Is a lightening bolt neutral plasma?
Like already said by others, again you fail to deliver anything of real substance. I have
already answered this question on page 102, post 4049, which subsequently have ignored.
Two things you do not seem to understand, the difference between (1) a discharge in the neutral (as in non-ionized) atmosphere of the Earth (lightnigh) and (2) currents flowing in a quasi-neutral plasma (as in highly ionized).
In (1) there can be large charges build up (on the clouds) without any repercussions, it will just sit there until ... the dielectric (in this case the Earth's neutral atmosphere) breaks down because of the too large potential difference over the dielectric. The fair-weather electric field in the atmosphere is about 50 to 200 V/m.
If the dielectric breaks down a ionized path is created from the Earth to the cloud (the so called precursor) and that gives the cloud the possibility to discharge its excess of electrons. So, I would have no problems here to say that that discharge channel has a net (negative) charge when the lightning strikes.
Now in (2) we have a completely different situation because we are dealing with a plasma alone. Now to keep it at MM's level we will look at it with ideal MHD glasses, with the restrictions it brings: i.e. all equations are averaged over the longest gyroperiod of the ions (so we are dealing with a fluid, the hydro in MDH), and there are no large scale electric fields because the plasma is ideal (which means no large charges can build up because of the mobility of the ions/electrons).
One of the important differences between (1) and (2) is that in (2) there is no dielectric that can break down (i.e. create an ionization channel). And then we are just left with
the MHD equations where for ideal MHD the conductivity as to be set to ∞ or the diffusivity to 0. However, as Alfvén writes in Cosmical Electrodynamics (first edition reprint 1953, chapter 3.24, page 56) the conductivity for an average plasma in the cosmos is on the same level as copper. But that does not make that large scale electric fields and charge separations can occur in a plasma.
Now, assuming Alfvén was correct with his MDH (and I guess we can safely assume that) then we works with the same equations as anyone else and thus he would write that in a volume V of plasma, with V much larger than the Debye sphere (for obvious reasons) the total charge would be:
Q
V = Σ
k n
k q
k
where the index k runs over all ion species and the electrons. Then again, he would write for the current in the volume:
JV = Σ
k n
k q
k vk
where one should note that Q
V is a scalar, whereas
JV is a vector.
Now, in MHD electrical currents are usually driven by changes in the magnetic field:
d
B/dt = ∂
B/∂t + (
v.▼)
B
etc. etc.
but that still does not lead us to the implicit statement that MM gives that whenever in a plasma
J ≠ 0 then also Q ≠ 0.
