November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 1 Thin Liquid Wall Behavior under IFE Cyclic Operation A. R. Raffray 1 , S. I. Abdel-Khalik 2 , D. Haynes 3 , F. Najmabadi 4 , J. P. Sharpe 5 and the ARIES Team 1 Mechanical and Aerospace Engineering Department and Center for Energy Research, University of California, San Diego, EBU-II, Room 460, La Jolla, CA 92093-0417 2 School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0405 3 University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive, Madison, WI 53706-1687 4 Electrical and Computer Engineering Department and Center for Energy Research, University of California, San Diego, EBU-II, Room 460, La Jolla, CA 92093-0417 5 Fusion Safety Program, EROB E-3 MS 3860, INEEL, Idaho Falls, Idaho 83415-3860 15th Topical Meeting on the Technology of Fusion Energy Washington, D.C. November 20, 2002
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November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 1 Thin Liquid Wall Behavior under IFE Cyclic Operation A.
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November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 1
Thin Liquid Wall Behavior under IFE Cyclic Operation
A. R. Raffray1, S. I. Abdel-Khalik2, D. Haynes3, F. Najmabadi4, J. P. Sharpe5 and the ARIES Team
1Mechanical and Aerospace Engineering Department and Center for Energy Research, University of California, San Diego, EBU-II, Room 460, La Jolla, CA 92093-0417
2School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-04053University of Wisconsin, Fusion Technology Institute, 1500 Engineering Drive, Madison, WI 53706-1687
4Electrical and Computer Engineering Department and Center for Energy Research, University of California, San Diego, EBU-II, Room 460, La Jolla, CA 92093-0417
5Fusion Safety Program, EROB E-3 MS 3860, INEEL, Idaho Falls, Idaho 83415-3860
15th Topical Meeting on the Technology of Fusion Energy
Washington, D.C.November 20, 2002
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 2
Outline• IFE chamber operating conditions
• Thin Liquid Wall Configuration– Attractiveness and key issues
• Film Establishment and Coverage – Wetted wall
– Forced film flow
• Film Condensation
• Aerosol formation and behavior – Aerosol source term (including explosive boiling estimate)
– Aerosol formation and transport analysis
– Design windows (including driver and target constraints)
• Concluding Remarks
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 3
IFE Operating Conditions
• Cyclic with repetition rate of ~1-10 Hz • Target injection (direct drive or indirect drive)
• Driver firing (laser or heavy ion beam)
• Microexplosion
• Large fluxes of photons, neutrons, fast ions, debris ions toward the wall
- possible attenuation by chamber gas
Target micro-explosion
Chamber wall
X-rays Fast & debris ions Neutrons
Example of Direct-Drive Target (NRL) (preferred option for coupling with laser driver)
DT Vapor0.3 mg/cc
DT Fuel
CH Foam + DT
1 m CH +300 Å Au
.195 cm
.150 cm
.169 cm
CH foam = 20 mg/cc
Example of Indirect-Drive Target (LLNL/LBLL) (preferred option for coupling with heavy ion beam driver)
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 4
Energy Partitioning and Photon Spectra for Example Direct Drive and Indirect Drive Targets
NRL DirectDrive Target(MJ)
HI IndirectDrive Target(MJ)
X-rays 2.14 (1%) 115 (25%)
Neutrons 109 (71%) 316 (69%)
Gammas 0.005 (0.003%) 0.36 (0.1%)
Burn ProductFast Ions
18.1 (12%) 8.43 (2%)
Debris IonsKinetic Energy
24.9 (16%) 18.1 (4%)
ResidualThermal Energy
0.013 0.57
Total 154 458
Energy Partitions for Example Direct Drive and Indirect Drive Targets
Photon Spectra for Example Direct Drive and Indirect Drive Targets
• Much higher X-ray energy for indirect drive target case (but with softer spectrum)
• Basis for example wetted wall analysis presented here
(More details on target spectra available on ARIES Web site: http://aries.ucsd.edu/ARIES/)
(25%)
(1%)
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 5
IFE Thin Liquid Wall Configuration
Key processes: Thin film dynamics Condensation Aerosol formation and behavior These are assessed here with Pb
and flibe as example fluids
Injection from the back
Condensation
Ablation
Pg
Tg
Film flow
Photons
Ions
In-flight condensation
• Advantages of decoupling functions:– Armor function to accommodate
X-ray and ion threat spectra provided by renewable liquid film for longer lifetime
– Structural and energy recovery functions provided by solid blanket at the back for high efficiency
• Major issues:– Film establishment and coverage
• Film dynamics
• Injection method
• Geometry effects
• Recondensation
– Ablated material and chamber clearing requirements
• Ablation processes
• Film condensation
• Aerosol formation and behavior
• Driver and target requirements
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 6
Film Dynamics
• Two Injection Methods Considered
- Radial injection through a porous first wall ( “wetted wall” design)
- Forced flow of a thin liquid film tangential to a solid first wall (“forced film” design)
• Critical Questions Include:(1) Can a stable liquid film be maintained on the upper section of the chamber?
(2) Can the film be re-established over the entire cavity surface prior to the next target explosion?
(3) Can a minimum film thickness be maintained to prevent dry patch formation and
provide adequate protection during the next target explosion.
