FF-1 shows its true color—violet!
(5) CommentsLPP has now taken pictures with an ordinary video camera of the FF-1 pinch and its aftermath, thanks to an initiative by Derek Shannon. Video frames taken every 50 ms (see Fig. 3 and 4) show the violet flash of the pinch, the color expected from extremely hot plasma, and, interestingly, also show the fading glow of the still white-hot plasma 50 ms later. Aside from giving us real color photos of the pinch, these images show approximately how slowly the plasma cools off. The relatively slow cooling is good news for several reasons, including making it easier for a future generator to keep the boron in a gaseous sate. However, the conditions in a generator, with much denser gas, are quite different from our current conditions, so extrapolation must be done with care.
You can watch a full movie similar to the one from which these frames were taken here at the Focus Fusion Society website. We will be making more videos in the future, including with neutral density filters that will avoid the over-exposure at the time of the pinch.
First sample of new spark plugs produced
New radioactive isotope diagnostics set up
Comments
For a more in depth discussion, start a thread in the forums.Pretty cool! And this time the light can clearly be seen to come from the vacuum chamber viewport.
Question: is violet the color expected from an extremely hot plasma, or is it the color expected from an extremely hot deuterium plasma?
Oh, wait, how did I miss this?:
I’m looking forward to it.
this is what the light at the end of the tunnel looks like.
I am thinking that a bulk plasma like this will act more like a blackbody radiator with a peak output in the blue to UV end of the spectrum, rather like hot O-type stars. If deuterium emits in this range at certain recombination energy levels, that could be a narrow-band contributor (an emission spectrum peculiar to that atomic structure) (≈400 nm wavelength). I don’t know anything about deuterium’s emission spectrum, however. Does anyone have an estimate of the DPF plasma temperature in K or eV?
Adequate neutral filtering of the plasma formation may lose the blue glow surrounding it, but it would be interesting to valuable nonetheless. Make it so!
Jim
Jim, I don’t know what the plasma temperature was in that particular shot, but the best shots have been estimated to be on the order of 100-200 keV, or about 1 billion K.
Regarding deuterium’s emission spectrum, the Wikipedia article has some nice pictures and a line graph. I think blue, purple, or pink are exactly what you’d expect to see, even if the plasma isn’t acting as a blackbody radiator.
When it comes to boron, however, there should be a difference. If it’s acting as a blackbody radiator, the visible light should be blue or violet at extremely high temperatures. Otherwise, I believe the visible light should have a greenish hue.
Post a Comment