Sunday, May 6, 2012

Electric Sun: Another Problem with Heliospheric "Drift Currents"

I've pointed out a number of fundamental flaws in various 'electric sun' models based on very fundamental considerations of conservation of energy and particles (Electric Cosmos: The Solar Capacitor Model. I). 

One of the popular excuses Electric Universe (EU) 'theorists' presents in an attempt to circumvent these issues is invoking some population of low-energy electrons ("Drift electrons") that allegedly solve the energy transport problem.  This electron population also somehow manages to be totally undetectable by in situ instruments (see Electric Cosmos: The Solar Capacitor Model. III).

In this post, I'll explore another implication of a high electron density in space.  This property is utilized in a wide variety of science and technologies.

Irving Langmuir explored waves in plasmas (see Oscillations in Ionized Gases) back in the late 1920s and defined a quantity called the plasma frequency (see also wikipedia: Plasma waves & Waves in Plasmas).  When electrons in a quasi-neutral plasma are displaced from a strictly neutral configuration, an electric field is setup by the displacement that creates a restoring force.  This force pulls the electrons back to a more neutral configuration with the ions.  The electrons are easier to displace in this configuration because they are much lighter than the ions.  By the time the electrons are pulled back so the net density is zero, they have sufficient speed to overshoot the neutral configuration.  This process repeats if the electrons don't loose too much energy in the process through collisions with ions and other electrons, and this is an oscillation.  It's simple to show that the natural oscillation for a given electron density is

This plasma frequency also influences how electromagnetic wave propagates through a plasma.  Electromagnetic waves with frequencies below the plasma frequency are strongly absorbed by the plasma.  If the wave propagates at an angle that is not perpendicular to the plasma interface, the waves can also be reflected or refracted.   Frequencies above the plasma frequency can propagate through the plasma, but can be subjected to attenuation and dispersion - which changes their amplitude and speed as they propagate through the plasma.

Here we plot the plasma frequency of electrons (solid black line) and the plasma frequency of protons (dashed black line) in frequency and particle density space, marking the region in (density, frequency) space where electromagnetic waves cannot propagate.  I've also marked the electron density range corresponding to the Earth's ionosphere (10^4 - 10^6 electrons/cm^3). 

There is an important caveat to the graphic.  The no-propagation region applies to waves penetrating a plasma occupying a region very large compared to the wavelength of the electromagnetic waves.  Since the plasma actually attenuates the wave, it can propagate a distance into it.  This means that very low frequency (very long wavelength) radio waves can penetrate the ionosphere when the wavelength is large compared to the thickness of the plasma region.

From this plot, we see that electromagnetic waves with frequencies less than about 10 megahertz cannot propagate through the ionosphere without significant distortion.  These lower frequency ranges are historically known as the short-wave radio band (wikipedia) (covering 1,800kHz - 30Mhz), and the AM broadcasting band (wikipedia).  Due to ionospheric refraction, electromagnetic waves in the lower end of this frequency range can propagate long distances around the Earth by 'bouncing' off the ionosphere.

For radiowaves to reliably propagate through the ionosphere, as one needs for space travel, higher frequencies are needed.  The very first satellite, Sputnik 1 (wikipedia), broadcasted at 20MHz, just a little above the plasma frequency for the ionospheric electron density.  Modern satellite communication uses the Ku band (12-18GHz) (wikipedia), in the microwave frequency range.  These waves run into problems propagating through plasmas with densities higher than about 10^11 electrons/cm^3.

We see from the plot, that the fact that satellites in space can communicate at these frequencies places a firm upper limit on any possible population of 'drift electrons' in the solar system.  To continue this bogus claim of drift electrons, EU 'theorists' must deny much of the laboratory evidence  on which they hang their claims.

Some EU 'theorists' might try to argue that this effect does not apply in a neutral plasma.  Yet a neutral plasma has been where this phenomena has been theoretically analyzed and tested experimentally.  The only time it doesn't apply is if the ions and electrons are bound (which means it is at best a regular neutral atomic/molecular gas and no longer a plasma) and the electric field of the electromagnetic waves is not strong enough to ionize the atoms.  In a plasma, electromagnetic waves will act on electrons & ions relatively independently, and the charged particles will move in opposite directions in response to an electric field of the wave.  With  ions over 1800 times more massive than electrons, they accelerate in the electric field much more slowly.  The net effect is that the electrons move in response to the field while the ions remain largely at rest.

In an upcoming post, I'll explore some other implications of the plasma frequency.  One of the applications is that it can be used to analyze the electron density in regions.  This effect has been used to probe the electron density of the solar corona and is regularly analyzed in GPS signals for computing the signal time delay when propagating through the ionosphere.


Jeffery Keown said...

Sometimes, it seems as if the easier task would be noting what the EU guys got right.

But maybe that would have a negative effect on the whole of science.

W.T."Tom" Bridgman said...

To Jeffery Keown,

I actually tried to look at that question. The funny part is when I looked at anything where they *started* on the right track, they very quickly flew off the rails.

Anonymous said...

i think this applies, but forgive me if I am incorrect: It is a widely held belief that a large-scale electric field of any significant magnitude cannot be present in the heliosphere because of electric currents through the highly conductive plasma, present throughout the heliosphere, which would immediately neutralize any nascent electric fields. This paper questions that longstanding belief and describes a mechanism to account for such a field. Some of the galactic cosmic ray (GCR) ions lose almost all of their kinetic energy from solar modulation and, due to their short radii of gyration, are effectively deposited continuously throughout the heliosphere inside the solar wind termination shock. It is pointed out here that the deposition of these ions occurs at a greater rate than that for GCR electrons, and that a large-scale static electric field is sustained by the ions because of the time delay in the arrival of neutralizing electron currents.
IEEE Xplore electric and plasma socitey

W.T."Tom" Bridgman said...

To Anonymous:
What you describe would be more appropriate to the post Electric Universe Fantasies & Heliopause Electrons. II. but it is okay here.

Apparently the link to the paper you describe did not come through. Please try again, it sounds worthwhile to add to my collection.

The mechanism you describe is not unreasonable.

It is a field generated by velocity separations that is part of the Pannekoek-Rosseland field and some solar wind models (see 365 Days of Astronomy: The Electric Universe). The difference in kinetic energy of the charged particles provides the energy to maintain the field. The field would cover a large region, but it would probably be very weak. Integrating over the size of the heliopause, it could provide substantial acceleration to a small population of charged particles.

Such a mechanism is mathematically tractable and could yield actual testable values.

I would not be at all surprised if EUers try to appropriate it as 'their' idea.