Out of Nowhere... A Wild Tokawell Appears!

Discuss how polywell fusion works; share theoretical questions and answers.

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wodom86
Posts: 3
Joined: Tue Aug 04, 2015 8:57 pm

Out of Nowhere... A Wild Tokawell Appears!

Postby wodom86 » Sun Aug 09, 2015 8:15 pm

I have been working on the design and the math on this for roughly about a week and a half. Now this is a directy copy and past out of fusor.net because im not getting any bites over there. Hopefully you guys can help me.
Post 1
Chamber is 2 pipes one with 8" OD the other with a 2.5". 1/2" stainless plate welded to the bottom of both pipes with a hole in the middle of the plate where the smaller pipe is. It will be pressure tested and polished. The upper 1/2 stainless plate will be grooved to fit the 8" pipe wall and the 2.5" pipe wall. It will overlap the middle by 1/2" to insure the knife edge will get a seal. The groves will have rubber gaskets at the bottom of them and vacuum grease. The chamber will be pressed together with 9 bolts through 5/8" plywood. One on top and one on bottom. The bolt going through the center pipe will probably be made out of acrylic to prevent accidental induction.

The Chamber
https://tinkercad.com/things/0dK88YjHCmB

Outer pipe is missing so you can see the inside of the chamber. (please excuse my poor attempt at drafting, I'm still learning. This is only so you can get an idea of what im talking about.)

Poloidal Magnet:

The center pipe will have a induction coil wrapped around it and powered via a positive DC power source. The poloidal magnet will not only give the chamber a positive charge to repel Ions but will also help direct them back to the center potential. The magnet is not for Plasma Confinement more along the lines of preventing ion conduction through the chamber.

Toroidal Cage Magnet:

The Thesis posted below explains how 2 individuals were able confine electrons in an open torus magnet at 500 gauss with a potential of 10eV. 10eV is nowhere close to what we need for fusion but if it works on a small scale it should work on a larger scale. I will build the Toroid out of coiled copper INSULATED wire and have the 2 electrodes for electron source between coils close to the walls of the toroid to prevent electron conduction. The idea here is to have the toroidal magnet just strong enough to contain electrons only and not effect Deuterium Ions, and allow for D2 atoms to pass into the toroid, be stripped to an ION, accelerate down the hill and hopefully fuse. I am hoping to see somewhere around 12.5keV potential but I am afraid because of the design I may need a higher potential to be able to have more fusion chances. Ion injection is probably going to have to be required eventually for higher neutron counts obviously. Containment of electrons over Ions shouldn't be too difficult seeing as electrons weigh so much less than deuterium ions.

Thesis: http://www.ipr.res.in/library/onlineres ... ameerk.pdf

Summary:

This design, I am hoping will help prevent most grid/chamber collisions from electrons and possibly IONS. I am still learning physics, fusion, and electrical engineering so please bear with me. If you have input to be able to make this work PLEASE help haha. I am also to people tearing this thing apart because it won't work, just let me know why please.

Questions:

Does electron keV effect the amount of magnetic force required for confinement? Meaning, Does higher keV require more Gauss for confinement for electrons?

With the electrodes on opposite sides of the toroidal coil, 180 degrees out, is there a chance of arcing to the toroidal coil even if it is shielded? Last thing I want to do is run 15kv through a circuit that is only meant for like 200V.


Post 2
So insomnia got the best of me last night and i started drawing and thinking more on this design. I am thinking of having the Toroidal Coil Negatively charged. Even with small amounts of Positive charge it may repel already active IONs in the chamber away from the Coil, preventing them from falling into the potential well.

Feedback please. I am about to start ordering stuff to build the chamber and I dont want to get too deep into this design if it fundamentally will not work, granted i guess i could make a homemade Tokamak if thats the case.

Post 3
I need a little help with calculating magnetic force. Trying not to get so high as to effect deuterium IONs but confine electrons. I have done alot of math but I am at a stand still for calculating force and flux density. Any help would be nice. I am stuck here until i get some units to start wrapping coils.

