Author Topic: Fusion with space related aspects thread  (Read 574816 times)

Offline gospacex

  • Senior Member
  • *****
  • Posts: 2763
  • Liked: 343
  • Likes Given: 428
Re: Fusion with space related aspects thread
« Reply #2780 on: 04/18/2017 11:42 AM »
Plus again, we also need batteries, which are still very expensive and don't last forever.

Some types of batteries are cheap and last some 50 years. For example, nickel–iron batteries.
Ni-Fe drawback is that they are 2 times heavier than, say, lead-acid. Bad for cars, but for stationary storage, this factor is not significant.

Offline momerathe

  • Full Member
  • *
  • Posts: 132
  • Liked: 59
  • Likes Given: 33
Re: Fusion with space related aspects thread
« Reply #2781 on: 04/18/2017 02:04 PM »
I have a big question for tokamak devices and similar: how heavy are they for a given power, including boiler and ancillary equipment? When discussing space related fusion this is a key parameter. I get the feeling that it's incredibly heavy for the power output.

Excellent question. Ultimately, it's just a heat source, so the same considerations apply as to fission reactors in terms of turbines/generators and radiator mass.

(aside: is the output temperature as high as a fission reactor? that will affect efficiency)

If we're talking about propulsion, then direct drive concepts like *ahem* Direct Fusion Drive or that lithium liner concept (the name of which escapes me) will have the edge - if they ever get them to work.
thermodynamics will get you in the end

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 2814
  • Liked: 462
  • Likes Given: 698
Re: Fusion with space related aspects thread
« Reply #2782 on: 04/18/2017 11:25 PM »
I have a big question for tokamak devices and similar: how heavy are they for a given power, including boiler and ancillary equipment? When discussing space related fusion this is a key parameter. I get the feeling that it's incredibly heavy for the power output.

Excellent question. Ultimately, it's just a heat source, so the same considerations apply as to fission reactors in terms of turbines/generators and radiator mass.

(aside: is the output temperature as high as a fission reactor? that will affect efficiency)

If we're talking about propulsion, then direct drive concepts like *ahem* Direct Fusion Drive or that lithium liner concept (the name of which escapes me) will have the edge - if they ever get them to work.
I think that Tokamaks are the least ideal reactor type for space applications. They are just the ones we know best. The problems with Toks is that they are pretty much only suitable for "burning" deuterium and tritium and that comes with a large can of heavy equipment.
Reactors that do advanced fuels can usually use direct conversion. This would be much more compact and light weight. Plus you don't need FLiBe for breeding tritium (though for space applications, you could probably supply that from earth).