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Vapor Condensation Study Vapor Condensation Study for HIF Liquid Chambersfor HIF Liquid Chambers
byby
Patrick CalderoniPatrick CalderoniUCLA – Fusion Engineering SciencesUCLA – Fusion Engineering Sciences
1515thth International Symposium on Heavy Ion Inertial Fusion International Symposium on Heavy Ion Inertial FusionPrinceton Plasma Physics LaboratoryPrinceton Plasma Physics Laboratory
Princeton, NJ, June 7-11, 2004Princeton, NJ, June 7-11, 2004
Experimental research work major accomplishmentsExperimental research work major accomplishments
Developed an innovative and inexpensive scheme to generate flibe Developed an innovative and inexpensive scheme to generate flibe vapor in conditions relevant to fusion technology design studies vapor in conditions relevant to fusion technology design studies involving a liquid protection scheme (HIF, IFE, Z-pinch)involving a liquid protection scheme (HIF, IFE, Z-pinch)
Measured flibe vapor clearing rates suggest that high Measured flibe vapor clearing rates suggest that high repetition rates in HIF power plants are feasible provided repetition rates in HIF power plants are feasible provided that high purity of the molten salt is ensuredthat high purity of the molten salt is ensured
Found that for flow conditions characterized by high kinetic energy Found that for flow conditions characterized by high kinetic energy flibe vapor condensation is partially inhibited on metal surfaces flibe vapor condensation is partially inhibited on metal surfaces perpendicular to the main component of the vapor velocityperpendicular to the main component of the vapor velocity
HYLIFE-II parameters relevant to vapor condensation studies (Moir, 1994)HYLIFE-II parameters relevant to vapor condensation studies (Moir, 1994)
Total mass generated from x-ray absorptionTotal mass generated from x-ray absorptionon liquid surfaces: 14 kgon liquid surfaces: 14 kg
Total volume for vapor expansion: 280 mTotal volume for vapor expansion: 280 m33
Initial n: Initial n: 0.9x100.9x101818 #/cm #/cm33 (0.5x10(0.5x101818 #/cm #/cm33))Recovered n:Recovered n: 3x103x101313 #/cm #/cm33 (2x10 (2x101515 #/cm #/cm33))
Energy from explosion coupled with x-Energy from explosion coupled with x-ray and debris: 110 MJray and debris: 110 MJ
Energy density: Energy density: 7.85 kJ/g7.85 kJ/g (7.5 kJ/g) (7.5 kJ/g)
Structural surface for condensation: 40 mStructural surface for condensation: 40 m22
Surface from droplet injection: 1060 mSurface from droplet injection: 1060 m22
Ratio of surface area per unit mass of Ratio of surface area per unit mass of generated vapor: generated vapor: 785 cm785 cm22/g/g (4300 cm2/g (4300 cm2/g for LiF andfor LiF and 10205 cm 10205 cm22/g /g for flibefor flibe))
Droplet spray injection design:Droplet spray injection design:T = 843 KT = 843 KSpray flow rate = 2.4x103 kg/s Spray flow rate = 2.4x103 kg/s (1.6% of main flow rate)(1.6% of main flow rate)
Experimental approach: Experimental approach: staged design of vapor generation facilitystaged design of vapor generation facility
Characterization of superheated vapor source in comparison Characterization of superheated vapor source in comparison to other experiments using electro-thermal sourcesto other experiments using electro-thermal sources
Diagnostic developmentDiagnostic development
Limited availability, cost and toxicity of materials: Limited availability, cost and toxicity of materials: demonstrate efficiency, repeatability and reliability before using flibedemonstrate efficiency, repeatability and reliability before using flibe
Reduce residual non-condensable gases Reduce residual non-condensable gases
Stage 1: Lexan withStage 1: Lexan withArgon background (1 Argon background (1 Torr) Torr)
time: 0time: 0
time: 820 time: 820 s s
time: 1640 time: 1640 s s
Typical vapor parameters in the source : Typical vapor parameters in the source :
n = 10n = 101919 - 10 - 102020 # / cm # / cm33
T = 1-3 eVT = 1-3 eV
