nov 5-9, 2006 iaea meeting, vienna, austria 1 target and chamber technologies for direct-drive...
Post on 15-Jan-2016
219 views
TRANSCRIPT
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 1
Target and Chamber Technologies for Direct-Drive Laser-IFE
Presented by A. René Raffray
Scientific Investigators: M. Tillack, R. Raffray, F. Najmabadi
University of California, San Diego
1st RCM of the CRP on Pathways to Energy from Inertial Fusion - an Integrated Approach
IAEA HeadquartersVienna
November 5-9, 2006
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 2
Electricity Generator
Targetfactory
Modular LaserArray
• Modular, separable parts: lowers cost of development AND improvements
• Conceptually simple: spherical targets, passive chambers
• Builds on significant progress in US Inertial Confinement Fusion Program
Proposed Work Within Context of High Average Power Laser (HAPL) Program
Target injection
(engagement and surviva)
Chamber conditions (physics)
Final optics (+ mirror steering)
Blanket (make the most of MFE design and R&D info)
System (including
power cycle)
Dry wall chamber (armor
must accommodate ion+photon threat and
provide required lifetime)
• Multi-institution Activities led by NRL with the Goal of Developing a New Energy Source: IFE Based on Lasers, Direct Drive Targets and Solid Wall Chambers
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 3
Proposed Research(as part of HAPL Program)
a) Target engagement. We will develop and demonstrate systems to track direct-drive targets in flight and to steer multiple driver beamlets onto the targets with the precision required for target ignition. Bench-top experiments will be performed in order to demonstrate the feasibility of these systems and to characterize their performance.
b) Chamber design studies. We will develop chamber design concepts that integrate armor and structural material choices with a blanket concept providing attractive features of design simplicity, fabrication, maintainability, safety and performance (when coupled to a power cycle). Advanced concepts (including magnetic intervention) that could result in smaller less costly chambers, better armor survival and lower cost of electricity also will be investigated.
c) Chamber armor thermomechanics. We will perform modeling and experiments on candidate chamber armor materials. The goal of this work is to develop solid armors capable of withstanding cyclic thermomechanical loading expected in direct-drive IFE chambers.
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 4
Target Engagement
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 5
Year 1:Utilize lab-scale injection equipment to support the development of target engagement methods. Field and test individual elements, including Poisson spot detection, Doppler fringe counting, glint alignment, fast mirror steering and real-time software integration.
Year 2:Combine benchtop systems and extend performance.
Year 3:Perform integrated demonstration of target engagement. Install all engagement systems on a prototype injector using full-speed electronics, full-power light sources and full-aperture optics.
Proposed Work Plan for: a) Target Engagement
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 6
Target engagement research is performedin collaboration with General Atomics
L. Carlson1, M. Tillack1, T. Lorentz1, J. Spalding1
N. Alexander2, G. Flint2, D. Goodin2, R. Petzoldt2
(1UCSD, 2General Atomics)
Power plant requirements:• 20 µm engagement accuracy in (x,y,z) • ~20 m standoff to final optic• 5-10 Hz rep rate
• Purpose: To individually demonstrate successful table-top experiments of key elements, then integrate together.
• Final goal: Provide a “hit-on-the-fly” target engagement demo meeting accuracy requirements.
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 7
Benchtop experiments simulate all of the key elements of a power plant engagement system
• Poisson spot, fringe counting, crossing sensors, verification:
– Provide in-flight steering instructions & diagnostic, backup.
• Glint & coincidence sensor:
– Aligns beamlets & provides final steering instructions
crossingsensorsC2C3C1pulsed glint
laser (1064 nm)alignment & driver beam
(635 nm)
verification camera
retroreflectorcoincidence sensor
Poisson spot
camera
fast steering mirror
focusing mirrorwedged dichroic mirror
chamber center
Poisson (632 nm) & fringe counting
(1540 nm) beams
fringe counter
microlens array
collimating lens
drop tower R. Petzoldt, et al., "A Continuous,
In-Chamber Target Tracking and Engagement Approach for Laser Fusion," 17th ANS Topical Meeting, to be published in Fusion Science and Technology.
