A little more confusing input. I'm still not sure what A. Carlson means by ions following electrons out means. Since the electrons are presumably streaming in (via electron gun and recirculation) at the same rate that they are streaming out, the effects on the ions should be neutral, within certain assumptions on the distribution of the electrons within the area of concern. ie the electrons streaming in are high energy- high speed, so they transit the cusp region quickly, while most (?) of the exiting electrons are slowing as they climb outside against the pos charged magrid. Would this create a local increased density of electrons in this region- would this effect the nearby ions more? Is that what A. Carlson is considering. But, so long as the net electron numbers that influence the ions are biased towards the center of the machine befor the ion reaches the point of no return ( just past the centerpoint of the magrids where they (the ions) suddenly see the repelling pos. charge of the magrids, then they should be slowing and hopefully reversing, provided they have not been upscatered to much (?).
Or, is it more of a concern that the escaping electrons, though of low energy (speed), once they fight past the recirculating influence of the pos. magrid, still are neg. charges and will attract any pos ions, especially if their lifetimes are long enough so that significant numbers accumulate. I guess it is a matter of how long they hang around befor they reach the walls and are grounded.
Where the 10 MV comes from, I havan't a clue (a not uncommon occurance). If the ions are created from neutral gas, or injected from just inside the magrid, they experiance the ~ 10,000 volts acelerating force towards the center, once they pass through or rebound, they would stop at the same distance from the center and have another go. Only the upscattered ions could reach the magrid surface or reach an equivalent distance into the cusps ( again, I assume relative concentrations of electrons befor and behind them would define how faw into the cusps they go). Wild speculation- "10 MV" is what is needed to stop the highest energy upsattered ions efficiently enough for the average lifetimes of the ions to be long enough for breakeven fusion. If this shot in the dark is close, is it based on thermalized conditions, discounting arguments that that the ions are more monoenergetic, that the ions are annealed (what ever that is), etc? Or, is it referring to the central negative potential needed to overcome the more local repulsive potential of the magrid pos. charge (once the ions are past this point)? Am I even in the same ball park (or State)?
Dan Tibbets
Diffusion and Osmosis- an argument against ion cusp losses
Re: Diffusion and Osmosis- an argument against ion cusp loss
My point is (I think) that by constantly maintaining the electrical potential inside the Polywell by injecting new electrons, you are maintaining an energy gradiant, just like maintaining a positive atmospheric pressure gradient in reverse osmosis of sea water. If ions are escaping the Polywell despite this, then the energy gradiant (potential) is increasing. Unless there is some mechanism for the electrons to escape even faster, to compensate (or somehow the new electrons cannot enter) then energy is being produced for free (or at least concentrated more, and I've heard that the potential rises very rapidly as the imbalance between neg. and pos. charges increase) - the end of the world, rewriting of electrostatics, etc, etc...Art Carlson wrote:I think your way of looking at the system is essentially correct and not too different from the way I look at it. I'm not so clear on what conclusions you are drawing.
ie: a model would have to get around this if it is real.
Dan Tibbets
To error is human... and I'm very human.
The polywell plasma as a whole is certainly quasineutral, but it's not Maxwellian. Unless you are arguing potential wells don't form, the distribution of ions is not uniform (which reminds me, did we ever come up with a Debye length applicable in a Polywell?). And since the Polywell isn't ambipolar, logically there must be a force at the edge pushing electrons out, and for the ions the potential gradients of the electron-rich cusps are probably over the top of the central well they're trapped in (i.e. too far away)."Too far away"? Have I ever mentioned that the polywell plasma is quasi-neutral? There are ions everywhere.
It's an interesting idea and I always enjoy your equations, but from Rick's comments I suspect the WB-7 data rules out what you are proposing.
After reading the below chapter, I believe I'm referring to the long range electric field effects when I talk about the osmosis/ reverse osmosis model, while Dr Carlson is referring to the local inter-particle Coulomb potential (plugging the pores) in his arguments. In this chapter the author states several times that the long range effects dominate. There are some conditions that have to be met, so how closely this matches the effects within the Polywell cusps is uncertain.
