US scientists have made a breakthrough in nuclear fusion plasma heating efficiency by using metal screens. To achieve stable long-lasting fusion reactions, plasma must be kept super-hot, but unwanted slow modes pose a significant challenge.
Nuclear fusion has the potential to provide abundant clean energy on Earth, outperforming burning fossil fuels in terms of energy production. For instance, the energy released from burning 2,400 gallons of oil can be generated by just one gram of deuterium-tritium fuel without releasing greenhouse gases.
However, heating plasma to extreme temperatures is a daunting task. Scientists aim for temperatures seven to eight times higher than the Sun’s core, which requires innovative solutions. Researchers at the Princeton Plasma Physics Laboratory (PPPL) have developed a method using Faraday screens to overcome this hurdle.
Wave heating or radio frequency (RF) heating involves injecting electromagnetic waves into the plasma, causing charged particles to move faster and collide more frequently. This approach is similar to how microwaves in an oven interact with water molecules, generating heat through rapid vibration.
Despite its efficiency, RF heating has a limitation: it produces additional waves, known as slow modes, which lead to energy losses and reduce overall plasma temperature. The PPPL team ran simulations that confirmed a technique capable of preventing slow mode production, boosting plasma heating efficiency and increasing fusion reaction rates.
The breakthrough was achieved by placing Faraday screens at five-degree angles to the antenna generating electromagnetic waves. These metal screens act as protective barriers, blocking or reducing unwanted electromagnetic waves. Simulations showed that the screen allowed low-frequency heating waves to pass into the plasma while suppressing slow modes.
However, further research is needed to explore other methods for limiting slow mode production. By achieving ultra-high temperatures, scientists can unlock the full potential of nuclear fusion, providing a sustainable source of clean energy for the world.
Source: https://interestingengineering.com/energy/faraday-screen-for-plasma-heating-for-fusion