Explore the groundbreaking research that proposes eliminating a key component in spherical fusion reactors, potentially leading to more compact and cost-effective fusion power plants.
Reduction of the Fusion Footprint
Conventional spherical tokamaks have needed a huge solenoid — a coil of copper wound like a spring that runs up through the middle of the device — to make plasma. A coil in the center of the vessel, which consumes about a third of it.
A new solution has been proposed, however, by scientists from the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL), Tokamak Energy and Kyushu University in Japan As a result, they’ve come up with a design for a smaller spherical pilot plant where the plasma can be heated by nothing but microwaves, making the solenoid dispensable.
It is equivalent to constructing a small kitchen with limited armaments — simple and cheap. Thus, the removal of the ohmic heating coil leads to a cleaner and less cluttered nuclear fusion reactor layout, allowing more space for other components which means potential construction savings.
Taking Advantage of Microwaves
The breakthrough in this new design cameby way of microwaves. Microwave radiation can be created in a gyrotron. These gyrotrons would be mounted on the outside of the tokamak, orienting them inwards towards the plasma core.
Although the waves do not actually excite a current, their frequency resonates with that of negatively charged electrons moving in and out of the plasma by chance when they stray close to magnetic field lines. The substantial heating in addition to establishing current in the plasma is another task that is taken care of by a process called electron cyclotron current drive(ECCD).
This is easier said than done, though: you can’t simply flip the switch on the gyrotrons and get all the heating efficiency. And correct modeling has already led them to closely analyze multiple scenarios, including understanding at what angle the gyrotrons should be aimed to hit microwaves into the plasma in the most effective way. Using computer codes such as TORAY and TRANSP, they’ve scanned the aiming angles to search for the best solution so that it requires less power to drive the current needed.
What is more, the researchers also had to determine whether it was possible for the microwaves to backscatter off plasma or penetrate into (and back out of) the plasma chamber without perturbing its current or temperature. Efforts have been made to reduce these losses so that most of the microwave power is well utilized for heating and driving plasma.
Conclusion
It is an innovative solution in the march towards more compact, and cost-effective fusion power from spherical reactors. They used that ability to heat and drive the plasma with microwaves as more than a scientific endeavor; in their work, they see hope for the future of fusion energy — a green and virtually endless energy solution that’s long remained out of reach.
