I think its more useful to introduce it as a plasma device, that happens to release energy by fusion.  Rather than a fusion device that works by using plasma.  That way you can talk about the device in conext with other plasma devices people are familiar with such as candle flames, neon lamps, spark plugs, lightning.

One diagram that is often used to illustrate the point is a temperature vs density, or temperature vs density*confinement time plot showing the relationship between different plasmas, such as the images below.

For the slightly more detailed (but less pretty version) see page 41 of: NRL Plasma formulary.  This little formula book is a standard reference for any plasma physist and so contains lots of scary looking formulae.  The interesting thing is unlike most simplified versions of the diagram such as the NASA one below it includes plasma focus devices at the top right corner showing they achieve the highest density/temperature combination.

Maybe what we need is a new updated version of this diagram with thumbnails of flames, lamps, lightning, and where ITER, NIF and FF-1 stand.  Hopefully putting focus fusion ahead of where the competition are. Publish it under creative commons and plaster links to it all over the place.

Hi James,

I split the thread because the other poster specifically addresses the “bomb” issue, and there needs to be a poster that explicitly does that.

This plasma approach/upgrade you describe is also very much needed. 

On the topic of plasma that works its way to the topic of nuclear - check out the Leopoldo Soto videos.

By the way, where does FoFu fall on the 2nd chart?

OK Artists, designers et al - this looks like a priority.  Let’s get to it!

jamesr - 31 August 2010 10:27 PM

For the slightly more detailed (but less pretty version) see page 41 of: NRL Plasma formulary.  This little formula book is a standard reference for any plasma physist and so contains lots of scary looking formulae.  The interesting thing is unlike most simplified versions of the diagram such as the NASA one below it includes plasma focus devices at the top right corner showing they achieve the highest density/temperature combination.

Maybe what we need is a new updated version of this diagram with thumbnails of flames, lamps, lightning, and where ITER, NIF and FF-1 stand.  Hopefully putting focus fusion ahead of where the competition are. Publish it under creative commons and plaster links to it all over the place.

And here’s an image grab of the NRL diagram.  The Focus is indeed in the top right corner.

Rezwan - 31 August 2010 11:24 PM

By the way, where does FoFu fall on the 2nd chart?

wasn’t 70 keV ion temperature reported this spring? that places Focus fusion just a few ticks from the right-hand edge, within the yellow zone.

vansig - 02 September 2010 09:49 PM

Rezwan - 31 August 2010 11:24 PM

By the way, where does FoFu fall on the 2nd chart?

wasn’t 70 keV ion temperature reported this spring? that places Focus fusion just a few ticks from the right-hand edge, within the yellow zone.

The shaded ignition area, and green ‘burning’ line are for D-T fusion.  For pB11 the curves would be further to the right so the bottom of the curves lie at around 550keV

I’ve seen similar charts which extra information displayed, I’ll try and find them.

Here’s are charts from:
Steven J Schwartz’s “Astrophysical Plasmas Online Book” (PDF) (Fig. 2.1, page 12).
Donald A. Gurnett, “Introduction to plasma physics” (Fig 2.5, page 19)
Wolfgang Baumjohann’s “Basic space plasma physics” (Fig 1.2 page 4)

And more charts, from:
Kyōji Nishikawa’s “Plasma physics: basic theory with fusion applications” (fig 2.2, p.11)

I’m looking at all the charts posted in this thread so far.  What’s up with the variations on the axes?  No consistency.

Temperature:
(pardon lack of upper and lower case):

Temperature (K)
Temperature T(K)
Ion Temperature (K)
Electron Temperature (eV)
Electronic Temperature in Kelvin
log 10 T (eV) 
Central Ion Temperature, Ti(0)(keV)
log 10 Te (degrees K)

Density:

log10ne(electrons cm^-3)
Particle density
Electron density in cm^-3
Lawson parameter, nitE(10^20 m^-3 s)
Electron Number Density (cm^-3)
log 10n(cm^-3)
Confinement Quality, nt(m^-3 s)

Another unsettling thing - in some cases, Temp is on the x axis.  In most, it’s on the y axis.  And one chart has additional parameters (“Electron Plasma Frequency in Hz”)

Conversion chart required?
Which of these parameters is the most meaningful to a broader audience?  And how much of the variation should we also explain?  I suppose a little cheat sheet/ conversion/“you say “Electronic Temperature in Kelvin” I say “log10T(eV)”, let’s call the whole thing off…”  chart might be useful.

Human Perspective. 
How do we add human comprehension here?  Looking at the “characteristics of typical plasmas” poster, I see a neon sign and fluorescent lights are up there at 10^15 in density, and 10^4 in temperature.  They don’t seem so hot to me.  I’ve touched such lightbulbs before.  Is that really what 10^4 feels like? 

Also, the sun is up there, very dense and hot.  Is it denser than a person (where is a person on the chart?  In the lower solid corner?  How far over?  We’re pretty spongy.  Some spongier than others.)  Is the core of the sun fluffier than a person, or denser?  It’s not really that clear. 

Adding FAQs:
Since we’ll have hyperlinks on our poster, we can add all kinds of information.  Like - does fusion take place in a lightning bolt?  If lightning strikes me, will my brains fuse? 

Building in Experimental accessibility:
This question has come up for me a few times when I define plasmas.  First, definition of plasmas:

It is a collection of charged particles that respond strongly and collectively to electromagnetic fields, taking the form of gas-like clouds or ion beams. Since the particles in plasma are electrically charged (generally by being stripped of electrons), it is frequently described as an “ionized gas.”

The question is, if plasmas respond to magnetic fields, and are ionized gas, and Flames are plasmas, do they respond to magnets?  I’ll have to test this.  Need something to hold the magnet out with so I don’t get burned : )  The followup question is, couldn’t firefighters use magnetic fields to put out fires? 

Kids.

And where is the plasma TV on this chart?  What happens if I take a magnet next to my plasma TV?  As you can tell, I don’t have a plasma TV, so I can’t test this. 

A Game/toy idea: 
You know how kids toys have a pin the tail on the donkey sort of thing, you could pin the phenomenon in its correct area of temp/density.  To make it easier for young kids, you can have the board cut into the right shape so they are just fitting shapes.  But subliminally, they are learning. 

An animation (with exquisite production values : )) could bring this whole poster idea to life. We’d zoom around from plasma to plasma getting hotter or colder.  Playing “hot and cold” until we get to fusion, I suppose.

This could be fun!

I know what you mean about all the different choices for axes.  I think the most sensible bet it to keep them as temperature in Kelvin, and density in m^-3 - ie. SI units.  Combining the energy confinement time into the density axis (Lawson parameter) means highlighting any areas is specific to a particular reaction ie D-T.

For a fancier animated version you could include the confinement time as a third axis - so make it a 3D cube you are flying through.

Also alongside each axis you could have other reference points such as the density of water.

Style-wise I was looking recently at some of the xkcd posters such as http://xkcd.com/681/ or http://xkcd.com/482/ where the large scales of the universe are explained with ease (and a little humor)  Maybe we could get him on-board to do a fusion poster and post it on xkcd - that would generate some publicity!

If you want to see how a magnet bends a plasma, watch this: http://www.youtube.com/watch?v=3grPo81fBrA  The mugs were available from thinkgeek.com but I can’t see them on their site right now