Polywell Electrical System

[zimdlg]

Hi Everyone

This is my first post, I discovered this technology a month ago and have been reading up and watching videos on it since then. I think it looks very promising and I really hope WB8 lives up to everyones hopes.

I am especially interested in the direct conversion of the power to electricity in the H+B11 reaction and the associated HVDC systems. After all you can do as much fusion as you like but it you can't make the power available at a transmission substation busbar the system isn't worth much. I have read other threads on this topic in this forum but none that explain it to my liking. I want to see circuit diagrams for the whole system, has any work been done on that? I usually only understand things properly if it is laid out simply in a diagram.

I have done a 3-D drawing of the cube shaped polywell as I understand it. I was hoping to post it here for comment but I'm not sure how to put the image on a publically accessable server as the FAQ says I should.

Thanks
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[TomB]

@zimdig

"I am especially interested in the direct conversion of the power to electricity in the H+B11 reaction and the associated HVDC systems. After all you can do as much fusion as you like but it you can't make the power available at a transmission substation busbar the system isn't worth much. I have read other threads on this topic in this forum but none that explain it to my liking. I want to see circuit diagrams for the whole system, has any work been done on that? I usually only understand things properly if it is laid out simply in a diagram."

OK.Let's try. In text, though.

When the ion guns shoot Hydrogen and Boron11 nuclei into the electrostatic potential well, they have electrons left over, having stripped them off the fuel ions that were just sent down the electrostatic potential well. They need to find a positive sink. Direct conversion helps them do that.

In the Proton-Boron11 reaction, the end product is positively charged alpha particles, with an energy of about 2.35MEV. That means you can have them climb the potential well, and keep going to a screen/Alpha Trap just inside the surrounding vacuum sphere, which is charged to 2.35million volts positive in relation to the electron cloud at the bottom of the potential well.

Then you run a wire from the ion guns, with their excess electrons out through an electrical load, and back into the the Alpha Trap/screen, just inside the inner surface of the vacuum sphere. That is your completed circuit, if highly simplified.

Tried an ASCI diagram, but preview showed it not working. Sorry

Regards,

Tom Billings

[KitemanSA]

I am especially interested in the direct conversion of the power to electricity in the H+B11 reaction and the associated HVDC systems. After all you can do as much fusion as you like but it you can't make the power available at a transmission substation busbar the system isn't worth much. I have read other threads on this topic in this forum but none that explain it to my liking.

Try reading this and see if it doesn't help.

http://www.askmar.com/Fusion_files/Venetian%20Blind.pdf

It is pretty good.

[D Tibbets]

@zimdig

"I am especially interested in the direct conversion of the power to electricity in the H+B11 reaction and the associated HVDC systems. After all you can do as much fusion as you like but it you can't make the power available at a transmission substation busbar the system isn't worth much. I have read other threads on this topic in this forum but none that explain it to my liking. I want to see circuit diagrams for the whole system, has any work been done on that? I usually only understand things properly if it is laid out simply in a diagram."

OK.Let's try. In text, though.

When the ion guns shoot Hydrogen and Boron11 nuclei into the electrostatic potential well, they have electrons left over, having stripped them off the fuel ions that were just sent down the electrostatic potential well. They need to find a positive sink. Direct conversion helps them do that.

In the Proton-Boron11 reaction, the end product is positively charged alpha particles, with an energy of about 2.35MEV. That means you can have them climb the potential well, and keep going to a screen/Alpha Trap just inside the surrounding vacuum sphere, which is charged to 2.35million volts positive in relation to the electron cloud at the bottom of the potential well.

Then you run a wire from the ion guns, with their excess electrons out through an electrical load, and back into the the Alpha Trap/screen, just inside the inner surface of the vacuum sphere. That is your completed circuit, if highly simplified.

Tried an ASCI diagram, but preview showed it not working. Sorry

Regards,

Tom Billings

I get the impression that the your view is that the ions are injected in isolation. This would quickly build up intolorable coulomb forces. For each positively charged ion injected there is a companion electron injected from the electron gun, so the net charge inside the magrid is zero or neutral. But an excess of ~1 part per million excess of electrons are injected and these play a key role (though I continously confuse myself with circular arguments about how this might work). The ion and electron feeds would be adjusted to replace fuel ions as they are consumed and leave as the high sppeed fusion ions, and to replace leaked fuel ions , and leaked electrons.

Dan Tibbets

[chrismb]

For each positively charged ion injected there is a companion electron injected from the electron gun, so the net charge inside the magrid is zero or neutral. But an excess of ~1 part per million excess of electrons are injected and these play a key role (though I continously confuse myself with circular arguments about how this might work). The ion and electron feeds would be adjusted to replace fuel ions as they are consumed and leave as the high sppeed fusion ions, and to replace leaked fuel ions , and leaked electrons.

