1
Yasukazu IzawaInstitute of Laser Engineering, Osaka University
5th US-Japan Workshop on Laser IFE March 21-22, 2005General Atomics
Development of HALNA DPSSL for IFE
2
Tadashi Kanabe*, Masanobu Yamanaka**, Ryo Yasuhara, Junji Kawanaka, Noriaki Miyanaga, Takayoshi Norimatsu,
and Masahiro Nakatsuka Institute of Laser Engineering, Osaka University
*Fukui University** Graduate School, University of Advanced Photonics
Osamu Matsumoto, Toshiyuki Kawashima, Takashi Sekine, Takashi Kurita, Tadashi Ikegawa, Masahiro Miyamoto,
Takeshi Kanzaki and Hirofumi KanHamamatsu Photonics K.K.
Hiroyuki FurukawaInstitute for Laser Technology
ILE OSAKA
Contributors
Institute for Laser TechnologyILE OSAKA
3
ILE OSAKA
ţIgnition & burnRepetition testFIREX-IFIREX-II2005201020152020202520302035100J1kJţPower Generation: 2MWeţPractical Power Demonstration
Advanced LaserReactor Technology Development (Blanket, Liquid Metal, Final Optics, Tritium, Material, Safety)
Output:100Å`200MWeDEMODesign2003Experimental Reactor (LFER)EngineeringDesign
Laser: 200kJ/1Hz, Thermal output:10 MWthTarget Fabrication and Injection Reactor Chamber & Liquid Wall Technology10kJDriver DevelopmentConceptualDesign
By IFE Forum (2003)
Roadmap for Laser Fusion Energy Development
4
ILE OSAKA
Laser for implosion: 100kJ
Reactor chamber Laser for heating 100kJ
Target injector
Turbine generator4MWe
FIREX LFER (10MJ, 1Hz) DEMO1MJ Solid wall Liquid wall 200MJ, 3Hz
Laser Fusion Experimental Reactor (LFER)
5
ILE OSAKA
Two approaches for IFE driver development
◇ HALNA (High Average-power Laser for Nuclear-fusion Application) conceptual architecture consists of water-cooling, Nd:glass medium and zig-zag slab geometry and multi-pass amplifier.
◇ Current goals of the HALNA are 100 J pulse energy, 10 Hz operation and beam quality less than 5 times of diffraction limit (TDL) with 10% overall efficiency.
◇ New approach is to use cooled Yb: YAG ceramic slab. (20 x 20 x 5 cm for 1kJ, T = 150 ~ 225 K) (To be presented by J. Kawanaka)
6
ILE OSAKA
HALNA: High Average-power Laser for Nuclear-fusion Application
Output10 kJ (351 nm)OscillatorMirror1D ExpanderPolarizerFaraday Rotator PolarizerGain MediaSpatial F ilter1601002010010050014555Mirror6040150ω3KDP (for Main Amplifier Path)Isolator {Mirror130Mirror(for Main Amplifier Path)Pockels C ell & Mirror {250Phase-coupling Mirror2055(for Pre-Amplifier Path)Inputμ10 J /beamlet& λ/2 Plate Åõ(45 )Åõ(45 )(for Pre-Amplifier Path)Faraday RotatorMirrorÅEDiode-pumped solid-state laserÅEWater-cooled Nd:glass gain mediumÅEZig-zag slab geometryÅEMultipass amplifier architectureÅEPhase-coupled beam combining
10 kJ output energy at 351 nm10 Hz repetition rate10 % overall efficiency
LDLD (40 x 5 cm2) x 2Pumped region12 cm52.3 cmLDLD2 cm2 cm52.3 cm12 cmLDLD(40 x 1 cm2) Pumped regionHALNA 10(10 J x 10 Hz)HALNA 100(100 J x 10 Hz)HALNA 1K(1 kJ x 10 Hz)
(40 x 50 cm2) x 2Pumped regionLDLD2 cm56 cmLD52.3 cmLD0.2 MW diode-pumping2 MW diode-pumping20 MW diode-pumping
HALNA conceptual design includes diode-pumping, HALNA conceptual design includes diode-pumping, water-cooled glass and zig-zag slab optical geometry.water-cooled glass and zig-zag slab optical geometry.
7
FY2002 FY2003 FY2004 FY2005 FY2006
HALNA 10 (10 J x 10 Hz)
HALNA 50 (50 J x 10 Hz)
HALNA 100 (100 J x 10 Hz)
Pump intensity : 2.5 kW/cm2
Zig-zag slab geometry : SSG 10Beam fluence : 5 J/cm2
Pump efficiency : 50%Stored energy density : 0.5 J/cm3
Extraction efficiency : 50%Opt.-opt. Efficiency : 20%1/5 fracture limit operation Dual amplifier head
Full aperture : 12 cm2
Fluence : 8 J/cm2
Larger apertureEdge-cladding for parasiticFluence: 5 J/cm2
1/3 fracture limit
Part of research is supported by NEDO(New Energy and industrial technology Development Organization) under METI (the Ministry of Economy, Trade and Industry),Japan.