Argon background is ionized (10-100 ns) Argon background is ionized (10-100 ns) forming initial plasma column forming initial plasma column
Injected electrical power radiated to Injected electrical power radiated to surface, ablates material of interestsurface, ablates material of interest
Pressure gradient drives injection, Pressure gradient drives injection, ablation balances axial mass loss ablation balances axial mass loss
Energy stored in cap banks maintains Energy stored in cap banks maintains plasma at 1-3 eV for 100 micros plasma at 1-3 eV for 100 micros
expansion chamberexpansion chamber
volume: 4000 cmvolume: 4000 cm33
surface area: 1720 cmsurface area: 1720 cm22
Stage 2: Teflon and LiF in vacuum chamberStage 2: Teflon and LiF in vacuum chamber
time of flight view portstime of flight view ports
vaporvaporsourcesource
current incurrent in
current outcurrent out
Cathode: ¼’’ D Cathode: ¼’’ D 10’’ long W rod10’’ long W rod
Flibe Flibe liquid liquid pool: pool: 1.6 cm1.6 cm33 volume volume
Anode: Nickel crucible Anode: Nickel crucible with embedded high with embedded high density cartridge heaterdensity cartridge heater
Stage 3: Flibe Stage 3: Flibe vapor generationvapor generation
SS witness plates for SS witness plates for SEM and EDX analysisSEM and EDX analysis
Pressure sensor, water Pressure sensor, water cooled (Tmax = 260 C)cooled (Tmax = 260 C)
Total length: 34 cmTotal length: 34 cm
Expansion volume: 400 cmExpansion volume: 400 cm33
Surface area: 420 cmSurface area: 420 cm22
Insulation: high-vacuum Insulation: high-vacuum ceramic breaksceramic breaks
High-speed camera frames sequence from flibe discharge High-speed camera frames sequence from flibe discharge
100 100 ss
120 120 ss
140 140 ss
160 160 ss
180 180 ss
200 200 ss
220 220 ss
240 240 ss
260 260 ss
280 280 ss
300 300 ss
320 320 ss
Pressure data and residual gas composition: flibePressure data and residual gas composition: flibe
tt300300 = 4.27 ms (4.22 ms at 1.44 kJ) = 4.27 ms (4.22 ms at 1.44 kJ)
tt500500 = 6.58 ms = 6.58 ms
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96-81.0x10
-71.3x10
-72.5x10
-73.7x10
-74.9x10
-76.0x10
-77.2x10
-78.4x10
-79.6x10
-61.1x10
-61.2x10
Atomic Mass Units
TorrRGA Analog Scan Oct 14, 2003 05:03:48 PM
HH22
28,16 amu: 28,16 amu: hydrocarbonshydrocarbons
condensation is condensation is completed in 30 ms: completed in 30 ms: no residual BeFno residual BeF22
traces at 47 amutraces at 47 amu
44 amu:44 amu:COCO22
300 C300 C
500 C500 C
p(T) p(T) → n(T) → n(T) assumes assumes thermodynamic thermodynamic equilibrium with a equilibrium with a liquid surfaceliquid surface
Comparison with HYLIFE-II chamber clearing modelsComparison with HYLIFE-II chamber clearing models
n = nn = n00 x e x e-t/T-t/T
nn00 = 0.9x10 = 0.9x101818 #/cm #/cm33
nnendend = 3x10 = 3x101313 #/cm #/cm33
Clearing period for Clearing period for HYLIFE-II = 68 msHYLIFE-II = 68 ms
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49-8-3.2x10
-87.8x10
-71.9x10
-73.0x10
-74.1x10
-75.2x10
-76.3x10
-77.4x10
-78.5x10
-79.6x10
-61.1x10
Torr RGA Analog Scan
00:00 00:06 00:12 00:18 00:24 00:30 00:36 00:42 00:48 00:540
-78.0x10
-61.6x10
-62.4x10
-63.2x10
-64.0x10
-64.8x10
-65.6x10
-66.4x10
-67.2x10
-68.0x10Torr RGA P vs T Scan
H2
BeF2
LiF
CO2
Measured composition of flibe vapors Measured composition of flibe vapors in equilibrium with a liquid surface in equilibrium with a liquid surface
Heating sequence (linear) from 460 C to 700 C (about 30 min)
at 460 C
HH22
hydrocarbonshydrocarbonsCOCO22
BeFBeF22
Additional data: post-analysis of side collecting platesAdditional data: post-analysis of side collecting plates
Collecting plates parallel to the radial direction
300 C300 C 460 C460 C
Film forms during first Film forms during first expansion phase (100 expansion phase (100 s) when vapor velocity s) when vapor velocity is highly directionalis highly directional
Drops condense in the Drops condense in the chamber volume after chamber volume after the velocity has the velocity has become uniform and become uniform and deposit on the liquid deposit on the liquid film without mergingfilm without merging