Could someone please remind me, in this context, where these ion and electron guns sit? If an ion comes out of the ion gun and accelerates to where it is meant to, how does the electron make the same journey?

[D Tibbets]

For each positively charged ion injected there is a companion electron injected from the electron gun, so the net charge inside the magrid is zero or neutral. But an excess of ~1 part per million excess of electrons are injected and these play a key role (though I continously confuse myself with circular arguments about how this might work). The ion and electron feeds would be adjusted to replace fuel ions as they are consumed and leave as the high sppeed fusion ions, and to replace leaked fuel ions , and leaked electrons.

Could someone please remind me, in this context, where these ion and electron guns sit? If an ion comes out of the ion gun and accelerates to where it is meant to, how does the electron make the same journey?

Short answer- ion gun at one cusp, electron gun at another cusp. The streams of ions and electrons do not have to be in close proxemity so long as they end up in the same volume. In fact this unequal distribution is is maintained to drive the machine- potential well, slow ions in the perifery, fast electrons in the same area, and opposite in the center.

As far as maintaining global neutrality ( or the 1 ppm offset in the Pollywell) consider an ion drive on a space ship. As the ions are accelerated away from the space ship electrons are ejected from seperate electron guns into the ion stream . This prevents charge buildup on the space craft and the ions subsequently pulling the spacecraft back and defeating the effort to produce thrust.

What I'm wondering about is how these guns at two or more cusps effect recirculation.

Dan Tibbets

[zimdlg]

First of all I must say I'm not a physicist so sorry if my questions are elementary.

TomB:

I've read that electrons must first be fired with E guns into the polywell to create the wiffleball. The -ve electrons are trapped inside the polywell by the the +ve charge on the polywell and are prevented from hitting the polywell by the strong magnetic field around the polywell. The magnetic field also recirculates the electrons back inside the polywell if they do escape. The wiffle ball creates a very -ve potential well. Then the H+ and B11+ (only 1 +ve on each B11 ion I assume) ions are fired at the wiffleball. They accelerate towards the centre of the wiffleball and if a H+ and a B11+ impact just right they fuse to produce 3 fast alphas (see viewtopic.php?t=22, 5th post, Msimon) each with a charge of 2+, so thats a total of 6+ charge and 8.7 MeV ( http://en.wikipedia.org/wiki/Aneutronic_fusion ) from each fusion.

The two sets of deceleration grids have to be charged up to approximately +ve 1.2 MV and +ve 1.5 MV (see above ref), both slightly
below the charge of the two sets of alpha particles, which requires energy (how is this done?). Then the +ve alpha particles shooting out the wiffleball are then decelerated by the +ve electrical field as they approach the grids and are then neutralised (producing helium) when they touch the grid (vaccum pumps need to run to remove the helium). Is the decelertion done to some how gain energy from the alpha particles as they decelerate? Or is it done at a loss only to stop the high velocity alphas from damaging the grid as they impact it, and then energy gained from the current produced when they touch the grid?

Each alpha (2+) aquires two electrons (2-) from the grid as it touches and becomes a helium atom, so electons will have flow into the grid. I assume the grid voltage has to be maintained at the same level while a continuous steam of alphas are touching the grid (how is this done?), so that the new alphas coming from the wiffle ball are decelrated correctly. The voltage must be kept not to high so the alphas are repelled, and not to low so the alphas then impact the grid to fast and damage it.

It seems to me that work has to be done to slow the alphas down, a 8.7 MeV loss, and then all you're doing is neutralising the helium ions. So two electrons were removed from the H and B11 and the six are needed to neutralise the helium ions. Thats a net of four electrons flowing to the grid. Is this enough current to run the E guns, Ion guns, charge up and run and current through the magrid, charge up the deceleration grid, and run the vaccum pumps? Everything I've read seems sure the direct conversion to electricity will work but I don't really understand. Anybody please correct my understanding of this
process.

KitemanSA:

Thanks for the pdf but it seems to be intended to work with a tokamak not a polywell so not all of the parts of the system are relevant and it doesn't show how the grids are charged up and the rest of
the electrical system behind the grids.

chrismb:

My understanding is that the E guns are mounted on the inner wall of the vaccum chamber and fire the electrons through the centre of the electromagnets into the polywell. The ion guns are also mounted
on the inner wall of the vaccum chamber and fire the ions throught the gaps inbetween the electromagnets into the polywell. Or it could be the otherway round, maybe it doesn't matter. As D Tibbets said "ion gun at one cusp, electron gun at another cusp". I thought each cusp would have either an E gun or an ion gun firing through it. For the cube polywell thats 6 E guns and 8 ion guns (H opposite B11).

