target fabrication and injection in japan - from topics in...
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Target Fabrication and Injection in Japan
- From Topics in 3rd TFIT -
T. NorimatsuPresented at US/Japan workshop on
Laser IFE, March 21-22, 2005General Atomics, San Diego, CA
Outline
• New concept– Impact ignition by M. Murakami– Magnetic focusing of injected target by R. Tsuji
• Target Fabrication– Current status at ILE by T. Norimatsu– Laser Lathe by Y. Kawamura
• Injection and tracking– At Gifu University by H. Yoshida– At Hiroshima University by T. Endo
1
A New Twist for IFE- Impact Ignition -
Contents of talk・What is Impact Ignition!?・Gain model・Design window・2D hydrodynamic simulation
M. Murakami Institute of Laser Engineering, Osaka University
2
Advantages of Impact Ignition
(1) Simple Physics
(2) High Efficiency
(3) High Gain
(5) Low Cost
(4) No need for PW Laser
3
Gain Model
2 Rs
2 Rc
Impact-produced DT igniter
Compressed main DT fuel
ρs
ρc
v imp = (12Ts / 5mp)1/ 2 =1.1×108(cm /sec)
ELs =8πHs3Ts5mpηsρs
2 = 15 kJ ⋅ ηs−1 ρs100g / cm3⎛ ⎝ ⎜ ⎞
⎠ ⎟ −2
ELc = 3.3 ×1012α cρc
2/ 3Mc /ηc
Ed = ELc +ELs
Φ = Hc /(Hc +H0 )
G =ΦMcε 0 / Ed
Implosion velocity
Laser energy for igniter
Laser energy for compression
Total driver energy
Burn fraction
Energy gain
RT exp’t with shorter wavelength perturbation
Growth of the perturbations in the CHBr target is strongly suppressed in comparison with that in the CH target. S. Fujioka
(ILE. Osaka)
300 µm
1 ns
1 ns
Temporal evolution of growth factor
CH
CHBr
18-µm thick CHBrλp = 25 µm, a0 = 0.3 µm
25-µm thick CHλp = 20 µm, a0 = 0.2 µm
1
2
3
45678
10
2
3
45
Gro
wth
fact
or (a
rb. u
nits
)
2.52.01.51.00.50.0Time (ns)
4
Gain curves for Impact Ignition Targets
10
100
1000
10 100 1000
Total Driver Energy (kJ)
Ener
gy G
ain
αc = 3, ηc = 0.1, ηi = 0.1
200ρc (g / cm
3) = 100
300
ρi (g / cm3) = 100
200
300
9
2D Hydrodynamic Simulation
Isocontour map at a time shortly before the impact
Isocontour map at peak comp-ression shortly after the impact
11
Summary
• A totally new ignition scheme, ImpactIgnition, has been proposed.
• Impact Ignition has very attractive features.• Major breakthrouh expected in future
experiments is to demonstrate highimplosion velocities at relatively lowisentropes.
Pb Coating on Target for Magnetic Motion Control
Ryusuke Tsuji
Ibaraki University
3 rd Japan-US workshop18-19 Oct 2004 Osaka
Outline
• Development of orthogonal slit type pinholemotivation, principle
• Pb coating on target for magnetic controlsuperconductivity sustaining timeflight distancemagnetic lense
Pb coating of target• Au reflective coating is analysed
( e.x. R. Petzoldt et.al, Nucl. Fusion 42(2002)1351)
↓
• Pb is used in LiPb blanket• Pb has superconductivity (Tc=7.2K)• Target injection system accompanies cryogenic (T=18-
19K) apparatus↓
• Pb coated target cooled to 4.2K is superconductor
Magnetic Control (Magnetic Lense)
• Lense
• Magnetic Lense is considerd as static feedback
Monochromatic light focuses automatically (no dynamic control)
Trajectory of target of same velocity focuses automatically
S
N
Principles of simple magnetic lense
ya
f c
• Mometum transfer P(y)• Fdt=k/(a-y0)d × b/V= mV(y/c)+mV(y/f)
b
a
P(y)
y
Pb coating of target (Cont.)
