In:
Nuclear Fusion, IOP Publishing, Vol. 49, No. 10 ( 2009-10-01), p. 104018-
Abstract:
This paper presents the latest results on confinement studies in the TJ-II stellarator. The inherently strong plasma–wall interaction of TJ-II has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z , Li was chosen because there exists a reactor-oriented interest in this element, thus giving special relevance to the investigation of its properties. The Li-coating has led to important changes in plasma performance. Particularly, the effective density limit in NBI plasmas has been extended reaching central values of 8 × 10 19 m −3 and T e ≈ 250–300 eV, with peaked density, rather flat T e profiles and higher ion temperatures. Due to the achieved density control, a second type of transition has been added to the low density ones previously observed in ECRH plasmas: higher density transitions characterized by the fall in Hα emission, the onset of steep density gradient and the reduction in the turbulence; which are characteristics of transition to the H mode. Confinement studies in ECH plasmas indicate that lowest order magnetic resonances, even in a low shear environment, locally reduce the effective electron heat diffusivities, while Alfven eigenmodes destabilized in NBI plasmas can influence fast ion confinement.
Type of Medium:
Online Resource
ISSN:
0029-5515
,
1741-4326
DOI:
10.1088/0029-5515/49/10/104018
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
2009
detail.hit.zdb_id:
2037980-8
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