1
2
3
4
5
5
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 8
Poisson spot
camera
Poisson (632 nm) & fringe counting
(1540 nm) beams
• Goal is to know centroid position to ± 5 µm every 5 ms
• Looks achievable
#1. Transverse target motion is tracked using Poisson spot centroiding
2) Brightness/contrast adjustment ~1 ms
1) Capture image ~1 ms
3) Threshold pixels above a certain value ~4 ms
4) Remove border objects ~2 ms
6) X,Y centroid computed with < 5 µm error (1) ~1 ms
5) Particle filter ~1 ms
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 9
Poisson (632 nm) & fringe counting
(1540 nm) beams
fringe counter
reference leg
• A Michelson interferometer is used, with noise mitigation, signal processing and modifications for plane/spherical wave mixing.
#2. Fringe counting provides continuous z-axis tracking, with accuracy goal of ~1 part in 106
0
2
4
6
8
10
12
14
-7.65 -5.15 -2.65 -0.15 2.35 4.85 More
Scale (µm)
Frequency
Fringe count repeatability over 5 m using a 4-mm steel sphere
• So far, operation is limited in range and standoff (power, noise, bandwidth, …)
• May predict velocity (vs. full z-axis tracking)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 10
crossingsensorsC2C3C1drop tower
#3. Crossing sensors initiate fringe counting and may be sufficiently accurate to supplant the interferometer
C1
C2
C3
Real-time Position Prediction Repeatability at C3
0
1
2
3
4
5
6
7
8
Prediction Discrepancy (µm)
Number Observed
-75 -50 -25 0 25 50 75
• New real-time operating system reports on-the-fly placement repeatability of 45 µm (1) at C3.
=> Sufficiently precise to trigger glint laser
Sphere dropping mechanism
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 11
alignment & driver beam
(635 nm)
verification camera
chamber center
microlens array
collimating lens
4 mmfalling targetSide viewsimulated
driver/alignment beam
camera/PSDmicro lens array
collimating lens
micro lens array
collimating lens
simulated driver beam
#4. To demonstrate successful engagement, we developed a high-precision verification system
target target eclipses eclipses
verification verification beamletsbeamlets
(Diffraction-limited beamlet waist ~75 µm)
PSD Y Signal+V-Vtime0
Camera triggers here if timing prediction is perfect
1 µm precision when the target is within the 4 beamlets
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 12
pulsed glint laser (1064 nm)alignment & driver beam
(635 nm)
retroreflectorcoincidence sensor
fast steering mirror
focusing mirrorwedged dichroic mirrormicrolens
arraycollimating
lens
4 mmChopper wheel alternates between alignment signal... Driver/alignment
beam is steered to coincide with glint
signal
...and glint signal.
#5. The glint system provides final position update and closes the beam steering loop
Optics In Motion FSM
• Stationary demo performed with 18 µm accuracy in 8 ms
• Full demonstration in progress
1) Fast steering mirror keeps alignment beam
centered in the coincidence sensor.
2) Glint return provides error between alignment
beam & actual target position 1-2 ms before
chamber center.
3) Error signal provides final correction to FSM.1 2 3
7 ns
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 13
Time sequence of tracking & engagement demo - START
target is injected
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 14
alignment & driver beam
(635 nm)
Poisson spot
camera
chamber center
Poisson (632 nm) & fringe counting
(1540 nm) beams
microlens array
collimating lensPoisson spot
centroiding system begins transverse
tracking
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 15
chamber center
fast steering mirror
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 16
chamber centerretroreflectorcoincidence
sensorFSM maintains alignment
beam on coincidence sensor, which represents position where simulated
driver beam enters chamber
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 17
chamber centerzero-
crossingsensor
fringe counter
begin axial tracking by counting
interference fringes
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 18
chamber center
C2-C1 determines
velocity
C2C3C1
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 19
chamber center
C3 verifies timing
prediction
C3
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 20
chamber center
glint laser fires 1-2 ms before chamber
center, alignment beam turns off
pulsed glint laser (1064 nm)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 21
chamber center
focusing mirrorwedged dichroic mirror
glint return registers on
sensor, providing final steering instructions
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 22
chamber centerFSM steers driver beam to coincide with glint return
FSM
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 23
Time sequence - ENDchamber
centersimulated pulsed
driver beam engages target
verification camera confirms accurate
engagement
verification camera
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 24
Chamber Design Studies
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 25
Year 1:Perform initial scoping studies of advanced chamber options (including blanket and armor). Possible design scenarios range from large chambers without a protective chamber gas to smaller chambers with magnetic intervention. Studies include concept development and sufficient scoping design analysis to allow for a reasonable assessment of each concept based on key criteria including performance (when coupled to a power cycle), lifetime, fabrication, safety and maintenance.