Deuterium Relativistic mass at 15kve =3.3445237x10^-27 kg
Electron Relativistic mass at 15kve =9.3769863x10^-31 kg

Now im not sure if electron density is going to play a part into having to have a stronger field since technically it will be increasing the total mass inside of the toroidal coil.
Deuterium being several magnitudes heavier than electrons you would think this would be easy. I keep running into sub-earth magnetic field strengths, which brings up a few questions. Will the earth's magnetic field interfere with the chamber if i am running say something around .31 guass. How impossible that sounds to fabricate.


https://en.wikipedia.org/wiki/Orders_of ... etic_field)

according to this and my relative weight of my charged particles along with the momentum of each

electron - 6.65767x10^-29 kg-m/s

Deuterium - 4.02249x10^-21 kg-m/s

im starting to believe im going to have to build a weak toroidal coil and hope the ions will have enough energy to escape it

wodom86
Posts: 3
Joined: Tue Aug 04, 2015 8:57 pm

Re: Out of Nowhere... A Wild Tokawell Appears!

Postby wodom86 » Mon Aug 10, 2015 9:03 pm

Building the Toroidal Magnet today and possibly tig welding the chamber next week. Even though the Torus isn't "high" Beta. With the electrons confined to the toroidal magnet, it should allow fusion at certain conditions. I am afraid im going to have to do ion injection in order to get the concentration of ions high enough while keeping the vacuum levels lower.


Also what do you guys recommend for viewing port material?

D Tibbets
Posts: 2769
Joined: Thu Jun 26, 2008 6:52 am

Re: Out of Nowhere... A Wild Tokawell Appears!

Postby D Tibbets » Wed Sep 02, 2015 2:23 am

I've not totally ignored your proposal, but I have very little idea of what you are trying to do. A few comments.' What works for the small scale works for the large scale.'- afraid not. Tokamak research has shown the frustration in this regard. A low denbsity electron plasma may be containe3d, but higher density and charge buildup explodes the containment. Then there are the instabilities, ExB issues,etc.
A magnetic field that contains electrons but not ions may be highly problamatic. In the Polywells case the electrons are contained magnetically but the ions are not prinarily contained- but this is because the slectrostatic potential well holds the ions (mostly) away from the magnetic field. It is not that the magnetic field is fully, or even mostly transparent to the ions.
Trying to contain ions electrostatically with magnetic fields insulating the electrode is an option, but the leakyness of magnetic fields to ions especially a problem. This ExB diffusion of charged particles is significant. It is directly proportional to the momentum or square root of the mass of the particle. This is why electrons can be contained better by magneticd fields. Their momentum is at least ~ 60 times less so their gyroradius in a magnetic field is ~ 60 times less. The ExB diffusion occurs due t interparticle collisions and a partical can be knocked one gyroradius deeper into the magnetic field. After multiple collisions the charged particlal reaches the magnetic surface. Ions ~ 60 times faster than electrons. In the Polywell this problem is mostly avoided by having a central electrode that attracts the ions. The important point here is that theis electrode- the virtual cathode, is not a surface that the ions can hit, it is a space charge created by the energetic excess electrons. This avoids the grid collisions that is so limiting for fusors. I suspect you hope that magnetically shielding this centrall placed grid/ tube will resolve this issue also, but I doubt it, due to ExB losses if nothing else.

In Tokamaks, my understanding is that the ExB diffusion through the magnetic fields is what in part limits the density that can be achieved and drives the machines to such huge sizes. The other problem in Tokamaks are those pesky edge instabilities. Tokamaks actually manage to confine plasma of a given density much beter than cusp machines like the Polywell. But the density is limited in Tokamaks, exceed those limits and the losses become exponentially worse. A Tokamak that confines plasma at 10^19 particles / square meter with a confinement time of 1000 seconds is equivalent to a Polywell at 10^22 particle density with one millisecond containment. In the Polywell the resultant fusion rate may be one million times greater. That is why the confinement times are directly related to the acheivable fusion rate- the triple product.

Dan Tibbets
To error is human... and I'm very human.

wodom86
Posts: 3
Joined: Tue Aug 04, 2015 8:57 pm

Re: Out of Nowhere... A Wild Tokawell Appears!

Postby wodom86 » Thu Sep 03, 2015 4:46 pm

Thank you so much for your input, sorry i havent been on in a while my job has be quite busy. Yeah my basic idea is to create a electron well inside of the toroidal magnetic field with hopes that the ions will fall into it through the gaps between the wire. Granted that leaves the ions up for collision into the toroidal coil it cuts down on electron collisions. The idea for Cathode and Anode inside the torus are strictly for a source of electrons to enter the torus. Trying to have electrons float all willy nilly and getting into the toroidal field will prove quite difficult so starting them off there is the idea. The magnetic field inside the torus will not be containing ions (purposefully) just electrons. Any other ideas throw them at me :) as soon as this big deal at work is done i plan to start assembly, Lots of pictures for you guys in the process


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