Applications of Vacuum Technology in the NIF Laser System

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Applications of Vacuum Technology in the NIF
Laser System
John Hitchcock Pete Biltoft LLNL
UCRL-PRES-219314
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Agenda

• National Ignition Facility (NIF) missions
• Overview of the NIF
• Movies
• Description of N Vacuum Systems
• Target Chamber
• Spatial Filters
• Plasma Electrode Pockels Cell
• Diagnostic Vacuum Systems
• Summary

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Missions The NIF laser system is being built to
support important national security and research
activities

• Stockpile stewardship
• Development of laser fusion as an energy source
• Astrophysics

Use any search engine search for NIF.
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The NIF laser would not be possible without the
ready availability of stock and custom vacuum
hardware

• Vacuum pumps
• Roughing high vacuum (turbos, cryos)
• Vacuum gauges
• Hot and cold cathode ion gauges, rough vacuum
  gauges, capacitance manometers
• Valves
• Large 36 electro pneumatic gate valves to KF-25
  manual valves
• Feedthroughs
• Electrical, mechanical and fluid

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NIF Vacuum Volumes
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The NIF target chamber routinely achieves a
pressure of lt 5 x 10-6 Torr using a combination
of roughing pumps, turbo pumps and cryo pumps
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The NIF target chamber contains ports for
beamlines, laser diagnostics, vacuum pumps and
gauges
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Alignment of the target is accomplished with a
precision system called TASPOS
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View inside NIF target chamber showing target
positioner and workers on manlift inside the
vessel
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One quad of optics in the final optics assembly
as seen from inside the target chamber. Stainless
steel first wall panels surround the optics
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Installation of the final optics assemblies onto
the NIF target chamber required skilled workers
following stringent cleanliness protocols
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The target positioning system (TASPOS) includes a
vacuum vessel with flexible track inside.
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Target positioning sensor during initial
installation
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Target positioner inside TARPOS vacuum vessel
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Lower hemisphere of NIF target chamber showing
final optics assemblies installed
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Target positioning system vacuum vessel during
installation onto the NIF target chamber
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NIF spatial filters require one of the largest
clean-room rated vacuum systems in the world

• 2300 tons of vessels
• 105 torr vacuum
• MIL STD 1246C level 100 A/10 cleanliness

CSF End Vessel (2x)
TSF End Vessel (2x)
23.5m
60 m
TSF Beam Tubes
CSF Center Vessel
TSF Center Vessel
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Transport spatial filter vessels being installed.
These vessels are evacuated to a pressure of 5
x 10-5 Torr using turbo pumps
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The transport spatial filter vessels occupy a
significant portion of each of the two laser bays
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Upper hemisphere of NIF target chamber showing
beamlines and final optics assemblies
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1 x 1 PEPC in lab
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Beamlet PEPC
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Prototype of the Plasma Electrode Pockels Cell
(PEPC) line replaceable unit (LRU) during testing
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PEPC prototype during developmental testing
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PEPC during mock assembly (note aluminum
surrogates for optics)
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PEPC line replaceable unit on precision optical
alignment fixture
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PEPC line replaceable unit on precision optical
alignment fixture
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Utilities including foreline vacuum pump line
supporting the Plasma electrode Pockels cell
enter the LRU from the interface flange
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PEPC vacuum system (gas cell removed)
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Summary The NIF laser system would not be
possible without the technology and hardware
provided by vacuum equipment manufacturers

• Some of the specific components of the NIF laser
  that rely on vacuum equipment include
• Vacuum relay telescopes in the preamplifier
  modules
• Spatial filters
• Amplifier flashlamps
• Plasma Electrode Pockels Cell
• Final Optics Assembly
• Target chamber and target diagnostics
• Precision Diagnostic System

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Back-up Slides
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Implosions conducted on NIF will be compared with
computational models to optimize fusion
experiments
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The first attempt at fusion will be made in 2010
using the indirect drive fusion process
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All 192 beams of the NIF laser will be focused
onto a very small target
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The target assembly for direct drive is held at
19 K /- a few mK using a two-stage GM
cryo-cooler similar to those developed for cryo
pumps
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In 2012 the NIF laser will be reconfigured for
direct drive fusion
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The NIF beamline contains several key elements
that rely upon creation of stable vacuum
environments
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As a laser pulse moves through the NIF beamline
it passes through a variety of optics and
environments
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The lasing media for the NIF main amplifiers is
neodymium-doped glass. Vacuum chucks are used to
lift and position these slabs into LRUs
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Power lines that support operation of the main
amplifier flashlamps. Each of the 7000 flashlamp
tubes is 6 feet long and has an internal static
vacuum. Flashlamps are expected to last gt 20,000
shots.
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View of amplifier slabs from within the NIF
beamline