[chrismb]

My understanding is that the E guns are mounted on the inner wall of the vaccum chamber and fire the electrons through the centre of the electromagnets into the polywell. The ion guns are also mounted
on the inner wall of the vaccum chamber and fire the ions throught the gaps inbetween the electromagnets into the polywell. Or it could be the otherway round, maybe it doesn't matter. As D Tibbets said "ion gun at one cusp, electron gun at another cusp". I thought each cusp would have either an E gun or an ion gun firing through it. For the cube polywell thats 6 E guns and 8 ion guns (H opposite B11).

Sure, but aren't the electrons and ions headed towards the same region of the device, and this region has the same potential!? So one or t'other will have to 'roll up the [potential] hill'.

[D Tibbets]

My understanding is that the E guns are mounted on the inner wall of the vaccum chamber and fire the electrons through the centre of the electromagnets into the polywell. The ion guns are also mounted
on the inner wall of the vaccum chamber and fire the ions throught the gaps inbetween the electromagnets into the polywell. Or it could be the otherway round, maybe it doesn't matter. As D Tibbets said "ion gun at one cusp, electron gun at another cusp". I thought each cusp would have either an E gun or an ion gun firing through it. For the cube polywell thats 6 E guns and 8 ion guns (H opposite B11).

Sure, but aren't the electrons and ions headed towards the same region of the device, and this region has the same potential!? So one or t'other will have to 'roll up the [potential] hill'.

Absolutely. The electrons have to roll up this potential well. That is why they are provided with an initial kinetic energy of thousands of electron volts directed twoards the center (both the speed and vector are critical), while the ions only need enough energy to squeeze them into the internal magrid volume. Thanks to magnetic containment and (hopefully) efficient radial bouncing of the electrons off of the B-field border (and other issues that ere under debate), once the initial electron is injected it will repeatedly climb this potential enough times that net fusion power becomes possible.

[EDIT] The ions would not see the potential of the magrid as thay are created/released within this border. Again, having this gun located this deep inside the cusp has to have an effect on recirculation in that cusp. Presumably, it might harm electron recirculation, but help ion containment in that peticular cusp. Is how much this effects overall preformance taken into account?



Dan Tibbets

[TomB]

[quote="zimdlg"]First of all I must say I'm not a physicist so sorry if my questions are elementary.

TomB:
<snip of all the stuff that seems basically correct>

It seems to me that work has to be done to slow the alphas down, a 8.7 MeV loss, and then all you're doing is neutralising the helium ions. So two electrons were removed from the H and B11 and the six are needed to neutralise the helium ions. Thats a net of four electrons flowing to the grid. Is this enough current to run the E guns, Ion guns, charge up and run and current through the magrid, charge up the deceleration grid, and run the vaccum pumps? Everything I've read seems sure the direct conversion to electricity will work but I don't really understand. Anybody please correct my understanding of this
process.
================================================
This is mostly correct, except that you have forgotten what an electrical current is, and how it gives up energy. An electrical current is just movement of charges, usually on electrons. In between the point where the electrons leave the ion guns, and the point where they re-enter the Polywell activity at the screen/Alpha Trap, they run through a "load". That "load" is where work is done, whether heating, running electric motors, or whatever, by the current of electrons, before they finally get back inside the vacuum sphere, to neutralize those alpha particles into Helium atoms at the screen/Alpha Trap.

The high positive potential on the Screen/Alpha Trap can be viewed as "pulling" the electrons through the "load", where energy is expended doing that work. In order for the high positive charge to do that, however, the alpha particles must deliver that positive charge on the alphas up the electrostatic potential well. You may view the extraction of energy from the alphas as happening while climbing towards that highly positive screen, and the extraction of energy from the whole Polywell system as happening in that current that passes through the load.

Yes, the balancing of various parts of this circuit to get smooth continuous operation is *definitely* a *non-trivial* task. Getting it right will be no small part of doing the full engineering for a power production Polywell system.

Regards,

Tom Billings

[D Tibbets]

First of all I must say I'm not a physicist so sorry if my questions are elementary.

TomB:

I've read that electrons must first be fired with E guns into the polywell to create the wiffleball. The -ve electrons are trapped inside the polywell by the the +ve charge on the polywell and are prevented from hitting the polywell by the strong magnetic field around the polywell. The magnetic field also recirculates the electrons back inside the polywell if they do escape.....