20 J x 10 Hz DPSSLfor NEDO project
ILE OSAKA
Research and development plan for HALNA 100
8
ILE OSAKA10J/10Hz system HALNA 10 has been developed.
1053 nm10 J, 10 Hz, 10 ns< 5x TDLWaterOscillatorPre-AmpSpatial filter - 1Spatial filter - 2Laser OutputLD modulesNd:glassFaraday rotatorExpanderApertureSlab amplifier headLD module for pumpingSlab amplifier : 8x10x240 mm 4 pass, Diamond geometryFaraday rotator for thermal effect compensation
Pre-AmpOscillator
Zig-zag slabAmplifierSpatial filter
9
Left bank(Module 1)
Right bank(Module 2)
Output peak power 120 kW
Emission wavelength 803 ±1nm,
Bandwidth < 4 nm (FWHM)
Material AlGaAs
Peak pump intensity 2.5 kW/cm2
Wall plug efficiency > 50 %
Diode current 100 A
Repetition rate 10 Hz
Pulse width 0.2 - 0.4 ms
Duty 0.2 - 0.4%
PHOTON IS OUR BUSINESS
Pump module performance
Total 2,400 bars have been integrated into two pump diode modules. Those have been activated in October, 2003
10
0
40
80
120
160
0
15
30
45
60
0 20 40 60 80 100 120 140
Peak power and efficiency
Module 1 (Left bank)
Module 2 (Right bank)
Module 1 (Left bank)
Module 2 (Right bank)
Current [A]
HALNA driver requirements
52.1 % at 100A
52.8 % at 100A
145.4 kW at 120A
145.7 kW at 120A
Repetition rate : 10 HzPulse Width : 200 μsCooling water temp. : 25 deg.
55 %
E-O
con
versio
n e
fficien
cy [%
]
Pe
ak
po
we
r [k
W]
0
0.2
0.4
0.6
0.8
1
1.2
790 795 800 805 810 815 820
Spectral profile
Module 1 (Left bank)Module 2 (Right bank)
Wavelength [nm]
LD Current : 100 ARepetition rate : 10 HzPulse Width : 200 μsCooling water temp. : 25 deg.
FWHM : 3.39nm
Peak wavelength : 804.13 nm
Inte
nsi
ty
[a.u
.]
Total 290 kW output peak power was successfully achieved from total 2,400 diode bars at 804 nm.
Left bank (1,200 bars)Lasing !
ILE OSAKA
11
Emission cross section 3.6 x 10-20
Fluorescence lifetime 350 µs
Thermal conductivity 1.02 W/mK
Thermal expansion coefficient 8.5E-6 K-1
dn/dt 1.8E-6 K-1
Absorption coefficient 2.31 W/cm
Physical propertiesHAP-4(Nd:1.1wt.%), HOYA Co.
Amplifier housing
34 cm (length) x 1 cm (width) with slab aspect ratio 2:1
Sol-gel coated at incident faces
Geometry for preventing parasitic without edge cladding
□
□
□
ILE OSAKAILE OSAKA
Nd doped phosphate glass laser material is suitable Nd doped phosphate glass laser material is suitable for high energy DPSSL applications.for high energy DPSSL applications.
12
Results of thermal effect analysis
Thermal analysis by LASCAD and THESLAC codes optimized slab dimension.
Physical properties.
Insulator
Height of glass
Teflon 10mm : É…=0.25W/mHighly insulatedmaterial10mmÅFÉ…=0.025W/m
without heat flux
(mm)
Maximumtemperature
diffrence ( K )
thermal lens focallength ( m )
Effciency ofpump light ( % )
Depolarizationloss (%)
Maximumtemperature
difference ( K )
thermal lensfocal length ( m )
Thermal lensfocal length ( m )
21 3 140 88 5.4 -100
22 4 90 97 6.2
23 6 90 100 7.7
24 100
25 8 28 100 6.7 7 35
(1) (2) (2)
LASCAD gives temperature, stress and deformation of laser glass .THESLAC code calculates wavefront distortion and birefringence.
ILE OSAKA
Nd:HAP4
Thermal conductivity:É… 1.02E+00 W/(mK)
Coefficien of thermal expansion 8.50E-06 1/K
Elastic modulus 68800 N/mm^2
Poisson's ratio 0.236
Refractive Index 1.533
Temperaturdependence of refractivindex dn/dT 1.80E-06 1/K
Absorption coefficient, 0.231 W/mm:
Heat efficiency factor 0.3Slab pumping geometry
LD module
Insulator
Height of glass
5°
13
Thermal modeling revealed optimum slab height for minimizing thermal lensing effects
1.Temperature distribution
4.Thermal birefringence3.Wavefront distortion
Tem
pe ra ture ( K )
Lo ss ( % )
Slab height ( mm ) Slab thickness ( m
m )
λ( μm )
-5
0
5
10
15
20
25
-2 0 2 4 6 8 10 12
2. Thermal deformation
Sla
b he
ight
( m
m )
Slab width ( mm )
Slab height ( mm )Slab th
ickness ( mm )
Slab height ( mm )Slab th
ickness ( mm )
Thermal analysis results by THESLAC code ■ Optimum range of slab height
ILE OSAKA
Slab height must be carefully decided, taking into account of pump efficiency and thermal lensing effects.
