ile osaka concept of koyo-f and formation of aerosols and micro particles t. norimatsu presented at...
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ILE Osaka
Concept of KOYO-F and Formation of Aerosols and
Micro Particles
T. NorimatsuPresented at TITAN workshop on
MFE/IFE Common ResearchUCSD, Feb. 10-11, 2009
ILE Osaka
Common task on TITAN
• To construct system integration model on tritium and thermo fluid system
• Identify key issues • & design priorities• Identify baseline design(s) • - FFHR, ARIES• - KOYO• Assess concept attractiveness• & feasibility• Perform analysis of key issues
Goal
Now….
ILE Osaka
Outline
• Introduction of KOYO-F and the critical issues
• Researches on chamber clearance– Code development (by H. Furukawa, ILT)
• Experimental check 1 (by T. Norimatsu)• Experimental simulation with laser ablation
(to be presented by K. A. Tanaka)
– Experimental simulation on hydrodynamic instabilities on ablation by alpha particles(by Y. Shimada, ILT)
ILE Osaka
Conceptual laser fusion reactor KOYO-F based on fast ignition
Electrical output power 1200 MW
• Target gain 167• Fusion yield
200MJ/shot• Laser 1.2 MJ x
16Hz,12% • 4 modular reactors with
32 compression beamsand 1 ignition beam
• System efficiency 40%
ILE Osaka
Reactor with cascade flow of liquid LiPb
• Coolant Li17Pb83
• Chamber/Blanket wall Ferrite / SiC/SiC
• Fusion yield 200 MJ x 4 Hz
• Thermal output 916 MW• Chamber size (inner/outer/high)
3m / 5m/14m• pulse load 0.3 MJ/m2
• peak load 2 x 1012 W/m2
• Average thermal load 1.2 MW/m2
• Neutron load 5.6 MW/m2
• Solid angle of beam ports < 5%• TBR 1.3
ILE Osaka
KOYO-F with 32 beams for compression and one heating
beam• Vertically off-set
irradiation
• Cascade surface flow with mixing channel
• SiC panels coated with wetable metal
• Tilted first panel to make no stagnation point of ablated vapor
• Compact rotary shutters with 3 synchronized disks
Chamber
ILE Osaka
The surface flow is mixed with inner cold flow step by step to reduce the surface
temperature
Chamber
If the surface flow is a laminar flow, vapor pressure is too high to reach designated pressure of 5-10 Pa.
ILE Osaka
Thermal flow of KOYO-F
SGTurbin
500℃
300℃300℃
50MW
210MW
70MW
70MW
240MW
80MW
80MW
500℃
F2+F3 (80cm)12.84 ton/s
Average flow 7.8 cm/s
F1 (20cm)8.56 ton/s
Average flow 24.3 cm/s
Flow rate 21.4 ton /s
904MW
Watercycle
Chamber
LiPb cycle
Chamber
t=0.5 oC/shot t=1.3 oC/shot
Thermal shock in closed blanket p=0.1MPa
ILE Osaka
Critical issues in chamber 1(from J-US WS on reactor 2007)
• Probability for direct exposure of the same place <1/103 – 1/104
– If we assume maintenance period of 2 years and acceptable erosion of 3-mm-thick, the probability for direct exposure of the same place with particles must be less than 1/104.
– Improve flow control, material selection, chamber radius
• Protection of beam ports– Our first plan was to keep the surface temperature less than
surrounding area to enhance the condensation. But this would not work because of the small temperature dependence of condensation.
– Porous metal saturated with liquid LiPb– Magnetic field
Dry surfaceLiquid LiPb
Dr Kunugi demonstrated a stable flow >3 mm using water
Dr. Kajimura showed protection of the beam port by a 1T magnetic field.
ILE Osaka
Critical issues in chamber 2 (from J-US WS on reactor 2007)
• Chamber clearance– Formation of aerosols– Large ( ~10 m) particles due to RT instabilities and related
secondary particles
• Tritium diffusion through the heat cycle– To be solved during TITAN
ILE Osaka
Outline
• Introduction of KOYO-F and the critical issues
• Researches on chamber clearance– Code development (by H. Furukawa, ILT)
• Experimental check 1 (by T. Norimatsu, ILE)• Experimental simulation with laser ablation
(to be presented by K. A. Tanaka, Osaka U.)
– Experimental simulation on hydrodynamic instabilities on ablation by alpha particles(by Y. Shimada, ILT)
ILE Osaka
We estimated the ablation process using ACORE. Stopping power in ionized vapor
was calculated.