• Target ParametersConventional spherical direct driveRadius 2[mm]Pb coating thickness 0.05[μm]
( Skin depth of Pb is 0.04 [μm] by A. C. Rose-Innesand E. H. Rhoderick, “Introduction to Superconductity, 2 nd ed.” Pergamon 1978)
Initial temperature 4.2[K] Tc=7.2[K]
S.C. sustaining time
Allowable heat Qmax from s.c.(4.2K) to n.c.(7.2K)
• Qmax = mCΔT = 4πr2 Δrρ∫4.2 7.2 C(T)dT
( C(T)=βT3+γT, β, γ, M. Horowitz et.al. PR88(1952)1182 )= 1.914×10-7 [J]
m: Mass of Pb layer C: Specific heat of PbΔT: Temperature increase (4.2K to 7.2K) r: Radius of target Δr: Thickness of Pb layerρ: Density of Pb
S.C. sustaining time (Cont.)
• t in 10 m long injection system (4.2K) with holeinjection point : endinjection speed 100 [m/s]injection hole with 2[cm] radius open
reactorinjection system
S.C. sustaining time (Cont.)
0.5×Qmax = (1-R) σ T4 πr2 ∫0 t F(t)dt
=0.1× 2.3226× 0.2513×∫0 t F(t)dt
Heat is transported from the holeF(t) =πa2 / (2π(L-Vt)2)T=800, V=100, L=10, a=radius of the hole
t = 0.09425 [sec] ( R = 0.9 case)D =9.425[m]
Enough sustaining time (distance) is obtained
Summary
• Orthogonal slit type pinhole is under development (to be presented in 4 th Japan-US Seminar)
• Pb coating on target is proposed. Target with Pb coating at 4.2 K becomes superconductor. It enables us to control motion of the target in the injector by the magnetic field
• Static magnetic lense system for target control is proposed. If the release point and the velocity of the target are fixed (even though the direction varies), then we can expect that the magnetic lensesystem can focus s.c. target at fixed point
ILE, Osaka
Fabrication of FI Target for FIREX and Fuel Loading for Future Reactor
T. Norimatsu
Institute of Laser Engineering, Osaka UniversityPresented at Japan/US workshop on IFE Target Fabrication, Injection and Tracking
ILE, Osaka
Outline
• Introduction– Program,
• Status of Target Fabrication in Japan– Collaborative work– Activities at ILE
• Fueling system for Reactor– Thermal cavitation technique – Pneumatic/coil gun hybrid system,– Estimation for operation power
ILE, Osaka
The FIREX-I project has been started under collaboration with National Institute for Fusion Science.
FY 02
FY 03
FY 04
FY05
FY 06
FY 07
FY 08
FY 09
FY 10
FY 11
FY 12
FY 13
FY 14
FIREX-I (Heating of DT plasma to 5keV)
FIREX-II (Demonstration of ignirion and burn)
10kJ/10ps Upgrade to 50kJ1 PW 1 kJ/1 ps
Construction of compression laser
Upgrade to 50kJ
Gekko XII 10 kJ/2ns/0.53um
Fuel capsule with cone
(CoLab)
(CoLab)
(ILE)
(ILE)
(ILE)
(NIFS)
(CoLab)
(NIFS)
Laser for heating
Laser for compression
Construction of heating laser
Implosion experiment of cryogenic target
D 2 D T D T D T
Licence work
Cryogenic plane target
Demo of cryogenic foam method
Characterization of solid layer
D EF
D EFCryostat for implosion Exp. 1
Cryostat for implosion Exp. 2
Low density foam
トリチウム回収装置上部冷凍機
下部冷凍機
トリチウム
供給装置
Diameter 2mm Solid DT 100um DT 60 mCi
ILE, Osaka
Fabrication of transparent foam shell for FIREX-I, low density foam shell for FIREX- II and LiPb cone for reactor are critical issues.
