To those who have kept tabs on nuclear fusion research the past decades beyond the articles and soundbites in news outlets, it’s probably clear just how much progress has been made, and how many challenges still remain. Yet since not that many people are into plasma physics, every measure of progress, such as most recently by the South Korean KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak, is met generally by dismissive statements about nuclear fusion always being a certain number of decades away. Looking beyond this in coverage such as the article by Science Alert about this achievement by KSTAR we can however see quite a few of these remaining challenges being touched upon.
Recently KSTAR managed to generate 100 million degrees C plasma and maintain this for 48 seconds, a significant boost over its previous record from 2021 of 30 seconds, partially due to the new divertors that were installed. These divertors are essential for removing impurities from the plasma, yet much like the inner wall of the reactor vessel, these plasma-facing materials (PFM) bear the brunt of the super-hot plasma and any plasma instabilities, as well as the constant neutron flux from the fusion products. KSTAR now features tungsten divertors, which has become a popular material choice for this component.
Researching the optimal PFMs, as well as plasma containment modes and methods to suppress plasma instabilities are just some of the challenges that form the road still ahead before commercial fusion can commence.
