Engineering Papers⌕ Search

Engineering topics

Maruyama, So

Publications and source records attributed to Maruyama, So.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Pellet Injection Technology and Its Applications on ITER

Cryogenic pellet injectors for use in fusion research have been under development at Oak Ridge National Laboratory for over 30 years. The original application of the technology was to add fuel to magnetically confined plasmas to replace D-T ions that are consumed in the fusion reactions or lost due to transport out of the confining magnetic fields. This application is still the primary use for pellet injection and is planned for implementation on the ITER burning plasma experiment. More recently, there have been additional applications for the injection of cryogenic pellets in the areas of disruption and edge-localized mode mitigation. Injectors for these applications are also being implemented for ITER, which require refinements of the technology for production and shattering of very large pellets and production of very small high repetition rate pellets, respectively. Details of these applications and injection system designs are presented.

Baylor, Larry R.↗
DOE OSTI2016

Pellet Injection Technology and Application to Mitigate Transient Events on ITER

The technology to form and accelerate cryogenically solidified pellets of hydrogen isotopes has long been under development for fueling fusion plasmas. Injectors are being designed to provide this capability for fueling ITER with DT pellets injected from the inner wall. In addition to this fueling application, the pellet technology is being further developed for ITER to mitigate transient heat fluxes and energetic particle impacts from disruptions and edge localized modes (ELMs). Large shattered impurity pellets have been found to effectively mitigate disruptions and small pellets of deuterium have been used to trigger on demand rapid small ELMs to limit the transient heat flux damage from otherwise large naturally occurring ELMs. Both of these technologies are being implemented for ITER.

Baylor, Larry↗
DOE OSTI2015

Disruption Mitigation System Developments and Design for ITER

A disruption mitigation system (DMS) is under design for ITER to inject sufficient material deeply into the plasma for rapid plasma thermal shutdown and collisional suppression of any resulting runaway electrons. Progress on the development and design of both a shattered pellet injector (SPI) that produces large solid cryogenic pellets to provide reliable deep penetration of material and a fast opening high flow rate gas valve for massive gas injection (MGI) is presented. Cryogenic pellets of deuterium and neon up to 25 mm in size have been formed and accelerated with a prototype injector and a full scale prototype MGI valve is now in testing. Implications of the design with respect to response time and reliability at the proposed injector locations on ITER are discussed.

Baylor, Larry↗
DOE OSTI2015

Fast Acting Eddy Current Driven Valve for Massive Gas Injection on ITER

Tokamak plasma disruptions present a significant challenge to ITER as they can result in intense heat flux, large forces from halo and eddy currents, and potential first-wall damage from the generation of multi-MeV runaway electrons. Massive gas injection (MGI) of high Z material using fast acting valves is being explored on existing tokamaks and is planned for ITER as a method to evenly distribute the thermal load of the plasma to prevent melting, control the rate of the current decay to minimize mechanical loads, and to suppress the generation of runaway electrons. A fast acting valve and accompanying power supply have been designed and first test articles produced to meet the requirements for a disruption mitigation system on ITER. The test valve incorporates a flyer plate actuator similar to designs deployed on TEXTOR, ASDEX upgrade, and JET [1 3] of a size useful for ITER with special considerations to mitigate the high mechanical forces developed during actuation due to high background magnetic fields. The valve includes a tip design and all-metal valve stem sealing for compatibility with tritium and high neutron and gamma fluxes.

Fast Acting Eddy current↗