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Wayne R. MeierLawrence Livermore National Lab
Per PetersonUC Berkeley
Introduction to Thick-Liquid-Wall Chambers*
ARIES MeetingApril 22-23, 2002
* This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.
ARIES HIF Modeling - WRM 4/22/022
Thick-liquid-wall chambers: Key features and issues
HYLIFE-II
• Thick liquid “pocket” shields chamber structures from neutron damage and reduces activation
• Oscillating jets dynamically clear droplets near target
• No blanket replacement required, increases chamber availability
• Suited for indirect-drive targets
Key Issue: Chamber Clearing. Can the liquid pocket and beam port protection jets be made repetitively without interfering with beams? Will vapor condensation, droplet clearing and flow recovery occur fast enough to allow pulse rates of ~ 6 Hz?
ARIES HIF Modeling - WRM 4/22/023
Why Thick Liquids?
• Replace fusion materials questions with fluid mechanics questions
– These are questions that can be answered without a $1 billion test facility
• Maximize fusion power density
– Bring final focus/transport elements close to target
– Improve economics
UC Berkeley
ARIES HIF Modeling - WRM 4/22/024
Liquid-protection parameter space provides multiple options for target chambers
.
10510.50.1
DynamicClearing
Wetted Wall
Gravity Clearing
MultipleChambers
Thick Liquid
High Yield
No MaterialsTesting
Smaller DriverEnergy
Higher PowerDensity
4
6
10
12
Repetition Rate (Hz)
Mag
net
Sta
ndof
f (m
)
UC Berkeley
107
108
109
1010
1011
1012
1013
1014
1015
10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
The use of thick-liquid protection reduces the first wallneutron flux as well as the average neutron energy.
Dry Wall
Thick-Liquid Protection
Neu
tro
n F
lux
(n/c
m2 -s
)
Neutron Energy (MeV)
Casen,tot
(n/cm2-s)
En,avg (MeV)
Dry Wall 2.7 1015 3.25
Thick-Liquid
3.9 1014 0.47
Approximately 58 cm of flibe is needed to protect the wall against neutron damage and ensure that it would meet Class C requirements.
10-1
100
101
45 50 55 60 65
WDRWDR goal
Was
te d
isp
osa
l rat
ing
Thickness (cm)
100
101
102
0 10 20 30 40 50 60
dpa goalFirst wall dose (dpa/year)
DP
A/f
ull-
po
wer
-yea
r
Thickness (cm)
55 cm of flibe reduces the first wall damage rate to <3.3 dpa/fpy (100 dpa in 30 fpy).
58 cm of flibe is required to reduce the SS304 first wall waste disposal rating to <1.
ARIES HIF Modeling - WRM 4/22/027
Top/Bottom Mid-Plane
Several potential liquid pocket geometries can be assembled from existing single-jet nozzles
High amplitudejet oscillation
Low amplitudejet oscillation
Porous liquid structuresuppresses shock
transmission (> 0.125 secshock transit time)
All porous jets mergeat pocket top
and bottom to fullyenclose target
and shield structures
Use of cylindrical jets for beamgrid allows flow control to
correct pointing errors
Large dimensionpocket opening:• reduces effects of liquid motion on venting,• provides directed debris jet to a separate condenser,• smoothness of oscillating jet surface now less important
Several variants of the HYLIFE-II pocket will be examined.
Asymmetric venting reducespocket symmetry and
debris jetting up beam lines
UC Berkeley
ARIES HIF Modeling - WRM 4/22/028
ARIES HIF Modeling - WRM 4/22/029
Driver/chamber interface
Credit: K. Springer & R. Holmes, LLNL
Key Issue: Self-consistent design. Can super-conducting final focusing magnet arrays be designed consistent with chamber and target solid angle limits for the required number of beams, standoff distance to the target, magnet dimensions and neutron shielding thickness?
ARIES HIF Modeling - WRM 4/22/0210
Cut-away view shows beam and target injection paths
ARIES HIF Modeling - WRM 4/22/0211
Work has progressed to detailed 3D neutronics models - predicting >30 year magnet lifetime
12
34
56 1
23
45
60.00E+00
5.00E+18
1.00E+19
1.50E+19
2.00E+19
2.50E+19
• There is a strong peaking of the fast neutron fluence at the center of the magnet array due to neutron scattering between neighboring penetrations.
