Li collection experiments on T-11M and T-10 in framework of Li closed loop concept

S.V.Mirnov1, A.G.Alekseev1, A.M.Belov1, N.T.Djigailo1, A.N.Kostina2,

V.B.Lazarev1, I.E.Lyublinski3, V.M.Nesterenko1, A.V.Vertkov3, V.A.Vershkov4.

1 GSC PF TRINITI 142 190 Troitsk Mosc. Reg. Russia.2 NRNU MEPhI, Kashirskoye sh., 31,Moscow, 115409 Russia

3 FSUE “Red Star”, Elektrolitnyj pr. 1A, Moscow, 113 230 Russia4 RSC “Kurchatov Institute” Kurchatov Acad. Sc. 1 Moscow 123 192

Russia

The 2nd International Symposium on Lithium Applications for Fusion Devices April 27-29, 2011

Princeton Plasma Physics LaboratoryPrinceton, NJ, USA

The concept of a steady state tokamak with plasma facing components (PFC) on the basis of the closed loop of liquid lithium circulation

demands the technological decision of three tasks:

lithium injection to the plasma, lithium ions collection before their deposition on the vacuum vessel and

Li returning from collector to the injection zone.

Main subject of paper is the investigations of Li collection by different types limiters, intersected the scrape-of-layer (SOL) of T-10 and T-11M

tokamaks.

For practical solution of this problem in Т-11М and Т-10 tokamak experiments have been applied Li-, C-rail limiters and special ring SS R-

limiter-collector (T-11M).

The quantitative analysis of the sample-witnesses located on Т-11М limiters showed, that nearby 60±20% of the lithium injected during plasma

operating of Т-11М had been collected by limiters. It confirms a potential opportunity of collection of the main part of the

injected lithium by the limiters-collectors located in the SOL area of steady state tokamak.

T-11M and T-10 tokamaks

T-11M: R/a=0.7/0.25m, Jp=50-100kA,

BT =1.2T, Δt=0.2s

T-10: R/a=1.5/0.35m,

Jp=200-300kA, BT=2.5T, Δt=1s

T-10 experiment

T-10 lithiation

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Li closed loop concept

Dust explosion in LHD (1641sec)

Li CPS emitter

T-11M experiment

Scheme of new “W-Li limiter” of T-11M with water cooling/heating in steady state regime

Li tank

W - felt

Water cooling

200oC

TOKAMAK PLASMA

W Li limiter test on W Li limiter test on Т-11МТ-11М29.03.2011 12:44:4129.03.2011 12:44:41

Video registrationVideo registration

Parameters of video registration:

640 × 480 points

Frequency -250Hz, exposition 4ms

in light LiI (670,8 nm);

ne~1-2 1019m-3

Jp=50kA t~160ms

Li limiter in T-11M chamber

Field of

view

Li collection by lateral sides of W-Li CPS limiter

The quantitative analysis of the sample-witnesses located on Т-

11М limiters showed, that 200+/- 30 mg lithium, which is nearby 60±20% of the lithium

injected during plasma operating (~1000 shots) of Т-11М had been collected by lateral sides (e+i) of

single W-Li CPS rail limiter.

Li distribution in SOL of rail limiters

a- exponential decrease with dept ~6cm, b-second decrease with dept ~1 cm – as result of Li collection by C-ring limiter

T-11M experiment with second ring limiter (R limiter)

as Li collector

The quantitative analysis showed:

1. that a total amount of Li collected by lateral sides (e+i) of W-Li CPS rail limiter during next ~1000 shots decreases roughly two times, up to 110 mg

2. the R-limiter collected ~ 100 mg, that is in sum roughly 200mg again, which is again nearby 60±20% of the lithium injected during plasma operating.

That means the R-limiter can be used in future as high effective Li collector

The next steps

Plasma-rail limiter

interaction

T-11MCold expositioninitial Tlim<100C

Hot expositioninitial Tlim>200C

“Badminton model”

Several identical Li-limiters in tokamak chamber can be used as emitters and collectors in turn by

periodical change their relative mechanical position

in SOL or by use of local magnetic perturbations

KRAMER G.J., BUDNY B.V., GORELENKOVA M. et al. “Fast ion Effects during Test Blanket Module Simulation Experiments in DIII-D” APS 52nd Annual Meeting DPP

Nov. 2010 55 № 15 XO4 4 p375.

Two kinds of lithiation procedure were successfully tested in T-11M and T-10 tokamaks: the conventional “passive” method with preliminary coating of some part of tokamak PFC by lithium and “in-situ” coating by the permanent use

of lithium rail limiter during tokamak discharge (T-11M).

The last method seems as useful for future tokamak steady state operation.

Two kinds of lithium collection were tested in T-11M experiments: by lateral surfaces of rail lithium limiter and by

circular R-limiter introduced in shadow of rail limiter

Conclusions 1

Conclusions 2

The T-11M experiments with Li collection by lateral sides of rail limiter with W-wings showed that a significant part (60+/-

20%) of Li, injected to the plasma and diffused than out plasma column, can be collected by this way.

The T-11M experiments with a circular Li R-collector, inserted into plasma SOL in the shadow of main tokamak rail limiter,

showed that this kind of collector can accumulate the significant part (up to 50%) of Li diffused out plasma column.

The both kinds of collectors can be used for closing of lithium loop circulation in future.

Conclusions 3

Lithium emitter-collector concept with several identical Li-limiters, which can change their

emitter and collector role in turn ( “badminton model”) can be suggested for use in SOL of ITER-

like tokamak-reactor.

T-10 experiments showed that migration of Li deposit around the torus from lithiation (gettering) region was low. Li films was absent in the vacuum

port of T-10 opposite to the lithiation port.

Thank you for attention

J.Bohdansky and J.Roth Temperature dependence of sputtering behavior of Cu-Li alloys

Nucl. Instr.and Methods in Physics Research B23 (1987) 518