Solar wind questions?

Hi fella's
My question arises because I understand
the solar wind consists of free protons "p+"
and electrons "e-" emitted in vast quantities
from the sun. The figures I've read suggest
the mass output is 10^9 kg/sec at an average
of speed 600 km/sec.

1) In some theoretical fashion, the p+ and e-
within the solar wind may recombine to form
Hydrogen atoms and in that process radiate.
(anyone know if we have available some data
on that radiation)?

2) Given the solar wind does consists of
p+ and e- particles, would those form a
dipole that could receive certain frequency's
and thus attenuate them by converting
the energy of those frequency's into relative
momentum w.r.t a dipole of the p+ e- pair?
Regards
Ken S. Tucker

On 30 Mar, 09:09, "Ken S. Tucker" wrote:
Hi fella's
My question arises because I understand
the solar wind consists of free protons "p+"
and electrons "e-" emitted in vast quantities
from the sun. The figures I've read suggest
the mass output is 10^9 kg/sec at an average
of speed 600 km/sec.

1) In some theoretical fashion, the p+ and e-
within the solar wind may recombine to form
Hydrogen atoms and in that process radiate.
(anyone know if we have available some data
on that radiation)?

In principle a plasma obviously does recombine, but the point is that
the recombination cross section decreases very rapidly with increasing
relative energy of the electrons and protons (~E^-3). The solar wind
plasma particles have an energy of about 1 keV and the recombination
cross section for this is only about 10^-25 cm^2. If one considers
that the density of the solar wind is only around 10^cm^-3, this means
that the particles would on average have to travel about 1/(10^-25*10)
= 10^24 cm before they recombine (and this neglects even that the
density decreases further as the solar wind expands). This is more
than the size of our galaxy, and the probability to observe a
recombination event in our solar systen is therefore very much
negligible.


2) Given the solar wind does consists of
p+ and e- particles, would those form a
dipole that could receive certain frequency's
and thus attenuate them by converting
the energy of those frequency's into relative
momentum w.r.t a dipole of the p+ e- pair?

In principle yes, although this would be a question of the relative
momenta of the electrons and protons as a whole, not individually (a
plasma is only macroscopically bound, not microscopically). However,
given the small solar wind plasma density of about 10^cm^-3 and the
small magnetic field of at best 100 nT, this could only happen at a
frequency of around 10^5 Hz, and you won't get such a frequency
through the ionosphere in the first place as both the ionospheric
plasma density and magnetic field are much higher (which results in
everything below about 10^7 Hz being absorbed or reflected). Otherwise
you could indeed put energy into the solar wind this way (as it is
done for the ionospheric plasma), although this would be rather
limited due to non-linear effects (see my page
http://www.plasmaphysics.org.uk/research/plasrese.htm ).

Thomas

On 2 Apr, 15:49, "Thomas Smid" wrote:
On 30 Mar, 09:09, "Ken S. Tucker" wrote:

Hi fella's
My question arises because I understand
the solar wind consists of free protons "p+"
and electrons "e-" emitted in vast quantities
from the sun. The figures I've read suggest
the mass output is 10^9 kg/sec at an average
of speed 600 km/sec.

1) In some theoretical fashion, the p+ and e-
within the solar wind may recombine to form
Hydrogen atoms and in that process radiate.
(anyone know if we have available some data
on that radiation)?

In principle a plasma obviously does recombine, but the point is that
the recombination cross section decreases very rapidly with increasing
relative energy of the electrons and protons (~E^-3). The solar wind
plasma particles have an energy of about 1 keV and the recombination
cross section for this is only about 10^-25 cm^2. If one considers
that the density of the solar wind is only around 10^cm^-3, this means
that the particles would on average have to travel about 1/(10^-25*10)
= 10^24 cm before they recombine

I have to correct myself he I did not take into account that the
velocity of electron in a plasma of 1 keV (2*10^9 cm/sec) is
actually higher than the 600 km/sec velocity of the solar wind. One
has to calculate this therefore over the recombination frequency
10^-25*10*2*10^9 which results in a time of 5*10^14 sec. Now during
this time, the solar wind travels 600*5*10^14 =3*10^17 km = 10^4 pc,
which is still of interstellar/galactic dimensions, i.e. the
recombination within the solar system is negligible.

Thomas

On Apr 2, 7:49 am, "Thomas Smid" wrote:
On 30 Mar, 09:09, "Ken S. Tucker" wrote:

Hi fella's
My question arises because I understand
the solar wind consists of free protons "p+"
and electrons "e-" emitted in vast quantities
from the sun. The figures I've read suggest
the mass output is 10^9 kg/sec at an average
of speed 600 km/sec.

