Speaker
Mr
Francisco Tabares
(Spain)
Description
In the present work, three different experiments concerning the specific features of plasma –lithium interactions will be addressed.
First, a solid bar of lithium with biasing and displacement capabilities has been exposed to the plasma edge in TJ-II under lithiated wall conditions. Heating powers up to 0.8 MW (ECRH and NBI) were injected into the plasma, leading to unmitigated power densities at the bar tip up to 30 MW/m2. Edge parameters were characterized by a supersonic He beam diagnostic and Li I, LiII and Hα emissions at the bar and its proximity were recorded.
Secondly, we have performed a search for other characteristic effects of lithium surfaces, other than the well-known low recycling. We recorded the I–V characteristics and Li emission signal of lithium covered metallic electrodes in H and He Glow Discharge plasmas. The plasma parameters and electron energy distribution were obtained from the analysis of a Langmuir probe signal and from the measurement of the 728/706 (singlet to triplet) emission lines of He in the corresponding discharges. At small negative potentials of the electrode, an apparent excess of ion current is driven, which is well correlated with the presence of secondary electron emission from the surface upon suprathermal electron bombardment, but with enhanced yields over the bibliographic values.
Finally, a liquid lithium limiter (LLL) based on the Capillary Porous System (CPS) has been installed and tested in TJ-II [4]. The movable limiter has Langmuir Probes and thermocouples for diagnostic as well as biasing capabilities. Upon exposure to the plasma, the limiter can be fully outgassed under vacuum in order to assess the hydrogen retention characteristics and its dependence on operation temperature.
Country or International Organization of Primary Author
Spain
Primary author
Mr
Francisco Tabares
(Spain)
Co-authors
Dr
Alexey Vertkov
(Red Star Public Corporation)
Ana Belen Martin-Rojo
(Ciemat)
Dr
David Tafalla
(Ciemat)
Dr
Eider Oyarzabal
(Ciemat)
Dr
Enrique Ascasibar
(Ciemat)
Dr
Jose Antonio Ferreira
(2TVSC CERN, CH-1211 Geneva 23, Switzerland)
Dr
Maria Antonia Ochando
(Ciemat)
Dr
Valeri Balakirev
(Red Star Public Corporation)
