I'm assuming this (like most ideas from a semi-amateur like myself) only sounds useful until it gets hit by the harsh reality of the way things actually work. So you can tell me what's wrong with it.
But here goes:
Build a classic Farnsworth Fusor using the normal design but instead of using bare wire for the grid, replace it with wire which is surrounded by ceramic standoff material and then is wrapped in a second wire which goes around the inner wire.
The inner wire is energized with a negative charge compared to the ions and as such draws them inward. The outer wire, however, has a net positive charge, but is lower in potential than the inner wire of the grid. The ions are initially attracted and accelerated inward by the negative potential but when they get very close to the grid, the positive outer charge becomes the more powerful influence and therefore tends to deflect them away from the grid.
Potential (I'm thinking not)
Idea for Reducing Collisions with Gird using Coaxial Grid
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
If you were using DC voltages, I think the ions would feel the net force of the fields. So they would more or less cancel out, and the ions would still be attracted to the inner negative wire, just at a lower potential.
I think something interesting with pulse more or RF could done with a similar grid configuration.
I think something interesting with pulse more or RF could done with a similar grid configuration.
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Richard Hull
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Re: Idea for Reducing Collisions with Gird using Coaxial Grid
The problem is one of simple physics.
The inner wire is far more negative to attract the ions. The outer wire is positive to repel ions. The net field is what the ions will see which is the high negative field summed to the positive field.
The inner wire -20kv, outer wire +5kv net field -15kv Thus the net field attracts ions to enter the grid region, ideally at 15kev energy. (we just wasted 5kev of possible fusion energy) As the particle approaches the +5kv grid wire it will be turned but not repelled as the particle is at 15kev energy. We do not want any ions turned or deflected as they enter the grid region. We want them focused.
Richard Hull
The inner wire is far more negative to attract the ions. The outer wire is positive to repel ions. The net field is what the ions will see which is the high negative field summed to the positive field.
The inner wire -20kv, outer wire +5kv net field -15kv Thus the net field attracts ions to enter the grid region, ideally at 15kev energy. (we just wasted 5kev of possible fusion energy) As the particle approaches the +5kv grid wire it will be turned but not repelled as the particle is at 15kev energy. We do not want any ions turned or deflected as they enter the grid region. We want them focused.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
Does distance matter? Doesn't repulsion/attraction vary as the square of the distance?
And who's "Gird"?
And who's "Gird"?
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
Distance does matter. I got the image of a of two wire separated from each other ceramic breaks, and having open uninsulated wire.
The "net field" felt would be between the shell (at neutral ground) and both the wires. Which at the kV range can be approximated to just adding the two field potentials.
If you want to get really fancy and include the difference in distance, you could integrate the field force equation, F=kq1q2/r^2, and again add the potential energy of the fields.
The "net field" felt would be between the shell (at neutral ground) and both the wires. Which at the kV range can be approximated to just adding the two field potentials.
If you want to get really fancy and include the difference in distance, you could integrate the field force equation, F=kq1q2/r^2, and again add the potential energy of the fields.
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
Think of it like the gravitational field around a star:
As a star's diamiter changes the net field outside the star remains unchanged.
The math works out the same way with a large vs small diamiter wire the net field is indistinguashable from a smaller wire with the same net charge. So wrapping a weak negitive wire around a strong positive wire is identical to a single slightly weaker but still positive wire.
As a star's diamiter changes the net field outside the star remains unchanged.
The math works out the same way with a large vs small diamiter wire the net field is indistinguashable from a smaller wire with the same net charge. So wrapping a weak negitive wire around a strong positive wire is identical to a single slightly weaker but still positive wire.
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
No, I do not think it is the same.
Because of the inverse square law on sufficient small distances from the positive charged wire, the field gets positive. On the other hand, on a large scale the positive charge is dominated and on even larger scales, it is shielded completly!
Look at these images:
http://web.mit.edu/8.02t/www/802TEAL3D/ ... age052.jpg
http://web.mit.edu/8.02t/www/802TEAL3D/ ... age050.jpg
I think the idea is woth to think about. Problem is the high energy of the particles.
Because of the inverse square law on sufficient small distances from the positive charged wire, the field gets positive. On the other hand, on a large scale the positive charge is dominated and on even larger scales, it is shielded completly!
Look at these images:
http://web.mit.edu/8.02t/www/802TEAL3D/ ... age052.jpg
http://web.mit.edu/8.02t/www/802TEAL3D/ ... age050.jpg
I think the idea is woth to think about. Problem is the high energy of the particles.
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
If you're looking at the yellow image, the ions will try to follow the field lines right into the orange point charge (if its negative), in every case the the lines lead right back to the orange point. In the best scenario, the ion's path coming in are only bent slightly. Bending paths are bad in fusors when you want beam-beam fusions.
Re: Idea for Reducing Collisions with Gird using Coaxial Grid
Yes, I was thinking you would have an analog of the cathode-anode fields in a vacuum tube. The greater the separation, the greater the local influence of the anode.