liquid wall (litium)

8/7/2019 Liquid Wall (litium)

1/16

Brief Remarks on

Status and ProgressFusion Technology/Chamber Techn

Chamber TechnologyAll Technical Disciplines Related to Components Surround

-First Wall/Divertor/Blanket/Vacuum Vessel/etc.

-Presented at the Fusion Power Associates Annual Meeting, San Diego, July 17, 2000

-Presented by M. Abdou with input from R. Mattas, C. Wong, A. Ying, N. Morley, and S.


2/16

The Fusion Technology Community is Workin

Partnership with the Physics Community to Mak

the Challenging Area of Chamber Techn

New Initiatives (motivated by the US Restructured Program an

ALPS: Advanced Limiter-Divertor Concepts

APEX: Advanced Chamber Technology Concepts

Emphasis of the Initiatives1.Innovation

-To improve attractiveness and lower the cost and time of R&D

2.Science- Understanding and advancing Engineering Sciences prerequisite f

- Outreach to scientific community outside fusion

3.Partnership- Among different areas within technology

- Between the Physics and Technology Communities


3/16

Chamber Technology Research is Ex

Innovative Concepts for

1. Solid Walls

2. Liquid Walls

Goals to Calibrate Progress

1. High Power Density Capability

2. High Power Conversion Efficiency

3. High Availability

4. Simpler Technological and Material Constrai


4/16

EVOLVE: Example of Innovative

Solid Wall Concept

Cooling: Vaporization of Lithium at ~1200&

Structure: High-Temperature Refractory (W-5Re)

Attractiveness: High Efficiency (58%), low pressure/low stress,

low flow rate/no insulators

Key Issues:

1) Tungsten fabrication and radiation effects2) Modelling of 2-phase flow with MHD3) Afterheat4) Failure rate?


5/16

The Joint Physics-Technology, APE

Effort is Making Progress i

Exploring Liquid Walls

Key Scientific Issues and Current Effort

1.Effects of LWs on Core Plasma- Bulk Plasma-Liquid Interactions Modeling (PPPL

2.Edge Plasma-liquid Surface Interactions (Largest E- Modelling (LLNL, ANL, others)- Experiments (CDX-U, DIII-D, PISCES, U. IL)

3.Free Surface Hydrodynamic Control and Heat Tranwithout MHD) in Complex Geometries including P

Inverted Surfaces.- Modelling (UCLA, ANL, PPPL, SBIR)- Experiments (UCLA, PPPL, ORNL, SNL)


6/16

Motivation for Liquid Wall Resea

What may be realized if we can develop good liquid walls

Improvements in Plasma Stability and Confinement(QDEOHKLJK VWDEOHSK\VLFVUHJLPHVLIOLTXLGPHW

High Power Density Capability

Increased Potential for Disruption Survivability

Reduced Volume of Radioactive Waste

Reduced Radiation Damage in Structural Materials-Makes difficult structural materials more problems t

Potential for Higher Availability-Increased lifetime and reduced failure rates

-Faster maintenance


7/16

)ORZLQJ/0:DOOVPD\

,PSURYH3ODVPD6WDELOLW\DQG&RQILQ

Several possible mechanisms identified at Snowmass

Presence of conductor close to plasma boundary (Kotschenreuthe

considered 4 cm lithium with a SOL 20% of minor radiusPlasma Elongation > 3 possible with > 20%

Ballooning modes stabilized

VDE growth rates reduced, stabilized with existing technology

Size of plasma devices and power plants can be substantially redu

High Poloidal Flow Velocity (Kotschenreuther)

LM transit time < resistive wall time, about s, poloidal flux doe

Hollow current profiles possible with large bootstrap fraction (redpower) and EB shearing rates (transport barriers)

Hydrogen Gettering at Plasma Edge (Zakharov)Low edge density gives flatter temperature profiles, reduces anom

transport

Flattened or hollow current density reduces ballooning modes and


8/16

Plasma-Liquid Surface Interactions Athe Core Plasma and the Liquid

- Multi-faceted plasma-edge modelling is in progress- Experiments have started (in PISCES, DIII-D and CD

Liquid lithiu

Processes modeled for impurity shielding of core


9/16


10/16

-

At 1 MW/m2 heat flux, lith(~200 C) in seconds.

