alternate capsule support for inertial confinement fusion ... · bigelow, tu poster weber, wed...
TRANSCRIPT
LLNL-PRES-725630
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC
Alternate Capsule Support for Inertial Confinement Fusion TargetsTarget Fabrication Meeting 2017
Las Vegas
Michael Stadermann
March 15th, 2017
LLNL-PRES-xxxxxx
2
Team
Target Fab:Ethan Alger
Chantel Aracne-Ruddle
Suhas Bhandarkar
John Bigelow
Tom Bunn
Chris Choate
Sean Felker
Joe Florio
Chuck Heinbockel
Steve Johnson
Jeremy Kroll
Xavier Lepro
Abbas Nikroo
Physics:
Louisa Pickworth
Harry Robey
Vladimir Smalyuk
Chris Weber
General Atomics:
Jay Crippen
Martin Havre
Javier Jaquez
Neal Rice
Capsule support presentations:Aracne-Ruddle, Tu Poster
Bigelow, Tu Poster
Weber, Wed 10:40
Felker, Wed 11:00
Crippen, Wed 11:20
Alfonso, Wed 11:40
LLNL-PRES-xxxxxx
3
Tents can cause perturbations that affect the implosion
300 mm
Pressure
exploding tent pressure wave
capsuleablation
As the tent explodes and capsule ablates, they create misaligned pressure and density gradients, which produce a local vorticity perturbation
Weber, Wed 10:40
LLNL-PRES-xxxxxx
4
There are three principal categories of capsule support
Ranking and down selecting based on feasibility and physic value (both near and long term) is key to making progress and assessing resource needs
No capsule or fill tube contact
wires parallel
to page
wires page^
Fill tube contact but No capsule contact
wire page^
Fill tube only Supported capsuleSupported fill tube
• 10 µm tube desired
• Vibration and sag are
issues
• Many support variations
• Potentially can use 10 µm
tube
• Extra mass in hohlraum
• Vibration and sag needs study
• Assembly development
• Many support variations
• Potentially can use 10 µm tube
• Capsule contact needs to be
minimal
• Foam
• Stalk
• Membrane
• Sleeve
• Wire cage
• Foam
• Tent (modified angle)
• Stalks
• Different tube
material
Capsule and fill tube contact
LLNL-PRES-xxxxxx
5
There has been no shortage of ideas on possible alternate solutions
Larger diameter fill-tubeReduced tent angle
requires 4-part
hohlraum
Polar contact with disk
thin HDC
disk
to ensure
tangential
contact
Minimal wire support
wires parallel
to page
wires page^
Gravity support
standard
fill-tubetent or
wire to
support
FT near
capsulelower support
for symmetry
Annular tent support
thicker tent
with hole in
center
supports FT,
does not touch
capsule
Gravity support + LEH
shields
LEH shield
Cantilevered fill-tube
wire page^
HDC tube
extension
for support
HDC tube support
Fill tube only Supported capsule TentsSupported/clamped fill tube
low-density
(3 mg/cc)
foam
Block foam support
Only a partial list of solutions is shown.
LLNL-PRES-xxxxxx
6
Each concept undergoes a series of evaluations
Aracne-Ruddle, Tu Poster
Felker, Wed 11:00
Felker, Wed 11:00
Weber, Crippen, Alfonso Wed 10:40-12:00
LLNL-PRES-xxxxxx
7
Simulation gives us a prediction of performance
Replacing the tent is predicted to improve yield by up to 5x.
LLNL-PRES-xxxxxx
8
Supporting the capsule by only the fill-tube provides the smallest perturbation, but presents some serious issues
Note that these movies are for a 30 µm diameter fill-tube vs. the standard 10 µm
30 µm FT @ 40 Hz
30 µm FT @ 65 Hz
0
0.002
0.004
0.006
0.008
0.01
0.012
0 50 100 150 200
grm
s
Freq (Hz)
Z direction on
off
Accelerometer measurement on TARPOS
from GA
LLNL-PRES-xxxxxx
9
The first alternative support method built into a target was a free-standing 30 µm fill tube
Regular 10 µm fill tube Free standing 30 µm fill tube
The 30 µm fill tube required substantially more glue at the capsule joint, as well as a fill tube refit.
No large performance increase was expected, but the implosion shape should be affected.