• Estimated magnet life is 40-90 years depending on beam-to-structure clearance.
3D Tart model for HYLIFE-IIFast neutron flux for 36 magnet array
ARIES HIF Modeling - WRM 4/22/0212
IFE system phenomena cluster into distinct time scales
• Nanosecond IFE Phenomena– Driver energy deposition and capsule drive (~30 ns)– Target x-ray/debris/neutron emission/deposition (~100 ns)
• Microsecond IFE Phenomena– X-ray ablation and impulse loading (~1 s)– Debris venting and impulse loading (~100 s)– Isochoric-heating pressure relaxation in liquid (~30 s)
• Millisecond IFE Phenomena– Liquid shock propagation and momentum redistribution (~50 ms)– Pocket regeneration and droplet clearing (~100 ms)– Debris condensation on droplet sprays (~100 ms)
• Quasi-steady IFE Phenomena– Structure response to startup heating (~1 to 104 s)– Chemistry-tritium control/target fabrication/safety (103-109 s)– Corrosion/erosion of chamber structures (108 sec)
Pri
nci
pal
foc
us
for
IFE
Tec
hn
olog
y R
&D
...
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0213
All IFE scientific topics can be identified and characterized by time scale and spatial location
Time Scale (Phenomena Duration)Spatial Volume Nanosecond
(Target Gain)Microsecond Millisecond
(Rep. Rate)Quasi-Steady
(Safety/Reliab.)
Capsule Neutron/ion/x-ray emission
—
Hohlraum (if used) X-ray and debrisemission
—
Driver energy transport paths Beam transportand focusing
Debrisaccumulation
Pocket Void/Ve nt Paths — —
External Condensing Region —
Target debrisexpansion/
interaction withablation debris,venting, impulse
Debriscondensation
—
Target-facing Surface Layers X-ray deposition Ablation/impulse
Blanket (liquid/solid) Neutron heatingrelaxation
Liq. hydraulics/solid thermal
mechanics
Activation, neutrondamage (solids),
safety
Final focus elements — — Damage rate
Chamber structures
Neutron andgamma
deposition
— —
Coolant recirc./heat recoveryloop
— — —
Safety, tritium,activation,corrosion
Accelerator/laser systems Driver physics — Driver rep. rate and reliability
Target injection — — Accel./heating —
Target fabrication — — — Safety/reliability
Balance of plant — — — Safety/reliability
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0214
Millisecond Chamber Phenomena
• Liquid pocket disruption and regeneration
– Pressure waves travel large distances over millisecond time scales, so liquid flow is incompressible
– Major liquid phenomena can be reproduced in scaled water experiments
• Ablation and target debris condensation
– Occurs on droplet sprays physically isolated from liquid pocket
– Condenser region baffling optimized for recovery and concentration of volatiles (He, DT, Hg, etc.)
– Experiments can used pulsed power to generate vapor/plasma from prototypical chamber materials (UCLA work)
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0215
The TSUNAMI code predicts microsecond venting phenomena
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0216
Porous Liquid Can Attenuate Shocks
• Impulse from x-ray ablation and pocket pressurization generates shock
• Simple “snowplow” model gives shock transit time as function of liquid void fraction :
• Shocks require > 100 ms to arrive at outside of porous pocket liquid
• Caveat: pocket openings may collimate high-velocity liquid
xxs
vs
xi
t = t1vl
t = 0
0
I
PjDj
t 1 xs
2
2I
Tim
e (s
ec)
0
0.2
0.4
0.6
0 0.5 1 1.5 2Shock Position (m)
I = 1000 Pa sec
- 50 cm line density
= 0.5
0.7
0.3
0.1
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0217
Navier-Stokes governs liquid hydraulics phenomena
Mass and momentum conservation
v 0 v
t v v
p 2v g
Free surface pressure boundary condition with impulse load I
p pv 1
r1
1
r2
where pv ,ave
IU
L
U
Lpv dt
0
L U
Nondimensionalize with appropriate scaling parameters:
v* v/ U * L p* p/ U 2 t* f t r* r / L pv*
pv L
IUGiving governing equations:
* v* 0 Stv*
t* v* *v* *p*
1
Re*2
v* 1
Fr
g
g
p* I*pv*
1
We
1
r1*
1
r2*
Major simplifications: No EOS, No energy equation No MHD
A scaled system behaves identicallyif initial conditions and St, Re, Fr,I*, and We are matched...