Thermal lensfocal length
Maximum temperature difference
Thermal lensfocal length
Maximum temperature difference
14
0
5
10
15
0.0 0.1 0.2 0.3
Input [J]
Output [J] Pumping length Beam width
268mm 10mm
268mm Å@8mm
Output energy greater than 10 J is predicted .
Input energy vs. output energyBeam width vs. output energy Input energy : 0.1 J
ILE OSAKA
Output energy was analyzed based on Frantz- Nodvik and Eggleston- Frantz equations.
Pumping length : 26.8 cm Pumping energy : 48 J
15
The HALNA10 has successfully yielded 84-W average power at 10 Hz in December, 2004
10.6 J operation at 1 Hz 84 Waverage operation at 10 Hz
Filling factor : 49%
2TDL
Near-field Far-field7.6mm
17
mm
Near-field
Filling factor : 63%
26 ns (FWHM)
Far-field
ILE OSAKAILE OSAKA
2TDL
16
Component Parameter Goal Result
Pump diode
Output peak power 120 kW 145 kW
Pump intensity 2.5 kW/cm2 2.59 kW/cm2
Emission wavelength803 ±1nm,
<4 nm(FWHM)
804.1nm,
3.4 nm(FWHM)
E – O efficiency 55% 52%
Slab amplifier
Small Signal Gain 10 8.5
Pumping efficiency 45% 45%
Total system
Repetition rate 10 Hz 1 Hz 10 Hz
Output energy 10 J 10.6 J 8.4 J
Extraction efficiency 45% 43.9% 34.9%
O – O efficiency 20% 19.9% 15.8%
E – O efficiency 10% 10.3% 8.2%
Filling factor 50% 49% 63%
Beam quality < 5TDL80%
(<5TDL)70%
(<5TDL)
ILE OSAKAILE OSAKA
The HALNA 10 has virtually accomplished their The HALNA 10 has virtually accomplished their goals, demonstrating the feasibility of IFE drivergoals, demonstrating the feasibility of IFE driver
17
Yb: doped fiber oscillator
Nd: YLF regenerative amplifier (8mm, 0.5J/10ns)
Nd: glass slab amplifier (5 x 1 x 30 cm, 4 pass)
2 slabs: 25J/10ns, G0 = 3
1 slab: 20J/10ns, G0 = 6.3
Wavefront control: deformable mirror/phase conjugate mirror
ILE OSAKA
HALNA 50/20 has been designed and is under construction.
18
HALNA 50/20 with thermally-edge-controlled slab (TECS) amplifier
ILE OSAKAILE OSAKA
200-kW diode module(2000 bars)
200-kW diode module(2000 bars)
Cooling water
Laser slab
Edge claddingEdge heater
Laser beam
Diamond geometrydue to zigzag path
Delivery optics
38 cm
Laser material: Nd:phosphate glassSlab size: 5 x 1 x 30 cmPump energy: 80 JSmall signal gain: 3/pass
19
Overlapping pump irradiation from each diode stack is effective in obtaining 10% uniformity on the slab face
50
0-200 -150 -100 -50 50 100 150 200Position in mm
0
25
-50
-25
Po
sitio
n in
mm
VerticalHorizontal
Pump area : 300 mm x 50 mm Pump intensity : 1.3 ~ 2.5 kW/cm2
Pump duration : 150 ~ 300 µs Stored energy density : 0.19 ~ 0.32 J/cm3
Small signal gain : 3.0 ~ 6.3 /pass
Pump distribution on slab face (simulated by 3-D ray tracing)
Diode facet
Laser slab
Pump light
Lens cassette
Effective pump area
ILE OSAKAILE OSAKA
20
ILE OSAKA
◇ HALNA driver for IFE has been developed.
◇ The HALNA 10 has achieved 8.4 J at 10 Hz with beam quality of 2 xDL in December, 2004.
◇ A larger slab amplifier with 5-cm2 aperture has been designed, and it is under construction. ◇ In 2005, the dual slab system will demonstrate the 20 J x 10 Hz operation with a wavefront correction for the NEDO project.
◇ In 2006, a half of HALNA 100 will be constructed with 10-cm2 aperture, the 50 J x 10 Hz operation will be the objective of the moment.
Summary
21
ILE OSAKA
ILE at Osaka collaborates on HALNA project with Hamamatsu Photonics and ILT
22