1) In some theoretical fashion, the p+ and e-
within the solar wind may recombine to form
Hydrogen atoms and in that process radiate.
(anyone know if we have available some data
on that radiation)?

In principle a plasma obviously does recombine, but the point is that
the recombination cross section decreases very rapidly with increasing
relative energy of the electrons and protons (~E^-3). The solar wind
plasma particles have an energy of about 1 keV and the recombination
cross section for this is only about 10^-25 cm^2. If one considers
that the density of the solar wind is only around 10^cm^-3, this means
that the particles would on average have to travel about 1/(10^-25*10)
= 10^24 cm before they recombine (and this neglects even that the
density decreases further as the solar wind expands). This is more
than the size of our galaxy, and the probability to observe a
recombination event in our solar systen is therefore very much
negligible.

2) Given the solar wind does consists of
p+ and e- particles, would those form a
dipole that could receive certain frequency's
and thus attenuate them by converting
the energy of those frequency's into relative
momentum w.r.t a dipole of the p+ e- pair?

In principle yes, although this would be a question of the relative
momenta of the electrons and protons as a whole, not individually (a
plasma is only macroscopically bound, not microscopically). However,
given the small solar wind plasma density of about 10^cm^-3 and the
small magnetic field of at best 100 nT, this could only happen at a
frequency of around 10^5 Hz, and you won't get such a frequency
through the ionosphere in the first place as both the ionospheric
plasma density and magnetic field are much higher (which results in
everything below about 10^7 Hz being absorbed or reflected). Otherwise
you could indeed put energy into the solar wind this way (as it is
done for the ionospheric plasma), although this would be rather
limited due to non-linear effects (see my pagehttp://www.plasmaphysics.org.uk/research/plasrese.htm).

Thomas


Thank you Dr. Smid.

On Apr 2, 7:49 am, "Thomas Smid" wrote:
On 30 Mar, 09:09, "Ken S. Tucker" wrote:

Hi fella's
My question arises because I understand
the solar wind consists of free protons "p+"
and electrons "e-" emitted in vast quantities
from the sun. The figures I've read suggest
the mass output is 10^9 kg/sec at an average
of speed 600 km/sec.

1) In some theoretical fashion, the p+ and e-
within the solar wind may recombine to form
Hydrogen atoms and in that process radiate.
(anyone know if we have available some data
on that radiation)?

In principle a plasma obviously does recombine, but the point is that
the recombination cross section decreases very rapidly with increasing
relative energy of the electrons and protons (~E^-3). The solar wind
plasma particles have an energy of about 1 keV and the recombination
cross section for this is only about 10^-25 cm^2. If one considers
that the density of the solar wind is only around 10^cm^-3,

missed an exponent there but that's ok, may not
have appeared on my cyberscope.

this means
that the particles would on average have to travel about 1/(10^-25*10)
= 10^24 cm before they recombine (and this neglects even that the
density decreases further as the solar wind expands). This is more
than the size of our galaxy, and the probability to observe a
recombination event in our solar system is therefore very much
negligible.

Ok, thank you. I was a bit worried that the recombination
may provide a 3K radiation background ;-), I trust that's
ruled out?

2) Given the solar wind does consists of
p+ and e- particles, would those form a
dipole that could receive certain frequency's
and thus attenuate them by converting
the energy of those frequency's into relative
momentum w.r.t a dipole of the p+ e- pair?

In principle yes, although this would be a question of the relative
momenta of the electrons and protons as a whole, not individually (a
plasma is only macroscopically bound, not microscopically). However,
given the small solar wind plasma density of about 10^cm^-3 and the
small magnetic field of at best 100 nT, this could only happen at a
frequency of around 10^5 Hz, and you won't get such a frequency
through the ionosphere in the first place as both the ionospheric
plasma density and magnetic field are much higher (which results in
everything below about 10^7 Hz being absorbed or reflected). Otherwise
you could indeed put energy into the solar wind this way (as it is
done for the ionospheric plasma), although this would be rather
limited due to non-linear effects (see my pagehttp://www.plasmaphysics.org.uk/research/plasrese.htm).

Did so. One of the reasons I asked these questions in
the OP, was to determine if so-called "free-electrons (e-)"
or "free-protons (p+)", defined as being distinct from being
specifically in a dipole relation, may individually absorb
ElectroMagnetic Radiaton (EMR).

The suggestion is that Quantum Electrodynamics (QED),
permits photons (aka EMR) to be absorbed by e- particles,
and perhaps p+ 's as well in the solar wind.