At low T film is thinner At low T film is thinner and breaks due to quick and breaks due to quick cooling and cooling and solidificationsolidification
Surfaces are gold Surfaces are gold plated for SEM analysisplated for SEM analysis
Additional data: post-analysis of front collecting platesAdditional data: post-analysis of front collecting plates
Collecting plates perpendicular to the radial direction
300 C300 C 460 C460 CFilm condensation Film condensation is inhibited at 300 Cis inhibited at 300 C
At 460 C thin film At 460 C thin film starts at fixed r from starts at fixed r from plate side center plate side center (flow stagnation point)(flow stagnation point)
EDX analysis confirms EDX analysis confirms qualitative resultsqualitative results
Additional data: post-analysis of collecting platesAdditional data: post-analysis of collecting plates
Further evidence Further evidence of volumetric of volumetric condensationcondensation
Evidence of liquid Evidence of liquid displacement by the displacement by the pressure front pressure front generated during the generated during the discharge: large liquid discharge: large liquid drops are entrained in drops are entrained in the flow and deposit the flow and deposit around the crucible and around the crucible and the collecting platesthe collecting plates
300 C300 C 300 C300 C
460 C460 CLarge drop is flibeLarge drop is flibe
sidesideplateplate
frontfrontplateplate
ConclusionConclusion
Condensation rates of flibe vapor in conditions relevant to IFE power plant studies Condensation rates of flibe vapor in conditions relevant to IFE power plant studies have been measured experimentally - Vapor density decays exponentially with a have been measured experimentally - Vapor density decays exponentially with a time constant of 6.58 mstime constant of 6.58 ms in the range between 5x10 in the range between 5x101717 cm cm-3-3 and 2x10 and 2x101515 cm cm-3-3
Extending to Extending to HYLIFE-IIHYLIFE-II expected density cycles the expected density cycles the vapor clearing ratevapor clearing rate is is 68 ms68 ms, compatible with the desired 6 Hz repetition rate, compatible with the desired 6 Hz repetition rate
Data suggest that for flow conditions characterized by high kinetic Data suggest that for flow conditions characterized by high kinetic energy flibe vapor condensation is partially inhibited on surfaces energy flibe vapor condensation is partially inhibited on surfaces normal to the main component of the vapor velocity normal to the main component of the vapor velocity
Control of the impuritiesControl of the impurities dissolved in the molten salt is a fundamental issue for dissolved in the molten salt is a fundamental issue for applications that require recovery of vacuum conditions in the 10applications that require recovery of vacuum conditions in the 101313 #/cm #/cm33 range range
Discharge parametersDischarge parameters
Teflon I and V for 10 and 5 disk configurationTeflon I and V for 10 and 5 disk configuration
LiF I for different energy experimentsLiF I for different energy experiments
I for flibe experimentsI for flibe experiments
HYLIFE-II conceptHYLIFE-II concept
Liquid protection for Inertial Fusion Energy power plant chambers
Thick liquid “pockets” or thin liquid layers shield chamber structures: Thick liquid “pockets” or thin liquid layers shield chamber structures: fluid mechanics questions replace materials questionsfluid mechanics questions replace materials questions
Neutron damages and activation of flowing liquid accumulate only in the short Neutron damages and activation of flowing liquid accumulate only in the short residence period - no blanket replacement required, increases availabilityresidence period - no blanket replacement required, increases availability
The molten salt flibe:The molten salt flibe:
High Tritium Breeding Ratio High Tritium Breeding Ratio
Low electrical conductivity Low electrical conductivity
High neutronic thickness High neutronic thickness
