Nuclear fusion sees sudden bursts of potential breakthroughs

Commercially viable nuclear fusion would be a giant step tow­a­­rds solving global energy equat­ions. Imagine a way to produce ch­eap inexhaustible power, which is moreover clean, with no emissions and no radiation or waste products. There’s also no chance of Chernobyl/ Fukushima type meltdowns, or explosions.

Enormous investments have been made in fusion rese­arch since the potential payoff is so large but the problems have been intractable for 60 years. There’s hope now because of several breakthroughs since August last year, the latest one coming just about a week ago.

The power output from different fusion experiments has jumped, and Artificial Intel­li­gence and other new software has demonstrated ways to de­sign and control magnetic fields better, to hold the raw material for fusion. There are also tantalising signs that alternative, more energy-efficient ways to trigger fusion may work.

Fusion involves compressing the atoms of an element (usually a hydrogen isotope) to create an­other element (usually helium). The excess particles relea­s­ed in fusion are converted to energy. This happens inside a star. Hyd­rogen is by far the most abundant element in the universe — isotopes like deuterium can be easily pulled out of sea water.

So what are the problems?

Most obviously, a power source must produce a surplus of energy over whatever keeps it ticking. For example, setting fire to coal is energy-surplus. Triggering a fusion reaction that releases more energy than required to start fusion is called “Ignition” in nuclear jargon. Fusion has happened, but Ignition hasn’t happened yet.

The fusion of a kilogramme of deuterium could release at least four million times as much energy as burning a kilo of coal. But initiating fusion requires setting up conditions like a star, or even hotter — meaning insane combinations of very high pressures and temperatures of 150 million degrees Cel­sius. This requ­ires pumping huge quantities of power into a fusion reactor to get it going.

Various experimental designs involve creating plasma (hot, electrically charged gas), by bombarding hydrogen isotopes with high-energy lasers. The plasma may be contained within an electromagnetic field and superheated by lasers, until the electrons (which have negative charge) are stripped away and the plasma is electrically positive. At around 150 million C, fusion triggers.

The positioning and output of the lasers is important. The less power required to generate and maintain the magnetic fields, the better. The less energy required to run the lasers, the better. The more fusion that occurs, the better.

The strength and shape of the magnetic field is important. There are different designs. The voltages have to be adjusted thousands of times every second to contain plasma. Other designs use a different concept: “inertial confinement” of placing plasma inside a shaped metallic pellet, which is bombarded and destroyed when fusion starts. Again, shape is important.

In February, scientists at the Joint European Torus (JET) near Oxford, UK generated the highest sustained energy pulse ever created by fusion, more than doubling a record JET itself had set way back in 1997. The plasma is contained within a doughnut-shaped magnetic field at JET. A torus is the mathematical name of the doughnut shape. These designs are also called Tokamaks (Russian for doughnut) since they were invented by Russian scientists led by Andrei Sakharov.

The success of JET augurs well for a scaled-up design cal­led the ITER (which will handle 100 times the plasma volume). The $22-billion ITER is scheduled to start running in 2025 and it may achieve ignition. The ITER will be located in France but it is a collaborative project of many countries, including India. An AI from Alphabet Subsidiary DeepMind has demonstrated how it can manage magnetic fields better in an experiment on the Variable Configuration Tokamak (TCV) at Lausanne, Switzerland. This could make Tokamaks significantly more energy-efficient.

In August 2021, the Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) created a new record in terms of fusion output. The LLNL is also trying to develop a design with self-heating plasma where the fusion energy keeps the plasma boiling.

The University of Wash­ing­ton’s Fusion Z-Pinch Experi­ment (FuZE) project showed that another design, which uses pulsing electric fields to confine plasma, could also trigger fusion. Such a field pinches plasma. This creates instabilities that could interfere with fusion but experiments have proved fusion does occur. “Pinching” plasma could be a more energy efficient way to generate fusion power. Nasa is also funding what is called lattice-confinement designs in the hopes of developing a “cold fusion” design, to be used for small, portable reactors.

It may seem coincidental but after many years of being stalled, fusion research is seeing all these potential breakthroughs in a brief, sudden burst. Any breakthrough that does result in commercial fusion would bring new hope to a world struggling with high fuel prices and climate change.