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Author Topic: 4th state of matter  (Read 5595 times)
N3OX
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« Reply #15 on: January 07, 2012, 12:30:13 AM »

As an aside, I (instinctually) believe that the behaviour of plasma when used as an antenna will obviate several conventions, such as resonance and impedance. 

Resonance and impedance aren't "conventions", they're general concepts that apply to a wide variety of physical systems.  A plasma antenna will have an electrical impedance that needs to be matched to 50 ohms at any given frequency.   If it is a good antenna it won't have an impedance that varies too much with the amplitude of the applied RF... if it does it will cause severe distortion in your transmitted signal Grin

Quote
The categories of substances that can be included in the definition 'plasma' as a description are many.  Emphasis many.  Which will work best?  How should they be managed for communicatiuon purposes?

There's one particular type of plasma in a special container that has proven to be extraordinarily useful for antennas over the years.. the free electron sea in a piece of copper or aluminum is a plasma held in a nice well defined place in space by attraction to a lattice of positively charged ions.  All of my antennas are plasma antennas in a sense Cheesy

There are some antennas out there that use plasma parts where it's absolutely recognizable as a "container of plasma" ... gas ions in some glass, for example.  There's an interesting article I read about a very short dipole surrounded by a double glass globe full of cold plasma kind of like a fluorescent tube.  The globe plasma and RF frequency are chosen so that the electrical permittivity and magnetic permeability are both negative (in usual materials like glass or air or vacuum both of those constants are positive).

This "double negative" plasma shell matches the very low radiation resistance and high capacitive reactance of the antenna to free space radiation. The sphere is still pretty small with respect to a wavelength. But even with this fancy fragile glass sphere full of plasma, the basic concept is similar to other loaded antennas... stored energy lets you effectively radiate power from a small volume.  It's a funny sort of loading with a cool mathematical  form, but it's still a loaded antenna and has some bandwidth constraints and worries about efficiency and so forth.

For hot plasmas or plasmas where you're cranking up the amplitude of the plasma motion to high levels in operation you have to worry about noise or nonlinearity.  It's important, IMO, when you're trying to focus your thinking about this stuff to ask what problem you're trying to solve and then go off in the direction of that problem.  See if you can find some examples where someone who knows plasmas has used plasma to solve that problem or one like it.  If you can state the specific thing you think plasmas will be good for, and you ask "can plasma do X?" then someone (or a paper or book they wrote) can give you a "yes," "no," or "maybe" answer.

So what's wrong with metal (electron plasma) antennas?  What problem do you see with them that you think plasma (other plasma) might solve?  That will help people steer you toward some answers.  It may also steer you toward some things you didn't know about metal antennas... in the end if you solve the problems satisfactorily with or without plasma then maybe you're happy.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N7KTX
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Posts: 31




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« Reply #16 on: January 07, 2012, 01:57:20 PM »

N3OX     Thanks, Dan!  Nice to hear from someone with a Ph.D. in physics who's willing to discuss my interests.  The amateur radio community is lucky to have people like you.

I'm trying to think outside the box a bit.   Antenna technology seems like an area that's overdue for a breakthrough.

In response to your advice about being specific:  The shape and size of the plasma container being used as an antenna would be key in determining how and where it could be applied.  Everything I've come across so far that uses plasma as a medium is spherical in some respect.  I wonder if a flat plane would work?

I see the day when metal towers and large arrays are things we look back on.  I've been sniffing around on this subject for a while now and have found that its well attended.  So, not being in a position to contribute significantly to the theory end, I'd like to throw out the suggestion that amateur operaters such as myself might be able to contribute on another level.  Research in most fields eventually boils down to the tedious process of ruling out possibilities by trying them in direct application.  I would love to be involved in an effort like that.  Building containers of different sizes and shapes, filling them with ionized gasses, applying current, and measuring and recording the results is right up our alley.

Leg work.  Interesting to the point of fascination, educational, and challenging.  Not to mention, with proper guidance, productive.

Just a thought.

KF7OAE
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KATEKEBO
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« Reply #17 on: January 07, 2012, 08:56:20 PM »

The first three being solid, liquid, and gas, with the fourth state (plama) making up about 97% of the known universe.

Being an amateur astronomer, I feel compelled to make a small correction to this statement.  Plasma represents a very small fraction of the Universe.

74% of the Universe is comprised of Dark Energy
22% is Dark Matter
Only 4% of the Universe is barionic matter, or the "common" matter as we know it.  Out of that barionic matter, the vast majority (approximately 90%) is in form of interstellar gas and dust.  Only 0.4% of the total Universe is in form of stars, i.e. highly ionized plasma.  The amount of matter contained in planets or other types of "cold" dense bodies is so minuscule that it really doesn't count (on the cosmological level, although it is important to us, earthlings).

