Slashdot Mirror
Lab Produces 3.6 Billion Degree Gas
starexplorer2001 writes "LiveScience is reporting how scientists at Sandia's Z laboratory have produced superheated gas exceeding temperatures of 3.6 billion degrees Fahrenheit (2 billion kelvins). That's hotter than the interior of our sun, which is only 15 million degrees F. And they don't know how they did it. Do we want anything that hot on our planet?"
According to the summary, the Sun's interior is 15 million degrees Fahrenheit. According to the article, it's 15 million degrees Kelvin which makes the Sun's interior actually 27 million degrees Fahrenheit.
It says that the record was set for the hottest temperature ever on earth. Unfortunately, the value they list is not the highest value I can obtain for a really hot temperture. The hottest temperature I found occurs at RHIC and that is a trillion degress kelvin not fifteen million. http://www.bnl.gov/RHIC/heavy_ion.htm Could it be a record temperture for a certain type of reaction? Also to answer the question about is this safe. Yes it's safe. The temperatures only occur for such a small tiny tiny tiny fraction of a second that it really doesn't affect anything.
Ooo man the floppy drive is broken. No wait. The computer is just upside down.
http://en.wikipedia.org/wiki/Fusion_energy#Power_p lant_design
Also plasma is not a gas. The article points this out, but the title gets it mixed up. It is a 4th phase of matter associated with high conductivity and separation of ionic components
http://en.wikipedia.org/wiki/Plasma_(physics)
My work involved doing quantum molecular dynamics (QMD) simulations to extract equation of state (EOS) data for the tungsten wires used in the z-pinches. The highest temperatures I remember the simulations reaching, however, were only about 40,000 Kelvin.
All things glow when they heat up, and they do so in a predictable manner.
They may have been able to measure the wavelength of the electromagnetic energy coming off of the gas.
This explains it better than I ever could.
Actually the live science article is missing the most vital info.
I read this article on PhysOrg.com http://www.physorg.com/news11538.html (yes I'm to lazy to HTML'ize that link)
From the PhysOrg article: "The results, recorded by spectrometers and confirmed by computer models created by John Apruzese and colleagues at Naval Research Laboratory, have held up over 14 months of additional tests. "
What I don't understand is how these spectrometers even worked at these tempearatures, I would expect most things to go kaput at these temperatures.
From the journal article, emission line optical depth varies inverse squarely with the ion temperature. So they used the k-shell emission spectrum for the stainless steel plasma to determine what temperature would produce the observed lines.
Spectrometers measure the EM radiation. It doesn't need to actually touch the substance being measured.
Social scientists are inspired by theories; scientists are humbled by facts.
The container that holds the experiment is called a holhraum, just a cylindrical metal thingy. In the middle, wires are vertically strung around in a circle (see this pic). When you pass a current through the wires, they want to move towards eachother (Ampere's law). Since the situation is symmetrical, they all move towards the center, and the intense current, motion, and collision, turn the wires into a hot plasma, that doesn't stick around for long. The whole thing is over in well under a second, and the container holding the plasma is destroyed.
The paper with the proposed model explaining these findings is available here for anyone that can understand it. They refer to instabilities (of the Rayleigh-Taylor kind?) causing ion viscous heating as they are dissipated. When an array of wires is heated and implodes, most of the content of the wires remain unmoved at the beginning, with only the outer parts being converted to plasma and moving toward the center. The inner left-overs are eventually converted as well and make the trip, though not necessarily until after the peak energy radiation.
Mit der Dummheit kämpfen Götter selbst vergebens.
Rather than reading a digest from a science news site (not that it's a bad writeup) here is the press release from Sandia themselves.
Personally, I think the picture of the Z-machine is one of the coolest looking things I've seen. =)
Lost at C:>. Found at C.
For the curious, here's the actual abstract from the research paper, as published in Physical Review Letters:
Ion Viscous Heating in a Magnetohydrodynamically Unstable Z Pinch at Over 2×109 Kelvin
Pulsed power driven metallic wire-array Z pinches are the most powerful and efficient laboratory x-ray sources. Furthermore, under certain conditions the soft x-ray energy radiated in a 5 ns pulse at stagnation can exceed the estimated kinetic energy of the radial implosion phase by a factor of 3 to 4. A theoretical model is developed here to explain this, allowing the rapid conversion of magnetic energy to a very high ion temperature plasma through the generation of fine scale, fast-growing m=0 interchange MHD instabilities at stagnation. These saturate nonlinearly and provide associated ion viscous heating. Next the ion energy is transferred by equipartition to the electrons and thus to soft x-ray radiation. Recent time-resolved iron spectra at Sandia confirm an ion temperature Ti of over 200 keV (2×109 degrees), as predicted by theory. These are believed to be record temperatures for a magnetically confined plasma.
Also, there's a press release from Sandia National Labs.
I scanned the article. The article does not say that total energy observed was greater than the total input energy.
What the article says, and it's easy to be confused by this, is that the observed energy was greater than the kinetic energy of the implosion. However, one has to realize that the kinetic energy isn't the only significant source of energy in the system. There is also the energy in the magnetic field. The article goes on to elucidate a mechanism by which magnetic field energy is converted to thermal energy ions, which is then transferred to electrons to produce soft X-Rays.
Thus, the bottom line here is, unfortunately, that what happened in this experiment was that one component of the total energy input, magnetic energy, which normally is not converted into heat, was converted into heat by a new mechanism. This is what the authors meant by a new energy source. In other words:
NO FUSION.
Okay, time to move along folks, nothing to see here other than some really really really really hot plasma, which probably don't have the density to achieve sustained fusion...yet. =)
I spent three summers working in a trailer less than 50 meters from this machine. It always creeped me out a little. Several times a day, the sirens and flashy lights would go off outside the building, then about a minute later, we'd hear this huge "WUMPH". Our whole trailer would shake and the monitors vibrate. Despite understanding what was going on, I couldn't help but wonder about the safety of sitting next to an array of giant capacitors which get rapidly discharged all at once.
However, I must admit it does make cool pictures. The bright lines you see on most pictures are supposedly spare charge arcing across the giant pool in which they have to keep the whole thing submerged.