To answer some of your questions based on my limited understanding:
The positive charge on the magrid serves several purposes. First it accelerates the electrons that are released at initially low energy from an electron gun outside the magrid and aimed at a cusp. Once the electron is inside the magrid it no longer sees the charge (potential) on the magrid and ignores it. The ions have to be released/created at this border or inside it to avoid haveing to fight against this potential to get inside. The electrons, once inside, are contained efficiently by the magnetic field only. The charge on the magrid would only effect those electrons that managed to climb up high enough in a cusp that they are again outside the magrid. These electrons would then be reaccelerated back into the machine in a radial direction thanks to the geometry of the magnetic field in the cusp (just like the original electrons). Any ions that managed to climb this high in the cusp either on thier own or tagging along with an electron, would be accelerated to the vacuum vessel walls. I have a foggy notion that this may have an effect that decouples the ions from the electrons in this region and helps to avoid ambipolar charged particle flows through the cusps. The charge on the magrid does not directly effect the ions so long as they stay inside the magrid. The ions kinetic energy is almost entirely due to the magnetically confined electrons- a two stage process: the electrons are magnetically confined, and these electrons then confine the ions through the potential well. It's not that the magnetic field alone could not confine the ions, it's that the magnetic field cannot contain the ions well enough, otherwise Mirror machines and Penning trap type machines would work. Conversely, magnetic fields confine electrons much better due to thier much smaller mass/inertia compared to thier charge.

The direct energy conversion of the kinetic energy of charged fusion products works by converting the kinetic energy to electrical energy (without first going through a heating phase- direct high energy impacts on the surface). As an example a MeV alpha is slowed to KeV speed. That kinetic energy difference is net profit. The particle does not have to be decellerated to almost zero speed, just enough that you get the energy you want with a residual speed slow enough that the subsequent impact does not do damage (sputtering, radiation effects, etc.) It would be extreamly difficult to decellerate all of the alphas to the same terminal speed as no two alphas would have the same speed (speed coming from the two populations of alphas plus/minus the original speed of the fuel ions). The electrons used to then neutralize the alphas come from ground at the cost of only a relatively few eV.
Also, while the ions might be decellerated (give up thier kinetic energy) as they approach a like charged electrode, for several reasons* the deceleration grids will probably be oppositly charged and arranged so that the ions can fly past them and then be decelerated as they pull away. If the alphas leave the core as a modestly focused beam mostly through the cusps it presumably would greatly simplify the decelerater grid design while also sparing the magrid from high energy alpha bombardmant.

* primary reason is that like the magrid, there is no net electrical field effect inside a shell of electrodes (even an incomplete shell). It is not untill the charged particals are outside this shell that there is any effect.


Dan Tibbets

[zimdlg]

This post should have been posted after
chrismb Posted: Thu Jul 16, 2009 4:23 pm
Please view it that way.

The inside of the polywell has to be negative otherwise the positive ions will not accelerate to the middle, collide and fuse. The electrons are fired out the E guns on the wall of the vacuum chamber towards the middle. They are attracted to the +ve magrid but are prevented from touching it by the magnetic fields around the magrid. The electrons are compelled to follow the magnetic field lines into the polywell even though it is negative inside. Once they are inside they are trapped by the wiffleball effect. I assume the +ve ions are fired from ion guns at the vacuum chamber walls with enough velocity and into a cusp to overcome the repulsion from the +ve magrid. Once past the magrid an ion is attracted to the -ve wiffleball and will continue oscillate about the middle of the wiffleball until it collides with another ion and fuses.

[chrismb]

They are attracted to the +ve magrid but are prevented from touching it by the magnetic fields around the magrid. The electrons are compelled to follow the magnetic field lines into the polywell even though it is negative inside.

But if a charged particle is exposed to a magnetic AND electric field, then it will execute an ExB drift at right angles to the magnetic and electric fields. Sounds like the electrons will go nowhere but orbit around the magrids?

It is nice to think of charged particles just following magnetic field lines, but they don't do that in the presence of an electric field. They do the non-intuitive thing of going sideways to both fields.

[MSimon]

They are attracted to the +ve magrid but are prevented from touching it by the magnetic fields around the magrid. The electrons are compelled to follow the magnetic field lines into the polywell even though it is negative inside.

But if a charged particle is exposed to a magnetic AND electric field, then it will execute an ExB drift at right angles to the magnetic and electric fields. Sounds like the electrons will go nowhere but orbit around the magrids?

It is nice to think of charged particles just following magnetic field lines, but they don't do that in the presence of an electric field. They do the non-intuitive thing of going sideways to both fields.

You carefully align the particle guns so that the B field gradient is zero to minimize ExB drift. How carefully? That is an engineering question TBD.

The same holes (cusps) that allow particles out allow particles in.

[EricF]

The electrons used to then neutralize the alphas come from ground at the cost of only a relatively few eV.

once the alphas are neutralized back to plain old helium, is there a planned mechanism for extracting them from the vaccuum chamber, or is one of the engineering hurdles that still needs to be investigated once they determine direct conversion of the alphas is even realistic?