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“NIF-scale” runs the
gamut from its facility the size of a football stadium
and 192 beamlines (background) to an ignition target held
inside the hohlraum (foreground).
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FIRST conceived of nearly 15 years
ago, the National Ignition Facility (NIF) is up and running and
successful
beyond almost everyone’s expectations. During commissioning of the
first four laser beams, the laser system met design specifications
for everything from beam quality to energy output. NIF will eventually
have 192
laser beams.
Yet with just 2 percent of its final beam configuration complete,
NIF has already produced the highest energy laser shots in the
world.
In July, laser
shots in the infrared wavelength using four beams produced a total of 26.5
kilojoules of energy per beam, not only meeting
NIF’s design energy requirement of 20 kilojoules per beam but also
exceeding the energy of any other infrared laser beamline. In another campaign,
NIF produced over 11.4 kilojoules of energy when the infrared light was
converted to green light. And an earlier performance campaign of laser light
that had been frequency-converted from infrared to ultraviolet really proved
NIF’s mettle. Over 10.4 kilojoules of ultraviolet energy were produced
in about 4 billionths of a second. If all 192 beamlines were to
operate at these levels, over 2 megajoules of energy would result. That
much energy
for the pulse duration of several nanoseconds is about 500 trillion
watts of power, more than 500 times the U.S. peak generating power.
And how will
that vast energy and power be used? Scientists interested in the
behavior of materials at high temperatures and pressures
will be able to explore entirely new states of matter and generate
accurate data at extreme pressure. NIF can create temperatures—tens
of millions of degrees—similar to those inside the Sun and stars.
NIF’s
carefully controlled pulses can also drive experiments to pressures
never before seen in a laboratory setting. NIF will achieve pressures
higher than
a billion times atmospheric pressure, which is over a million times
the pressure at the deepest part of the oceans and equivalent to
pressures at the center of the Sun. Some of the earliest experiments
are designed to examine how various materials fail
and demonstrate the behavior of planetary fluids such as those
found inside Jupiter.
The sheer magnitude
of the National Nuclear Security Administration’s
(NNSA’s)
$3.448-billion NIF is staggering.
The building is the size of a football stadium, nearly 26,500 square
meters and 10 stories high, with several adjacent support facilities.
All that space is chock full. Commissioning Manager Bruno Van Wonterghem
comments
that this project has tested the limits of how much high-tech equipment
can be squeezed into a given space.
The laser system
is composed of more than 3,000 40-kilogram slabs of laser glass,
26,000 smaller glass optics, 3,000 laser mirrors and lenses,
and over 1,000 crystalline optics. More
than 7,600 of the largest flashlamps ever built, each of them 2
meters long, power
the laser system. When the full constellation of beams is operating
in 2008, NIF will deliver more than 50 times the energy of Livermore’s
Nova laser, which was decommissioned in 1999, or the
Omega laser at the University of Rochester Laboratory for Laser
Energetics.
“But the
most important thing about NIF,” says Ed Moses, NIF
project manager since 1999, “is not
the parts count. It’s how NIF is designed and integrated. Designing
and commissioning any large project demands a systems approach.
Putting together NIF’s many systems has been like playing chess against
a grand master. You can’t win if you only look one move ahead at a
small part of the board. We’ve had to look at the whole effort all
at once and as far ahead as possible.” Moses is quick to credit physicist
Mary Spaeth, NIF’s chief technical officer, and her systems engineering
team for delivering a
fully integrated and flexible target-shooting system as well as
Ralph Patterson, NIF’s chief operations officer, for managing the
budget and schedule strategy.
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(a) Construction progress
in 1997, (b) the completed NIF conventional facility, and
(c) a cut-away showing NIF’s interior. Installation
of optics and diagnostic instruments will continue through
2008.
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Built-In Flexibility
Unprecedented flexibility has been designed into NIF to maximize
its experimental capabilities. Changing
the laser’s energy or pulse shape is easy. Ultraclean modular optical
systems simply plug in all along the beampath and can easily be
removed for maintenance or upgrade. Diagnostic equipment at the target
chamber is also designed for “plug-and-play” operation.
The activation
of the first four beams, known as a quad, took place
a year earlier than originally planned. This campaign, known as
NIF Early Light, was designed to demonstrate NIF’s capability to deliver
high-quality energetic laser beams in support of experiments. Also, notes
Co-Commissioning Operations Manager Gina Bonanno, “By validating virtually
all representative parts of NIF with that first quad, we were able
to untangle some unforeseen snags. We think that the rest of the beam commissioning
can proceed smoothly.”
