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First Plasma on the Levitated Dipole Experiment
deglr6328 writes "In light of recent, somewhat disappointing news in the world of nuclear fusion research, it is worth noting that there are still reasons to keep up hope that some breakthroughs are yet to be made. At 12:53 pm on the 13th. of this month the Levitated Dipole Experiment achieved its first plasma. The Levitated Dipole Experiment(LDX), built at MIT's Plasma Science and Fusion Center as a joint project of Columbia University and MIT, is a magnetic confinement fusion research device, that unlike all previous stellarator, reverse-field pinch and tokamak like experiments, uses a superconducting levitated torus to confine its plasma. The LDX's achievement of first plasma is, in a way, about 17 years in the making even though it has only been in construction since 1999. The concept for LDX was first considered by Akira Hasegawa as he was studying the data coming in from the Voyager missions which flew through the (dipole) magnetospheres of the outer planets. He noticed that unlike laboratory confined fusion plasmas which tended to be unstable, difficult to control, and which lost energy quickly, the plasma of a magnetosphere is intrinsically more quiescent, stable and actually reacts favorably (increases its density/temperature) to outside perturbations such as ie. bombardment by a solar storm. A highly informative and interesting video of operations on the day of first shot can be found here. Congratulations to the scientists and engineers who have worked very hard on getting the project to this point and here's looking forward to the possibility that LDX will reveal fundamentally new physics in the arduous quest for clean fusion energy."
-- Still waiting for the Nike endorsement
Exactly. Groups like Greenpeace are so informed and ignorant they are hindering clean cheap energy. The amount of radioactive waste put into the atmosphere by coal is much greater than nuclear fission. Fission is clean and a lot more abundant than coal or oil. It will take some time but we should be gearing up for a hydrogen economy where hydrogen gas is used in everything from cars to cell phones. The hydrogen can come from nuclear power plants.
Call me crazy, but I think this is a good solution.
So then the phenomenon of life is merely a complex arrangement of atoms and nothing more?
We have no reason to believe otherwise.
In the case of LDX, however, tritium is completely unnecessary for operation, as it makes use of the Deuterium-Deuterium reaction.
And there's a lot of Deuterium in the oceans. I believe the estimate is that we could run our entire civilization off of the Deuterium present in just the first centimeter of the oceans for one or more years. And we'd put most of that water back, so you don't even have to worry about the oceans being taken away from all the little fishies. :-)
You would be referring to the David-Besse plant, not the Perry plant.
:) Try to remember that dying from a nuclear plant accident is orders of magnitude less likely for anyone on the planet than even dying from lightning - even if you are a golfer :)
It wasn't a "hole" it was a crater and pitting from boric acid leakage that damaged the reactor vessel. According to some other articles I saw in a quick Google search, they have a emergency sump system that would recirculate any coolant that leaked thru that hole back into the reactor - there would have been no meltdown *
The boric acid was stopped by a stainless steel outer layer that was another of the layers of defense. It could have eaten thru that, too, but it would have taken many years, many more than elapse between the regular inspections (AMAF it was when the plant was taken down for refueling - which happens pretty seldom - that they discovered the damage) and this was a *very* unusual accident, one which has prompted a considerable amount of redesign. Note that David-Besse and similar plants are also very old designs.
*NO* power production system is safe. NOT EVER. But fission plants have a much better safety record than any of the others do, which was drinkypoo's point. Look at the coalmine disasters, natural gas production facility disasters, and other dangers we face from "conventional" energy production. Even including Chernobyl fission has killed or injured FAR fewer people and environments than any of the other technologies.
Anyway, try to make an effort to get your facts straight and read about the events you describe before fear-mongering. If nothing else it helps other people take you seriously.
BTW, I lived near and got power from a fission reactor for twelve years out of my life. Never bothered me nor any of the people who lived there, either. Of course we Minnesotans know that our winters are much more likely to kill us than a power generation plant is
* Although there is a question of whether the filters in the emergency coolant containment system could have clogged, this problem is being addressed and has already been fixed in many plants - this according to info that's already fairly old and fixes have been implemented.
Cheers,
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
OK, I'll bite (I am a chemist :-).
Those guys indeed knew how to use their calorimeter, but they did not concern themselves with any other part of science, and, hence, in the interpretation of their measurements (not in the measurement results per se) they have made several trivial mistakes. Sadly, that is the way many scientists who are in possession of some exotic/expensive piece of equipment behave. I've seen it many times.
Now about cold fusion... Unfortunately, it is physically impossible, and for a reason. The Coulomb barrier to bring together 2 hydrogen nuclei is enormous, and it is the reason why 10^6 K (or maybe even hotter) temperature is normally needed to start the reaction. At more human conditions, nuclei could, of course, tunnel through the Coulomb barrier and fuse as much as they want. Problem is, this tunnelling is extremely slow (rate is actually easy to calculate - I think it will be in any college radiochemistry course), and it won't be sufficient to sustain the reaction, or even measure its heat on the macroscopic scale.
