Tests show high-temperature superconducting magnets are ready for fusion

Fusion timelines and credibility

• Longstanding joke that fusion is always “25 years away” is discussed.
• Some argue this is outdated cynicism: recent Commonwealth Fusion milestones have been hit on schedule, with a target of “commercially relevant net energy” around 2025 and commercial plants roughly ~2030.
• Others stress that big energy projects (e.g., fission plants, aircraft) routinely slip by a decade or more, so fusion plants will too.
• Several commenters are frustrated by decades of overhyped PR, arguing fusion is still too far away to affect near-term climate planning.

Economics vs other energy sources

• Doubts that fusion will ever beat fission on cost; others note fission itself is often more expensive than solar plus storage.
• Debate over whether high German electricity prices are caused by renewables or by political/tax decisions and shutdown of cheap existing reactors.
• Some claim fission is “overregulated” and that this drives costs; others point out nuclear’s accident risk and historical military subsidies.
• Handling of fission waste is said by some to be a small cost component; others focus on its very long-lived radiotoxicity and argue for advanced reactors to “burn down” waste.

Fuel cycle and materials constraints

• Practical near-term fusion is assumed to be deuterium–tritium, even if not always stated.
• Tritium is rare because it decays; designs rely on breeding it in lithium blankets.
• Lithium is abundant overall, but Li‑6 enrichment and beryllium supply are serious bottlenecks; current Li isotope separation capacity is tiny, and one ARC-scale reactor would consume a large fraction of annual Be production.
• Some mention alternative schemes (e.g., DD and D–He3) that could produce tritium as a byproduct, but these remain speculative in this thread.

Magnet technology (REBCO, HTS, and MRIs)

• REBCO high‑temperature superconducting (HTS) tapes enable much stronger fields, shrinking reactors and dramatically improving economics compared to older superconductors.
• Mechanical and quench-protection design relies on REBCO bonded to strong metal substrates and copper caps; in a quench, current diverts into copper.
• “Bare” REBCO tapes can be used because their conductivity vastly exceeds the metallic substrate, so current naturally follows the superconducting path.
• Operating well below the critical temperature (e.g., ~20 K, not 77 K) allows much higher current density and fields.
• REBCO is not yet common in MRI machines due to brittleness, limited global supply (CFS reportedly bought most of it), and the fact that current helium use and cost in MRIs is manageable, especially with sealed, low-helium designs.

ITER’s role and limitations

• Stronger HTS magnets cannot simply be retrofitted into ITER; higher fields would change plasma parameters and impose vastly larger mechanical (J×B) forces than the structure is designed for.
• ITER is framed as a burning plasma lab, not a commercial prototype. Some argue newer compact designs with stronger magnets may leapfrog ITER for commercial relevance, though ITER data on high-temperature plasma behavior is still seen as valuable.

Operational and waste considerations

• Even assuming magnet success, commenters emphasize unsolved issues: component degradation under neutron bombardment, intense activation making maintenance difficult or impossible by humans, and complex blanket/breeding systems.
• Fusion waste is expected to be shorter-lived and may be regulated more like particle accelerators than fission plants, but some note that fission waste volume is already small, and regulation differences remain a policy question.