Z-Machine at Sandia Labs Aims for More Power

Vexar writes "Memorable for its Back-to-the-Future room of electric arcs in 1998, Sandia Labs' Z-Machine is getting $61.7 Million in new funding. In addition to more physics textbook-worthy photos, the scientists at this lab intend to hit the all-important, fusion-ready 2.0 million degrees C."

Comments

Weapons research

[RobertB-DC]

Amazing research, though when they talk about reaching fusion temperatures, it looks to me like they're talking about modeling the fusion reaction of a Hydrogen Bomb, not creating a safe, clean power source. To wit:

Z's advance in power is expected to make a major contribution to the Department of Energy's (DOE) science-based approach to stockpile stewardship, which must use giant computing and laboratory experiments to provide the basis to sustain the nation's nuclear stockpile without above- or below-ground tests.

There were two milestones in temperature: the first for weapons physics configurations was 100 eV (1.2 million degrees). The achieved value was 140 eV (1.6 million degrees). The second temperature milestone in a configuration suitable for target compression experiments was 150 eV (1.7 million degrees). Sandia has achieved 140 eV (1.6 million degrees).

X-1 will provide laboratory data on the physics of nuclear weapons implosions and their effects. The data are necessary to validate the increasingly sophisticated computational models of weapon performance, without underground testing.

He points out that Sandia's teraflops computer, capable of a trillion operations a second, and the other advanced computers being developed for DOE's science-based stockpile stewardship program "will be needed to reach our goals. We will succeed with creating high-yield fusion when we can fully harness the power of both our teraflops and terawatts."

It's still debatable whether the "stewardship" of nuclear weapons is really a Good Thing. It means that you're keeping the frickin' things around and functional, instead of simply dismantling them. Do we really need a stockpile of Weapons of Mass Destruction? That said, this research looks to be amazingly cool, and I'd hope it would lead to "consumer" fusion in the same way that nuclear bomb research led to nuclear fission reactors.

Interesting that the scientists are still being allowed to talk about their research... unlike their counterparts doing antimatter research.

Re:Weapons research

[j_cavera]

Tens of megajoules of energy applied to a small target for a few nanoseconds. How can this not be fun!? That said, this is not being looked at for practical purposes right now. The point is for fundamental research into an ill-understood region of plasma physics. At this point, the best outcome of their experiments would be to identify the plasma instabilities in this regime and correct for them. Future spin-offs would be in terrestrial energy production and plasma or fusion space propulsion, both of which don't scale well outside of the lab due to (you guessed it) instabilities in the plasma. Oh, yeah. It also resembles a nuclear weapon detonation, kinda. Of course advances in plasma physics go to weapons research and vice versa.

Re:Weapons research

[merlin_jim]

Amazing research, though when they talk about reaching fusion temperatures, it looks to me like they're talking about modeling the fusion reaction of a Hydrogen Bomb, not creating a safe, clean power source.

They recognize as a side effect that they are refining plasma physics models and if you look at their experimental logs (troll around on their site a little and you'll see it), you can find experiments being run that are definitely designed to measure the physics of fusion temperature plasmas, with the stated goal of developing control algorithms for tokamaks.

ok now onto the <rant type=biased>

Tokamaks are fundamentally stupid ideas for two reasons. First off, ALL of the designs that are currently being discussed for funding and prototyping suffer transmutation of structural members. It takes a huge energy cost to get a tokamak started, and the designs that're being discussed undergo transmutation due to neutron and proton bombardment. Structural elements that are vital to the safe operating of the reactor will have to be replaced on a regular (6-18mo) basis to prevent a failure mode.

Which brings us to the second reason. You've got a big ring of extremely high-temperature, high-pressure, high-charge fluid material. Due to that charge, that ring is going to be fundamentally unstable. They're talking about controlling that with dynamic feedback electromagnet rings. The problem being that there's a stability jumping problem. And at the energies involved, quantum effects are very nearly on the scale necessary to jump to different stability modes.

Of course all the alternative stability modes result in the plasma stream contacting the reactor wall. Which will result in burn-through. I don't think the behaviour will be bomb-like (unlike a fission reactor, this failure mode is self-quenching), but it's still a catastrophic failure mode and probably will spread radioactive material all over the place. Think chernobyl-style quarantine without the explosion at the beginning.