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0218
Single-jet experiments provide jet geometries for constructing integrated pockets
UCB Stationary Jets (1.6 cm x 8.0 cm,view from flat side, Re = 160,000, We = 29,000)
Bad:Breaks up Better: No Droplets
Stationary Oscillating
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0219
Recent experiments show that cylindrical jets can be sufficiently smooth for beam-line protection
honeycombRe = 100,000
screen/nozzle
cutter blade Re = 70,000 (no conditioning)
Re = 186,000
Jet with 1.5 : 1.0 nozzlecontraction ratio
Flow Conditioning
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0220
IFE thick liquid experiment scaling
Partial Pocket, HITF, and ETF scaling all preserve impulse effects
Single/Multiple Jet Integral Systems
Phase II Phase III DEMOHYLIFE Single Jet Partial
PocketHITF ETF HYLIFE
Geometric Scale 1 0.24 0.24 0.33 0.42 1Target Yield (MJ) — — — — 30 350
Volumetric Flow (m3/s) 0.84 0.01 0.16 4.76 8.58 75.00Oscillation Frequency (Hz) 6.0 27.1 12.2 9.1 9.5 6.0Nozzle Velocity U (m/s) 12.0 13.0 5.9 6.9 7.8 12.0Number of Jets 1 1 10 89 89 89Jet Dimensions D (cm) 7 1.68 1.68 various various variousJet Dimensions W (cm) 100 8.1 16 various various variousPumping Power (kW) 356 2 21 907 1,530 31,800
Storage Tank Size (m3) N/A 4 4 300 N/A N/AJet Reynolds Number Re 160,000 160,000 99,000 160,000 43,700 160,000Jet Weber Number We 103,000 21,000 7,900 15,200 18,100 103,000Froude Number Fr 7.3 19.4 7.3 7.3 7.3 7.3Working Fluid Flibe Water Water Water Flibe Flibe
Phase I
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0221
Computational tools have provided new insights
Computation plays thekey role in predicting impulse
loads to jets
CFD provides importantinsights for jet response
Droplet formation
UCLA
Droplet ejectionfrom cylindrical
jet surface
Tsunami simulation of vapor venting through jet
array
Code/experimentcomparison for
shock propagationover tube array
U. Wisc.UCB
Regions flattened by interaction with neighboring jet
Simulations from UCLA
Flow Direction
CollidingHYLIFEslab jets
ARIES HIF Modeling - WRM 4/22/0222
The electro-thermal plasma source: a powerful and cost effective solution for pulsed vapor generation
• Based on existing knowledge from other experiments (NCSU)
• Capable of generating prototypical vapor density of flibe in a practical size chamber
• Discharge characteristics (fast rise time, short period) adequate to simulate IFE post-shot event
New plasma gun is being developed for liquid flibe high-T environment:
• ceramic insulator instead of plastic
• gun entirely inside the vacuum chamber
Technical issues:
• achieve unaided breakdown at 550 C flibe vapor pressure (0.2 mTorr)
• avoid chemical contamination from ablation of insulating materials and secondary discharges
ARIES HIF Modeling - WRM 4/22/0223
A number of alternatives have been considered for thick liquid concepts
• We have evaluated flibe, flinabe, LiPb, Li and LiSn for pumping power requirements and TBR
• Calculated thickness of the liquid pocket is such that FW damage is limited to 100 dpa after 30 FPY operation
• Pumping power considers velocity head, friction loses and lift power
• LiPb and LiSn pumping power requirements are excessive
• Li has a large tritium inventory and poses fire hazards
• Only flibe and flinabe stand as reasonable options
Liquid Composition Thickness required (m)
Pumping power (MW)
TBR (1-D)
Flibe BeF2 (34%) LiF (66%) 0.56 48.46 1.25
Flinabe1 BeF2 (33.4%) LiF (33.3%) NaF (33.3%) 0.62 55.26 1.07
Flinabe2 BeF2 (37.5%) LiF (31.5%) NaF (31%) 0.62 63.23 1.07
LiPb Li (17%) Pb (83%) 1.03 681.76 1.61
Li Li (100%) 1.25 65.01 1.80
LiSn Li(50%) Sn (50%) 0.59 158.91 1.15
ARIES HIF Modeling - WRM 4/22/0224
Some possible areas to for ARIES to study
• Design space of blanket thickness/wall radius/radiation damage limits for different first wall structural materials
– Possible higher damage limit thinner blanker or smaller chamber reduced pumping power and/or closer final focus magnets
• Alternate structural material (ferritic, SiC, C/C?) and compatibility with flibe and hohlraum materials (D-K Sze?)
