The great challenge of nuclear fusion is achieving the necessary conditions for atomic nuclei to fuse at all. This works well on the sun. However, replicating this on a small scale without the almost infinite pressure of 330,000 earth masses is difficult.

At the same time, every optimization or simplification of the structure represents a further step towards ultimately obtaining more energy from fusion than is put into the operation of the system.

A novel design developed by researchers at the Princeton Plasma Physics Laboratory, U.S. Department of Energy, the University of Kyushu and a private company is one of them.

After all, not only is one component dispensed with during construction, but the energy required to produce the plasma is also significantly reduced. To use the scientists' metaphor: Instead of using a toaster, a microwave will be used for heating in the future.

Double savings

This means that the high-performance heater inside the tokamak, which uses ohmic resistance for heating like a toaster, can be dispensed with. This means that the entire reactor can be built much more compactly and fewer components need to be used precisely where maximum temperatures are reached.

Microwave radiation, on the other hand, which can also be used for heating at home, is emitted from outside. According to the paper, it is also possible to achieve remarkable savings in the power supply.

Instead of the previous 15 to 25 mega amperes of current, "only" 8 mega amperes are required to generate the microwaves in order to reach a temperature of around 100 million degrees.

Further simulations are now required to determine the optimum angle of incidence and time intervals between the pulses. Finally, other factors must be taken into account under the extreme conditions. Among other things, such strong microwave radiation induces currents in the plasma flow, which also contribute to heating, but can also cause instabilities.