MSimon wrote:There seems to be a problem in engineering thinking.
Thought experiment:
1. You build a machine it takes up 1 m^3 and delivers 1 KW. You can build them in 1KW increments.
2. Your friend builds a better machine. It delivers 100 KW per m^3. Its smallest size is 10,000 m^3.
Which will you buy?
Energy density isn't everything.
And of course the steam plant vs direct conversion throws a little wrench into the economics. And scalability.
Power density is not everything. That is only power density. And nothing else.
You say "better machine" on machine having 100 times higher power density (100 kW/m3 vs. 1 kW/m3) And at 10^17 m^-3 number density Polywell will have million times lower power density.
What do you think, what Mr. Carter meant saying “hard to keep particles separately at higher than 10^17 number density”?
That means that Debye length will be lower than geometrical dimensions of device after which set of electrons and ions will converted into plasma and is hardly separating (inevitably strong fields are needed for separation).
Did you ever see working direct energy converter or direct energy conversion was offered in last century for partial compensation of cusp losses? Can you imagine its design and explain how that will be compact and cheap as Polywell’s funs state? If to recall that electrons and ions there obligatory should be separated and for that you need dramatic expansion of plasma.
Well, you leave out one minor point. The density where the reaction actually occurs. I ran the numbers. It has been a while. But a 3m dia Polywell should be good for 100 MW. For the same magnet current if you can cut everything in 1/2 and volume by 1/8th you should be up to 200MW. That is a 16X improvement in density. Can you pump it? Probably.
And no steam plant with its 30% to 60% losses. Direct conversion should come in at or below 30% losses with no steam plant required.
Engineering is the art of making what you want from what you can get at a profit.
MSimon wrote:But a 3m dia Polywell should be good for 100 MW. For the same magnet current if you can cut everything in 1/2 and volume by 1/8th you should be up to 200MW. That is a 16X improvement in density. Can you pump it?
Yes, I can.
But please:
• inform resilts for 0.4 or whatever dia machine
• please inform also why for showing of real scalability the field of six short solenoids was not improved from 0.8 to e.g. 2 T? Difficult? Expensive? No!
• And ok - 3 m dia reactor. And very good to use energy conversion with e.g. 90% efficiency. But now please also inform the initial number density in stream entering into direct converter and also your assumption how long that converter should be? 10 m? 50 m? 200 m? Or 1000 m?
Thanks.