I've pictured the fusion rocket as essentially a fusion bottle, open at
one end. The fusion exhaust won't necessarily have a lot of radioactive
particles, but is putting out high-energy radiation directly.
Essentially, you're riding a powerful particle accelerator and hitting
anything behind you with cosmic rays.
HEPlaR is a something of a magic tech, to give us more of a hard SF
feel, without completely doing away with what's come before.
On 12-07-11 15:01, Jeff Dougherty wrote:
>
>
>
> There's no a priori reason that a fusion or fission drive has to have
> radioactive exhaust products. However, most if not all nuclear
> reactions are going to have radioactive byproducts, and if the working
> fluid for your exhaust comes into contact with the reactor it's going
> to pick them up. To cite an extreme example, the exhaust for NASA's
> NERVA rocket design was predicted to be highly radioactive, because
> the high-speed flow of liquid hydrogen through the fission core would
> actually erode the uranium fuel elements and expel particles of
> uranium with the exhaust, enough so that fuel element erosion rather
> than uranium depletion would be the limit on the core's working life.
> In order to avoid this, you need some kind of heat exchanger s ystem
> to keep the working fluid for your reactor and the working fluid for
> your exhaust separate. On a conceptual level, this is what HEPlaR
> does. But- in the real world introducing a head exchanger into the
> system is always going to cut down on efficiency somewhat, because
> there's never going to be a perfect transfer of heat from one side of
> the exchanger to the other. As far as I can tell, FF&S assumes that
> by the time you get to HEPlaR TLs the exchangers are efficient enough
> that the loss is negligible compared to the benefit of not having your
> ship glow in the dark.
>
> Of course, there's always the possibility of a starship operator
> antisocial enough to cut out the exchanger and get even more
> efficiency out of his drive, and screw whoever's underneath the ship
> when it comes down. Virus anyone?
>
> Mweh. Heh heh heh...
>
> -JTD
>
> Any sufficiently stupid human is indistinguishable from a computer.
>
>
--
Edward Swatschek -
one end. The fusion exhaust won't necessarily have a lot of radioactive
particles, but is putting out high-energy radiation directly.
Essentially, you're riding a powerful particle accelerator and hitting
anything behind you with cosmic rays.
HEPlaR is a something of a magic tech, to give us more of a hard SF
feel, without completely doing away with what's come before.
On 12-07-11 15:01, Jeff Dougherty wrote:
>
>
>
> There's no a priori reason that a fusion or fission drive has to have
> radioactive exhaust products. However, most if not all nuclear
> reactions are going to have radioactive byproducts, and if the working
> fluid for your exhaust comes into contact with the reactor it's going
> to pick them up. To cite an extreme example, the exhaust for NASA's
> NERVA rocket design was predicted to be highly radioactive, because
> the high-speed flow of liquid hydrogen through the fission core would
> actually erode the uranium fuel elements and expel particles of
> uranium with the exhaust, enough so that fuel element erosion rather
> than uranium depletion would be the limit on the core's working life.
> In order to avoid this, you need some kind of heat exchanger s ystem
> to keep the working fluid for your reactor and the working fluid for
> your exhaust separate. On a conceptual level, this is what HEPlaR
> does. But- in the real world introducing a head exchanger into the
> system is always going to cut down on efficiency somewhat, because
> there's never going to be a perfect transfer of heat from one side of
> the exchanger to the other. As far as I can tell, FF&S assumes that
> by the time you get to HEPlaR TLs the exchangers are efficient enough
> that the loss is negligible compared to the benefit of not having your
> ship glow in the dark.
>
> Of course, there's always the possibility of a starship operator
> antisocial enough to cut out the exchanger and get even more
> efficiency out of his drive, and screw whoever's underneath the ship
> when it comes down. Virus anyone?
>
> Mweh. Heh heh heh...
>
> -JTD
>
> Any sufficiently stupid human is indistinguishable from a computer.
>
>
--
Edward Swatschek -