LLNL-PRES-xxxxxx
10
“Polar contact” design uses stiff polyimide films with carbon that have a very small contact to the capsule
Final assembly of ‘crowned’ halfraums
Several 4-part hohlraum targets have been shot on NIF.
Simulation predicts a smaller perturbation over a smaller angle.
Aracne-Ruddle, Tu Poster
LLNL-PRES-xxxxxx
11
Support fill tube design use a thicker fill tube or stalk to hold the 10 µm fill tube at a distance from the capsule
Supported fill tube subassembly
Capsule-stalk distance: 200 µm
complete
support rod
fill-tube
Capsule-stalk distance: 200 µm
3-part fill tube subassembly
Layerable test articles are being built.
Bigelow, Tu Poster
LLNL-PRES-xxxxxx
12
The Tetracage design uses four fibers to support the capsule
5 µm Toray fibers (carbon)
Finding an appropriate fiber material has been the primary development challenge.
Aracne-Ruddle, Tu Poster
LLNL-PRES-xxxxxx
13
Magnetic levitation is being evaluated in a longer-term project
Steig, McCall, Baker, Bayu-Aji, Bae, Kucheyev
14LLNL-PRES-######
The first two support options showed the expected shift in x-ray shape
+P4 x-ray shape from tent was removed with alternate mounts
x-ray
image
from tent-
only sim.
Polar
Tent
30m
m
FT
+P4 is assumed to be caused by tents.
P4
/P0
More sensitive implosions and other supports remain to be tested.
30m
m FT
ne
utr
on y
ield
Neutron yield was similar to related experiments
Polar
Tent
15LLNL-PRES-######
Conclusion
We have investigated alternative capsule support strategies to mitigate perturbations caused by the tent.
Three designs have emerged as most promising: 4-part hohlraum, supported fill tube, tetracage. Two designs have been fielded on NIF
Alternate support targets shot show the expected x-ray shape change.
17LLNL-PRES-######
As BT moves later and yield drops, gain from polar tent is reduced. Only 20-30% improvement
1.75x
improvement
*
N160829N160509
30mm FTPolar
Tent
N140520
w/ polar
tent
N160829
polar
tent sim
1.5x
w/
standard
tent
1.35x
1.2x
Good performance from this high foot platform is needed to observe improvements from tent
18LLNL-PRES-######
Other platforms are more sensitive to the tent – we would expect a larger improvement
Yield-over-clean (no a-dep.) from a standard tent
0.50.60.70.80.9
1
LowFoot
ASLF ASHF(T-1)
HighFoot
(T-1.5)
HighFoot(T-1)
HighFoot(T0)
• Largest effect at the high convergence
(Low Foot and Adiabat Shaped Low Foot)
• Limited reproducibility
• Reduced tent impact at High Foot
• Established reproducibility for T-1, but
questioned by recent experiments
High foot
a ~ 2.5
Low foot
a ~ 1.5
19LLNL-PRES-######
0.70
0.75
0.80
0.85
0.90
0.95
1.00
standardtent
40umFT
polartent
foamtent
support100um
support200um
support300um
The supported fill-tube may be the best tent replacement option
YOC=0.17
w/ a-dep.
Yield/clean (no a-dep.) for 175mm thick (T-1)
high foot implosions (N140520)
Minimal degradation with ≥200
mm stand-off distance
Degradations
from foam
modulations?
*Note: other
calculations
do not
include a FT
Need to validate
imprint with HGR
20LLNL-PRES-######
An alternative capsule mount is being studied to improve the performance of ICF implosions on NIF
New mounting options exist that show promise in removing the tent perturbation
Many unexpected observations from experiments – transforming our understanding of how perturbation develop from engineering features
Simulation capability has been developed to evaluate these effects and understand their on performance
More experiments are needed to expand our understand of these effects and evaluate these support options
in-flight radiograph
showing tent scar
21LLNL-PRES-######
2-part fill-tube
10 mm diameter
30 mm diameter
22LLNL-PRES-######
Each concept undergoes a series of evaluations
Materials test
Assembly test
Dynamic test
• Measure material properties
• Determine basic feasibility
• Assemble target surrogate
• Test centering and static stability
• Perform vibration testing
• Perform cryo cycling test
Layering test
HGR shot
• Requires a full test target
• Test layering on ITPS
• Measure perturbation caused by support
• Use data to validate code prediction
• Measure perturbation growth at higher
Ta
rget
Fab
ric
ati
on
Te
sts
NIF
Exp
eri
me
nts