Need help figuring out a possible fusion engine

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Discussion Overview

The discussion revolves around the design of a fusion engine for a fictional spacecraft intended for a long-duration journey to Alpha Centauri, exploring various fusion reactions and their feasibility for propulsion and fuel management over a 40-year trip.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose using a proton-proton fusion reaction, questioning its feasibility for long-duration space travel.
  • Others argue for deuterium-tritium (DT) fusion for acceleration and deuterium-deuterium (DD) fusion for deceleration, citing the stability of deuterium.
  • A participant suggests that DT fusion releases significantly more energy than DD fusion, making it advantageous for initial acceleration.
  • Concerns are raised about the decay of tritium during the long coasting phase, questioning the practicality of a breeding system for tritium.
  • Some participants explore the idea of using antimatter as a fuel source, but concerns about safety and cost lead to a preference for fusion.
  • Discussion includes the potential use of helium-3 in fusion reactions, with participants noting the challenges of achieving the required conditions for stable fusion.
  • A proposal is made to use the helium-4 produced from DT fusion for ion drives, suggesting a dual propulsion system.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility of different fusion reactions, with no consensus reached on the best approach. The discussion remains unresolved regarding the practicality of tritium breeding and the use of antimatter.

Contextual Notes

Limitations include the dependence on theoretical advancements in fusion technology and the unresolved implications of long-term fuel storage and decay rates.

Who May Find This Useful

Writers and enthusiasts interested in speculative science fiction, particularly those exploring advanced propulsion systems and fusion technology in space travel.

  • #31
Yes that isn't a problem, I already included Radiators for the heat :)
 
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  • #32
I would like to have other kind of questions. Could a D-T engine go off like a bomb, or simply melt down? Would such meltdown make the environment heavily radioactive for a long time? I guess it would be still a low thrust high specific impulse drive, whether it produces thrust directly or powers ion thrusters.
 
  • #33
You can design an engine based on bombs. Project Orion uses that idea.
A reactor cannot explode like a bomb, there is simply not enough fuel and not enough time - as soon as something goes wrong, the confinement is lost, the plasma expands and the reaction stops immediately. The reactor can handle the power output of several seconds before melting down, so in the worst case the plasma melts the innermost surface of the reactor chamber. Replace it (and let its radioactivity decay over time - that is necessary anyway), done.
 
  • #34
GTOM said:
I would like to have other kind of questions. Could a D-T engine go off like a bomb, or simply melt down? Would such meltdown make the environment heavily radioactive for a long time? I guess it would be still a low thrust high specific impulse drive, whether it produces thrust directly or powers ion thrusters.

This was a long-time belief in the Battletech universe, but the developers actually deconstructed this idea in one of their technical source manuals several years ago.
 
  • #35
Aside from the sheer improbability of cost and availability, this is one of the reasons I strayed away from an Antimatter or Orion type drive. Early on I was in favor of The Orion style design but ultimately I didn't like the idea of my ship sitting on thousands of warheads for decades through deep space. one malfunction and there goes the whole thing. Being able to stockpile several thousand warheads for private use was also out of the realms of possibility even for a sci-fi story.
 
  • #36
Nuclear warheads are safe to store - just remove a part of the trigger or some other vital part. They only work when fully assembled.
 

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