Atomic Process Code
Ionization Degree, Population, Energy Level
Stopping Power Code EOS Code Emissivity and Opacity Code
Stopping power Ionization DegreePressure, Specifiic heat
Emissivity, Opacity
ACORE (Ablation COde for REactor)
0
4
8
12
Number Density
(cm-3)1014
1018
1022
Temperature (eV)
10
1
0.1
0.01
Z*
Ionization rate of Pb
Ziegler’s model
dE
dxni Inl
l
n Pnl
Z0e2
Inl
2
Gv
vnl
Present model
G V 3/2
V 2 2
31 ln 2.7 V
V 0.206
4 2 20
02 2
4 4e e
e e e
e Z n n edE hK
dx m v n v m
0
100
200
300
400
500
0
10
20
30
40
50
0 2 4 6 8 10
= s , T=300 K
Ziegler
Present
Z*W
( M
eVcm
2 / g
)
Z* (E
)
Energy (MeV)
alpha
ILE Osaka
ACONPL (Ablation and CONdensation of a PLume)
p 11
ILE Osaka
Treatment of Phase Transition in ACONPL
p 12
○Equation of Motion of Ablation Surface ( The boundary of liquid and neutral gas or plasma )
Tv Tl xv t Lv : Latent Heat of Vaporization
Tv : Temperature of Ablation Surface
○Equation of Energy in Liquid
Ul x,t l Cl x,T x,t T0
T t dTl x,t
Ul
crtl Cl x,T T0
Tvap dT Lv
Tvap : Vaporization TemperatureIf Ul >Ul
crt, Peeling will occur.
xv x xmax
Qp : Heat quantity due to charged particles
Qx : Heat quantity due to absorption of X-ray
t
x v t kBTv /m i exp m i Lv / kBTv
l
l
T x, t x
xxv
Lvt
xv t
U l x, t t
T x, t Q p x, t QX x, t Qrad x, t
ILE Osaka
Treatment of Hydro Dynamics in ACONPL
○ 1 Fluid and 2 Temperature Model, Lagrange Scheme
Pnv : numerical viscosity
1
3 exp 1
B
q 2
TsT
3/2
Tc q
Vaporization Temperature ( Condensation Temperature )
q : Latent heat of Vaporization( Kelvin)
d x,t dt
x,t v x,t x,t dvx,t
dt Pe x,t Pi x,t Pnv x,t
x, t cve Te x, t t
qe x, t Te Ti Pthe x,t v x, t
QP x, t QX x, t Qrad x, t
x, t cvi T i x, t t
qi x, t Te T i Pthi x, t Pnv x, t v x, t
x, t cvi 2
3q Ti x, t
3 dd t
4-th term of right hand side is temperature increment due to phase transition from gas to liquid (clusterization).
ILE Osaka
p 16
Tc q
1
3 exp 1
B
q 2
TsT
3/2
q : Latent Heat of Vaporization( Kelvin)
◯Two-Phase Mixture Effects
Temperature of Clusters
Condensation Rate
Rate of Nucleation
Cluster Growth
Super Cooling Parameter Reference B. S. Luk’yanchuk, S. I. Anisimov et. al.,
SPIE 3618 (1999) 434-452.
y x, t x, t g x, t
x, t T i x, t T x, t / T i x,t
0 2
0
, , 11 , exp
, ,nuc
d x t x t Ty x t
d t T x t x t
2 / 3 1/ 30
0
, ,1 , 1 expg
d g x t x t qg T y x t g
d t T
, 2 , , ,1 21 , 1 , ,
3 , 3
dT x t T x t d x t d y x ty x t y x t q T x t
d t x t d t d t
Condensation of a Plume
◯ Condensation Temperature
ILE Osaka
To check the code, 10m thick Pb membrane was heated and aerosols
were captured on a witness plate.
ILE Osaka
There is geometrical effect on the diameter of particles.
0
100
200
300
400
500
0 5 10 15 20 25 30 35
Diameters of particles on witness plate and rod
on Plateon Rod
Distance (mm)
Geometrical effect
The minimum diameter givesaerosol diameter.Model for large particles
ILE Osaka
Diameter of particles agreed with simulation result.
Particles on continuous membrane
The continuous membrane was formed with leading, super-cooled plume.
ILE Osaka
Density, Temperature and velocity profile of ablated material.
102
103
104
105
106
107
108
109
0.0 0.5 1.0 1.5 2.0
alfaalfa (debri)deuteriumtritiumprotonherium3
Inte
nsi
ty (
W/c
m2
)
Time (s)
ILE Osaka
Density, Temperature and velocity profile of ablated material.
102
103
104
105
106
107
108
109
0.0 0.5 1.0 1.5 2.0
alfaalfa (debri)deuteriumtritiumprotonherium3
Inte
nsi
ty (
W/c
m2
)
Time (s)1016
1017
1018
1019
1020
1021
1022
1023
0
1 104
2 104
3 104
4 104
-1 0 1 2 3 4 5
Time = 2000 ns
Number Density
Te
v (m/s)
x (cm)
ILE Osaka
Number density at the next target injection is estimated to be 107/cm3.
107
108
109
1010
1011
1012
1013
1014
1015
0
500
1000
1500
2000
-1 0 1 2 3 4 5
Time = 2000 ns
nc
Te
x (cm)
If interaction with opposite plume, clusters in this region will disappear after collisions with the opposite wall.
Clusters in this region expand to chamber volume before next target injection.