• FIREX-I(Heating to 5keV)– Fabrication of Transparent
foam shell to allow characterization
– Machining of fragile foam shell
• FIREX-II(Ignition and burn)– Low density foam
• Reactor(Gain >170)– Mass production of LiPb cone– Fuel loading
3 mm
5 mm
2 mm
0.8 mm
0.5 mm
For FIR EX -I
For FIR EX -II
3.46 mm
5 mm
8.5 mm
5 m
m
3.5 mm
15o
1.06 mm
24.5oFor R eactor
ILE, Osaka
We are going to demonstrate RF foam method with NIFS.
For FIREX-IThe first step of Cryogenic foam method is to evaluate the quality of ice
•Diameter:500µm•Fuel layer:~20µm•With glass tube•D2 or DT fuel
Liquid phase
Freezing -15 % in volume
Partially dry foam?
Porus ice?
How much DT sublimates through the feeder / vent hole?
?
ILE, Osaka
Specification of Cryogenic Target and Apparatus are;
Cryogenic Target
• Diameter:500µm• Fuel layer:~20µm• With glass tube• D2 or DT fuel
Apparatus
• 4K-GM Cry cooler• Minimum temperature:<10K• With four view ports• Prevent target vibration:<several µm
For FIREX-I
~20µm<1µm
500µm
Glass tube
ILE, Osaka
Apparatus to demonstrate foam method is almost fabricated. Cooling test will start soon at NIFS.
Target Chamber
4K GM Cry cooler• 1st Stage: 45 W @50K• 2nd Stage: 1.5 W @4.2K
Welded Bellows
Target
ILE, Osaka
Target Fabrication at ILE
• For central ignition– Fabrication of polyimide shell by emulsion process
• For fast ignition– Foam shell
• PMMA, TMPT foam• RF foam
– Parabroide Cone• Diamond lathe• Laser lathe (To be reported by Y. Kawamura, Fukuoka
Institute of technology)
ILE, Osaka
If the foam is PMMA, we can make required foam shell with gas barrier and reentrant cone.
OW2
1st orifice
2nd orifice
W1
XYZ stage(for 1st orifice)
3rd orifice
XY stage(for 3rd orifice) Gas barrier coating by
interfacial polycondensation
• Fuel shell– Emulsion method followed
by interfacial polycondensation method
– Hole boring on frozen foam shell
• Cone– Electro plating on
removable mandrel machined with diamond lathe
ILE, Osaka
Hole for cone could be bored into frozen foam with normal drill. Large scattering, however, disables optical characterization of cryogenic layer.
Ice
Freeze dry of foam shell
X-ray image SEM image of hole side
ILE, Osaka
We are now applying previous method 1)
for shell process
Frin
ge v
isib
ility
Foam thickness ( µm)
0.1
1
0 50 100 150 200
3%1.5%
0.9%
0.3%
Previous foamsOptical image of a 220 µm diameter foam ball in the air. TMPT 3%, AIBN 3%, Thermally initiated polymerization.
A B
255
0 White
Black
Fringe visibiliy = B/A
1) M. Takagi, T. Norimatsu, Y. Izawa and S. NakaiMat. Res. Soc. Symp. Proc. 372 199-202 (1995)
ILE, Osaka
We have started fabrication of Resorcinol -Formaldehyde (RF) foam 1) that is transparent due to its fine structure.
RF foam shells with the density ranging 150-250 mg/cc are successfully fabricated but further effort is necessary to improve the uniformity.
•In the case of RF foam, freezing method can not be used to hold the shell during drilling because phase separation takes place, which increases the scattering of light.
Excimer laser etching
1) Stephen M. Lambert , George E. Overturf Journal of Applied Polymer Science, Vol.65,2111-2122(1997)
ILE, Osaka
To make a hole on fragile RF foam shell with gas barrier 1), we used excimer laser etching followed by punching.
ArF laser
Cushion
Mask
Vacuum chuck
Punch out
0
5
10
15
20
25
30
0.01 0.100 1.000
Fluence [J/cm2]
Etch
Rat
e [u
m/1
00pu
lse]
PS
RF-foam [120mg/cc]
GDP
1) Shells were presented by GA.
