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: Inner Grid
Date: Apr 20, 4:55 pm
Poster: Richard HullOn Apr 20, 4:55 pm, Richard Hull wrote:
Bob,
It is great that you are pulling it all together.
No. You shouldn't have to worry about the perturbances.
When I make an inner grid, I just start making small great circles to a pattern and vary the length of each piece of wire slightly up or down from the pattern pieces and go like crazy making 20 or more loops as once you are on a roll, having set up for the operation, 20-25 are as easy as 5 (virtually).
I next grade the rings, size wise, in steps. A few are identical, etc. Next I look at the array and find the center of the distribution then I choose two rings smaller than the center of this distributionand use the smaller for the inner most ring. I then have a slotted jig to hold the rings together as vertical longitude lines. This jig is a very small copper collar cut from 1/2-3/4 water pipe and slit on one end with three saw cuts to yeild 6 slots separated by 60 degrees. The Smallest ring is droped in first, next I place a second slightly larger ring which fits well in the jig and and over the first ring. Finally, a third yet larger ring (center of the distribution). All the time, I check for bulging or out of round conditions caused by rings that are too small or too large. When totally satisfied, I tack weld or silver solder the polar crossing. The jig is then manipulated down and rotated sideways to exit the three circle globe now forming. The jig is reinserted and carefully aligned to the opposite polar region which now needs to be soldered or welded. Now I have a free standing, sturdy three circle sphere. Next the final two circles (larger still) are added to "x" over at 90 degree angles to one another at the equator. If all is just perfect, the jig could be used provided it can be removed afterwards. (usually never the case)
I most often just clamp the wires in place and weld or silver solder the crossing of three wires at this equatorial region and finally, the other side.
This is really all the points that require rigid welds or solderings. One can tack each crossing along all wires from here if desired, but each time you solder, you run the risk of screwing you work up.
Finally, I use a rigid conducting post of .125" stainless wire between the insulator feed through and the inner grid. I cover this with an alumina tube (McMaster-Carr), to prevent discharge to it or glowing. It is a tricky operation, but each person will attach the grid to suit. I would be worried about the free swinging central grid which you propose, but the coulombic force might be faily weak at the 10KV level for a demo fusor. Smart money might go for the rigid stalk type support. If you decide to go pendulous let me know how it works.
The outer grid is just not critical at all! spend the bulk of your effort on the inner grid as it is the toughy and the determining factor for whether or not you can hit star mode. (sphereocity and centration.)
Hope this helped.
Richard Hull