Magnetic containment of the ions

[icarus]

So, R. Nebel's comments about alphas being directed out the cusps by the strong magnetic field, in reactor-type conditions, does open up another question.

What is the effect on the wiffleball and electron-sheath interaction with ions when the magnetic forces experienced by the ions becomes comparable or larger than the electrostatic forces due to the potential well?

The current understanding, as far as I'm aware, has that the ions are largely contained and annealed by an IEC-like electrostatic field process due to electron excess in the plasma wiffleball. In this model, the electrons are strongly contained by the magnetic field but the ions are largely unaffected by magnetic field but hang around due to electrostatic attraction towards the confined electrons. Now if the alpha products are being strongly effected by a 5-10 T mag. field in reactor conditions and they are much more energetic than the ions, what does that do to the crucial confinement balance-of-forces between magnetic and electrostatic of the ions and electrons?

Doesn't this just lead us back to the thermalised plasma regimes?

[D Tibbets]

Perhaps a refinement of how the system seems to work is in order. In one (or more) of his papers Bussard mentions that the electron cloud is mostly contained well away from the magnets. Only the electrons that have slowed down considerably approach the stronger magnetic field strenths /lines where thier motion becomes more lateral (as opposed to radial). Aparently these electrons then preferentially leak through the cusps and this helps slow the thermalization of the overall electron population (as new high energy electrons are injected). Conversely, higher energy/ upscattered electrons, if pointed directly at a cusp maybe more likely to escape(?). So, there may be a mechanism for eliminating the too weak and too strong electrons and thus maintaining a more monoenergetic population.

Since the electrostatic effects predominates for the ions they are mostly in a region where the centrally directed forces predominate over the lateralizing effects of the stronger magnetic fields found near the magnets. Up scatered ions can approach closer to the magnets, and the magnetic field is thus dominate and the ions can assume lateral motions along field lines Leaking these ions through the cusps would also presumably help delay thermalization (non radial motion) of the ion population.
I don't know how that works with higher energy fusion ash to allow it to exit cusps at ~ full energy.

To answer your question about increasing magnetic field strength on competing forces, I'm guessing that it is a wash (balanced). As the B field increases the Beta=1 condition is pushed deeper into the center, so the electron cloud is compressed more, and this would keep the ions in tighter orbits, away from the magnetic dominate areas. Although, there are presumably some interactive limits on the size- B field strength- drive energy- electron and fuel injection rates- etc. variables. For instance if both the B field and the drive energy is increased 10 fold I would guess that the Wiffle ball size would be unchanged (assuming linier relationships).

Obvously, my understanding is limited, so take my comments with a grain of salt .


Dan Tibbets

[chrismb]

Now if the alpha products are being strongly effected by a 5-10 T mag. field

viewtopic.php?p=13296#13296

v{3MeV alpha}=12Mm/s
gyroradius=mv/qB=([4*1.6E-27]kg).([12E6]m/s)/([3.2E-19]C).([5]T)=5cm.

Presumably this is why it is necessary to make the claim that the alphas will escape through cusps, because if they tried it through magrid-generated fields circumferential about the centre and of +5T magnitude, then they'd just bung up the system by sitting in gyro-orbits. They'd have to exb drift over to cusps before exiting and wouldn't shoot straight out. The idea that fusion products (save for neutrons) will zoom straight out of the reaction volume and not take part in all the magnetic and electric fields appears to be quite false.

[MSimon]

Now if the alpha products are being strongly effected by a 5-10 T mag. field

viewtopic.php?p=13296#13296

v{3MeV alpha}=12Mm/s
gyroradius=mv/qB=([4*1.6E-27]kg).([12E6]m/s)/([3.2E-19]C).([5]T)=5cm.

Presumably this is why it is necessary to make the claim that the alphas will escape through cusps, because if they tried it through magrid-generated fields circumferential about the centre and of +5T magnitude, then they'd just bung up the system by sitting in gyro-orbits. They'd have to exb drift over to cusps before exiting and wouldn't shoot straight out. The idea that fusion products (save for neutrons) will zoom straight out of the reaction volume and not take part in all the magnetic and electric fields appears to be quite false.

Let me ask again. Why did Dr. B think there would be a significant heat load on the MaGrids? He assumed the load would be equal to the area of the grids divided by the total containment area i.e. about 20%.

And further - the magnetic fields will focus the alphas. Alphas that can go straight through the "holes" will have the highest probability of leaving. Others stand a good chance of being deflected.