In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: Fusor Operation - a general question
Date: Jul 04, 3:23 pm
Poster: Dave Cooper
On Jul 04, 3:23 pm, Dave Cooper wrote:
Thanks Jim for some good insights. A bit more here in response to explore some things you wrote.
>>This would be nice, but the nature of the ion and its coulomb forces do not allow this level of ballistic precision. While it has not been confirmed beyond a reasonable doubt, many IEC researchers agree that most of the fusion reactions in the fusion zone are not head on collisions but side collisions, thus the correlation between the higher voltage and higher reaction rates.
You are right here, of course. It is a very important point, which although aware of it, I didn't state very clearly.
The picture I have of the fusor central region, is a high particle density at sufficiently high kinetic energy level (> 20 keV) for fusion to occur. Truly head-on collisions would be exceedingly rare. And fusion will not occur until the nuclear energy barrier is overcome, meaning the particles pass closer than few nuclear radii,
The aggregate of all this is an overall fusion probability greater than zero, resulting in the observed reaction rate as a function of current, voltage and gas density.
>>The electrons that form the virtual cathode are those that remain inside the cathode grid in a state of dynamic ballistic motion, in an out of the reaction zone. It's when these particles come to there U-turn points (do to electrical attraction and repulsion) that for that split second the particle charge forms a space charge that acts a virtual electrode...
...The inner cathode grid in a fusor is a steady unbending structure that sets in motion the chain of events that lead to virtual cathodes, without it many have found it impossible to generate the virtual electrodes that fusor's depend on for there continued reactions.
This is a key point. It seems that in order for the alternating shells of electrons and deuterons to exist, two things (at least) must occur. The interaction of deuterons passing through the electron cloud must be minimal- i.e.: collision cross sections small emough. and, losses to the structures themselves (opacity) must be tolerable.
>>The most serious problem here is that there is no source of electrons and therefore you have just ions. The problem is that I think the dominant force in this scheme will be Earnshaw's theorem, because both the reaction zone and the outer wall will be positive or in other words potential hills for the ions to overcome.
>Add to this the fact that you need reaction rates above 10^12 just to get 1watt of energy out put and you have a serious problem.
Perhaps I have made subtle shift into a different device in my description above...but... it seemed to me, the virtual electrodes of the Farnsworth's devices are not the key to the fusing process, but rather just one form of ion delivery and recirculation. In order for what I described here to work, I presumed all non reacting ions would be neutralized at the ground shell and then gathered up and re-injected (ionized ) for another trip.
Reaction rates of 10^12 are just micro amperes of reacting ions...which at 20 kev or so..gives a return on investment of nearly 50 to one. (1watt to 0.020 W input)... not counting pumpdown energy and chamber/grid heating. The one shot and recirc approach seems to sidestep grid losses entirely.
Use of the more expensive but much less power hungry ion pumps.. would help toward a breakeven, since they typically operate at about 7 - 12 kV at low pressures or only about 0.007 to 0.012W per uA of background ion current.
- Re: Fusor Operation - a general question - Richard Hull Jul 05, 8:47 am
- Re: Fusor Operation - a general question - Dave Cooper Jul 06, 2:59 am
- Re: Fusor Operation - a general question - Dave Cooper Jul 04, 11:07 pm