In any case, as mentioned above by Dan, plasmas electrical properties are similar to any other conducting material, so much that stellar plasma can be simulated at earthly conditions using mercury, for the purpose of studying its behavior in magnetic fields, leading to a field of physics called fluid magnetohydrodynamics.  So essentially any plasma antenna can be replicated using more convenient materials, such as metals.  On the other hand, hot plasma is a source of broadband electromagnetic radiation, something that would certainly not be appreciated in an antenna.

My astro $0.02.

Bucki (KD8KQH)

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AD6KA
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« Reply #18 on: January 08, 2012, 12:38:20 PM »

Exactly HOW MANY EXPERIMENTS have you performed
using plasma as antenna? How Many?
10, 15, 20?
How man Doc Brown?
Was Marty McFly there to help you?

Quote
My question to the reader of this posting is:
  What, if anything, is already known on this subject?  
The types of plasma are broad and varried. (SP)  
Any help to narrow the field of my experiments would be much appreciated.

So basically, you are asking a bunch of lay people
to do your research for you, right?
"What, if anything, is already known on this subject?"
Go to a a good college library and go through the
Applied Physics journals.

"The types of plasma are broad and varried.(sp)"
You get that from Wikipedia or Encyclopedia Britannica?
Wiki isn't a scientific or academic source.
Any Tom, Dick or Harry can and do post articles & rebuttals there.

You jump on here with your "I regreted (SP) the misnomer the minute I posted it.  
I'm impressed. Not many folks would know the difference.  
Bose/Einstein condensate is correct"
....look how smart I
(and some of us) are.

Then you come up with this impressive sounding but
completely SILLY, unfounded, unsupported BS like you are
the new Einstein. (Oh, and Tesla's ideas were proved wrong
about the time your granny was born!

"As an aside, I (instinctually) believe that the behaviour of plasma when used as an antenna will obviate several conventions, such as resonance and impedance.  I believe that we are looking at the interpretation of waveform energy via a new format.  We've depended on resonance since the days of Tesla, but we are now fooling around with a new media.  I'd describe it as reflection, looking into a new mirror."

BWAHAHAHAHAHAHAHAHAA!
Ken, AD6KA
« Last Edit: January 08, 2012, 12:50:12 PM by AD6KA » Logged
N7KTX
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Posts: 31




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« Reply #19 on: January 08, 2012, 07:26:15 PM »

KATEKEBO

Thanks for the input, Slawomir.  As to the percentages of composition of the universe, I suppose it comes down to interpretations.  The Dark Energy (74%) and Dark Matter (22%) you mentioned may have properties that qualify them as forms of plasma, since plasma is just a state, not matter of its own.  There may be room for both sets to be correct.  Matter doesn't have to be highly ionized in the way found in stars to be described as plasma.

I agree, as well, that hot plasma would not be welcome in, around, or near my radio shack in its free state.  The local fire marshal would probably object.  At any rate, the weaker 'cold' plasma is all that's practical to experiment with here in the old back yard.  In my case, I'm just having fun with a thought that won't go away.

KF7OAE
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N7KTX
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« Reply #20 on: January 08, 2012, 07:59:10 PM »

AD6KA

Despite your tone, thanks for the input Ken.  Nothing ventured, nothing gained.

By the way, the number of experiments, crude though they have been, is 7.  Some overlapped, but 7 seems about right.  This thing has me by the tail, and I'm here in this forum to see what others might have to say.

I'm serious when I say that I believe there's another way, besides the usual ways, to 'see' radio waves.  I'm looking around for the means to do it.  No commercial motive, no ties to industry.  Just curious.  I've never asked others to do my work for me.  What I'm looking for is a little guidance while I work on this strange thing alone.  Narrows the field a bit when people who know the subject take a moment to mention a little of this or that, here and there.

Plasma may not even be the right medium to achieve my goals.  Its just the tree I'm barking up at the moment.

Anyway, thanks again for the comments, Ken.

73s

KF7OAE
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N3OX
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« Reply #21 on: January 09, 2012, 07:40:52 AM »

Plasma may not even be the right medium to achieve my goals.

Some unusual things you can do with linear plasma, like negative index of refraction, can be mimicked by structured patterns and volumes of metal and dielectric.  In the current fashion these structured materials are generally called "metamaterials" though there are some other terms like "spoof surface plasmons" for some of the things that surface waves can do on structured metal/dielectric surfaces.  This general idea of using structured materials to get effective permittivity and permeability that you can't find in any known bulk material has been known for a long time.  For example, my copy of J.D. Kraus's "Antennas," first published in 1950, has information on building what he calls "artificial dielectric" out of metal strips or spheres embedded in a dielectric.  

Non-linear plasma can do more interesting things but it is not suitable as a transducer to go from AC electrical signals to EM radiation because it will generally generate new frequencies and cause spurious emission.