Moses adds, “Because
each NIF bundle—an upper and lower quad—is
essentially independent from the others, NIF will be operational
while the installation of additional beams proceeds.”
By June 2006,
a total of 48 beams, a cluster, will be operational. After that,
the other clusters will be installed and commissioned at a much faster rate.
NIF, a cornerstone
of NNSA’s Stockpile Stewardship Program, will provide
assurances of the performance and reliability of the U.S. stockpile. Even
with just a few beams operational, NIF will make significant contributions
to astrophysics, hydrodynamics, materials science, and plasma physics. By
2008, all 192 beams will be routinely firing in experiments that will create
physical regimes never before seen in any laboratory setting—to benefit
maintenance of the U.S. nuclear weapons stockpile, spur advances in
fusion energy, and open up new vistas in basic science.
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The
slabs of laser glass needed in NIF’s optics are the
largest ever made. Laser glass technology has improved dramatically
to meet the needs of NIF.
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Building Success
Thousands of
Livermore engineers, scientists, and technicians have been involved
in NIF over the last 15 years, first in proposing that such
a massive laser might even be possible and later
in designing the specialized equipment housed inside, much of it the
first of
its kind. Hundreds more construction personnel, employees of equipment
suppliers, and testing and commissioning experts have brought the NIF
dream to reality.
When Livermore
broke ground for NIF’s conventional facilities (the building and
supporting infrastructure), Valerie Roberts was NIF’s construction
manager. Her team knew this phase
of the project was the largest the Laboratory had ever attempted, and
it had to be complete by the end of September 2001. But the construction
schedule couldn’t anticipate everything. In November 1997, El Niño
rains flooded the NIF site. A month later,
a backhoe uncovered the remains of a 16,000-year-old mammoth. Niffie,
as local schoolchildren named him, had
to be excavated by an archaeological team from the University of California
at Berkeley.
Meanwhile, NIF’s
target chamber was being built. The spherical chamber
is made from 6,800-kilogram,
10-centimeter-thick flat aluminum plates, each like a segment of a
volleyball. The plates were cast in West Virginia, shaped in France,
precision-edge machined in Pennsylvania, and then shipped to Livermore
where they were fit
together and welded. After assembly, 192 holes of various sizes were
precisely located and bored for laser beams, diagnostic instruments,
targets, and other
equipment that will
be put into the chamber. The completed chamber was hoisted onto a concrete
pedestal inside the target building in June 1999.
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NIF’s
192 beams are organized into bays, clusters, bundles, and
quads. Quads (each group of four beams) are the basic building
blocks of a NIF experiment, with each quad having the same
pulse shape and time delay.
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The chamber
serves as an optical bench holding all of the frequency conversion and
focusing optics. It is designed to withstand debris and neutron
and gamma radiation from experiments and to maintain vacuum and cryogenic
environments for experiments.
As the conventional
facility took shape, the team developed a revised baseline plan to implement
NIF Early Light. Its goal was to activate the
first beamlines more than a year ahead of schedule. Thus, before the
building was complete, workers were already beginning to install the laser
beampath.
By the time construction
of the conventional facility was completed in September 2001, the first
modular
line replaceable unit (LRU) had been installed and its cleanliness
requirements measured and verified. Says Associate Project Manager
Doug Larson, “The
LRU engineering team designed over 20 different types of LRUs, successfully
balancing cost
with precision, stability, and cleanliness requirements. Although some
assemblies are the size of a
phone booth, all must repeatably position optical surfaces to within
a fraction of a millimeter.” A month later, the master oscillator,
which provides the low-energy seed laser pulse for NIF, generated its
first light.
By August 2002,
the first Laser Bay 2 beamline was successfully aligned using a light
source propagated through an entire beamline. The alignment
provided the first test of the integrated operation of laser controls,
safety, and utilities systems. “While this accomplishment may appear
simple, it was actually quite remarkable,” says Jeff Atherton, project
manager for the beampath infrastructure system. “It validated the precision
construction
and surveys required to achieve NIF’s pointing accuracy over the length
of its 300-meter beampath—which is like throwing a strike from Pac
Bell Park
in San Francisco to Dodger Stadium
in Los Angeles.”
