Assembly of Complex Hydrodynamics Targets for Advanced Radiography Capability (ARC) on The National Ignition Facility
(NIF)
National Ignition Facility • Lawrence Livermore National Laboratory • Operated by the US Department of Energy
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and General Atomics𝟏 under Contract DE-NA0001808.
Advanced Radiographic Capability
• ARC has been integrated onto an existing set of four NIF
beam lines to facilitate reuse of the existing NIF main
amplification system.
ARC on NIF
Configuration of ARC on NIF
Using ARC, NIF researchers will be able to record the
physics of targets at 50 billion frames per second
ARC Imaging
ARC Diagnostic Targets
• There have been two diagnostic targets designed and built to
evaluate the performance of the complex hydro ARC platform.
• The first platform is a high energy backlighter (HEBL) target
that is designed to test the performance of the silver micro
wire and take an image of a calibrated mesh grid to establish
resolution and background
HEBL and PQ Targets
Back lighter standoff of
28mm from Au
mesh grid
10um Ag wire suspended
on .5mm X .5mm
Kapton sheet
37mm square mesh
resolution grid to establish
BL performance
• ARC uses a split-beam configuration, propagating two
short-pulse beams for each NIF aperture. Staggering the
arrival of the eight ARC beamlets onto special back-lighter
targets will enable creation of an x-ray “movie” with tens of
trillionths of a second resolution
• The second experimental platform is hohlraum driven with
a 2.5mm diameter copper foam sphere tented in the center
that represents the image of the sphere
Back lighter standoff of
28mm from center of the
hohlraum with 32mm
resolution grid on the side
2.5mm copper foam
sphere tented with 90nm
formvar in the center
of the hohlraum
10mm Ag wire position
with 50mm of the center
of the hohlraum
ARC Pre-Qualifier (PQ) Target
Platform Evolution
• First shot results showed 3 unwanted sources of x-rays
contaminating the image
Eliminating Extra X-Ray Sources
Kapton substrate source
causing a smeared image
“Blow-by” source caused by
ARC passing the backligher
and interacting with other
target materials
Double image caused by
boron fiber holding the
backlighter
• The smearing caused by the Kapton was reduced be using
the Type 2 backlighter with a smaller area, unfortunately it
also increased the effect of the blowby source.
• The blowby source took more effort to mitigate.
The unconverted light shield went through several redesigns
to try to mitigate the blow by source.
• The boron fiber that supports the backlighter substrate had
a 10um tungsten core that acted like a second backlighter
producing the double image. The boron fiber was replaced with
a silicon carbide stalk of the same size, mitigating this source
Original unconverted
green CH light shield
10um Al coated onto the shield and
backing plate as well as
5mm of parylene
Cone to protect the ARC beams from
interaction with unconverted lightThicker shield
without holes
• The Fineline green additively manufactured plastic was
transparent to 75% of the NIF unconverted light. 10um of
Aluminum was added onto the shield eliminating this source.
An exit cone was added to allow the arc beam
to exit after passing the backlighter without
interacting with the CH shield and to keep the
unconverted light from entering
BL Type 1: .5mm x.5mm x.008mm
Kapton sheet with .010mm x.5mm
Ag wire centered
BL Type 2: .3mm x.250mm x.008mm
Kapton sheet with .010mm x .300mm
aligned to the top edge of the Kapton
Platform Completion
TanDM mounted target with 35mm
backlighter standoff, smaller Type 2 BL
substrate and ARC exit cone
Cryo Tarpos mounted target 28mm backlighterstandoff, larger Type 1 BL and no exit cone
• The first successful shot was fielded in December 2016 with
a longer backlighter standoff. The longer standoff distance
removed the backlighter from the unconverted light created
when the main NIF beams are fired into the hohlraum. This
target used the smaller backlighter and substrate and allowed
ARC beams that missed the backlighter to travel out the exit
cone without interacting with other materials. The 35mm
standoff distance provided a lower resolution image than the
28mm standoff.
Successful ARC Pre Qualifier Targets
• The second successful shot was fielded in January 2017 with
the original 28mm standoff. The exit cone was abandoned and
the larger Type 1 backlighter was employed to absorb all of the
ARC beams, eliminating the possibility of blow by. The Type 1
backlighter creates more image smearing, which is an
acceptable trade off given the higher image resolution
Matthew Arend, Richard Seugling, Danielle Hare, Jonathan Ward, Randy Strauser1, Dawn Lord, Richard Vargas, Donovan Casaray
Complex Hydrodynamics and ARC
• LLNL researchers needed a new imaging capability that
could help them understand how shockwaves and
material features evolve under extreme conditions
important to stockpile stewardship. While the ARC laser
system was commissioned in 2015, developing the
experimental platform capable of acquiring high-quality
data for Complex Hydro took over a year, requiring the
team to resolve numerous design and system
integration problems
HEBL HEBL PQ
First Complex Hydro ARC Radiograph
Now that the capability has been successfully demonstrated,
the team is moving forward with the first programmatic data
shot in March 2017
Successful ARC PQ Radiograph
High Energy Backlighter Target (HEBL)
P2661734
ARC Backlighters