Maximum size allowed by energy flux constraints

krenshala · Post by **krenshala** » Thu Jun 21, 2012 8:03 pm

MSimon, did you happen to come up with a (rough) length for the venetian blind collector, or even a "relative to the magrid" scale for it? I could swear I read somewhere it would be at most meters, but certain posts around the forums here claim at best tens-of-meters for the collector, and I was curious what your (BoE) numbers came up with if you had gone that far.

MSimon · Post by **MSimon** » Fri Jun 22, 2012 2:03 am

krenshala wrote:MSimon, did you happen to come up with a (rough) length for the venetian blind collector, or even a "relative to the magrid" scale for it? I could swear I read somewhere it would be at most meters, but certain posts around the forums here claim at best tens-of-meters for the collector, and I was curious what your (BoE) numbers came up with if you had gone that far.

I don't recall. My best guess is a doubling or tripling of the linear dimensions. It all depends on the volts/meter you can support and that is an ionization problem. The same problem you have with figuring the voltage vs size of the Magrid and the density you can operate at. Remind me of the technical term if you recall it.

krenshala · Post by **krenshala** » Fri Jun 22, 2012 4:31 pm

MSimon wrote:
krenshala wrote:MSimon, did you happen to come up with a (rough) length for the venetian blind collector, or even a "relative to the magrid" scale for it? I could swear I read somewhere it would be at most meters, but certain posts around the forums here claim at best tens-of-meters for the collector, and I was curious what your (BoE) numbers came up with if you had gone that far.
I don't recall. My best guess is a doubling or tripling of the linear dimensions. It all depends on the volts/meter you can support and that is an ionization problem. The same problem you have with figuring the voltage vs size of the Magrid and the density you can operate at.

So, for a 3m diameter Magrid, a worst case based on your guess would be +9m linearly from each face? Hmm. Bigger than I expected, but then that gets back to "its a guess" and "its an engineering (challenge|problem)".

MSimon wrote:Remind me of the technical term if you recall it.

Unfortunately, I'm horrible with names. Numbers, on the other hand ...

MSimon · Post by **MSimon** » Fri Jun 22, 2012 4:40 pm

I believe the number I came up with was on the order of 10m. i.e. it would just fit on a "small" ship. Shielding would be fore and aft and practically nothing to the sides. i.e. no fusion in such a ship while operating in port. A 1 MW DG set would be more than adequate for in port maneuvering. Nukes traditionally carry two of those so no problem. More on a carrier of course.

mvanwink5 · Post by **mvanwink5** » Fri Jun 22, 2012 8:14 pm

Why not use DD for ships with steam generation for powering turbines? Wouldn't that give a smaller footprint?

MSimon · Post by **MSimon** » Fri Jun 22, 2012 8:45 pm

mvanwink5 wrote:Why not use DD for ships with steam generation for powering turbines? Wouldn't that give a smaller footprint?

Because Steam Ships are being phased out in favor of electric drives.

And don't forget the footprint of the steam plant. And the maintenance - requiring a larger crew.

And the footprint does not get a LOT smaller because you have to use the "reactor" to generate steam. Which requires thickness and insulation. And a tad more shielding (1.5 times as much - roughly). And everything has to run hotter - lowering life.

It is all interrelated. And don't forget the mass of the steam plant.

And it is early days yet. It might be possible to shrink the dimensions by 20% with some experience. Or it may be so large that only carriers can handle such a plant. But fast oilers powered by Polywell might solve some logistics problems.

We won't know the optimum until we have some working designs in hand.