Z-Pinch Renaissance

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Re: Z-Pinch Renaissance

Postby williatw » Mon Aug 26, 2019 4:37 pm

Skipjack wrote:I love the Fusion Driven Rocket. It is foil liner compressed FRCs. It has a lot of thrust compared to other fusion engine designs and a Isp of 5000 is still plenty good. That said, if the Sheared Flow Stabilized Z- Pinch works, it would have this design beat in terms of Isp and thrust, which is quite crazy.

I am not an engineer Skipjack BS degree in Chemistry. But I remember from molecular kinetics that the higher the exhaust velocity (ISP is exhaust velocity divided by g) the higher the temperature. And ISP of 356,800 seconds (from the posted link for Z-pinch using D-He3) corresponds to a likely exhaust/plasma temperature well into the millions of degrees. Even if the plasma isn't coming in contact with the walls of the rocket at that temp. it (the plasma) would radiate EM intensely. Probably well into the UV range if not maybe soft X-rays; don't know. A thrust of 3.3×105 N corresponding with a stated power output of 3.3×1012W indicates a large throughput of such super-heated plasma. How much supplemental shielding/coolant would that take and how much would that add to the mass of our Z-pinch fusion rocket? The beauty of John Slough's design is that it masses at I believe around 100 tons. He obviously wanted something that could be launched into orbit by current rocket technology. Having said that there is no reason with Musk's reusable BFR on the horizon that Slough's design couldn't be scaled larger; nuclear pulse rockets actually get more efficient with larger size/mass. A larger collapse radius for the coils of Lithium would produced longer acceleration times/faster velocity/higher compression temperature/pressure insuring more complete fusion for instance. That might increase ISP/thrust considerably; also it seems that Slough's approach is more doable with current technology.
Last edited by williatw on Mon Aug 26, 2019 5:26 pm, edited 1 time in total.

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Re: Z-Pinch Renaissance

Postby Skipjack » Mon Aug 26, 2019 4:47 pm

I don't want to have this thread drift too much off topic. I just want to add that I love MSNW's Fusion Driven Rocket design. I think it is amazing, since it does get a lot of thrust and has none of the problems you mentioned. I am not sure about the temperature problems of the Z- Pinch design. As for being mature. It seems that the SFS Z- Pinch is developing really quickly and the potential is huge. Meanwhile the FDR has seen very little funding in recent years and it is very different from Helion's Fusion Engine design (which has been making great progress). So I am not sure whose approach is more "doable". I think both have merit and both should be looked into.
What excites me about the Z- Pinch approach is that it has (indirect) funding through ZAP's work and it could have a very high T/W ratio, which is also important.

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Re: Z-Pinch Renaissance

Postby Giorgio » Mon Aug 26, 2019 5:34 pm

Same feelings. I guess that before the end of the year we should know more.
A society of dogmas is a dead society.

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