A new method on recycling coefficient measurement using impurity pellet injection in a large helical device

Journal Article · Fri Jul 15 04:00:00 EDT 2005 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1946567· OSTI ID:20722960

Nozato, Hideaki; Morita, Shigeru; Goto, Motoshi ^[1]

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1. Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

Recycling coefficients of carbon, aluminum, and titanium were evaluated using a new technique combining impurity pellet injection with high-spatial resolution bremsstrahlung measurement in hydrogen and helium plasmas on the large helical device. The recycling coefficient of impurities was investigated by measuring absolute intensities with the visible bremsstrahlung array. The time evolution of the bremsstrahlung signals was modeled by an impurity transport code adjusting the diffusion coefficient, convective velocity, and recycling coefficient. As a result, a finite value of the recycling coefficient was required in the case of carbon, whereas aluminum and titanium were explained as nonrecycled particles. It was also clarified that the recycling coefficient of carbon had a larger value in hydrogen plasmas (R=0.5-0.65) than in helium plasmas (R=0-0.2), suggesting the formation of hydrogen molecules.

• OSTI ID: 20722960
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 7 Vol. 76; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALUMINIUM
BREMSSTRAHLUNG
CARBON
DIFFUSION
HELIUM
HYDROGEN
LHD DEVICE
MOLECULES
PARTICLES
PELLET INJECTION
PLASMA
PLASMA CONFINEMENT
PLASMA IMPURITIES
RECYCLING
SIGNALS
SPATIAL RESOLUTION
STELLARATORS
TITANIUM
VELOCITY