I also personally think that there are a lot of boring conventional techniques for making smaller, better antennas for ham radio that don't involve anything that's even in the least bit of interest in the professional world right now.  IMO there's a lot that can be done by just applying some good skeptical measurements and refinements to really simple things like small coil loaded antennas.  I actually don't think we need a breakthrough.  At this point a lot of people simply do not care how well their antennas work, especially small ones.  If they can make a few contacts with it, it's a "great antenna" even if it's 10dB down from some other approach (which might be simpler to build!)  Often the people who care how well their antennas work have an irrational worry that shrinking antenna size from "full size dipole" or "full size yagi" will give an unacceptable compromise.  

And the biggest problem IMO is that the interaction between the "full size or nothing" folks and the "my awful small antenna is a wonderful breakthrough" folks ends up being kind of pathological.  People will tell the owner of a small shrunken antenna that it's a "dummy load" and then the owner of the small antenna will work Botswana on it and "prove that it isn't lossy."  All the while the small antenna could be burning up 85% or 90% of the applied RF as heat.... not enough to make it unusable but certainly enough that it could be improved substantially.

We have a hard time even having the discussion about THAT kind of stuff, and I feel like a lot of our homebrewer/experimenter energy is devoted to chasing "the next big thing" rather than solidifying our engineering abilities, our understanding of the huge body of existing theory and techniques and our ability to do simple backyard scientific measurements on the relative performance of what we're running.

Of course, if you find plasmas exciting and want to experiment with plasmas, that's great.  Go for it.  It's a hobby, and it's a big hobby.  You gotta do what interests you.    For me, there's so much knowledge and so many solid ideas even in the far past (probably along with a few choice bits of "buzzwordy" stuff from recent work) that we're simply not tapping into.  

« Last Edit: January 09, 2012, 07:42:23 AM by N3OX » Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N7KTX
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Posts: 31




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« Reply #22 on: January 09, 2012, 02:22:51 PM »

N3OX

Well, Dan, thanks again for the time you took on the last post.  Metamaterials, especially.  The negative index of refraction, and the methods used to produce it, are subjects that will keep me busy for a while.  A very odd lattice fence may appear in my back yard.  Thanks.  Your earlier reference to a double negative plasma shell will also keep me busy for a while.  I'd like to apply the idea to a flat plane instead of a sphere.  But, then, I'd also like to hit Powerball some time soon.

You suggested that refinements in the types of antennas now in use leave a lot of room for improvement, so much so that any radio operator who chases out the details would find that there's no real need for improvement.  I agree, but that's not why I'm doing this.  I'm just attracted to the concept.  Maybe I'm a little obsessive/compulsive.  The antennas I'm using now work quite well.  I may or may not come up withsomething better, but I bet I can do something different.  Besides, its fun.

73s

KF7OAE

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KATEKEBO
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« Reply #23 on: January 10, 2012, 12:35:23 PM »

The Dark Energy (74%) and Dark Matter (22%) you mentioned may have properties that qualify them as forms of plasma, since plasma is just a state, not matter of its own. 

KF7OAE

Neither Dark Energy nor Dark Matter are plasma.

Dark Energy is an unknown force responsible for the expansion of the Universe.  It can also be called Vacuum Pressure.  We don't know what it is, but we know that it's effect is the acceleration in the expansion of the Universe.  Without Dark Energy, the expansion of the Universe would be slowing down due to the effects of gravity.

Dark Matter is an unknown form of matter that does not absorb nor emit electromagnetic radiation.  Hence, it is completely invisible.  But Dark Matter has mass, and interacts gravitationally with conventional (barionic) matter.  For example, we know that a halo of Dark Matter surrounds the Milky Way galaxy because we can observe its effects on how regular matter moves in the Galaxy.

S. Bucki KD8KQH


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N7KTX
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« Reply #24 on: January 12, 2012, 05:08:03 PM »

KATEKEBO

I share your interest in astronomy and astrophysics (come cosmology), but to a lesser degree at the moment than my focus on EM.  I've got an idea about waveform propagtion that won't let me be.  You said that dark matter is an unknown form of matter that doesn't absorb or emit EM.  To me that means that, even though its not well understood as yet, its not completely unknown.  At least some of its properties are known.  Fascinating stuff.

Aside from that, let me say something more about my theory.  Several layers of the earth's atmosphere act as reflectors of radio waves.   To me that means that if it can be reflected (and to some degree absorbed) by ionized gas in the atmosphere, then it can be detected and interpreted in a useful way by ionized gas containers on the surface for use in radio communications.  I know that much study has been devoted to the concept by people better informed than myself, but I can't let that stop me from looking into the subject independantly.  After all, its a hobby. 

My next effort will be filling a radio-transparent container with argon, minus the dopant inclusions that are used to produce the lightning bolts in the novelty globes that have been around for many years.  I'd like to try some of the less common noble gasses, but an 80 cubic foot tank of purified neon costs about $5,000.00.  I'm not curious enough to sell my Harley.  Yet.

Step by step by step.

KF7OAE
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