Researchers achieve milestone on path toward nuclear fusion energy
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[January 27, 2022]
By Will Dunham
WASHINGTON (Reuters) - U.S. government
scientists said on Wednesday they have taken an important step in the
long trek toward making nuclear fusion - the very process that powers
stars - a viable energy source for humankind.
Using the world's largest laser, the researchers coaxed fusion fuel for
the first time to heat itself beyond the heat they zapped into it,
achieving a phenomenon called a burning plasma that marked a stride
toward self-sustaining fusion energy.
The energy produced was modest - about the equivalent of nine nine-volt
batteries of the kind that power smoke detectors and other small
devices. But the experiments at a Lawrence Livermore National Laboratory
facility in California represented a milestone in the decades-long quest
to harness fusion energy, even as the researchers cautioned that years
of more work are needed.
The experiments produced the self-heating of matter in a plasma state
through nuclear fusion, which is the combining of atomic nuclei to
release energy. Plasma is one of the various states of matter, alongside
solid, liquid and gas.
"If you want to make a camp fire, you want to get the fire to hot enough
that the wood can keep itself burning," said Alex Zylstra, an
experimental physicist at Lawrence Livermore National Laboratory - part
of the U.S. Energy Department - and lead author of the research
published in the journal Nature.
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"This is a good analogy for a burning plasma, where the fusion is now
starting to become self-sustaining," Zylstra said.
The scientists directed 192 laser beams toward a small target containing
a capsule less than a tenth of an inch (about 2 mm) in diameter filled
with fusion fuel consisting of a plasma of deuterium and tritium - two
isotopes, or forms, of hydrogen.
At very high temperatures, the nucleus of the deuterium and the nucleus
of the tritium fuse, a neutron and a positively charged particle called
an "alpha particle" - consisting of two protons and two neutrons -
emerge, and energy is released.
"Fusion requires that we get the fuel incredibly hot in order for it to
burn - like a regular fire, but for fusion we need about a hundred
million degrees (Fahrenheit). For decades we've been able to cause
fusion reactions to occur in experiments by putting a lot of heating
into the fuel, but this isn't good enough to produce net energy from
fusion," Zylstra said.
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U.S. government scientists said on Wednesday (January 26) they have
taken an important step in the long trek toward making nuclear
fusion - the very process that powers stars - a viable energy source
for humankind
![](http://archives.lincolndailynews.com/2022/Jan/27/images/ads/current/stclara_lda_SPONSOR_090519.png) "Now, for the first time, fusion
reactions occurring in the fuel provided most of the heating - so
fusion is starting to dominate over the heating we did. This is a
new regime called a burning plasma," Zylstra said.
Unlike burning fossil fuels or the fission process of existing
nuclear power plants, fusion offers the prospect of abundant energy
without pollution, radioactive waste or greenhouse gases. Nuclear
fission energy comes from splitting atoms. Fusion energy comes from
fusing atoms together, just like inside stars, including our sun.
Private-sector ventures - dozens of companies and institutions- also
are pursuing a fusion energy future, with some oil companies even
investing.
"Fusion energy is the holy grail of clean limitless energy," said
Annie Kritcher of Lawrence Livermore National Laboratory, lead
designer for the experiments conducted in 2020 and 2021 at the
National Ignition Facility and first author of a companion paper
published in the journal Nature Physics.
In these experiments, fusion produced about 10 times as much energy
as went into heating the fuel, but less than 10% of the total amount
of laser energy because the process remains inefficient, Zylstra
said. The laser was used for only about 10 billionths of a second in
each experiment, with fusion production lasting 100 trillionths of a
second, Kritcher added.
Zylstra said he is encouraged by the progress.
"Making fusion a reality is an enormously complex technological
challenge, and it will require serious investment and innovation to
make it practical and economical," Zylstra said. "I view fusion as a
decadal-scale challenge for it to be a viable source of energy."
(Reporting by Will Dunham, Editing by Rosalba O'Brien)
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