Scientists at a federal nuclear weapons facility have made a potentially significant advance in fusion research that could lead to an abundant source of energy in the future, according to a government official.
The advance is expected to be announced Tuesday by the Department of Energy, which said a “major scientific breakthrough” has been achieved at Lawrence Livermore National Laboratory in California. Jennifer Granholm, Secretary of Energy, as well as White House and other Energy Department officials are expected to attend. The Financial Times reported on Sunday that scientific breakthrough involves the National Ignition Facility, or NIF, which uses giant lasers to create conditions that briefly mimic nuclear weapon explosions.
The government official, who spoke anonymously to discuss the results which are not yet public, said the fusion experiment at NIF achieved what is called ignition, where the energy of fusion generated is equal to the laser energy that triggered the reaction. Ignition is also called energy gain of one.
Such a development would improve the United States’ ability to maintain its nuclear weapons without nuclear testing and could pave the way for future advances that may one day lead to the use of laser fusion as an energy source.
Although it has yet to be announced publicly, the news quickly bounced around among physicists and other scientists who study fusion.
“Yesterday a scientist friend sent me a note that Livermore exceeded the energy gain by one last week and would announce the result on Tuesday,” said Stephen Bodner, a retired plasma physicist who has long been a critic. the TIN. email Monday morning. “They deserve kudos for achieving their goal.”
What is Merger?
Fusion is the thermonuclear reaction that powers the sun and other stars – the fusion of hydrogen atoms into helium. The mass of helium is slightly less than that of the original hydrogen atoms. Thus, by Einstein’s iconic equation E=mc², this difference in mass is converted into an explosion of energy.
Fusion that could be produced in a controlled way on Earth could mean an energy source that does not produce greenhouse gases like coal and oil, or long-lived hazardous radioactive waste like current nuclear power plants.
How to do starless fusion?
Most fusion efforts to date have used donut-shaped reactors known as tokamaks. In reactors, hydrogen gas is heated to temperatures high enough for electrons to be stripped from hydrogen nuclei, creating what is called a plasma – clouds of positively charged nuclei and negatively charged electrons . The magnetic fields trap the plasma in the shape of the donut and the nuclei fuse together, releasing energy in the form of neutrons flying outward.
Tuesday’s announcement, however, involves a different approach. The NIF consists of 192 gigantic lasers, which fire simultaneously at a metal cylinder the size of a pencil eraser. The cylinder, heated to approximately 5.4 million degrees Fahrenheit, vaporizes, generating an implosion of X-rays, which in turn heats and compresses a BB-sized pellet of frozen deuterium and tritium, two heavier forms of hydrogen . The implosion fuses the hydrogen into helium, creating the fusion.
What advances in laser fusion have been made so far?
The primary purpose of the NIF, built at a cost of $3.5 billion, is to conduct experiments that help the United States maintain its nuclear weapons without nuclear test explosions. Proponents also said it could advance fusion research that could lead to viable commercial power plants.
However, the NIF initially generated virtually no mergers. In 2014, Livermore scientists finally reported successbut the energy produced was then miniscule – the equivalent of what a 60 watt bulb consumes in five minutes.
Last year, Livermore scientists reported a major jump, a burst of energy – 10 quadrillion watts of power – that was 70% of the energy of the laser light hitting the hydrogen target.
But the burst – essentially a miniature hydrogen bomb – only lasted 100 trillionths of a second.
Sunday’s Financial Times report suggests that Livermore will announce that in the latest experiment, the fusion energy produced exceeded the amount of laser energy hitting the hydrogen target.
For this to happen, the fusion reaction had to be self-sustaining, meaning that the torrent of particles flowing from the hot spot in the center of the pellet heated the surrounding hydrogen atoms and caused them to fuse together as well.
What are the barriers to fusion energy?
An important caveat is that the claim focuses on laser energy hitting the hydrogen target. NIF’s lasers are extremely inefficient, meaning that only a small fraction of the energy used to power the lasers actually makes it to the beams themselves.
More modern technology such as semiconductor lasers would be more efficient but still far from 100% fusion; for this to be practical, the fusion energy output must be at least several times greater than that of the incoming lasers.
Does Tuesday’s announcement mean we’ll soon have cheap fusion power?
Even if scientists figured out how to generate larger bursts of fusion, immense technical hurdles would remain.
The NIF experiments studied one burst at a time.
A practical fusion power plant using this concept would require a machine gun rhythm of laser bursts with new hydrogen targets sliding into place for each burst. Then, the torrents of neutrons escaping from the fusion reactions should be converted into electricity.
The laser complex fills a building with a footprint equal to three football fields – too big, too expensive, too inefficient for a commercial power plant.
A manufacturing process to mass-produce precise hydrogen targets should be developed.