Why “Ignition” is
NIF’s Middle Name
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The
idea for the National Ignition Facility (NIF) grew
out of the decades-long effort to generate self-sustaining
nuclear fusion reactions in the laboratory. Livermore’s
Director Emeritus John Nuckolls was among the first
to conceive of the idea shortly after the laser was
invented. Theorists, supported by years of experiments,
have defined the conditions required to compress and
heat a fuel of deuterium and tritium (isotopes of hydrogen)
to temperatures and pressures that will ignite and
burn the fuel to produce energy gain.
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The
energy and power of NIF’s 192 beams will compress
and heat a tiny fusion capsule to those extreme conditions.
Unlocking the stored energy of atomic nuclei will produce
about 10 times the amount of energy required to initiate
the self-sustaining fusion burn. With ignition experiments,
scientists can examine the conditions associated with
the inner workings of exploding nuclear weapons, understand
the processes that power the Sun and stars, and enhance
our ability to eventually produce fusion energy for
electrical power production.
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In September
2003, the construction team completed the three-year effort to build
the beampath through which
laser beams are transmitted, from the preamplifier system to the switchyard.
Through these ultraclean enclosures, with their controlled temperature
and humidity, 192 precision-aligned laser beams will eventually zoom
to the switchyard
in about one-millionth of
a second.
“Perhaps
the most beautiful part
of NIF is being built right now,” adds Chief Engineer Rick Sawicki,
who has been part of the NIF team since 1993. The mirror frames that
redirect the linear arrangement of laser beams to the center of the spherical
target
chamber are creating “a forest of shining silver beamlines coming through
the floor
and ceiling of the target bay.”
Throughout construction
and commissioning, safety has been the number one priority. In July
2003, the construction team surpassed 3.3 million work
hours in 950 consecutive days without any workdays lost to injuries.
The National Safety Council honored NIF with Perfect Year awards for
2001 and
2002, and the project team received a Construction Industry Safety
Excellence Award from the Construction Users Roundtable. Site Manager
Vaughn Draggoo,
Site Safety Manager Arnie Clobes, and NIF Safety Integrator George
Stalnaker are justifiably proud of this outstanding safety record accomplished
in a
complex work environment.
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Inside
NIF’s 10-meter-diameter target chamber.
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Record-Setting Beam Quality
A key to
NIF’s
ultimate worth and ability to perform physics experiments is the quality
of its laser light. To
test and commission the laser, shot campaigns are carefully planned
and modeled in advance.
In November 2002,
commissioning teams completed a series of laser shots that verified the absence
of parasitic oscillations within NIF’s main
and power amplifiers. Parasitic oscillations are “renegade” light
beams that divert from the main laser path. If present, they can degrade
laser performance or even damage laser components. They can occur because
of reflections all along the amplifiers’ “hall of mirrors.”
A few weeks later,
in early December, the first amplified infrared laser light ran through
Laser Bay 2 and into Switchyard 2. This 43-kilojoule shot in four beams exceeded
a NIF milestone of 10 kilojoules of amplified light per beam. Long before
that first quad of beams was fired, extensive scientific modeling had characterized
almost every facet of its performance: the shape of the beam, the distortions
collected as the beam travels through the amplification system, and the shape
of the pulse.
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In
April 2003, the NIF team celebrated 3 million hours without
a lost workday injury. By July, the number of hours had grown
to 3.3 million.
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Modeling
results were used in the engineering efforts to perfect all aspects of
the
laser beam. For example, modeling predicted the gain profile,
that is, the intensity of the beam front after it has been fully amplified.
Because a uniform beam is essential, an intensity mask installed in
the preamplifiers compensated for the anticipated gain profile. Similarly,
the deformable mirrors
(described below) compensate for predicted beam distortion and allow
the beam’s focal spot in the target chamber to be nearly perfect. Calculations
also indicated the need for modifications that smooth the temporal
shape of the beam.
In April, when
the commissioning team ran the infrared shot campaign that produced
83 kilojoules, reaching this energy milestone requirement of
20 kilojoules per beam was not a surprise. By July, the team achieved
energy of 26.5 kilojoules per beam, for a total of 106 kilojoules.
Models predict that 30 kilojoules of infrared light per beam can be
attained.
The result of
this huge modeling and technology effort is the best beam quality ever demonstrated
in a fusion-class laser system and the highest-energy
infrared, green, and ultraviolet laser system operating anywhere in
the world.
