A new method on recycling coefficient measurement using impurity pellet injection in a large helical device
- 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, Vol. 76, Issue 7; Other Information: DOI: 10.1063/1.1946567; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
Similar Records
Observations of centrally peaked impurity profiles following pellet injection in the Alcator-C-italic tokamak
Coaxial pellets for metallic impurity injection on the large helical device