From Plasma Physics and Fusion Energy
by Jeffrey Friedberg
(It was aviable free online at one time. I obtained it via a link which I cannot find now. The link was provided by someone here I believe, possibly M. Simon)
Chapter 7-Definition of a Fusion Plasma, page 128:
..."Smoothing out the charge distribution would intuitively seem to be a reasonable approximation for charges located far from a given point. However, for charges located very near the point, one might think that the inter-particle Coulomb potential would be the dominant factor because of the divergence of the 1/r dependence of öCoul for small r. In a plasma this is not the case. The reason is that in a plasma the particle density is sufficiently low that two charges rarely get close enough to each other for the two-particle Coulomb potential to dominate the long-range electric field generated by the smoothed out distribution of the entire charge population."
I'm still having a hard time grasping the significance of the Debye sheath/ length/ sphere. What is a reasonable Debye length in the Polywell with an assumed pressure of ~ 0.1 micron ( approaching the density outside of the magrid, not the hopefully much higher density in the center), and a potential well of ~ 10,000 eV? And, the Debye length assumes a Maxwellian distribution around a certain temperature (eV). If the Polywell is mono-energetic or at least narrow in its ion velocity range near the bottom and top of the potential well, the Debye length would be smaller (to what degree?). And, assuming that the mean ion energy at the top of the potential well is away from the cusp, could this energy level (essentially zero) be the baseline for calculating the energy of up scattered ions that do enter the cusp regions. ie- the energy (temperature) of the ion is not the well depth (10,000 eV) plus any up scattered energy, but the energy is 0 ( kinetic energy of the ion at the top of the well) plus up scattered energy. Using this relative energy to derive the Maxwellian (or 'squeezed Maxwellian') distribution of the ions might end up in a much shorter Debye length.
Does any of this make any sense?
Also, somewhere I read of the speed of sound in the plasma being used in some arguments. In the same chapter, it's mentioned that in fluids like liquids or gases this is appropriate, but in plasmas the effects (pressure/ electric field effects) spread at the speed of light.
Dan Tibbets
From Plasma Physics and Fusion Energy
by Jeffrey Friedberg
(It was aviable free online at one time. I obtained it via a link which I cannot find now. The link was provided by someone here I believe, possibly M. Simon)
Chapter 7-Definition of a Fusion Plasma, page 128:
..."Smoothing out the charge distribution would intuitively seem to be a reasonable approximation for charges located far from a given point. However, for charges located very near the point, one might think that the inter-particle Coulomb potential would be the dominant factor because of the divergence of the 1/r dependence of öCoul for small r. In a plasma this is not the case. The reason is that in a plasma the particle density is sufficiently low that two charges rarely get close enough to each other for the two-particle Coulomb potential to dominate the long-range electric field generated by the smoothed out distribution of the entire charge population."
I'm still having a hard time grasping the significance of the Debye sheath/ length/ sphere. What is a reasonable Debye length in the Polywell with an assumed pressure of ~ 0.1 micron ( approaching the density outside of the magrid, not the hopefully much higher density in the center), and a potential well of ~ 10,000 eV? And, the Debye length assumes a Maxwellian distribution around a certain temperature (eV). If the Polywell is mono-energetic or at least narrow in its ion velocity range near the bottom and top of the potential well, the Debye length would be smaller (to what degree?). And, assuming that the mean ion energy at the top of the potential well is away from the cusp, could this energy level (essentially zero) be the baseline for calculating the energy of up scattered ions that do enter the cusp regions. ie- the energy (temperature) of the ion is not the well depth (10,000 eV) plus any up scattered energy, but the energy is 0 ( kinetic energy of the ion at the top of the well) plus up scattered energy. Using this relative energy to derive the Maxwellian (or 'squeezed Maxwellian') distribution of the ions might end up in a much shorter Debye length.
Does any of this make any sense?
Also, somewhere I read of the speed of sound in the plasma being used in some arguments. In the same chapter, it's mentioned that in fluids like liquids or gases this is appropriate, but in plasmas the effects (pressure/ electric field effects) spread at the speed of light.
Dan Tibbets
To error is human... and I'm very human.