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The
interiors of NIF’s many laser components form a hall
of mirrors. Parasitic oscillation paths that could degrade
the laser’s performance have been mitigated.
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Modeling
that predicted (a) the gain profile (shape of the beam after
amplification) was also used to design (b) a reciprocal intensity
mask for the preamplifiers so the resulting beam would have
uniform intensity. The result is shown in (c) an actual measurement
of a NIF intensity profile.
(J/cm2 = joules per square centimeter; mm = millimeters.)
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Controlling It All
Commissioning
Operations Managers Gina Bonanno and Steve Johnson are working
with Van Wonterghem to assure the facility’s success. “Making
sure everything works and works together,” is how Johnson sums up his
job.
“Because of the size of the project and with so much going on at once,
little things come up every day that have to be dealt with,” adds Bonanno. “We
are constantly evaluating priorities, deciding on trade-offs. Some
part isn’t
going to be here on time. How do you work around this challenge?”
Physicist Ralph
Speck, 75 years old and mostly retired, is assisting with
NIF commissioning, too. He has been involved in the commissioning of
almost all of Livermore’s lasers since Janus, and he led the commissioning
of Nova in the early 1980s. Speck says, “The engineering on NIF is
better than on any big laser I’ve ever worked on before—and I’ve
worked on almost all of them.”
Today, laser
shots to commission the laser and for the first physics experiments
are running at up to three a day. None of them would be possible
without NIF’s control system. According to Associate Project Manager
Paul Van Arsdall, the likes of the integrated computer control system
have never before been seen on a laser. (See S&TR, November 1998, Controlling
the World’s Most Powerful Laser.)
NIF’s control
system will eventually handle the computerized monitoring and control
of some 60,000 elements throughout the system, including safety
interlocks, alignment systems, mirrors, lenses, motors, sensors, cameras,
amplifiers, capacitors, and diagnostic instruments. Twenty-four hours
a day, the system supervises shot setup and countdown; oversees machine
interlocks to protect hardware, data, and personnel; generates reports on
system
performance;
provides operators with graphical interfaces for control and system
status displays; performs alignment, diagnosis, and control of power
conditioning and electro-optic subsystems; and monitors the health of all
subsystems
and
components.
The Technologies That
Make NIF Possible
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The
National Ignition Facility’s (NIF’s) laser
components shape and smooth the initial pulse, amplify
it over a quadrillion times, and precisely direct it
at a tiny target in the target chamber. Many components
have required significant advances in laser technology,
while others are entirely new. As subsystems were developed,
most were tested on Beamlet, a scientific prototype
that operated from 1994 to 1998. Project Manager Ed
Moses refers to six of the laser’s systems as
the “six miracles of NIF,” because without
these breakthroughs, NIF would be far less capable
or perhaps could not have been built at all.
The
first miracle, at the beginning of the
system, is the injection laser system.
It makes the seed for the laser beams—a
light pulse that contains all the spatial,
temporal, and spectral information that
the big laser glass systems amplify.
All components of the injection laser
system must operate in perfect harmony
so that each quad of beams will have
its specified energy and timing. The
48 injection laser systems are the most
sophisticated lasers of their kind.
Next
stop for the pulse is the
main amplifier. For every
bundle of eight beams, an
amplifier module uses 128
slabs of neodymium-doped
phosphate glass surrounded
by flashlamps to amplify
the beams many times over
as they travel back and forth
through the glass.
Amplifiers
and other optical components
have been made modular to
reduce system downtime and
enhance maintenance. Over
the years, Livermore scientists
learned of the need to maintain
a clean environment around
the path of the laser to
avoid damaging the laser’s
optics and degrading the
beam. The optical modules,
known as line replaceable
units (LRUs), are assembled
in the Optics Assembly Building,
a clean-room facility adjacent
to the main building. Robotic
assembly facilitates the
handling of parts as heavy
as 1,800 kilograms. LRUs
are transported to the laser
area via a portable clean
room to maintain cleanliness
all the way through installation
and alignment. LRUs can easily
be removed and refurbished
or upgraded.
