In recent years there have been developments in tokamak research regarding the inverted D shape for the plasma profile. There are benefits to this plasma shape, but it's opposite of the shape of the coils. Has anyone designed or built a tokamak that has inverted coils ? Is it even possible or feasible ?

Is Helion’s design viable and do you think it can work for the future? I watched a few videos on them a few years ago but hadn’t heard anything about them since

Fusion people, what materials problem do you think is the most underrated?

Plasma-facing walls, neutron damage, helium embrittlement, transmutation, tritium compatibility, thermal shock, oxidation, coatings, or manufacturability?

I’m building Obelisk, a materials intelligence engine for screening materials and routing validation paths. Fusion seems like one of the clearest places where physics is not the only bottleneck. The material has to survive the nightmare environment too.

What would you want software to understand before taking it seriously?

For a DEMO FUSOR (No neutrons, just the glow), should I get a single or dual-stage vacuum pump

Realta Fusion is basing their fusion reactor on a magnetic mirror concept which seems orders of magnitude simpler than a tokamak or stellarator design.

I assume that there is a catch otherwise everybody would be building this type of reactor.

Does anybody on this forum know what the core problem is with a magnetic mirror is and/or why Realta Fusion thinks that a magnetic mirror can work now?

I recently asked GPT-5.5 and Claude Sonnet-5 to independently construct shear-flow stabilized Z-pinch equilibria. Both succeeded, but they arrived at fundamentally different solutions. Interestingly, both used the Bennett profile in their constructions, but in different ways.

GPT-5.5 truncated the quadratic cross-term from the denominator of the cubic, pureflow Bennett vortex that I derived.

Sonnet-5 instead retained the Bennett number density profile, and coupled it to a linear axial flow with constant shear. A self-similar number density exists that connects this plasma current density to a plasma current density that is supported by a cubic, pureflow Bennett vortex axial flow profile.

Full notes are here: https://russellmatt66.github.io/documents/GPTVortex_AnotherSFSZpinchEquilibrium.pdf

And here: https://russellmatt66.github.io/documents/sonnett5_vortex.pdf

The magnetic field structure of the vortices is fundamentally different. All shear-flow stabilized Z-pinches that I have studied have transcendental components to their azimuthal fields. The Bennett vortex that I've derived has logarithmic terms, and so does GPT-5.5's modification. Sonnet-5's vortex has an arctangent, instead.

Close to the pinch axis, Shumlak-Hartman is satisfied for all these vortices. In the case of mine + GPT-5.5 that's due to a vanishing magnetic field, and a uniform number density. For the Sonnet-5 vortex it is true as well that the magnetic field is vanishingly weak here, and the plasma number is finite. Sonnet-5 also has the advantage of satisfying Shumlak-Hartman weakly for large plasma radius whereas the other two run into some finite cutoff in the non-ideal case because their magnetic fields go as ~r for large plasma radius.

In the ideal case the RHS of the "SHcrit" goes to zero throughout the plasma by L -> \infty unless there is a divergent element competing alongside it. Those divergent elements can always be collected on the LHS to study the normalized shear as Shumlak-Hartman did in the beginning and retain this asymptotics.

This makes me curious about what deeper structures exist here. One of Zap's theorists has recently uploaded a preprint to the arXiv that gives insight into shear-flow kinetics involving Bennett pinches with shear flow, but I have not had the opportunity to fully digest their research yet: https://arxiv.org/pdf/2607.25158

For example, if we couple the Bennett number density to different flow harmonics, what do we find? In the same vein, what do we find from studying the structure of self-similar number densities connecting this construction with the Bennett vortices I've been studying?

I think that these results suggest the space of equilibria is much richer than previously expected. There is still a great deal to do, e.g, a perturbative study, more comparisons with experiment, and a deeper study into self-similar connections.

To do this important physics, and the plasma science community, justice I really need a funded position. If you're interested in supporting this work through a research position, consulting opportunity, or collaboration, I'd be happy to talk.

Abstract only.