Year 2:Conclude scoping studies and perform assessment and comparison of different chamber options to converge on the most attractive concept(s). Develop possible design solutions for ion dumps in the case of magnetic intervention.
Year 3:Perform detailed design analysis of preferred concept(s) including more detailed study of chamber integration (blanket, armor and ion dumps as required in the case of magnetic intervention) and design interfaces (ancillary coolant, power cycle and assembly & maintenance requirements).
Proposed Work Plan for:c) Chamber Design Studies
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 26
Design and Analysis Based on 350 MJ-Class Baseline Direct-Drive Target Spectra
• Energy partition:- Neutron ~75%- Ions ~24%- X-rays ~1%
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 27
Energy Deposition Profile in W, SiC and C Armor for 350 MJ-Class Baseline Target Spectra Spectra in a 10.75 m
Chamber
Target micro-explosion
Chamber wall
X-rays Fast & debris ions Neutrons
• Lifetime is a key issue for armor- High T and dT/dx- Ion implantation (in
particular He)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 28
Ion Power Deposition Profile in W Armor
• Time of flight effect due to energy range of ions
Calculation based on 0.1 s time increment
Fast ions
Debris ions
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 29
Temperature History and Gradient for W Armor in a 10.75 m Chamber Subject to the 350 MJ-Class Baseline Target Threat Spectra
• 1-mm W on 3.5 mm FS at 580 °C• No chamber gas• Peak temperature ~2400°C
1 mm thick W armor
Coolant at 580°C
3.5 mm thick FS Wall
EnergyFront
h= 10 kW/m2-K
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 30
Required PXe as a Function of Yield to Maintain TW,max<2400°C for 1800 MW Fusion Power and Different Rchamber
0
10
20
30
40
50
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300 350 400 450
Xe
Pre
ssu
re (
@S
T)
(mto
rr)
Rep
etit
ion
Rat
e
Yield (MJ)
3.5 mm FSTcoolant=572°C
h=67 kW/m2-K
chamber60 40
1 mm WR (m)5.7
6.5
7
8
10
Armor Survival Constraints Impact the Overall IFE Chamber Design and Operation
• W temperature limit of 2400°C assumed for illustration purposes (~1.2 J/cm2 roughening threshold from RHEPP results)
• Limit to be revisited as R&D data become available
• Example chamber parameters for 0 gas pressure:- Yield = 350 MJ; R=10.5 m; Rep. rate ~ 5 for 1750 MW fusion
• Desirable to avoid protective chamber gas based on target survival and injection considerations
• Large chamber for W survival
• Other advanced concepts for more compact chamber and armor survival, e.g.- Magnetic intervention- Phase change armor
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 31
Self-Cooled Li Blanket for Large Chamber
• The design is based on an annular geometry with a first Li pass cooling the walls of the box and a slow second pass flowing back through the large inner channel.
• Large chamber size led to the division of blanket modules in two (upper and lower halves).
Inner Li Channel
Annular LiChannel
Sandwich insulator: FS-SiC-FS
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 32
IP LPHP
Pout
Compressors
RecuperatorIntercoolers
Pre-Cooler
Generator
CompressorTurbine
To/from In-ReactorComponents or Intermediate
Heat Exchanger
1
2
3
4
5 6 7 8
9 10
1BPin
TinTout
η ,C ad η ,T ad
εrec
Self-Cooled Li Blanket Coupled to Brayton Cycle through a Heat Exchanger
Example results for regular FS (Tmax<550°C) and ODS FS
(Tmax<700°C)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 33
Advanced Chamber Based on Magnetic Intervention Concept Using Cusp Coils
• Use of resistive wall (e,g SiC) in blanket to dissipate magnetic energy (~70% of ion energy can be dissipated in the walls).
• Dump plates to accommodate all ions but at much reduced energy (~30%).
• Dump plates could be replaced more frequently than blanket.
Chamber/blanket study underway: - SiCf/SiC as structural material - Pb-17Li and flibe as breeder/coolant- Other?
