Powering the future with plasma fusion

When it comes to finding new sources of energy, the Australian Plasma Fusion Research Facility (APFRF) is looking onwards and upwards - quite literally, in fact. The Sun and the stars are powered by fusion energy - fuel formed from the fusion of hydrogen into helium - in a process which the facility hopes to help reproduce here on Earth.

Plasma fusion is considered a clean form of nuclear technology by which hydrogen isotopes are heated to many millions of degrees, causing them to fuse together and release vast amounts of energy. It has several advantages over nuclear fission: the raw materials can be extracted from seawater; the end product is helium, not a long-lived radioactive isotope; and the reaction cannot get out of control. The Australian Plasma Fusion Research Facility represents Australia’s involvement in the international fusion effort.

Located in The Australian National University’s (ANU) Plasma Research Laboratory, the $35 million APFRF was originally known as the National Plasma Fusion Research Facility, opened in 1997 and based around Australia’s largest fusion experiment: the H-1 Heliac stellarator. The device confines hot plasma within a magnetic field 10,000 times stronger than the Earth’s and is the only stellarator in the Southern Hemisphere.

Now the facility has been significantly upgraded thanks to a Commonwealth investment of $7 million under the Education Investment Fund’s Super Science Initiative. Dr Boyd Blackwell, a senior fellow in the Plasma Research Laboratory, said the four-year upgrade has improved the APFRF in a number of ways.

“The radiofrequency heating system is the biggest single cost in this upgrade,” said Dr Blackwell, referring to the system which heats the plasma to millions of degrees - hotter than the core of the Sun. “You need a lot of power - 400 kW - to do that and, as a research facility, we needed flexibility in that power.”

The facility purchased a 2x200 kW RF heating system comprising two RF power amplifiers from Ampegon, based on the company’s new Digital Radio Mondiale transmitters, and a cooled antenna with a flexible matching system constructed in the ANU Research School of Physics and Engineering workshops. These sources provide five times more power than the previous devices, consume less power, are fully remotely controlled and can run independently at different frequencies. Dr Blackwell said, “We can change the frequency over a range of 4-20 MHz, and we can program the shape of the pulses that generate the plasma.”

He went on to say that the facility used upgrade funding to develop a number of innovative remote plasma measurement systems because, due to the high temperatures involved in plasma fusion, “you have to look at it from a long way away”.

“Australia … is renowned for development of remote instrumentation for plasma, and our lab in particular specialises in imaging,” Dr Blackwell said. “That means that you don’t make just one measurement - you don’t even make a bunch of measurements, you make a whole picture worth of measurements.

“A lot of the upgrade funding went into developing a number of those instruments - you could call them ultrafast cameras, if you like, because they produce images in the end, but they’re much more than a camera. For example, they produce images of the radio waves that heat the plasma, or the fluctuations in the plasma.”

One of these instruments, developed at the APFRF, has recently provided the first images of the magnetic field inside a tokamak plasma, which will help researchers better understand confinement, said Dr Blackwell. Professor John Howard, the director of the facility, is continuing this research with this instrument on Korea’s National Fusion Research Institute (NFRI) flagship experiment ‘KSTAR’.

The facility has also developed a plasma device called the Magnetised Plasma Interaction Experiment (MAGPIE), which creates conditions approaching those at the edge of a fusion reactor. Dr Blackwell explained that the materials used to create fusion reactor walls must be able to withstand an extremely high heat load, as well as the atom displacement caused by the bombardment of neutrons that carry the energy.

“MAGPIE can create peak fluxes of one million watts per square metre under the right conditions, so we can put carbon, tungsten, molybdenum and other very high-temperature materials in there, and we can create a plasma nearby and can study the interaction between the plasma and the materials,” he said. APFRF’s collaborator on the experiment, the Australian Nuclear Science and Technology Organisation (ANSTO), meanwhile creates the atomic displacements to simulate the neutron damage.

In a recent experiment, MAGPIE discovered small bubbles forming on the surface of a tungsten-lathanum alloy after exposure to high-energy helium plasma. As noted by Dr Blackwell, “That is not good, because it means that little pieces will fall off. If the little pieces fall off, they cool the plasma and dampen the reaction. Fortunately, MAGPIE is able to reproduce this on a small scale. Under very well controlled conditions, we can use the excellent tools we have in Australia … to try to probe the cause of these bubbles and hopefully in the end prevent them.”

The project is very much a collaborative one, utilising the resources of not only ANU and ANSTO but also the Australian Synchrotron. According to Dr Blackwell, “It wouldn’t work without all that [collaboration] happening.” This work has in fact led to two new collaborations: one involving the ANU positron facility and another with the Dutch Institute for Fundamental Energy Research.

The facility is powering the future in more ways than one. Although APFRF doesn’t have the budget to break any world records, Dr Blackwell described it as “as much as anything, an excellent student and postdoc training platform”, enabling students to “get hands-on experience with brand new ideas in remote measuring systems” - more so than if they were under the pressure of handling billion-dollar devices. Many Australian graduates have gone on to do great things around the world, he said, including Dr David Campbell, a University of Sydney graduate, who is Assistant Deputy Director-General and Director of Plasma Operations with ITER - a multibillion-dollar, multinational experiment currently being built in France by a consortium of 35 nations.

When it commences operation in 2020, ITER aims to demonstrate the technological and scientific feasibility of fusion energy on a large scale, with a volume 10 times larger than any existing magnetic fusion experiment. From 50 MW of input power, the ITER machine is designed to produce 500 MW of fusion power - on par with a small power station - making it the first of all fusion experiments to produce net energy. Dr Blackwell said APFRF hopes to one day contribute to the global project, ideally providing theoretical and data analysis as well as an imaging instrument which takes advantage of ideas developed at the facility. He noted that Australia’s participation is not yet secured, but the capabilities provided by the recent upgrades are “all part of ‘Powering Ahead’, the Australian fusion community’s strategic plan to build up momentum and hopefully win increased funding for fusion science Australia-wide”.

So how long until we can live in a world powered essentially limitless, safe, greenhouse gas-free fusion energy? Dr Blackwell admitted that the steps of demonstration, commercialisation, production and infrastructure replacement could easily take 100 years, but ultimately concluded, “I think we’ll have a very clear answer about whether it can be done with magnetic confinement or not in 10-20 years.” It’s clearly an exciting time for plasma fusion research and, thanks to the APFRF, Australia can anticipate being part of this new age of clean energy production