• Mechanical design of oscillating nozzle and flow conditioning system
• Chamber/driver interface design issues/options
ARIES HIF Modeling - WRM 4/22/0225
More slides on thick liquid wall chambers
Per F. PetersonDepartment of Nuclear EngineeringUniversity of California, Berkeley
April 17, 2002
Design Methods for Thick Liquid Protection of IFE Target Chambers
IFE Tutorial: http://www.nuc.berkeley.edu/thyd/icf/IFE.html
• Introduction: Chamber concepts, and the thick-liquid option
• Scaling review: Importance of time/spatial scales and phenomena coupling
• Bottom up: Understanding and modeling specific chamber phenomena and their coupling
– Nanosecond phenomena– Microsecond phenomena– Millisecond phenomena <--- Liquid hydraulics– Quasi-steady phenomena
ARIES HIF Modeling - WRM 4/22/0227
IFE target chamber must meet four requirements
• Regenerate chamber conditions for target injection, driver beam propagation, and ignition at sufficiently high rates (i.e. 3 - 6 Hz)
• Protect chamber structures for several to many years or allow easy replacement of inexpensive modular components
• Extract fusion energy in high-temperature coolant, regenerate tritium
• Reduce radioactive waste generation, inventory, and possible release fractions low enough to meet no-public-evacuation standards.
Chamber will be 9-15% of total capital costDesign, not chamber cost, is the most important issue
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0228
Experiments can take advantage of recent scaling advances
• In IFE strong phenomena decoupling occurs in both time and space– Spatial decoupling boundaries
• small or unidirectional mass and energy fluxes• large time scale differences—slow side sees integral effect of fast
– Temporal decoupling boundaries• large time scale differences —slower phenomena sees integral effect of
fast– Inside these boundaries, phenomena
interactions must be considered• Phenomena change differently with reduced
geometric scale, time scale ratios for important coupled phenomena must be preserved to study interactions
S. Levy, 1999
Liquid pocket formation and hydraulic response can be studiedseparately from ablation, venting and condensation, using asimulant fluid (water) at reduced geometric scale.Reduces experiment cost by factor of ~50 to not use molten salt
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0229
Nanosecond phenomena control scientific viability
Time Scale (Phenomena Duration)Spatial Volume Nanosecond
(Target Gain)Microsecond Millisecond
(Rep. Rate)Quasi-Steady
(Safety/Reliab.)
Capsule Neutron/ion/x-ray emission
—
Hohlraum (if used) X-ray and debrisemission
—
Driver energy transport paths Beam transportand focusing
Debrisaccumulation
Pocket Void/Ve nt Paths — —
External Condensing Region —
Target debrisexpansion/
interaction withablation debris,venting, impulse
Debriscondensation
—
Target-facing Surface Layers X-ray deposition Ablation/impulse
Blanket (liquid/solid) Neutron heatingrelaxation
Liq. hydraulics/solid thermal
mechanics
Activation, neutrondamage (solids),
safety
Final focus elements — — Damage rate
Chamber structures
Neutron andgamma
deposition
— —
Coolant recirc./heat recoveryloop
— — —
Safety, tritium,activation,corrosion
Accelerator/laser systems Driver physics — Driver rep. rate and reliability
Target injection — — Accel./heating —
Target fabrication — — — Safety/reliability
Balance of plant — — — Safety/reliability
Nanosecond phenomena:
• Target gain > Must be understood to judge the scientific viability of IFE
• Target output > Must be understood to predict chamber response
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0230
Millisecond phenomena control repetition rate
Time Scale (Phenomena Duration)Spatial Volume Nanosecond
(Target Gain)Microsecond Millisecond
(Rep. Rate)Quasi-Steady
(Safety/Reliab.)
