Questions About Focus Fusion for Hard Sci Fi

[Rocket Surgeon]

Hi All!

First time posting here, been interested in Focus Fusion for a while! I’ve got a few questions for a hard sci fi world I’m putting together.
Apologies if this is the wrong place to ask this, feel free to move and/or delete it.

So on to the questions:
1) How well does/would a DPF fusion device work with D-He3 fuel? I know LPP is aiming to use p-B11 and I remember reading that DPF works better for heavy fuels, BUT D-He3 has lower ignition conditions doesn’t it? Would it make sense to convert over to D-He3 if/when a good source of He3 was accessed?

2) Can a DPF be used to create a beam of high energy/temperature Ions without fusing them? or would there be a better way to do this?

3) How well does DPF fusion scale and how do you scale it? To increase the fusion yeild/ energy of the Ion beams do you up the voltage/current? make the DPF bigger? longer? increase the cathode radius or shrink the anode? What varible do you change in order to increase the fusion yeild assuming you have no restrictions on cost?

Thanks for any help you guys can provide and if there are any sources that would also help, please feel free to add them here.

Thanks again!

[JimmyT]

Did you mean to say Hydrogen 3, as in tritium?

[JimmyT]

In answer to your question #2. Yes a DPF can produce a high energy/temperature ions, but it does so by fusing them. At least some or most of them, that’s where a substantial fraction of their velocity comes from. I’m not certain why fusing them is undesirable?

Question #3 on scaling: Can’t scale the machine. Can’t make it bigger or smaller. At least not from what we know NOW. No reason you couldn’t operate several of them together though. There is a little bit of tweeking you can do to mess with the ion beam vs X ray emissions. All the energy the DPF releases is released in the form of either x-rays or ion beam. Higher voltage increases the fraction emitted as x-rays, which for an ion propulsion system (which I assume you’re aiming at) is undesirable.

[Henning]

Rocket Surgeon wrote:
1) How well does/would a DPF fusion device work with D-He3 fuel? I know LPP is aiming to use p-B11 and I remember reading that DPF works better for heavy fuels, BUT D-He3 has lower ignition conditions doesn’t it? Would it make sense to convert over to D-He3 if/when a good source of He3 was accessed?

The DPF now reaches consistently temperatures high enough for p11B fuel, see latest LPP report.

Rocket Surgeon wrote:
2) Can a DPF be used to create a beam of high energy/temperature Ions without fusing them? or would there be a better way to do this?

A low power DPF (actually low current DPF), or a DPF with diffuse pinch, creates a beam of high energy ions without fusing.

So the DPF was researched as an ion thruster around 2000 by Texas A&M University for NASA, but there already fusion occured. Eric Lerner was part of that team.

Rocket Surgeon wrote:
3) How well does DPF fusion scale and how do you scale it? To increase the fusion yeild/ energy of the Ion beams do you up the voltage/current? make the DPF bigger? longer? increase the cathode radius or shrink the anode? What varible do you change in order to increase the fusion yeild assuming you have no restrictions on cost?

Scaling by itself is not the problem. You can scale it linearily in size as well in power. The scaling law for the DPF seems to be I^4 (current to the fourth power). So the goal is pumping as much energy through a small device as possible.

The problem is the cooling of the anode, which probably isn’t scaleable as easily. The proposition is to have a beryllium anode through which helium gas is pumped for cooling.

[Patientman]

Rocket Surgeon – Are you using the information for science fiction? or fiction about science? How would Hydrogen 3, as in tritium be beneficial to the process of energy generation, if pB-11 is a step above?

The transfer to electricity seems to solve many other issues in current generation scenarios in both space travel and providing a mechanism for lifting payloads into space. DPF also solves the expense immediate problem of infrastructure costs. Upgrading the power grid becomes null, thus distributive small power plants and a paced roll-out of a secure grid occurs. The age of the 500 mega watt $10 billion dollar facility will fade away. Research into trillion dollar facilities will also be dropped, hopefully. Miniaturization would be nice, but not yet understood or realistic.

The need to read not speed. 🙂

[Author]

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