Once melted, JxB forces dand type-I ELMs displaced

was removed.

Lithium was measured in displacement despite of th

area fraction of the DIII-D

Contaminated lithium withand was not displaced.

Significant neutral lithiumcharge exchange neutrals w

in the private region.

Further details will be obtadata analysis, the 4

thdedic

detailed modeling.

DiMES has exposed three lithium samples at the DIII-D lo

to locked mode and type-I ELMs events

Li I light from DiMES

during locked mode (t ~ 16 ms)

1.3 R(m) 1.4 1.5

ROSP

J

graphite

Melt layer movementof Lithium

SS

backplate


11/16

NSTX Provides an Excellent Opportunitythe Physics and Technology Benefits an

Liquid Walls

Example of one of theoptions being explored:

- Flowing Liquid Walls on

Center Stack and OB Divertor


12/16

Litindo

in

Film thickness varies as flowing lithiumproceeds center stack downstream as a

function of velocity

0.00 0.40 0.80 1.20 1.60 2.00DISTANCE,M

0.004

0.006

0.008

0.010

0.012

FILMTHICKNESS,M

Uo=2m/s

10m/s

4m/s

6m/s

8m/s

MHD draginsignificant

0.00

0.00

40.00

80.00

120.00

SUR

FACETEMPERATURE,K

Results of MHD and Heat Transfer Calcu

Stack Lithium Film(The effect of the poloidal fieldet been taken into account)

Flow damping occurs as a result of the Mfield.

However, during normal operation, lithiureasonable surface temperatures along

-1.5

-1

-0.5

0

0.5

-0.03

-0.02

-0.01

0

0.01

0.02

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

Center stack poloidal coordiante (m)

P

NSTX Center Stack Magnetic Field

Characteristics

-0.5

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5

Projected nstx_center stack_heat fluxrofile (total power = 10 MW)

Height Above Midplane[m]

ANSYS Model surface heatflux

Flowing Lithium Surface TempAcceptable along the NSTX Cewith an Inlet Velocit of 2 m/s


13/16

Modeling of Free-Surface MHD Fluid F

A powerful code is under development at UCLA (in collaboration with

professors) to predict free-surface fluid flow behaviour with MHD effects The code has been applied to flowing liquids in NSTX

Key Results: Applied currents in LMs are very useful in:1.restraining LM against back wall to: a) overcome centripital instabilitie

wall separation;

2.accelerating fluid in divertor region to allow higher heat removal capinventory

Flow sketch (left) and the contour lines of the

induced magnetic field in the wall+liquidregion (right)

Flow development in

field with and witho

Br=0.02 T. Bz=1.0-0

1 - j=0; 2 - j=4 kA/

3 - j=8 kA/m2; 4 - j

+

-

Bz(x)

By(x)

0

1

2

3

4

5

6

7

8

9

10

X/ho

-1 0 1

Y / h

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

Wall Liquid

0 2

0.7

0.8

0.9

1.0

1.1

Thickness/InitialThickness


14/16

1RYHO&RQFHSWWR$FKLHYH7ZR6WUHDP/ A h v t y h r s h p v t u r y h h v u y r r

r q p r h v h v

6ORZO\PRYLQJOD\HUEHKLQGLWDWKLJKWHPSHUDW

HIILFLHQF\

Y

X

g

R

0 1 2 3 4

streamwise coordinate, m

0.00

0.40

0.80

thicknessoftheflow,m

MHD drag slows downsubmerged walls

Free surface layer can ahigh velocity

UCLA Data


15/16

Chamber Technology

5 Year Goals

Liquid Walls (LWs)

1.Develop a more fundamental understanding of freeflow and plasma-liquid interactions

2.Operate flowing LWs in an experimental physics NSTX)

3.Initiate construction of an Integrated Thermofluid Facility for MFE/IFE

4.Understand advantages & implications of LWs in

Solid Walls

5.Advance novel concepts that can extend the capabiattractiveness of solid walls

6.Contribute to international effort on key feasibilityUS has unique expertise


16/16

liquid wall (litium)

Documents