ILE, Osaka
Spiky structure is attributed to shrinkage of RF foam by UV irradiation.
• When the density of foam is about 1, etched surface was flat. Irradiation of UV light induces shrinkage of RF foam.
ρ=1.02 g/cc, etched surface was flat. ρ=250 mg/cc, Shortly after beginning of etching.Cracks appeared on the etched surface.
ILE, Osaka
We found promising method to make a hole on RF foam.
300 µm
30 µm10 µm
Laser Machining in air Laser Machining in water
• Laser machining in air make deformation of nearby foam, resulting large opening. Machining in water can make sharp cut.
ILE, Osaka
Fabrication of parabolic cone as a focusing device.• In a future power plant, some focusing mechanism is necessary to heat the
compressed core up to the ignition temperature because of diffraction limit of the final optics.
• This paraboloid mirror design enables 80% of laser energy in 300 µm spot focused on the 40 µm diameter spot with one bounce.
100
0
100
0 100 200 300 400 500
40 µm
10 µm
Focusing point300 µm
(200 nm Au coating)
Estimated beam waist 300 µm
100µm10µm
40µm
Paraboloid mirror
Focusing spot
Target Injector
Compression beam
Ignition beam
Final optics
30 m
ILE, Osaka
To test the focusing effect, paraboloid cone was fabricated with diamond lathe.
0
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
0 50 100 150 200 250 300 350
Y = M0 + M1 * x + . . . M8 * x 8 + M 9 * x 9
7 7 5 .5 4M 0
-8 .2 1 1 4M 1
0 .0 2 2 1 4 8M 2
0 .9 9 8 8 9R
Distance (µm)
Dis
tanc
e (µ
m)
After edge detection, inner surface finish is calculated to be 2µm in RMS.
ILE, Osaka
Summary
• Mass production of the FI target strongly depends on the successof foam method. If we could well understand the foam method so that we can skip individual optical characterization, transparent foam is no longer necessary and mass production of shells, machining and fuel loading are in our scope.
• Remaining issue in FI target is;– Demonstration of foam method using transparent foam shell,
which will start soon with collaboration of ILE and NIFS.– Mass production of cone
ILE, Osaka
Summary (continued)
• Concept of fuel loading by thermal cavitation method is proposedfor batch process in future power plant.
– Remaining issue; Ice quality, Sublimation during cooling
• Preliminary estimation of driving power for fueling system was 1MW / 2 Hz unit, which seems acceptable.
Thank you for your attention
Possibility of the application of the five axis laser micromachining systemto the ICF target fabrication
Yoshiyuki Kawamura Fukuoka Institute of Technology
3rd Japan US Work shop on target fabrication, Oct.18.04
Experimental setup for five axis laser micromachining
TTL board
5 axis stage
4th harmonic of Q switched Nd-YAG laser (266nm, 10ns, 0.1mJ, 30Hz)
Five axis stage
Five axis stage
Laser beam
X axisZ axis
ωaxis
Θ axis
Y axis
Fabrication of a micro sphere using 3 axis (ω, x, z) laser micro machining
Diameter: 260μm
Alignment between these 3 axes is essential for precision machining
Micro windmill
Micro windmill of diameter 780μm that have ten blades.
Enlarged view of blades.
Windmill & Bearing
Micro globe (polyimide)
Micro globe with the diameter of 1 mm.
One cent coin and micro globe.
ILE have the plane to focus the ignition laser into the center of the target using a micro parabolic mirror
100 0 1000
100
200
300
400
500
40 µm
10 µm Focusing point
300 µm
(200 nm Au coating)
3 mm
5 mm
Li17Pb83
2 mm
40 µm
Estimated beam waist 300 µm
100µm10µm
40µm
Paraboloid mirror
Focusing spot
by Prof. Norimatu (ILE)
To make parabolic cone, aluminum mandrel was machined with laser lathe.
y = -0 .028x2 + 6 .9391x - 206 .18
0
50
100
150
200
250
0 50 100 150 200 250
X(μm)
Y(μ
m)
試料Eの実際加工ライン
二次近似曲線
To check the focusability, concave mirror was copied with epoxy resin.
