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Real-time wall conditioning by controlled injection of boron and boron nitride powder in full tungsten wall ASDEX Upgrade

Journal Article · · Nuclear Materials and Energy
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  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Max-Planck-Institut fur Plasmaphysik, Garching (Germany)
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In ASDEX Upgrade with full-tungsten wall, boronization is an important tool to control tungsten sources and allow reliable operation at low collisionality. The duration of the beneficial effects is limited by the erosion of the boron layer, in particular on the tungsten ion-cyclotron antenna limiters. We report results from experiments exploring injection boron-rich powders in tokamak plasmas as a way to replenish boron coating and extend the lifetime of boronization effects. Pure boron and boron nitride powders were introduced gravitationally in plasma discharges at rates up to 60 mg/s for durations up to 3 s. Boron injection with cumulative amounts >100 mg appeared to improve wall conditions similarly to boronization, with indications of reduced influx of oxygen and tungsten from the antenna limiter. Moreover, cumulative injection of 340 mg of B appeared sufficient to enable successful execution of low collisionality scenarios critically relying on freshly boronized walls.

Research Organization:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-09CH11466
OSTI ID:
1506117
Journal Information:
Nuclear Materials and Energy, Journal Name: Nuclear Materials and Energy Journal Issue: C Vol. 19; ISSN 2352-1791
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (8)

Wall conditioning in ASDEX Upgrade journal June 2007
Influence of boronization on operation with high-Z plasma facing components in Alcator C-Mod journal June 2007
Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Mod journal May 2005
A multi-species powder dropper for magnetic fusion applications journal October 2018
Effect of boronization on ohmic plasmas in NSTX journal March 2002
Wall conditioning in fusion devices and its influence on plasma performance journal September 1996
Regime of very high confinement in the boronized DIII-D tokamak journal November 1991
Review of in Situ Boronization in Contemporary Tokamaks journal August 1997

Cited By (2)

Wall conditioning in fusion devices with superconducting coils journal January 2020
Active conditioning of ASDEX Upgrade tungsten plasma-facing components and discharge enhancement through boron and boron nitride particulate injection journal October 2019

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY