Transcript Внутренний слайд

142190, Troitsk
Moscow region,
Russia
EXAMINATION OF THE VESSEL CONDITION OF Т11-M
TOKAMAK AFTER TWO-YEAR OPERATION WITH LITHIUM
LIMITER
O.I. Buzhinskij, V.A. Barsuk, V.G. Otroshchenko
Prepared by
Prof. Oleg Buzhinskij
Head of Boundary Physics
Federal State Unitary Enterprise State Scientific Center
Troitsk, Institute for Innovation and Fusion Researches,
142190, Troitsk Moscow reg., Russia
[email protected]
142190, Troitsk
Moscow region,
Russia
R – 0.7m
a – 0.25m
Bт - 1Т
Ip - 90kA
Poh~100kVt
∆t ~ 0.1-0.2 s
Problem of a choice of constructional
materials for protective shields , limiters,
divertor plates of modern tokamaks,
including ITER, remains to present day open.
As the alternative decision of this problem,
application in a tokamak liquid metal as the
renewable coating is proposed. On the
tokamak Т11-M within two years tests of the
lithium limiter on the basis of capillary porous structure have been carried out.
Experiments were carried out in conditions of
He- and Н- plasma discharges at RF-heating.
VISUAL EXAMINATION OF THE T-11M VESSEL CONDITION
Visual inspection of the vacuum chamber and ports surface has shown
availability of appreciable amount of a light grey color substance,
covering by a loose layer the significant surface areas of chamber and
ports wall, especially near to the lithium limiter location, and also a
usual metal incrustation with temper colors through of various thermal
loadings on the vessel material. The surface of molybdenum chamber
wall had numerous damages as craters in depth from 8 up to 15
microns.
Below, has shown the photos of section placed close to the Li limiter
position.
Vessel section in the
Li limiter position
142190, Troitsk
Moscow region,
Russia
Inner part of vessel section near
the Li limiter position
142190, Troitsk
Moscow region,
Russia
Outer part of vessel section near
the Li limiter position
142190, Troitsk
Moscow region,
Russia
The same T-11M vessel section after
boronization in plasma shots.
142190, Troitsk
Moscow region,
Russia
x 90
The X-ray microanalysis of a deposited matter from the molybdenum first
wall surface near a lithium limiter has shown, that into composition of the given
substance there are Мо in the main and insignificant amount of copper.
X-ray difractometer analysis has shown, that a substance on the Mo first
wall is a mix of phases: basic phase Li2CО3 and Li2МоО4, that approximately is
one third of all substance composition.
142190, Troitsk
Moscow region,
Russia
The X-ray microanalysis of a deposited matter
from the bottom port wall, also located nearby
to a lithium limiter, there are the same
elements and in addition Fe in a small amount.
Because of the tool restrictions of the given
analysis method a detection capability of
lithium traces has missed.
X-ray difractometer analysis has shown in the
substance composition from a port surface as
the main phase it was found LiОН-Н2О, there
is also Li2СО3 phase. However, repeated
analysis of the substance, fullfilled once more
in three weeks has shown, that LiОН-Н2О
phase completely disappears, and Li2СО3
phase is the main phase. Phase state of Мо in
the substance composition from a port clear
was not revealed.
x 1000
x 100
142190, Troitsk
Moscow region,
Russia
x 90
The microphotographies of the molybdenum first wall surface, obtained
on scanning electron microscope in secondary and back-scattered electrons,
and also exposure of the same area in X-rays Mo-La1,2 и K-Ka1,2 have
shown, that surface represents a deposited layer with great number of craters
on separate areas in depth from 8 up to 15 microns. The undamaged surface
includes Мо with a Fe impurity.
142190, Troitsk
Moscow region,
Russia
Let's consider possible mechanisms of a formation of the discovered
compounds. Yet at a stage of the tokamak working operation the lithium
cans to interact with hydrogen of an operating environment at the
temperature about 500С:
2Li + Н2 —> 2LiH
Moreover, the oxygen existing in the discharge vessel at an attainable
underpressure degree on the given facility and the temperature 500С
intensively interacts with the chamber wall molybdenum with formation of a
volatile oxide:
2Мо + ЗО2 —> 2МоО3
In the same conditions there is also an oxidation of lithium:
4Li + О2 —> 2Li2O (at the temperature 200С this process is
very active).
At the temperature 1100С it is probably a direct interaction of oxides
with formation of the lithium molybdate:
Li2O + МоОз —> Li2MoO4 so, for example, are formed the lithium
niobates and tungstates).
Conclusion
142190, Troitsk
Moscow region,
Russia
The analysis of the molybdenum first wall surface after work with a
lithium limiter has shown presence of a Li deposited layer with numerous
local damages as craters in depth from 8 up to 15 microns. The undamaged
surface of the first wall includes Мо with impurities of Fe and also K and Са
in several areas.
Chemical compounds of lithium: Li2CO3, Li2MoO4 и LiOH-H2O have
been identified during the analysis of substance composition and products
of interaction with the plasma, forming on the first wall during plasma shots.
Graphite limiter surface with a boron carbide coating has not shown
any changes.