Intuitive fred888: reprint of the Sweet-Parker theory of magnetic reconnection

Wednesday, April 9, 2014

reprint of the Sweet-Parker theory of magnetic reconnection

One of the reasons the earth is more vulnerable to solar flares since about 2000 or so is because our magnetosphere which used to protect us more from Solar Flares and Cosmic Rays is degrading towards what Mars is like. Though people might live on Mars they likely would have to live underground if they didn't want their genetics to mutate at this point. The ground (likely below 10 to 20 feet) would protect them from the weak magnetosphere's effects if they lived deep enough. We are slowly moving towards that here on earth as well where we might have to live underground as the magnetosphere continues to errode.

One of my theories is that generating electricity by breaking magnetic fields here on earth might be a factor in reducing our magnetosphere over time. Or like humans are degrading the climate of earth there might be factors that are causing the degredation of our protective magnetosphere that we are not presently aware of.

As the magnetosphere continues to degrade and the weather also continues to degrade how will mankind survive on this planet?

One of the ways is to live further underground while sleeping and at night. I think over time as more and more people become aware of this likely more and more people will choose to live underground to protect themselves from solar flares and cosmic rays so their genetics don't mutate too much over time and cause more and more extreme birth anomalies. However, then there are things like dioxin for which there are no safe levels of for any living thing that cause mole pregnancies in women or babies with multiple heads or arms and the same for animals, birds, snakes etc. So, whether it is solar radiation, cosmic rays, degrading magnetosphere (which might also be affecting the weather a lot) or whether it is man made pollutants that are killing people, all these things need to be taken into consideration for a healthy genetics for human beings ongoing without extreme forms of mutation creeping into the norm.

Here is the Sweet-Parker theory in regard to what is happening to the magnetosphere:

The next word button might be easier to read from where it takes you there since the HTML Blogger uses will decrease the width other wise:

The Sweet-Parker Reconnection Model or Theory
Here are other related articles to this subject written and compiled about the same time:
The Physical Process that causes cracks in the Mag...
magnetic reconnection at the magnetopause is not a...
What will happen when sun's poles reverse?
2010:Cluster Satellite detects rifts in Earth's Ma...
Condition of Magnetosphere 11 years ago
Sun Flips Poles during weakening Magnetosphere on ...
Sun's magnetic field is about to flip, warns NASA

Wednesday, August 7, 2013

The Sweet-Parker Reconnection Model or Theory

As I read about Magnetic Reconnection the Sweet-Parker Model or Theory it somehow made a lot of sense to me because it explained how "Time-independent magnetic reconnection" can happen seemingly very fast and much faster than one would think logically without considering changes to the time space continuum during this process of magnetic reconnection.

The Sweet-Parker Model

At a conference in 1956, Peter Sweet pointed out that by pushing two plasmas with oppositely directed magnetic fields together, resistive diffusion is able to occur on a length scale much shorter than a typical equilibrium length scale.^[1] Eugene Parker was in attendance at this conference and developed scaling relations for this model during his return travel.^[2]
The Sweet-Parker model describes time-independent magnetic reconnection in the resistive MHD framework when the reconnecting magnetic fields are antiparallel (oppositely directed) and effects related to viscosity and compressibility are unimportant. The ideal Ohm's law then yields the relation

$E_y = V_{in} B_{in}$

where $E_y$ is the out-of-plane electric field, $V_{in}$ is the characteristic inflow velocity, and $B_{in}$ is the characteristic upstream magnetic field strength. By neglecting displacement current, the low-frequency Ampere's law, $\mathbf{J} = \frac{\nabla\times\mathbf{B}}{\mu_0}$ , gives the relation

$J_y \sim \frac{B_{in}}{\mu_0\delta},$

where $\delta$ is the current sheet half-thickness. This relation uses that the magnetic field reverses over a distance of $\sim2\delta$ . By matching the ideal electric field outside of the layer with the resistive electric field, $\mathbf{E}=\eta\mathbf{J}$ , inside the layer, we find that

$V_{in} \sim \frac{\eta}{\mu_0\delta},$

where $\eta$ is the plasma resistivity. When the inflow density is comparable to the outflow density, conservation of mass yields the relationship

$V_{in}L \sim V_{out}\delta,$

where $L$ is the half-length of the current sheet and $V_{out}$ is the outflow velocity. The left and right hand sides of the above relation represent the mass flux into the layer and out of the layer, respectively. Equating the upstream magnetic pressure with the downstream dynamic pressure gives

$\frac{B_{in}^2}{2\mu_0} \sim \frac{\rho V_{out}^2}{2}$

where $\rho$ is the mass density of the plasma. Solving for the outflow velocity then gives

$V_{out} \sim V_A \equiv \frac{B_{in}}{\sqrt{\mu_0 \rho}}$

where $V_A$ is the Alfvén velocity. The dimensionless reconnection rate can then be written as

$\frac{V_{in}}{V_A} \sim \frac{1}{S^{1/2}}$

where the dimensionless Lundquist number $S$ is given by

$S \equiv \frac{\mu_0 L V_A}{\eta}.$

Sweet-Parker reconnection allows for reconnection rates much faster than global diffusion, but is not able to explain the fast reconnection rates observed in solar flares, the Earth's magnetosphere, and laboratory plasmas. Additionally, Sweet-Parker reconnection neglects three-dimensional effects, collisionless physics, time-dependent effects, viscosity, compressibility, and downstream pressure. Numerical simulations of two-dimensional magnetic reconnection typically show agreement with this model.^[3] Results from the Magnetic Reconnection Experiment (MRX) of collisional reconnection show agreement with a generalized Sweet-Parker model which incorporates compressibility, downstream pressure, and anomalous resistivity.^[4]

^{end quote from wikipedia under the heading: Magnetic Reconnection and subheading "The Sweet Parker model".}

^{So,
even though some factors are not represented in this theory, still it
addresses more why reconnection rates are not time dependent and to a
little degree why the changes are not directly related to the time space
continuum (at least the way most of us that are not paid researchers in
the field might view it).}

^{So,
my thought is: "If Magnetic reconnections are not directly relatable to
the time space continuum, could extreme events occur without any
warning here on earth regarding our magnetosphere? My thought is that
potentially unfortunately the answer likely is: Yes! However, then you
might have to go to probabilities. And I'm not entirely sure how you
would even begin to go about that.}

^{If
I look at this as an intuitive only and not in a scientific way it is
my thought that we are in for it in a way not seen in the last century
on earth. What does that mean? It likely means that in addition to
extreme weather events we may also see extreme Cosmic Ray events. But
because we all don't have cosmic ray detectors in whatever area we live
in on earth (maybe we should), we will only notice when the sun is out
or above the clouds that our eyes might hurt even with sunglasses on.
(Which is something I have noticed lately while traveling). However,
this isn't something I can scientifically prove.}

Intuitive fred888

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