[moogly]

> Theory dictates that with stronger magnets, the reactor can be scaled down (with the square/cube, can't remember exactly), and thus cost and time to develop

OTOH, in a tokamak, the plasma volume (and potential energy output) scales quadratically with the torus' aspect ratio (ratio of major to minus radius), so I'm not sure that tokamak-based fusion really is particularly suitable to miniaturization.

[DennisP]

Tokamak output scales with the square of reactor volume but the fourth power of magnetic field strength, so with sufficiently powerful magnets, scaling down the size can be an option.

[gloriana]

However, you as you scale down, all the radiation damage effects per unit volume or unit surface area increase rapidly causing higher material activation and maintenance cost.

[beambot]

This technical deep-dive by Dr. Dennis Whyte goes into the scaling considerations: https://www.youtube.com/watch?v=rY6U4wB-oYM

TLDR: Tokamak economics scale in size with 1/B^5 -- so doubling the magnet field strength reduces the physical size substantially. This factor dominates other scaling parameters by a substantial margin, and is entirely enabled by high-temperature superconductors. A host of other key fusion parameters also scale beneficially with B^x (for some value of x) -- most of which are discussed in first half the video.

[ppaattrriicckk]

I had no idea, thanks for sharing.

Again, I'm very much a layman to this subject, but how does miniaturization necessarily affect that particular aspect ratio? Since it's literally a ratio of two dimensions of the torus, shouldn't this be invariant to the overall size? (Assuming all things being equal, which I have no idea whether holds.)

[XorNot]

Miniaturization has never been realistic with tritium fusion anyway due to neutron production - you need several metres of material to stop them, otherwise your reactor is just kicking off radioactive oxygen into the atmosphere.

[kuprel]

Wouldn't the aspect ratio remain constant as you scale down?

[dylan604]

Unless you forget to hold the shift key as you drag.

[IceDane]

This guy clearly does nuclear fusion.

[mrandish]

You win HN for today...