The resulting nc at the next target injection is;
50 m
8 X 106 /cm3
ILE Osaka
Influence of aerosols on target injection can be ignored.
Chamber center Wall
Nc=107 cm3
3m
Total mass of aerosols in the column
1.06 x 10-4 g
Target mass
Aerosol mass = 2 x 10-4
(0.4 m in the thickness of deposition layer)
We can ignore the influence on target trajectory.
ILE Osaka
Future work
• Influence of ions as “seeds” for clusters
• In this simulation, clusters move with fluid.– PIC code
• Interaction with opposite plume– Stagnation at the center– Condensation on the opposite wall
ILE Osaka
Outline
• Introduction of KOYO-F and the critical issues
• Researches on chamber clearance– Code development (by H. Furukawa, ILT)
• Experimental check 1 (by T. Norimatsu)• Experimental simulation with laser ablation
(to be presented by K. A. Tanaka)
– Experimental simulation on hydrodynamic instabilities on ablation by alpha particles(by Y. Shimada, ILT)
ILE Osaka
To understand the ablation phenomena by alpha particles, we used laser backlighting.
• To know the influence of internal hot zone due to Bragg’s peak, we used back-light heating of Pb membrane.
• Electric discharge was used to check simulation code for aerosol formation.
Energy density Pulse width Heating process PurposeKOYO-F 0.35 MJ/m2 0.05s Volumetric
Laser 0.15 MJ/m2 0.015 s Surface RT instabilityDischarge 1.5 MJ/m2 100 s Volumetric Check simulation
Particle loads Energy deposition
Volumetric heatingBragg’s peak
ILE Osaka
Experimental setup. Laser-scattering measurement was used to observe flying
situation of metal
Punch out laser
50 mmProbe laser
2×10-4 torr
Nd:YAG laser
Intensity: 0.5 – 1 GW/cm2 Spot size : 700 - 800 mφ Pulse duration : 15 ns
Cylindricallens
CCD camera
Scatteredlights
Target(glass plate with coated tin or lead)
27
Linefocus
9 s 12 s15 s
Laser
Glass plate
Dot targetDiameter: 500 m(smaller than laser spot size)
ILE Osaka
Spouted gas and small particles, and large particles were detected at 10-mm
away from glass plate
10 mm
2s 4s 6s 8s 10s 12s
500m
6s
800m
9s 12s
Averaged density2×1018 (cm-3)
28
15s
Diameter~10 μm
Gases
Gases small particles
Large particles
ILE Osaka
RT instability and break up would make larger( 3m), slow (100-500m/s) particles.
Dot target
Laser
High speedgases
RT Instability
Gas,
clusters
Smallparticles
Largeparticles
High density
columns
Glass plate
Depend on thickness of targetetc.
λ
few joules energy It may cause secondary ablation of panel 29
bigparticles
3km/s
0.5km/s
ILE Osaka
Stagnation at the center needs more analysis
Laser back lighting Electric discharge
cos cosn
Volumetric heatingPlaner heating
Tilted first panel concept may reduce the stagnation to 1/5 of cylinder case.
Recently we started simulation on collisions of plumes.Preliminary result indicates condensation and formation of droplets are not critical because the kinetic energy of leading plume is much higher than latent heat of condensation.
80% 20%
(At end of after glow)
ILE Osaka
Summary
• Aerosols and particles– In KOYO-F, the diameter of aerosols 100 – 200 nm – No influence on target trajectory and performance
if we ignore the interaction with opposite plume.
• Hydrodynamic process must be considered to discuss formation of particles.
• Remaining issue: • Secondary particles• More detailed estimation of stagnation at the chamber
center31
ILE Osaka
Cooled Yb:YAG ceramic laser will be used for both compression and ignition
beams.
Lasers
60kJ x 8 beams
FiberOscillator
Pre-Amplifier(~ kJ, NIR) Main-Amplifier
(~ MJ, NIR)
3rd Harmonics
2nd Harmonics PulseCompressor
compression Laser(1.1MJ, blue, ns)
Heating Laser(0.1MJ, NIR, ps)
OPCPA
PulseStretcher
Mode-lockOscillator
Compression laser 1.1 MJ, 12%Heating laser 0.1 MJ, 5%
ILE Osaka
Target for KOYO-F
Fuel shell
DT(gas) (<0.01mg/cc) 1,500 mDT(Solid) (250mg/cc+10mg/cc Foam) 300 mGas barrier (CHO, 1.07g/cc) 2 mCH foam insulator (250mg/cc) 150 mOuter diameter 1,952 mMas of fuel 2.57mg
Total Mas of shell 4.45mg
Basic specification Compression laser 1.1 MJ
Heating laser 70kJ Gain 165 Fusion yield 200MJ
Cone Material Li17Pb83 Length 11mm Diameter 5.4 mm Mas 520 mg
3.9 mm
15o9 mm
11 mm
5.4 mm3 mm4.0 mm
Plastic coating
Prabolic mirror
Foam insulator Solid DT+Foam
Tritium burn ratio 23%