The
neodymium-doped phosphate
laser glass, the second miracle,
is the result of a six-year
joint research and development
program with industrial partners
Schott Glass Technologies
and Hoya Corporation. This
effort, led by Associate
Project Manager Jack Campbell,
developed a revolutionary
process for manufacturing
meter-size slabs of laser
glass that is 10 times faster,
5 times cheaper, and with
better optical quality
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than previous batch processes. The team won an R&D
100 Award and
a Lawrence Livermore Science and Technology Award for developing
this process.
The
next miracle is the plasma electrode Pockels cell
(PEPC, pronounced like the soft drink) in the main
amplification system. Each PEPC uses a thin slice
of KDP (potassium dihydrogen phosphate) crystal measuring
40 by 40 centimeters and sandwiched between two gas-discharge
plasmas. The plasmas are so tenuous that they have
no effect on the laser beam passing through the cell,
yet they serve as effective conducting electrodes.
The PEPC is an optical switch, allowing the laser
light to pass through the amplifiers four times.
Says Moses, “As if NIF weren’t big enough
already, it would be almost 250 meters longer without
the PEPC and probably could not have been built.”
The
fourth miracle was the development
of technologies to quickly
grow large, high-quality
KDP crystals and to machine
them to NIF’s tight
tolerances. KDP is used in
the PEPCs to switch the polarization
of the light and in the final
optics to convert laser light
from infrared to both green
and ultraviolet light. About
600 large slices of KDP were
needed, and growing big enough
crystals by traditional methods
would have taken years. A
fast-growth method, pioneered
in Russia and perfected at
Livermore, produces crystal
boules of the required size
in just months. This team
also won an R&D 100 Award.
To machine and finish the
crystal slices to NIF tolerances,
the KDP crystal manufacturer
is using methods developed
by Livermore precision engineers.
As
the NIF beams fly through
the amplifiers, they accumulate
wavefront aberrations from
miniscule optical distortions
in the amplifier glass and
other materials. To compensate
for the distortions, Livermore
researchers developed a sort
of “prescription lens,” a
40-centimeter deformable
(movable) mirror, another
miracle. Each laser beamline
incorporates a deformable
mirror with 39 computer-controlled
actuators on the back to
adjust its surface. The mirror
corrects distortions in the
beam profile so that it can
be focused to a submillimeter
spot in the target chamber.
The
sixth and final miracle is
NIF’s control system. “Without
this system, NIF could not
be the well-integrated system
that it is,” says Moses.
As in all of NIF, flexibility
is designed into the control
system. After more than a
decade of experience with
Nova, Livermore designers
know NIF will evolve over
its projected 30-year lifetime.
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(a)
A KDP crystal for NIF’s
optical system and (b) a deformable mirror to eliminate
wavefront aberrations in the laser beam.
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NIF’s Reason for
Being
Exploring
the world of high-energy-density physics is NIF’s entire
reason for being. Using NIF’s unique capabilities, scientists will
delve into
the inner workings of nuclear weapons, astrophysical phenomena such
as supernovae, and materials under extreme conditions.
Physicist Brian
MacGowan is the program manager for the facility diagnostics that collect
information during each experiment. He notes
that because the first quad of beams is highly efficient in delivering
energy to the target, NIF can create energetic laser pulses with the
longest duration and most precisely tailored shape ever achieved on
a large glass
laser system. NIF also has the flexibility to generate
a range of pulse shapes and durations with varying power and energy.
Tailored pulses will be key for all experiments on NIF, providing the
capability to drive materials and complex targets to states of high
energy density.
Permanent facility
diagnostics in NIF’s
target area include x-ray imaging systems, high-speed framing cameras,
and the largest-ever VISAR laser interferometer,
which measures the velocity of shock waves. Eventually, as many as
40 diagnostic tools can be installed, either permanently or temporarily,
on the target chamber. Also in place is the full-aperture backscatter
detector under the target chamber. Characterizing the light backscattered
from experiments
provides information about laser–plasma interactions that is critical
for future fusion experiments.
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NIF’s
control system handles the computerized monitoring and control
of 60,000 elements throughout the system.
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Inside
the target chamber, the target alignment sensor positioner
(at far left) is being used to align a tiny target, which
would be at the tip of the target positioning system entering
from the right. The green light illuminates objects within
the chamber.
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With NIF’s
tailored pulses, physicists can generate the longest lasting high-density
plasmas ever produced. A set of early experiments will use special
gas-filled targets, whimsically called gas bags, to produce large-scale
plasmas that approach the conditions expected to be found in later
gas-filled hohlraum
fusion experiments.
