- 4276 - NUCLEAR FUSION - becomes a power plant? In December, 2022, after more than a decade of effort and frustration, scientists at the US National Ignition Facility (NIF) announced that they had set a world record by producing a fusion reaction that released more energy than it consumed. They have now proved that the feat was no accident by replicating it again and again.
------------- 4276- NUCLEAR FUSION - becomes a power plant?
- The stadium-sized
laser facility, housed at the Lawrence Livermore National Laboratory (LLNL) in
California, has achieved its goal of ignition in four out of its last six
attempts, creating a reaction that generates pressures and temperatures greater
than those that occur inside the Sun.
-
- The NIF was
designed not as a power plant, but as a facility to recreate and study the
reactions that occur during thermonuclear detonations after the United States
halted underground weapons testing in 1992. The higher fusion yields are
already being used to advance nuclear-weapons research, and have also fueled
enthusiasm about fusion as a limitless source of clean energy.
-
- The NIF works by
firing 192 laser beams at a frozen pellet of the hydrogen isotopes deuterium
and tritium that is housed in a diamond capsule suspended inside a gold
cylinder. The resulting implosion causes the isotopes to fuse, creating helium
and copious quantities of energy. On December 5, 2022, those fusion reactions
for the first time generated more energy, roughly 54% more, than the laser
beams delivered to the target.
-
- The facility set a
new record on 30 July when its beams delivered the same amount of energy to the
target, 2.05 megajoules, but, this time,
the implosion generated 3.88 megajoules of fusion energy, an 89% increase over
the input energy. Scientists at the laboratory achieved ignition during two
further attempts in October (see ‘A year of progress’). And the laboratory’s
calculations suggest that two others in June and September generated slightly
more energy than the lasers provided, but not enough to confirm ignition.
-
- Tiny variations in
the laser pulses or minor defects in the diamond capsule can still allow energy
to escape, making for an imperfect implosion, but the scientists now better
understand the main variables at play and how to manipulate them.-
-
- It’s a long way
from there to providing fusion energy to the power grid, however, and the NIF,
although currently home to the world’s largest laser, is not well-suited for
that task. The facility’s laser system is enormously inefficient, and more than
99% of the energy that goes into a single ignition attempt is lost before it
can reach the target.
-
- Developing more
efficient laser systems is one goal of the DOE’s new inertial-fusion-energy
research program. This month, the agency announced $42 million over four years
to establish three new research centers, each involving a mix of national
laboratories, university researchers and industry partners that will work
towards this and other advances.
-
- So far, most
government investments in fusion-energy research have gone towards devices
known as “tokamaks”, which use magnetic fields inside a doughnut-shaped ‘torus’
to confine fusion reactions. This is the approach under development at ITER, an
international partnership to build the world’s largest fusion facility near
Saint-Paul-lez-Durance, France.
-
- Back at the NIF,
the latest series of experiments features a 7% boost in laser energy, which
should, in theory, lead to even larger yields. The first experiment in this
series was one of the successful ignitions, on 30 October 30,2023. Although it didn’t break the record, an
input of 2.2 megajoules of laser energy yielded an output of 3.4 megajoules of
fusion energy.
-
- Costing $3.5
billion and housed at Lawrence Livermore National Laboratory in California, the
NIF was designed to bolster nuclear-weapons science. Advances there could also
help to develop nuclear fusion as a safe, clean and almost limitless source of
energy.
-
- The facility’s 192
laser beams delivered 2.05 megajoules of energy to a frozen pellet of the
hydrogen isotopes deuterium and tritium, suspended in a gold cylinder. The
resulting implosion caused the isotopes to release energy as they fused into
helium, generating temperatures six times hotter than the core of the Sun. The
reactions produced a record 3.88 megajoules of fusion energy.
-
- Other facilities
have generated more fusion energy over longer periods of time, most notably in
tokamak reactors, which use powerful magnetic fields to confine fusion
reactions. This is the technology under development by the $22-billion ITER
project, an international collaboration near Saint-Paul-lez-Durance, France.
-
- In the long run,
researchers are confident that the facility, with some upgrades, will be able
to achieve its goals and increase the yields by an order of magnitude, which
would put scientists in a position to begin work on a prototype laser fusion
energy reactor.
-
-
December 19, 2023
NUCLEAR FUSION -
becomes a power plant?
4276
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