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 34
It Could Be More Advantageous to Position Dump Plate In Separate Smaller Chamber
• Could use W dry wall dump, but would require large surface area and same problem with thermomechanical response and He implantation
• Could allow melting (W or low MP material in W)
Hybrid case•Dry wall chamber to satisfy target and laser
requirements•Separate wetted wall
chamber to accommodate ions and provide long life•Have to make sure no
unacceptable contamination of main chamber
Ion Dump Ring Chamber
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 35
b) Chamber armor thermomechanics
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 36
Year 1:Perform armor thermomechanics simulations experiments for a range of laser energy (peak sample temperature) and a variety of shot rates (10 to 105) for powder metallurgy tungsten samples.
Year 2:Perform armor thermomechanics experiments on different candidate armor material such as single-crystal tungsten.
Year 3:Perform armor thermomechanics experiments on candidate armor material bonded to candidate first wall material (e.g., tungsten bonded to ferritic steels).
Proposed Work Plan for:b) Chamber armor thermomechanics
Nov 5-9, 2006 IAEA meeting, Vienna, Austria
Chamber Armor Thermomechanics Experiments: Dragonfire Laser Facility
F. Najmabadi, J. PulsiferUC San Diego
Objective:Develop and field simulation experiments of the thermo-mechanical response of the
first wall armor of an IFE chamber to target fusion yield.
Description:A laser generates on the test specimen similar surface temperature and temperature
gradients found in an IFE chamber wall (e.g. YAG laser with a rep rate of 10 Hz). Surface temperature as well as mass ejecta from the specimen is measured in-
situ and in real time. Material response of specimen is determined after laser exposure by a variety of
microscopy techniques.
Objective:Develop and field simulation experiments of the thermo-mechanical response of the
first wall armor of an IFE chamber to target fusion yield.
Description:A laser generates on the test specimen similar surface temperature and temperature
gradients found in an IFE chamber wall (e.g. YAG laser with a rep rate of 10 Hz). Surface temperature as well as mass ejecta from the specimen is measured in-
situ and in real time. Material response of specimen is determined after laser exposure by a variety of
microscopy techniques.
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 38
Facility Description
In-situ microscopy <25 m resolution large standoff K2 Infinity
optics
translator electronics
Sample heater 500˚C base temperature
Optical thermometer collector
Sample manipulator xy translation external control located close to window
INSIDE VACUUM:
OUTSIDE VACUUM:
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 39
Optical thermometer measures surface temperature while QCM measures mass ejecta
Sample holder at 5000C base temperature
Window allows both IR and UV lasers
Quartz Crystal Microbalance (QCM) for measuring ejecta.
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 40
In-situ microscopy allows us to monitor microstructure evolution during testing
Basler camera and K2 Infinity microscope
– 1280x1024 resolution– 25 fps– STD objective
(higher mag available)
USAF resolution target:
- 64 line pairs/mm- 16 m resolution
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 41
Some results with powder metallurgy tungsten: Sample behavior changes at ~2,500K
1000
1500
2000
2500
3000
3500
0 50 100 150 200 250
Laser Energy (mJ)
Maximum Temperature (K)Room Temperature Sample
500oC Sample
5% Error size
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 42
Damage appears at 2,500K (not correlated with T)
12A, 100mJ, 773K, Max: 2,200K (~1,400K T)14A, 150mJ, RT, Max: 2,500K (~2,200K T)
11A, 200mJ, 773K, Max: 3,000K (~2,200K T)15A, 150mJ, 773K, Max: 2,700K (~1,900K T)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 43
Effects of Shot Count and Temperature Rise
103 shots 105 shots104 shots
15A, 150mJ, 773, Max: 2,700K (~1,900K T)
14A, 150mJ, RT, Max: 2,500K (~2,200K T)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 44
Effects of Shot Count and Temperature Rise
103 shots 105 shots104 shots
14A, 150mJ, RT, Max: 2,500K (~2,200K T)
11A, 200mJ, 773K, Max: 3,000K (~2,200K T)
Nov 5-9, 2006 IAEA meeting, Vienna, Austria 45
Summary of Possible Collaborative Areas of Interest
• Target engagement
• Chamber armor material development and testing
• Advanced chamber/blanket design study
• Power plant studies