In recent years, many positive strides have been made that are bringing the “fusion era” closer to reality. Most recently, scientists working with the Experimental Advanced Superconducting Tokamak(EAST) – aka. the “Chinese artificial sun” – set a new record by super-heating clouds of hydrogen plasma to over 1 million degrees – a temperature which is six times hotter than the Sun itself.
While scientists are capable of fusing atoms of hydrogen to produce energy, the stumbling block has always been reaching what is known as the “break even point”. This is where the energy produced by a self-sustained fusion reaction is equal to the energy needed to initiate it. And while we have no yet reached this point, scientists are getting closer all the time.
Currently, the two most popular methods for producing fusion power are the inertial confinement approach, and the tokamak reactor. In the former case, lasers are used to fuse pellets of deuterium (H², or “heavy hydrogen”) to create a fusion reaction. In the latter, the process involves a torus-shaped confinement chamber that uses magnetic fields and an internal current to confine high-energy plasma.
By super-heating this plasma and keeping its stable, a self-sustaining fusion reaction can be created. Whereas other tokamak reactors rely on magnetic coils to keep a plasma torus stable, the Chinese EAST reactor relies on the magnetic fields produced by the moving plasma itself to keep the torus in check. This makes it less stable, but allows physicists to increase heat levels.
After a four month-long campaign, the EAST science team was able to integrate four types of heating power in order to reach a new temperature record. These included lower hybrid wave heating, electron cyclotron wave heating, ion cyclotron resonance heating and neutral beam ion heating. Through these combined methods, the plasma current density profile was optimized.
Once the science team managed to optimize the coupling of the four different heating techniques, they were able to create a cloud of charged particles that contained electrons heated to more than 100 million °C. They also exceeded a power injection level of 10 MegaWatts (MW), and boosted the plasma stored energy to 300 kilojoules (kJ).
This is not the first time that scientists at CASHIPS have reported reaching a fusion milestone. In 2016, the team announced that they had produced hydrogen gas that was three times hotter than the core of the Sun (approx. 50 million °C; 90 million °F), and were able to maintain this temperature for a record-breaking 102 seconds.
With this latest experiment, the EAST team not only doubled the temperature of the plasma torus (setting a new record), they also managed to resolve a number of issues that are crucial to achieving steady state operations. For instance, they resolved the confinement of particle and power exhaust, the timing of which has to be just right in order to maintain a sustained fusion reaction.
The experiment also provided key data for the validation of heat exhaust, transport and current drive models, all of which will be crucial to the realization of several major fusion projects. These include the International Thermonuclear Experimental Reactor (ITER), the Chinese Fusion Engineering Test Reactor (CFETR) and the DEMOnstration Power Station (DEMO).
Originally built in 2006, EAST has become a fully open test facility that allows the global scientific community to conduct steady-state operations and physics research.