Reply To: Great News!

[asymmetric_implosion]

Joeviocoe wrote:

The switch problem is the materials erode leading to a plasma/vapor of that metal. When the current turns off, the plasma/vapor expand and coat all surfaces. After some number of shots, a thin metal film builds up on the insulating ceramics or plastics that normally hold off the high voltage. The finite conductivity can lead to problems with voltage hold off, excessive leakage current in the switch. These conditions can lead to pre-fire and large jitter.

That is why I mentioned a gas flow system that keeps the material vapor from coating the switch internals. The flow gas must be inert and kept hot to prevent solidification. But that should be doable.

asymmetric_implosion wrote:
Many problems in fission can be mitigated. After fuel is burned it can be reprocessed extracting the useful components and burning the other products in an accelerator. Proliferation is a concern but thorium cycles can by-pass many of those concerns. Ask the Indians about whether they are investing in fusion or thorium fission. The Chinese have a more diverse picture but they are investing in tokameks for their fusion program.

I certainly like the diverse approach to energy that the world has in general. I wish the U.S. was as bold sometimes.
LFTRs and even Travelling Wave reactors are important to fund and develop regardless of any progress on the fusion front.
I was just remarking how improper it was to regard fission as an energy silver bullet when it was the ‘new thing’ on the block.
Focus Fusion may be the holy grail, but that just means it tackles many issues at once. But it won’t save the planet without help. Different reactors for larger marine propulsion or large centralized power needs. Stacking 100 DPFs seems impractical. A 100MW polywell might serve better.

Gas flow is used in these switches and they still have only 5E6 lifetime in the case of spark gaps. Thyratrons cannot flow gas and work correctly. There are other components in the switch I didn’t mention that are required for operation and stagnant gas is a must.

I think the US has a pretty diverse energy investment. Coal is king but we use natural gas, fission, solar, hydro and wind. DOE is supporting all these efforts via numerous funding vehicles and incentive programs. Nuclear is a tough sell in the US for a number of reasons. The main reason is legal. It only takes a few folks to file legal action which can shutdown a plant start up. The Nuclear Regulatory Commission is hearing license requests and new design approvals at a high rate these days and every one is heavily challenged. It takes years to get approval for a design let alone a site license. On the nuclear front, we are operating Gen II reactors in the US. Gen III reactors are going on-line in China while Gen IV reactors like traveling wave and thorium reactors could be licensed before Gen III reactors are built.

In my opinion the Polywell has a longer road to fusion than the PF. There are two sides in the Polywell argument going on in literature and from a pure physics standpoint the Polywell seems difficult. You rely on beam generation which is easily demonstrated at low density. As you increase density, which is required to achieve gain, Debye lengths and plasma fluid effects kick in limiting your ability to produce beams. The PF produces beams in a dense plasma because of it’s instabilities. The Polywell is a steady state device that is unlikely to see the same instabilities.