Capsule Neutron/ion/x-ray emission
—
Hohlraum (if used) X-ray and debrisemission
—
Driver energy transport paths Beam transportand focusing
Debrisaccumulation
Pocket Void/Ve nt Paths — —
External Condensing Region —
Target debrisexpansion/
interaction withablation debris,venting, impulse
Debriscondensation
—
Target-facing Surface Layers X-ray deposition Ablation/impulse
Blanket (liquid/solid) Neutron heatingrelaxation
Liq. hydraulics/solid thermal
mechanics
Activation, neutrondamage (solids),
safety
Final focus elements — — Damage rate
Chamber structures
Neutron andgamma
deposition
— —
Coolant recirc./heat recoveryloop
— — —
Safety, tritium,activation,corrosion
Accelerator/laser systems Driver physics — Driver rep. rate and reliability
Target injection — — Accel./heating —
Target fabrication — — — Safety/reliability
Balance of plant — — — Safety/reliability
Millisecond phenomena:
• Control the repetition rate > Must be understood to judge the engineering viability of IFE
• Initial conditions > Created by nanosecond and microsecond phenomena
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0231
Quasi-steady phenomena control safety and reliability
Time Scale (Phenomena Duration)Spatial Volume Nanosecond
(Target Gain)Microsecond Millisecond
(Rep. Rate)Quasi-Steady
(Safety/Reliab.)
Capsule Neutron/ion/x-ray emission
—
Hohlraum (if used) X-ray and debrisemission
—
Driver energy transport paths Beam transportand focusing
Debrisaccumulation
Pocket Void/Ve nt Paths — —
External Condensing Region —
Target debrisexpansion/
interaction withablation debris,venting, impulse
Debriscondensation
—
Target-facing Surface Layers X-ray deposition Ablation/impulse
Blanket (liquid/solid) Neutron heatingrelaxation
Liq. hydraulics/solid thermal
mechanics
Activation, neutrondamage (solids),
safety
Final focus elements — — Damage rate
Chamber structures
Neutron andgamma
deposition
— —
Coolant recirc./heat recoveryloop
— — —
Safety, tritium,activation,corrosion
Accelerator/laser systems Driver physics — Driver rep. rate and reliability
Target injection — — Accel./heating —
Target fabrication — — — Safety/reliability
Balance of plant — — — Safety/reliability
Quasi-steady phenomena:
• Control safety > Must be understood to judge the engineering viability of IFE and of experimental facilities
• Control reliability > Must be understood to judge the attractiveness of IFE
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0232
ARIES HIF Modeling - WRM 4/22/0233
Nanosecond Chamber Phenomena
• Driver energy transport– Shielding material standoff and gas density distribution– IRE will provide primary experimental test capability
• Target x-ray/debris/neutron emission– The most important questions are:
• partitioning of energy between x-rays, debris, and neutrons• effective x-ray black body temperature(s)• directional characteristics of x-rays/debris• control of emission by mass addition outside hohlraum
– High energy density/radiation dominates energy transport– Target design codes can model– Multidimensional effects likely important
in partition of energy between x-rays and debris kinetic energy
• Neutron shielding/energy deposition– 3-D codes (e.g. TART) can model
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0234
Microsecond Chamber Phenomena
• X-ray ablation, debris, venting, impulse loading (Chamber dynamics)– Experiments
• Z is currently the highest energy x-ray source available, has extensive DP diagnostics for x-ray ablation
• X-ray ablation - most important impulse source
• Reproduce 3-D gas dynamics/radiationtransport/reradiation/pocket pressurehistory
– Numerical modeling• Equations of state must
include vaporization, dissociation, ionization
• Radiation transport isimportant first 10’s ofmicroseconds
• Existing codes (2-D w/ TSUNAMI, 1-D w/ BUCKY)
Inserting wire array in Z
TSUNAMI results
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0235
Flibe x-ray ablation experiments on “Z” can be compared to simpler materials with known EOS’s (LiF, Li metal)