Hydrodynamics—the
behavior of fluids of unequal density as they mix—is
an important issue for stockpile stewardship and for understanding
the behavior of stellar evolution and supernovae. Weapons use solid
materials, but solid materials driven
to states of high energy density tend
to behave as if they were fluids. The hydrodynamic behavior of mixtures
of heavy and light materials is also key to understanding astrophysical
phenomena such as supernovae. Even in the first hydrodynamic experiments
using four
beams, in which one beam backlights the experiment, the remaining three
offer a major increase in capability over that available at other
experimental facilities.
NIF-scale cryogenic
ignition targets, placed inside a hohlraum, are expected to be ready
for use in 2006. When they
are combined with more laser beams, increasingly sophisticated fusion
experiments will begin. And when even more beams are firing on a target,
NIF will approach the high temperatures seen inside exploding nuclear
weapons. As ignition and higher-energy-density experiments become possible,
additional
diagnostics will be commissioned to detect neutrons, gamma rays, and
other phenomena important for the Stockpile Stewardship Program.
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The first
quad of beams is shown entering the target chamber. Thus
far, four instruments
mounted on diagnostic instrument manipulators have been
commissioned to take measurements during physics experiments.
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A series
of experiments planned for NIF will help scientists answer
questions about the structure
of Jupiter. NIF will be able to re-create the dense conditions
inside Jupiter.
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NIF into the Future
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Laboratory
scientists are working independently of the NIF project
to find ways to increase NIF’s flexibility and
improve its experimental capabilities in the future.
Researchers at the Laboratory are exploring how to
operate NIF’s lasers at two colors instead of
one, allowing even higher energies and longer pulse
lengths. Larry Suter, winner of the 2003 Edward Teller
Award for his contributions to inertial confinement
fusion research, has proposed that a high-energy green
laser system could provide more robust and higher-gain
ignition. Studies have shown that these conditions
could also be advantageous for experiments on equations
of state and strength of materials. Simply removing
one of the crystals in the final optics and changing
the focusing lens allow a single beamline or even all
beamlines to operate as green instead of ultraviolet.
A quad of NIF beamlines will be available for experiments
designed to study these options in the next two years.
Another
goal of current research is to explore
the benefits for some NIF beamlines to
function as petawatt lasers. The pulse
of an extremely high-power petawatt laser
lasts for just a few trillionths of a second—a
thousand times shorter than NIF’s
usual pulses—to deliver highly intense light onto targets. (See S&TR, October
2001, Further Developments in Ultrashort-Pulse
Lasers.) With a modification to the
master oscillator and a change to the final
optics, individual NIF beamlines can operate
as
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petawatt
lasers that will allow experimentalists both to improve
the high-energy and high-intensity backlighting for
experiments and to explore physics processes not accessible
with the baseline NIF system. The ability to generate
a high-energy petawatt laser will revolutionize NIF’s
already unparalleled scientific capabilities.
“NIF
has been designed to be a platform for
cutting-edge science in the decades ahead,” says
Project Manager Ed Moses. “NIF’s
flexible beamline architecture and plug-and-play
LRU configuration ensure that NIF can continually
respond to the needs of the experimental
community, serving us today and the young
scientists of tomorrow.”
A high-energy, short-pulse
petawatt laser will act as a novel source
of hard x rays, electrons, and protons
that can be used for radiography and heating
of matter.
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Expectations Are High
Well before
2008 and completion of construction, experiments on NIF will make significant
contributions
to stockpile stewardship, fusion energy, and basic science.
NIF Programs
Associate Director George Miller has noted that big facilities are seldom
known for the thing that they were originally designed to do.
As people learn to use the facility, they come up with ideas and inventions
that were never conceived
of by those who designed it.
Lawrence Livermore
Director Emeritus Dr. Edward Teller provides further wisdom on NIF’s
future. He
is certain that we cannot know now what NIF will accomplish because
the greatest scientific achievements are not expected.
Katie
Walter
Key Words: control system, inertial confinement fusion, KDP (potassium
dihydrogen phosphate) crystals, line replaceable units (LRUs),
National Ignition Facility (NIF), neodymium-doped phosphate laser
glass, plasma electrode Pockels cell (PEPC), Stockpile Stewardship
Program, systems engineering.
For further information contact Ed Moses (925)
423-9624 (moses1@llnl.gov).
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