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Sydney students are building a device capable of nuclear fusion – the process that powers stars and could unlock enormous amounts of carbon-free energy on Earth.

The magnet-powered, doughnut-shaped “tokamak” machine will be the first nuclear fusion device designed and built by students and will drive experiments aimed at bringing fusion to a commercial reality.

Harvey Ling (right) and a group of other nuclear engineering students at UNSW involved in designing a tokamak nuclear fusion machine.Credit: Brook Mitchell

Fusion unleashes four million times the energy of coal, uses hydrogen as fuel, is regarded as safer than fission reactors and produces far less radioactive waste.

Nuclear fusion is the opposite of fission, which powers current reactors by splitting uranium atoms to unleash heat and radiation.

Fusion forces two atomic nuclei together instead. The atoms merge and become a different element, and the leftover atomic mass converts to astronomical amounts of energy.

It’s the same reaction that erupts in the sun’s core. Nuclear fusion, put one way, would bottle the phenomenal power of a star.

But merging two atoms is difficult because the positive nuclei repel each other, like the same end of two magnets. The crushing gravity and immense heat of stars overcomes this repulsion and forces atoms to fuse.

“A fusion device tries to reach those extreme conditions,” Dr Patrick Burr, who’s heading up the program at the University of New South Wales, said. “We’ve got to find some way of accelerating these atoms so fast that you get them really close to one another.”

A tokamak achieves fusion with magnets that whip hydrogen plasma (a charged gas) around a circular vessel and heat the gas to between 100 and 300 million degrees.

Scientists can also trigger fusion by blasting fuel with lasers. In August, Californian scientists achieved net energy gain by firing a laser the size of a building at fusion fuel, generating 3.15 megajoules of energy from 2.05 megajoules.

A tokamak machine built by Tokamak Energy, an industry partner of UNSW’s student-built tokamak program.Credit: Tokamak Energy

“It’s not a spontaneous source of energy, but an amplifier of energy,” Burr said. “You put energy in and then it generates more energy out.”

The next step is to engineer the hardware that can maintain constant, safe, commercially viable fusion power that makes up for the massive amounts of energy used to blast a laser or fire up a tokamak.

“It’s not like 105 per cent more energy. It’s about achieving more like 500 to 1000 per cent or more. That’s commercially where we need to get to.”

Enter Burr’s students. As part of the program, honours student Harvey Ling dreamt up a blueprint tokamak design for his thesis with a stainless-steel vacuum vessel, electromagnets, copper cables and superconductors.

Part of the Lawrence Livermore National Laboratory in Livermore, California where a fusion experiment generated net gain energy.Credit: AP

“It’s super surprising that there’s not enough traction and interest in this space,” Ling said. “A lot of people don’t know what nuclear fusion is. They say, ‘Oh, I heard it’s just a thing of myth’. But I’m like, no, I’m actually working on nuclear fusion. This is a once-in-a-lifetime chance to finish off my degree with a bang.”

The tokamak will be able to fit on a tabletop and won’t actually be used to achieve fusion for now. But the students will conduct experiments on superheated plasma with the machine to help industry partners accelerate fusion research, for example studying how the machines handle plasma flares.

The program also aims to attract new talent to nuclear engineering.

“Graduates with knowledge in fusion energy is going to be the biggest bottleneck in making fusion a reality,” Burr said. “We have investment, but we lack people.”

While experts say the technology won’t be developed quickly enough to help decarbonise energy grids and arrest the climate crisis, fusion energy could define how we power civilisation in the second half of this century.

Most experts expect the technology to become commercially viable in 15 to 20 years, although scientists have been saying that since the 1950s. But with private investment surpassing $US6 billion ($9.4 billion), the nuclear fusion race is heating up.

“It just has endless possibilities, right?” Ling said. “Students and technical staff need to be upskilled to be ready for this new nuclear society.”

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