Chemical, radioactive Chemical, radioactive and thermal stability and thermal stability
Limited material availabilityLimited material availability
Uncertain composition and purity level of available material Uncertain composition and purity level of available material
Beryllium safety hazardBeryllium safety hazard
Lack of data on physical and chemical properties Lack of data on physical and chemical properties
For fusion system design:For fusion system design:
For small scale experiments:For small scale experiments:
Flibe composition is a compromise Flibe composition is a compromise between melting temperature (structural between melting temperature (structural costs) and viscosity (pumping cost)costs) and viscosity (pumping cost)
2 LiF + 1 BeF2 2 LiF + 1 BeF2 in molesin moles
0 1000 2000 3000 4000 5000 6000500 1500 2500 3500 4500 5500 6500
Temperature [C]
1.00E -005
1.00E -004
1.00E -003
1.00E -002
1.00E -001
1.00E +000
1.00E +001
1.00E +002
1.00E +003
1.00E +004
1.00E +005
1.00E +006
1.00E +007
1.00E +008
1.00E +009
1.00E +010
Va
po
r p
res
su
re [
Pa
]
Flibevapor
pressure
In equilibrium with the liquid In equilibrium with the liquid at 600 C, flibe vapor pressure at 600 C, flibe vapor pressure is about 1 mTorr, is about 1 mTorr, corresponding to a density of corresponding to a density of 1.2 101.2 101313 cm cm-3-3
Flibe low vapor pressure is Flibe low vapor pressure is a key property for efficient a key property for efficient driver coupling with the driver coupling with the fusion target at high fusion target at high repetition ratesrepetition rates
Reference dataReference data for flibe for flibe vapors are based on the vapors are based on the assumption of assumption of thermodynamic equilibrium at thermodynamic equilibrium at the liquid interface the liquid interface and ideal and ideal gas equationgas equation
Weight loss measurements Weight loss measurements
18 experimental runs 18 experimental runs with 10 Teflon disks with 10 Teflon disks as sleeve materialas sleeve material
1 with 5 disks1 with 5 disks
5.76 kJ5.76 kJ
2.54 kJ2.54 kJ
Volume ratio Volume ratio between source between source and chamber: 1:25and chamber: 1:25
Evidence of C soot Evidence of C soot deposition on source deposition on source componentcomponent
Pressure data: Lexan and TeflonPressure data: Lexan and TeflonDynamic sensor Dynamic sensor mounted at mounted at center of back center of back plate (high noise plate (high noise from vibration)from vibration)
Teflon = CFTeflon = CF22 chain chain
Residual gases (20-70 Torr):Residual gases (20-70 Torr):28 amu (C28 amu (C22HH22 - C - C22HH44 - C - C22HH66))
69 amu (CF69 amu (CF44))
20 amu (HF)20 amu (HF)
about 5 times decayabout 5 times decay
Jet velocity optical Jet velocity optical measurement systemmeasurement system
Diode axis separation:7.62 cmPeak time delay:6 microsecondsEstimated initial vapor velocity:10110 m/s
Jet velocity optical measurement system
Sensor closer to center of chamber sees a second peak in the light, about 2ms after triggering
Peak due to first reflection of the vapor jet at the chamber bottom
Vapor cools and expands in the chamber, emitting front does not reach the upper sensor
Estimated average velocity of vapor in the chamber after first reflection:320 m/s - 4 kV210 m/s - 3 kV
Flibe experiments results
Exponential decay fits data points good
Decay time constant t1 is a measure of the condensation rate
t1 = 4.22 ms
Flibe experiments results
Exponential decay fits data points good
Decay time constant t1 is independent from initial particle
density
t1 = 4.27 ms
Additional data: emission spectroscopyAdditional data: emission spectroscopy
Strong lines from neutral and first ionization state of both lithium and beryllium atoms are present in the spectrum
Be vapors diagnostic development:
• measure at different times the ratio of line intensity of Li I and Li II transitions
•steady-state emission calibration with langmuir probe will associate line ratio with thermodynamic vapor parameters (pressure and density)