• These Questions are Being Addressed through Complementary Modeling and Experimental Investigations- Example results illustrated here
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 7
Example of Wetted Wall Investigation
• Modeling simulation of 3-D evolution of liquid film surface based on:
- Liquid injection velocity through porous wall
- Surface disturbance amplitude, configuration and mode number
- Surface inclination angle
- Liquid properties
- Effect of film evaporation and/or condensation
• Results used to develop “generalized charts,” showing effects of these
variables on:- Frequency of liquid drop formation and
detachment,
- Size of detached droplets
- Minimum film thickness prior to droplet detachment
• Example results for 700 K Pb with initial thickness of 1.0 mm and injection velocity of 1.0 mm/s
• Random initial perturbation with maximum amplitude of 1.0 mm applied beginning of the transient
• In this case, droplet detachment occurs ~0.38 s after initial perturbation
t = 0.38 st = 0.37 s
t = 0.32 s t = 0.35 s
• Poster presented during Tue. afternoon session (1.27)
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 8
Examples of Forced Film Investigation
• Film detachment most likely to occur on downward facing surfaces in upper part of chamber
- Could interfere with beam propagation and/or target injection
• Experimental study to determine film detachment distance as a function of:
- Wetting and non-wetting surfaces
- Initial film thickness (1.0 to 2.0 mm)
- Film injection velocity (1.9 to 11.0 m/s)
- Inclination angle (0º to 45º) • Poster presented during Tue. afternoon session (1.31)
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100 120 140Fr
Film detachment distance vs. Froude number for horizontal downward-facing surfaces
wetting surface
Non-wetting surface
1.5 mm
2.0 mm
1.0 mmFilm thickness:
Flow of 1.5 mm thick film with a 5.0 m/s velocity around 25.4 mm dia., 2.4 mm high cylindrical “port.”
• Experimental study of behavior of thin liquid films flowing around cylindrical obstacles,
typical of beam and target injection ports
- Such obstacles will pose significant challenge to designers
- Efforts underway to examine behavior of thin films flowing past "streamlined" obstacles.
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 9
Film Condensation Rate is Fast
• Characteristic time to clear chamber, tchar, based on condensation rates and Pb inventory for given conditions
• For higher Pvap, tchar is independent of Pvap
- Probably more limited by heat transfer effectiveness
• As Pvap decreases and approaches Psat, tchar increases substantially
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
1x100 1x101 1x102 1x103 1x104 3x104
Vapor Pressure (Pa)
Pb:Film temperature = 1000KFilm Psat = 1.1 Pa
Vapor velocity = 0
Vapor Temp. (K)
1200
10,000
5000
2000
ƒƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ
æ
ææ æ æ æ æ æ æ æ æ
ø
ø ø ø ø ø ø ø ø ø ø
”
” ” ” ” ” ” ” ” ” ”
0
0.02
0.04
0.06
0.08
0.1
0.12
1x100 1x101 1x102 1x103 1x104 1x105 1x106
Vapor pressure (Pa)
ƒ
æ
ø
”
Pb film temperature = 1000KFilm Psat = 1.1 Pa
Vapor velocity = 0Chamber radius = 5 m
Vapor Temp.
10,000 K
5000 K
2000 K
1200 K • Typically, IFE rep rate ~ 1–10
• Time between shots ~ 0.1–1 s
• Pvap prior to next shot ~(1-10)Psat
• Can be controlled by setting Tfilm
• Of more concern is aerosol generation (in-flight condensation) and behavior
Example Analysis of Pb Vapor Film Condensation in a 10-m Diameter Chamber
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 10
Processes Leading to Vapor/Liquid Ejection Following High Energy Deposition Over Short Time Scale
Energy Deposition &
Transient Heat Transport
Induced Thermal- Spikes
Mechanical Response
Phase Transitions
•Stresses and Strains and Hydrodynamic Motion•Fractures and Spall
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 15
Concluding Remarks
• Wetted walls provide possibility of high efficiency and renewable armor
• Key issues are film establishment and chamber conditions prior to next shot
• Experimental and modeling effort under way to provide generalized charts for designing film injection system:- Wetted wall (droplet detachment, minimum film thickness…)
- Forced film flow (film detachment, beam port obstacles...)
• High energy deposition rate of X-rays would lead to explosive boiling- Provide bounding estimates for aerosol source term
• Aerosol modeling analysis indicate substantial # and size of droplets prior to next shot for both Pb and FLiBe- Preliminary estimates of constraints for indirect-drive target and heavy ion driver
- Marginal design window (if any)
• Future effort:- Completing generalized charts on film dynamics
- Better understanding aerosol source term and behavior
- Confirmation of target and driver constraints
November 20, 2002 A. R. Raffray, et al., Thin Liquid Wall Behavior under IFE Cyclic Operation 16
Other ARIES-IFE Related Presentations at 15th TOFE • S. Shin, S. I. Abdel-Khalik, D. Juric and M. Yoda, ”Effects of surface evaporation and
condensation on the dynamics of thin liquid films for the porous wetted wall protection scheme in IFE reactors,” Tue. afternoon poster session, 1.27
• J. K. Anderson, M. Yoda, S. I. Abdel-Khalik and D. L. Sadowski, “Experimental studies of high-speed liquid films on downward-facing surfaces,” Tue. afternoon poster session, 1.31
• M. Zaghloul, D. K. Sze and R. Raffray, “Thermo-physical properties and equilibrium vapor-composition of lithium fluoride-beryllium fluoride (LiF/BeF2) molten salt,” Tue.
afternoon poster session, 1.38
• L. El-Guebaly, P. Wilson, D. Henderson, L. Waganer, R. Raffray and the ARIES Team, “Radiological issues for thin liquid walls of ARIES-IFE study, Tue. afternoon poster session,
1.51
• J. P. Sharpe, B. J. Merrill and D. A. Petti, “Aerosol production in IFE chamber systems,” Thu. Morning oral session
• L. El-Guebaly, P. Wilson, D. Henderson, A. Varuttamaseni and the ARIES Team, “Feasibility of target material recycling as waste management alternative, “ Thu. Morning
oral session
• M. Zaghloul, “Ionization equilibrium and thermodynamic properties of high-temperature FLiBe vapor in wide range of densities,” Wed. afternoon poster session, 2.36