• LiF has been used as a non-toxic, well-characterized surrogate for flibe in recent experiments– Experiments at 41 J/cm2 match expected
wetted wall fluences• Koyo (laser chamber)• Osiris (heavy-ion chamber)
– Sesame EOS is available for LiF• Gives impulse prediction 10% less than ideal-gas
EOS– UCB/LANL predicted 2.8 m ablation
matches 3 - 4 m measured with LiF• Greater ablation, 4.2 m, is predicted for flibe;
will be confirmed in upcoming tests• Li metal has been tested at higher fluences
(~1000 J/cm2) under DP programs– Time-resolved diagnostics required due to
sample destruction– IFE samples can be treated with same
approach as DP effects testing work Cast and diced Flibe diskbeing handled in glovebox
14 mm
5 mm
LiF sample exposed to 41 J/cm2
shows clear ablation step
0.4 mm
ARIES HIF Modeling - WRM 4/22/0236
Liquid jets can be optimized with single-jet experiments
• Design issues:
– Inlet plenum provides turbulent flow
– Flow calming section reduces core turbulent eddy energy and size
• perforated plates
• honeycomb
• screens
– Converging section
• further suppresses turbulence
• increases core flow mean velocity uniformity
• thins wall boundary layer
• contraction ratio sets jet packing density
– Cutter (optional) removes boundary layer
– Residual nonuniformity in exit velocity generates jet surface roughness
Velocity nonuniformity providesexcess kinetic energy, aftervelocity profile relaxes
u r 3 dA
0
A
U 3A
BoundaryLayerCutter
Screen(Typical)
Honey-comb
PerforatedPlate
rJ
rO
rN
ConvergingNozzleSection
GlobeValve
InletDistrib.Plenum
O-Ring
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0237
Honeycomb and screens can reduce core turbulence in flow calming section
• Honeycomb can greatly reduce transverse turbulence and secondary flow amplitudes
• Jets exit from each honeycomb cell
• Breakup of jet kinetic energy into isotropic turbulent kinetic energy occurs downstream
• A screen at the honeycomb exit can trip smaller instability modes and cause more rapid turbulence decay
0
4
8
2
6
10
u (m
/s)Average Longitudinal Velocity u
Downstream of a Cell Centerline
0
0.1
0.2
0.3
0.4
0 4 6 8 10 12
u' /
u
Distance From Honeycomb Exit (cm)
Fluctuating Velocity Downstreamof a Cell Centerline
Fluctuating Velocity WithExit Screen
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0238
Neutron shielding requires significant standoff of beam-line shielding nozzles
Side View End View
Jets closer to target require longer stand-off distance L, and largerjet L/D degrades jet smoothness
NozzleBlock
# L
NozzleBlock# R
r
rpi
rpo
zji
a
zjo
Bank "L" Bank "R"
OscillatingPocket Liquid
Crossed JetArrays
L1L
NozzleBlock
# L
NozzleBlock# R
z
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0239
Beam standoff sets liquid envelope for jet grid
• The volume available for the liquid jet envelope depends on the required standoff angle from the beams, Sn
• The fraction of the liquid envelope that can be filled with liquid depends on:
– Surface roughness • jet L/D• area contraction ratio• boundary layer trimming
– Pointing error– Velocity error
• gravity deflection• dilation
– Flow control to cylindrical jets can partially correct pointing errors
a
ny
Rn
a
nx
Liquid-JetEnvelope
j = 0
j = 1
j = Na
i = 0i = -Na
rEnj
Beam ShieldingStandoff Envelope
LiquidJet
Gravity Deflection
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0240
Cylindrical jets can be arrayed for beam-line shielding
• Staggered geometry reduces collimation of liquid droplets and slugs down beam lines
• Pitch to diameter ratio Pn/2rJn will be between 1.6 and 2.5
rJnj
rEnj
rNnj
n
n-1/2
n-1
Pn
Staggered Jet Array Cross Sections Nozzle Cross Section
Cutter DischargeCollection Tray
Cutter BladesAttach to Bottomof Nozzle Block
Beam StandoffEnvelope
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0241
UCB vortex test stand is now studying vortex injection and extraction methods for beam-tube protection