So of course, I thought we may find evidence of that in
astrophysics, specifically the EMR solar wind attenutation.

Would it be reasonable to conclude the solar wind
is transparent, (aside from ionospherics of course,
I mean the effects well away from tiny planets)?

Thanks Dr. Smid, for understanding my questions.
Ken S. Tucker

[Mod. note: vast amounts of quoted text trimmed. Please retain only
what is necessary -- mjh]

On 3 Apr, 09:58, "Ken S. Tucker" wrote:
On Apr 2, 7:49 am, "Thomas Smid" wrote:
In principle a plasma obviously does recombine, but the point is that
the recombination cross section decreases very rapidly with increasing
relative energy of the electrons and protons (~E^-3). The solar wind
plasma particles have an energy of about 1 keV and the recombination
cross section for this is only about 10^-25 cm^2. If one considers
that the density of the solar wind is only around 10^cm^-3,

missed an exponent there but that's ok, may not
have appeared on my cyberscope.

this means
that the particles would on average have to travel about 1/(10^-25*10)
= 10^24 cm before they recombine (and this neglects even that the
density decreases further as the solar wind expands). This is more
than the size of our galaxy, and the probability to observe a
recombination event in our solar system is therefore very much
negligible.

Ok, thank you. I was a bit worried that the recombination
may provide a 3K radiation background ;-), I trust that's
ruled out?
A plasma with particle energies of about 1 keV produces largely x-rays
on recombination, not microwaves. One observes this for instance from
certain interstellar or intergalactic regions (where the volume is
simply much larger), or indeed from the sun itself (see
http://chabotspace.org/vsc/solar/cur...eyohkohsxt.asp ),
where the plasma density is still high enough to yield a noticeable
emission; further out the density becomes just too small for this
(although if the solar wind interacts with higher density cometary or
planetary atmospheres it can become noticeable again).

[Mod. note: the X-rays that you see from the solar corona are
bremsstrahlung or free-free radiation, not recombination radiation -- mjh]

In principle yes, although this would be a question of the relative
momenta of the electrons and protons as a whole, not individually (a
plasma is only macroscopically bound, not microscopically). However,
given the small solar wind plasma density of about 10^cm^-3 and the
small magnetic field of at best 100 nT, this could only happen at a
frequency of around 10^5 Hz, and you won't get such a frequency
through the ionosphere in the first place as both the ionospheric
plasma density and magnetic field are much higher (which results in
everything below about 10^7 Hz being absorbed or reflected). Otherwise
you could indeed put energy into the solar wind this way (as it is
done for the ionospheric plasma), although this would be rather
limited due to non-linear effects (see my pagehttp://www.plasmaphysics.org.uk/research/plasrese.htm).

Did so. One of the reasons I asked these questions in
the OP, was to determine if so-called "free-electrons (e-)"
or "free-protons (p+)", defined as being distinct from being
specifically in a dipole relation, may individually absorb
ElectroMagnetic Radiaton (EMR).

The suggestion is that Quantum Electrodynamics (QED),
permits photons (aka EMR) to be absorbed by e- particles,
and perhaps p+ 's as well in the solar wind.
I am not really familiar with QED and don't know whether such a
process is allowed there or not, but I would say that one needs some
kind of resonant system to absorb radiation, and individual particles
simply can't provide this. Besides, if individual electrons and
protons would absorb radiation, we would probably not receive any
radiation at all from the sun, given the high plasma density in its
lower atmosphere.


So of course, I thought we may find evidence of that in
astrophysics, specifically the EMR solar wind attenutation.

Would it be reasonable to conclude the solar wind
is transparent, (aside from ionospherics of course,
I mean the effects well away from tiny planets)?
Yes, it should be transparent to any radiation above 100 kHz or so,
i.e. there shouldn't be any attenuation.

Thomas

[Mod. note: the X-rays that you see from the solar corona are
bremsstrahlung or free-free radiation, not recombination radiation -- mjh

Well, I think the relative contributions of the various mechanisms are
very much debatable as they depend on the modelling assumptions used.
The fact that X-ray spectra of the sun look virtually identical to UV-
spectra (see for instance http://www.cbk.pan.wroc.pl/publicati...opole_htm.html
) does actually not suggest that different processes are at work.
Indeed, the emission lines can obviously only be caused either as a
result of free-bound (recombination) or bound-bound (electron impact)
transitions to a given atomic level.

Thomas

[Mod. note: I should have been clearer. The continuum is dominated by
free-free: the lines are bound-bound: free-bound is less important
than either, and of course gives a continuum not line contribution. -- mjh]