# Presentation: 076634

## 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*
*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

**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

**LIMIT --- **Top view

- 50 cm diameter

## LIMIT -- LIquid Metal Illinois Toroidal test facility

**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

## 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 

- 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 ****down****, J=200 A, B raised to 1000 Gauss**

## J X B up, J=200 A, B raised to 1000 Gauss

**J X B ****up****, J=200 A, B raised to 1000 Gauss**

## Force Calculation

## 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 down center post, J X B radially inward**
-                                            Flow is thinned and boring

## Flow down center post, J X B radially outward

**Flow down center post, J X B radially outward**
-                                            Flow is bunched and explosive

## Side view of J X B force radially outward

**Side view of J X B force radially outward**

## Ejected Material !

## Close up of ejected gallium from central column

**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