Henning wrote: Simulation isn’t as advanced as you may think. There are particle-in-cell simulations but with a density much too low for our purposes. Then there is a parametric calculation that tells you what you might expect with different diameters and pressures and so on.

As third solution there is the LPP simulation, which simulates the plasma as a fluid (with extra quirks), because you cannot handle individual particles anymore at this density. It only simulates a single plasma filament. And it isn’t finished yet.

None of them include the shape of the DPF, except being a cylinder, or a sub-part of it.

There are plenty of PIC codes that can handle the modest densities of a DPF plasmoid (ie around solid density) Inertial confinement simulations have to cope with 1000 times higher.

No one simulation would be able to cope with the full range of scales involved. I would think at least three simulations would be needed, each feeding into the next. First a cylindrical resistive MHD code with ionisation, coupled to the electrodes & circuit response. Then a two-fluid code to handle the filamentation and pinch. Followed by a PIC code for the plasmoid formation.

Once you get all that working for a simple deuterium plasma, only then can you move on to add the p+B11 ion species to the fluid stages, and including the strong magnetic field effect and radiative cooling to the PIC code.

I agree simulation of plasmas in general is not very advanced. Based on the current state-of-the-art codes for tokamaks & inertial fusion and how long they have taken to develop. I’d say it would take at least 10 years work by several reasonable size research groups for DPF models to get to even a comparable level of confidence.

I always like to bring up the comparison with steam engines – they were developed by people such as Watt in the 1770’s and improved by Trevithick in 1801, well before there was a good understanding of thermodynamics by the likes of Carnot in 1824. Certainly well before there was any way of modelling or theoretically calculating the efficiency of an engine design.

By experimenting we may crack fusion well before we know what’s going on at the microscopic scale. The trouble is that the scientific community has got used to building ever larger experiments on the scale of LHC, NIF, ITER, JWST etc. where the money men want hard evidence that projects on that scale will work before they part with the cash. We need more of the trial & error approach.