The mechanism proposed by Fleischmann did not take into account the extremely high activation energy for fusion. They did have a vague concept that there should be an activation energy, and that it is probably high, but they did not realize how high it is...
Actually, they typically do the opposite: they have the cadmium "control" rods get lowered DOWN into the reactor. Cadmium absorbs neutrons, so if something goes wrong, they just drop them and the reaction stops in a fraction of a second.
Not that this makes everything safe. Read the report on Three Mile Island sometime. It's long, but it's a fascinating read.
IANANP, BIWARPFMEAC*. I'd like to elaborate a little bit on this point:
Fission occurs when a heavy radioactive nucleus (in the control rods) absorbs a neutron and splits into two smaller nuclei and a few extra neutrons. These new neutrons can be absorbed by other heavy nucli, and more fission occurs.
Now most of the neutrons released move too fast to be absorbed by a nucleus; instead, they just bounce off. In order for a sustainable reaction to take place, a material - called the moderator - is required to slow down the neutrons so that they can be absorbed.
Most modern** nuclear reactors are pressure-water reactors. This means that they use water as both a coolant and as a moderator. If the water excapes, then the reaction fissles out.
However, Chernobyl was initially designed with a solid moderator built into the reactor vessel. (I think it was graphite, if I remember correctly.) It used water purely as a coolant. So when the coolant leaked, the reactor kept on fissing atoms and the reaction got out of control (although not fast enough for a thermonuclear reaction).
That wasn't the only problem. The reactor's personal paniced and tried to send the control rods in too quickly. While the control rods were halfway in, neutrons bounced into the bottom of the reactor and formed a critical amount for a chain reaction. At the same time, the heat of the reaction and loss of pressure from the origional malfunction turned the leftover water into steam pockets also in the bottom of the reactor. Soon after, an explosion ruptured the reaction vessel.
Perhaps the primary cause of the accident (and of TMI) was the confusing interface to the equipment! Some devices used red lights to signify emergency conditions, while others used green or another color. Instruments were hard to read and slow to respond. An ergonomical failure contributed to the accident.
Today, most control rooms have learned from the mistakes at TMI and Chernobyl. They are easier and more consistant to use. However, even more improvements are possible with new designs. It is a pity that nobody will allow the old workhorses ot be retired.
* I am not a nuclear physicist, but I wrote a research paper for my Engineering Analysis class.
** "Modern Nuclear Reactor" is somewhat of an oxymoron. Due to NIMBY feelings among the general public, most commercial nuclear reactors are old (60s-70s era) and modern designs are never given a chance despite the improvements in efficiency, safety, and (less) waste production. :-(
It is impossible to enjoy idling thoroughly unless one has plenty of work to do.
- Jerome Klapka Jerome
After producing two rings at the opposite end of a vacuum tube, they were guided by a magnetic field until they collided. At collision they repelled each other, and then were compressed. The rings heated up and stayed stable for 30 microseconds under compression ( which by plasma standards is a long time). The funding was cut off in 1978 because the concept was too far from the mainstream.
In 1999 John Brandenburg received a grant from NASA to move the experiment from Miami to Lanham MD (near NASA Goddard). He moved it and reassembled it, but never received an money to operate it. It stands gathering dust.
Right now, Paul Koloc is doing something similar in his garage, producing ball lightning ( a stable plasma structure that has been documented since Roman times). His project, Plasmak, has received some sbir funding. For more details on the Plasmak, look here.
From reading the white paper, I do not think the Trisops plasma is the same configuration as in the levitated dipole experiment. I do not have a clear idea of the structure of the Plasmak.
I list the Trisops papers below for anyone who wants to follow up.
Daniel R. Wells, Paul Edward Ziajka, and Jack L. Tunstall. Hydrodynamic confinement of thermonuclear plasmas TRISOPS VIII (plasma liner confinement). Fusion Tech., 9:83, 1986.
Winston H. Bostick and Daniel R. Wells. Azimuthal magnetic field in the conical theta pinch. Phys. Fluids, 6(9):1325, 1963.
"Simultaneous Electron Density and Ion Temperature Measurements of a Moderately Dense Plasma Using Doppler and Stark Broadened He-II Lines" (with others), Applied Optics (Letters) v 17, p1481, 1978.
"High Temperature, High Density Plasma Production by Vortex Ring Compression" (with others), Physical Review Letters, v 41 #3, p166, 1978. "
The Interaction between Two Force Free Plasma Vortices in the TRISOPS III Machine" (with others), Physics of Fluids, v 22, p379, 1979.