Plasma-facing material
ITER and many other current and projected fusion experiments, particularly those of the tokamak and stellarator designs, use intense magnetic fields in an attempt to achieve this, although plasma instability problems remain.
[1] Tungsten is widely recognized as the preferred material for plasma-facing components in next-generation fusion devices, largely due to its unique combination of properties and potential for enhancement.
Its low erosion rates make it particularly suitable for the high-stress environment of fusion reactors, where it can withstand the intense conditions without degrading rapidly.
Additionally, tungsten's low tritium retention through co-deposition and implantation is crucial in fusion contexts, helping to minimize the accumulation of this radioactive isotope.
Furthermore, the potential for developing radiation-hardened alloys of tungsten presents an opportunity to enhance its durability and performance under the intense radiation conditions typical in fusion reactors.
Understanding the behavior of tungsten in fusion environments, including its sourcing, migration, and transport in the scrape-off-layer (SOL), as well as its potential for core contamination, is a complex task.
Significant research is ongoing to develop a mature and validated understanding of these dynamics, particularly for predicting the behavior of high-Z (high atomic number) materials like tungsten in next-step tokamak devices.
In the context of future fusion power plants, tungsten stands out for its resilience against erosion, the highest melting point among metals, and relatively benign behavior under neutron irradiation.
When combined with copper's high thermal conductivity, these composites offer improved thermomechanical properties, extending beyond the operational range of traditional materials like CuCrZr.
Li has a low first ionization energy of ~5.4 eV and is highly chemically reactive with ion species found in the plasma of fusion reactor cores.
Results from these MCFD highlight additional benefits of liquid lithium coatings for reliable energy generation, including:[1][23][8] Newer developments in liquid lithium are currently being tested, for example:[9][10] Silicon carbide (SiC), a low-Z refractory ceramic material, has emerged as a promising candidate for structural materials in magnetic fusion energy devices.
However, tritium retention in silicon carbide plasma-facing components is about 1.5-2 times higher than in graphite, leading to reduced fuel efficiency and increased safety risks in fusion reactors.
[25][26] Additionally, the chemical and physical sputtering of SiC is still significant and contributes to the key issue of increasing tritium inventory through co-deposition over time and with particle fluency.
[30][31] Current research efforts focus on understanding SiC behavior under conditions relevant to reactors, providing valuable insights into its potential role in future fusion technology.
Silicon-rich films on divertor PFCs were recently developed using Si pellet injections in high confinement mode scenarios in DIII-D, prompting further research into refining the technique for broader fusion applications.
