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A Green Sun by Charles Gray
Posted: Sat Oct 22, 2011 4:48 am
Gray Actually Wrote the Novel I Tried to Write!
Posted: Sat Oct 22, 2011 7:26 pm
I just finished reading A Green Sun by Charles Gray, and I recommend it highly. It is available for $1.99 in Kindle format at
I did my best to write the Polywell novel that Charles Gray has actually written. I wrote a Prologue, 6 Chapters, and an outline; sent them out for review, and got back a resounding "Forget it!" My story was better (of course), and my Prologue was WAY better; but Gray's writing is MUCH better - especially his dialogues - and best of all, he actually finished HIS story! I am not sure why Mr Gray's novel avoids use of the word "Polywell," or why the novel does not credit Robert Bussard (however Gray does both in a note at the end of the novel). Most of Gray's technical detail is right on the money - though he is somewhat hazy on the direct conversion of the Alpha particle kinetic energy to HVDC. Also, I seriously doubt that that a commercial Polywell power plant significantly larger than 100 megawatts is within our nation's present capability - plus the wear and tear on the Polywell's parts from high energy alpha particle impacts will be significant. But these are trivial problems and do not detract from the story. Oh, one more thing - don't judge this book by its Prologue! I very much enjoyed the book.
Posted: Tue Oct 25, 2011 1:32 am
Posted: Wed Nov 23, 2011 10:37 pm
Re: Gray Actually Wrote the Novel I Tried to Write!
Posted: Tue Nov 05, 2013 7:37 pm
Re: A Green Sun by Charles Gray
Posted: Wed Nov 06, 2013 4:42 am
Bussard did apparently come up with the idea of the "Bussard Ram Scoop."used in SF. He wasn't aware of this till years later.
As for high energy alpha particles damaging the reactor- that is part of the benefit of direct conversion. Not only do you harvest the KE directly, you do so before they hit anything (they do not hit the magrid much) so spalling, heat damage, etc. is actually less than a D-D reactor . There are no significant neutrons to hit things. And the tritium and Helium 3 fusion products are also absent. These high energy fusion products would transfer their KE by impacting the walls to generate heat, etc. Direct conversion could also be utilized for these multiple products, but it would be more complex and still not change the neutron problem. Of course D-T fusion would be much easier in the Polywell but the fierce neutrons are even more of a problem (not to mention the tritium production problem).
The X- rays in a alpha particle producing P-B11 Polywell may be a relatively larger problem in the Polywell than high KE particle impacts. Because of this, the thermal wall loading in a P-B11 Polywell reactor may be less challenging than a D-D reactor. The P-B11 reactor may require ~ 3-4 times the surface area of an equivalent D-D reactor, and as a smaller percentage of the output would be thermal, the thermal wall loading engineering issues may be significantly less. Because of this, the P-B11 reactor may actually end up being the most compact option.
As for capacity, there is nothing limiting the growth (within reason). It is just that a break even + reactor would need to be ~ 100 MW output before fusion gains significantly overtake input costs (this is conservative D-D reactor estimates- an advanced P-B reactor may be a different story). A GW or even 10 GW reactor is not unreasonable. Bussard liked to stress though that the money economics favored multiple smaller machines over a single large machine*. Both because of size (radius) cost escalation- he used a general estimate of financial costs scaling as the radius cubed, and the preference of power companies for reactors of a few 100 MW power plants to be plugged into the power grid. That is one of the major problems with the Tokamak. If it works it will start at about 5-10 GW before it is profitable at the huge plant. But that makes economical distribution of that amount of localized power through the grid more challenging.
* Power companies seem to like the ~ 300-500 MW electrical output plants. Even when they need more local power they tend to cluster these smaller plants rather than building single megaplants.