Combine the two and I think you'll see why I say that a tokamak is a fundamentally stupid idea.
</rant>

Re:Weapons research

[deglr6328]

Jim you're on my slashdot friends list but I'm afraid I must completely disagree with you here. :o)

Tokamaks have problems, yes, but I don't think it's known weather these problems will prohibit their utilization as a fusion power source. For instance if a plasma instability forms in a tokamak while running (happens all the time) and the plasma bumps the divertor or the inside of the chamber it most certainly will not be bomb like and won't "result in burn-through" either. The introduction of (relatively) high Z material (carbon from graphite, iron, or aluminum from chamber walls) will result in INSTANT plasma quenching via the plasma radiating a huge portion of its energy through bremsstrahlung. This causes burn marks and other dust problems in the chamber but can't cause burn through of the thick metal vacuum chamber walls. And if there is a catastrophic breach of the plasma vessel it definitely, DEFINITELY will never be anything even close to a "chernobyl-style quarantine". At most, a couple grams of radioactive tritium (3-hydrogen) are contained in the vessel while "burning", even considering a total failure of containment and burnoff (a small explosion, to be sure) of all the hydrogen to form tritiated water (forming molecules of TOH or TOT rather than HOH) the amount of radioisotope release will be in the tens of KiloCurie range. Tritium is the least dangerous radioactive isotope that exists (I work with it daily), with a ~12 year half life and an average beta particle emission energy in the 5KeV range to a max of 18KeV, barely enough to go a few mm in air before being blocked; and owing to the fact that both hydrogen and water are volatile, it will be VERY quickly be evenly dispersed and diluted in the atmosphere and oceans. I doubt anyone working in the plant would die if assuming sufficient containment were used.

Tokamaks do have the issue of neutron activation to worry about among other things but I think these are at least workable problems. Remember, Tokamaks have held the world record for plasma temperatures and containment times for a very long time.

But ultimately you may be right, the Tokamak may prove unworkable from an economic energy generation standpoint. I think the project at MIT using a levatated dipole for more "natural" quiescent plasma containment looks very interesting (promising? maybe), for instance.

All of this said, BIG congratulations to the Sandia Z-machine people!! They deserve it. The energies and powers (~300 Twatts!) they've achieved are barely a factor away from those expected on the finished National Ignition Facility. The lab where I work supplied the parts for the laser called the Z-Beamlet they use to "backlight" targets so they can be viewed in X-rays as they're being imploded on Z. Looks like they've put it to good use. As new technologies like these (and others achieving PETAwatt powers) come online they will open completely new doors to fusion research This is an exciting time for very high energy experimental plasma physics.

Don't you think that's overkill?

[Dimwit]

I mean, c'mon, seriously, how much power does it really take to run Zork?

Not Infocom related...

[namekuseijin]

i thought it was about their z-machine for text adventure games from the eighties... :)

Oh goody...

[Ann Elk]

A new unit of measure:

Highly synchronized laser-triggered switches allow the stored energy to be discharged simultaneously through the 36 cables, each as big around as a horse and 30 feet long, arranged like spokes of a wheel and insulated by water.

Are we talking Shetland, Clydesdale, or Percheron?

Re:Oh goody...

[RobertB-DC]

A new unit of measure:
"through the 36 cables, each as big around as a horse and 30 feet long"
Are we talking Shetland, Clydesdale, or Percheron?

I have horses on my land, so measuring diameter in terms of horse-circumference actually seems pretty cool. But then, I have Appaloosas... by contrast, a Throughbred is deep in the front but narrow in the back, and would be better suited to measuring conical volume.

Of course, they used more traditional measurements as well:

Power is measured in house-minutes: Strangely, the power used in each trial is only enough to provide electricity to about 100 houses for two minutes.

I think one "spool of thread" is about equivalient to 1.5 milliHorses: Yet particles imploded in the accelerator's tiny targets -- about the size of a spool of thread

And of course, the standard measurement of distance, the LA/NY: -- reach velocities that would fly a plane from Los Angeles to New York in a second.