Side view showing operation at30° angle (extraction nozzle usedon right, vortex fan on left)
End viewsInjection
nozzle
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0242
Partial pocket experiments allow study of disruption
• 1/4-scale partial pocket multiple-jet experiments to study:
– Jet (various configurations) disruption by scaled propellant detonation
– Shock propagation and droplet/slug generation from multiple colliding jets
– Forced clearing of droplets confirmed by scattered light from laser-beam
SIDE VIEW TOP VIEWNozzle Block
Lexan SideWalls
Laser BeamConfirmsClearing
ScaledChemical
Detonation
PARTIAL POCKET SCHEMATIC
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0243
Chemical propellants can generate scaled impulse loads and disrupt thick liquid jets
• Numerical simulation allows comparison of scaled impulse for 1/4-scale jet disruption experiments
• Chemicals deliver impulse over longer time scale, but still rapid compared to > millisecond liquid response
.5m
r-axis
zz-axis
Chemical propellant jet IFE chamber
40sec 2sec
.125m
80sec 4sec4-cartridge firing deviceand impulse calibration
disk
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0244
Vacuum Hydraulics Experiment (VHEX) studies IFE jet disruption and regeneration
• Create hydrodynamically similar single jets and several jet arrays
• Transient flow into large vacuum vessel—water simulates flibe
t = 0 t = 0.8 ms(muzzle flash)
t = 1.6 ms(plume has hit)
t = 32 ms(peak deflection)
Impulse loadcalibration underway
UCB
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0245
Cartridges can provide required impulse loading
Single-jet disruption at 10.3 Hz
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0246
UCB disruption experiments are studying response of a 96-jet array to scaled impulse loading
- 6 msec
25 cm
2 msec 10 msec
“New” liquid interface Impulse-affectedregion- note divot
18 msec 26 msec
96-jet nozzleassembly in operation
Numerically-machined 96-jet nozzle
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0247
UCB has improved flibe vapor pressure predictions and identified a new salt composition allowing lower pressures
• Detailed activity coefficient data has allowed the vapor pressure of flibe to be accurately predicted at lower temperatures
• Ternary salt systems (“Flinabe,” LiF/NaF/BeF2) have been identified with very low melting temperatures (320°C)
– In beam tubes this low temperature molten salt creates a large reduction in the equilibrium vapor pressure (109/cc at 400°C)
Cooler
~350°C
RegenerativeHeat Exch.
Pump
ChamberFlibe
Pump VacuumDisengager
~600°C
Vortex Tube
.
1.00E+10
1.00E+11
1.00E+12
1.00E+13
1.00E+14
1.00E+15
460 500 540 580 620 660 700
temperature (C)
m o l e c u l e s / c ctheoretical modelORNL extrapolation
Recent flibe vapor pressureprediction
A degassing system may permitflinabe to be used for He/H2 pumping
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0248
Conclusions
• IFE has strong temporal and spatial phenomena decoupling– Pulsed complex systems: sequence from fast to slow phenomena
• Fast phenomena provide initial conditions for slower phenomena• First-principles modeling appears possible• Large temporal and spatial decoupling of subgroups of phenomena
simplifies experiments– Temporal decoupling: nanosecond/microsecond/millisecond/quasi-
steady– Spatial decoupling: driver/final focus/pocket/condensers/balance of
plant• Current status of liquid hydraulics research
– Single-jet nozzle designs are now available for constructing pockets• Reliability needs to be confirmed
– nozzle optimization studies to increase strength of nozzle components– single-jet molten salt experiments
• Liquid vortexes are still needed– Multiple jet interactions and pocket disruption/clearing now need study
UC Berkeley
ARIES HIF Modeling - WRM 4/22/0249
A head recovery system was designed to minimize pumping power
Downward flow redirected by vanes to pressurize exit pipesRef. P. House