LD
Milky liquid
CCD
フィルム
エポキシ系樹脂
放物面形状試料WorkEpoxy resin
Film
Parabolic micro cupper mold for the electroforming of the micro parabolic mirror
( surface roughness)
2 um
Boundary between the background shows that the surface roughness is less than 1um
Conclusions and future prospects
Fabrication of the advanced ICF target fabrication is one of the application of the five axis laser micromachining system. Micro cupper parabolic mold has been successfully fabricated using two axis laser micromachining.Machining error of the parabolic mold should be improved to be as small as 1μm.
Experimental setup of coil gun
Coil gun
×6
Length 14mmOD 90mmID 22mm30μH
Sleeve
Delay pulsar
Trigger
High voltagepower supply0-250 V
Oscilloscope
75×15φ(Al)
Stopper
Photodetector
LD
Nd:YAG laser(Minilite -Ⅱ)
CCDcamera Shunt Shunt Shunt
Trigger in
Coil gunLength 104 mmNumber of phases 3Number of barrel coils 6
BarrelLength 14 mmOuter diameter (OD) 88 mmInner diameter (ID) 20 mmNumber of turns 12Self inductance 30 μHCapacitance 1980 μFCharge voltage ≦ 300 V
SleeveLength 75 mmOuter diameter 15 mmThickness 1 mmMass 8.86 gMaterial Aluminum
Gifu Univ.
Maximum acceleration was 580G, which is sufficient to accelerate a target to 300m/s in 20m.
0
2
4
6
8
10
200 400 600 800 1000 1200
Time delay t C (ms)
Sle
eve
velo
city
vs
(m/s
)
↑tB
Vb = 250 Vt B = 200 μsmS = 8.86 gzinit = 12 mmTa = 300 KP = 106 Pa
Sim.
Expt.
μ
0.1
1
10
100
10 100 1000
Condenser bank voltage V b (V)
Sim. Expt.
580G
t B = 200 mst C = 600 μsms = 8.86 gzinit = 12 mmTa = 300 KP = 106 Pa
Gifu Univ.
(a)
(b)
100mm
TargetdetectorStopper
(a) The coil gun before target shot and (b) the irradiated target by Nd:YAG laser.
Correlational detection by matched filter
Opt. Wedge
He-Ne laserM
MFourier conv. lens f=5000
BEMatched filter
CCD camera
Inv. Fourier conv. Lens f=5001460 5032 502 502
3572
5.8mm
2mm
cone-target 1mm
Gifu Univ.
Accuracy of detection was 140 µm at 5 m apart.
Intensity (a.u.)
xout (mm)0
0.31
Inte
nsity
(a.u
.)
y out(
mm
)0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0
σ= 0.14mm
Target position x (mm)
Detected position xout×10 (mm)
Gifu Univ.
The accuracy will be improved withuniform irradiation,f-number,linearity of film to make filter.
Measurement of tumbling of Sabot in Barrel
Tumbling is measured by trajectory of reflected LD beam on screen
Off-axis position, r=2.5mm Coaxial position, r=0mm
Tumbling angle is smallcomparing with 3.9deg defined by clearance in barrel
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 0.5 1 1.5 2 2.5 3
Time (ms)
Tum
blin
g A
ngle
(°)
Coaxial position, r=0mm
Target container designφ6.213φ
2
14
9
φ6.213φ
2
14
φ7.2
6
φ6.213φ
2
14
φ6.213φ
2
14
9
φ6.7
6
Four configurations of target container are tested
φ6.213φ
2
14
φ6.213φ
2
14
φ7.2
6
φ6.213φ
2
14
9
(xav,yav) = (5.9,-5.5)σr = 27.3 mm
(xav,yav) = (9.8,-1.0)σr = 32.1 mm
(xav,yav) = (5.5,-5.9)σr = 31.8 mm
(xav,yav) = (9.0,-4.8)σr = 23.1 mm
φ6.213φ
2
14
9
φ6.7
6
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