasma Science

Additional Journal Information:

Journal Volume: 50; Journal Issue: 11; Journal ID: ISSN 0093-3813

Publisher:

IEEE

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; valves; bellows; testing; power supplies; force; prototypes; magnetic separation; disruption mitigation; fast valve; ITER; shattered pellet injection