Reply To: Could pB11 focus fusion device be modified to use thorium?

[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.