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L I M I T Liquid Metal Illinois Toroidal Test Facility Toroidally Symmetric Liquid Metal J X B Experiments. David N. Ruzic , J. Norman, J.P. Allain, M. Boaz, and N. Li Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign - PowerPoint PPT Presentation
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L I M I TLiquid Metal Illinois Toroidal Test
Facility
Toroidally Symmetric Liquid Metal J X B ExperimentsDavid N. Ruzic, J. Norman,
J.P. Allain, M. Boaz, and N. Li
Department of Nuclear, Plasma and Radiological Engineering, University of Illinois
at Urbana-Champaign
APS / DPP October 26, 2000
Outline
Motivation Experiment Pool Experiments Flow Experiments Analysis Future Work Acknowledgments
Motivation
Flowing liquid metal walls can… withstand high heat fluxes rapidly remove heat withstand disruptions reduce impurity influx introduce new operating regimes
Will they work as we expect? Build a device and test the LIMITs
LIMIT -- LIquid Metal Illinois Toroidal test facility
40 Coils
Pyrex reservoir
Ga reservoir
Pyrex center column
SS support structure
40
cm
height
LIMIT --- Top view
50 cm diameter
LIMIT -- LIquid Metal Illinois Toroidal test facility
LIMIT Characteristics
40 coils of 12 Gage wire. R=0.13 Ohms 27 V creates 200 Amps and produces
1000 Gauss at outside radius of center column
5 kW of heat limits duration of experiments
200 A available to pass through liquid metal Resistance of Gallium pool plus contact resistance is 0.015 Ohms.
Magnetic Field at 190 Amps
B Field
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9 10r(cm)
B(G
)
Electrodes
Copper tape Striped and flattened magnet wire
leads Two concentric circles at bottom of
pool to produce a uniform radial current
Current density will decease as R increases, but pool depth will decrease too near edge.
LIMIT --- with electrodes and pool of gallium
Power Supplies Courtesy of
PPPL and INTEL
Tokamak First Wall :self propelled metal concept
RB
1
externally supplied current
may cause metal to flow up outboard
wall
J X B up, J=200 A, B raised to 1000 Gauss
J X B down, J=200 A, B raised to 1000 Gauss
J X B down, J=200 A, B raised to 1000 Gauss
J X B up, J=200 A, B raised to 1000 Gauss
Force Calculation
0
2
4
6
8
10
12
0 1 2 3 4 5 6 7 8 9 10
r(cm)
B(*100 G)
J(A/cm^3)
F(*10^3 N/m^3)
How Big is this Force ?
On inner most 5 mm Force of Gravity = 0.3 N J X B Force = 0.09 N 30%
On inner most 1 mm Force of Gravity = 0.05 N J X B Force = 0.02 N 40%
Flow down the central column
One electrode near top One electrode near bottom Flow Ga down center column Current path created when Ga
reaches bottom J X B can be radially in or out
Electrodes after Ga wetting
Flow down center post, J X B radially inward
Flow is thinned and boring
Flow down center post, J X B radially outward Flow is bunched and explosive
Side view of J X B force radially outward
Ejected Material !
Close up of ejected gallium from central column
Analysis
200 A flows through a small cross section
Force of gravity downward = 0.0026 N
Force outward = 0.325 N
125 times gravity Ballistic droplets of Ga result and
impinge on far wall.
Conclusions Surface instabilities still arise in toroidally
symmetric configuration Magnetic propulsion not observed Expansion against free surface boundary is
seen Center stack flowing liquid metal can be
severely thinned Care must be exercised in center stack eddy
current formation to avoid injecting liquid metal into a plasma
Future Work
More experiments More galium to wet entire center
stack Secondary current configurations Comparison to theory Investigation of ripples
Acknowledgments
PPPL for equipment and funding DOE, APEX program Undergraduates:
Collen Marron-Beebe Hussain Nomanbhai Shadi Beidas