MatthewGrim
commented
6 years ago Comments on paper
Assumptions
First note is that in the assumptions listed, quasi-neutrality is definitely not the case for a Polywell. Maybe this is why the Kachan study gives such radically different results.
II
Section B: Temperature equilibration
I personally never thought the reactant species would have different temperatures.
Section C: Thermalisation
The argument about thermalisation being averaged over the period of the oscillation for both fusion raction rate and thermalisation makes sense. And they should in principle cancel, so I can agree with this argument. If this is true, there needs to be a lightweight way of re-introducing the beam like behaviour to the reactor.
Section D: Upscattering losses
I understand what upscattering is, but the assumptions behind this model of the loss is hard to understand without further digging.
Section E: Bremsstrahlung losses
The expression is clear, but again assumes an integration of Maxwellian velocities.
III
Profiles
Pretty sure recent work has improved these density profiles.
Cusp losses
Intuition about using electrostatic cusps is validated by Rider, it's not a good idea. For the case of a polywell, why is the limiting ion convergence distribution right? It's inherently non-Maxellian?
Grid Losses
For mag-grids I don't need to worry about these.
Maxwellian Distribution
Depends on whether the confinement time for the cusp losses makes sense. I need to think this through myself.
Results
I didn't realise the bremsstrahlung losses would increase for advanced fuels. In retrospect, it makes sense.
In the paper - A general critique of inertial-electrostatic confinement fusion systems by Todd Rider, IEC devices are heavily criticised for a variety of reasons, concerning radiation and thermalisation rates. This issue documents the replication of results from this paper to get a better understanding of the assumptions and their implications. I want to understand how fair these assumptions are to IEC devices, especially the Polywell.