Investigation of oxygen impurity transport using the O4+ visible spectral line in the Aditya tokamak.

Autor: Chowdhuri, M. B., Ghosh, J., Banerjee, S., Dey, Ritu, Manchanda, R., Kumar, Vinay, Vasu, P., Patel, K. M., Atrey, P. K., Joisa, Y. Shankara, Rao, C. V. S., Tanna, R. L., Raju, D., Chattopadhyay, P. K., Jha, R., Gupta, C. N., Bhatt, S. B., Saxena, Y. C.
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Zdroj: Nuclear Fusion; Feb2013, Vol. 53 Issue 2, p1-8, 8p
Abstrakt: Intense visible lines from Be-like oxygen impurity are routinely observed in the Aditya tokamak. The spatial profile of brightness of a Be-like oxygen spectral line (2p3p 3D3-2p3d 3F4) at 650.024 nm is used to investigate oxygen impurity transport in typical discharges of the Aditya tokamak. A 1.0m multi-track spectrometer (Czerny- Turner) capable of simultaneous measurements from eight lines of sight is used to obtain the radial profile of brightness of O4+ spectral emission. The emissivity profile of O4+ spectral emission is obtained from the spatial profile of brightness using an Abel-like matrix inversion. The oxygen transport coefficients are determined by reproducing the experimentally measured emissivity profiles of O4+, using a one-dimensional empirical impurity transport code, STRAHL. Much higher values of the diffusion coefficient compared with the neo-classical values are observed in both the high magnetic field edge region (Dmax inboard ~ 30m2 s-1) and the low magnetic field edge region (Dmax outboard ~ 45m2 s-1) of typical Aditya ohmic plasmas, which seems to be due to fluctuation-induced transport. The diffusion coefficient at the limiter radius in the low-field (outboard) region is typically ~ twice as high as that at the limiter radius in the high-field (inboard) region. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index