By Sebastian Anthony on November 6, 2014 at 3:02 pm
“Go big or go home” might be the unofficial motto of the United States — but in the case of the world’s newest and most advanced particle accelerator, that’s certainly not the case. The new plasma wakefield accelerator, constructed at the SLAC National Accelerator Laboratory in California, is just 12 inches long — or about 90,000 times smaller than CERN’s 17-mile-long Large Hadron Collider in Switzerland.
As you probably know, particle accelerators are usually very large. It’s not that we want to spend billions of dollars boring out a 17-mile tunnel deep underground (or even longer, in the case of some new accelerators that are being considered at the moment). It’s not like we choose to spend billions more creating a vacuum tube in that tunnel, wrapping it in superconducting electromagnets, and cryogenically freezing the whole thing. It’s just that, until now, that was the only way we knew how to reliably accelerate protons and electrons to close to the speed of light.
According to SLAC, there’s another method of particle acceleration that’s much more efficient, and can thus be used to build massive accelerators that are orders of magnitude more powerful — or alternatively, much smaller, lab-sized accelerators. The technology is called plasma wakefield acceleration — and, despite how awesomely complex it sounds, it’s actually fairly self-explanatory.
Basically, instead of a big vacuum tube, you have a container filled with plasma — usually a super-heated, very diluted gas (such as hydrogen). Then, y pulsing a laser, you can create a bunch of ionized electrons that travel through the plasma — and then you pulse the laser again to produce another bunch, which gathers energy from the wake of the first bunch… and so on, until you have a powerful particle accelerator. [Research paper: doi:10.1038/nature13882]
Plasma wakefield accelerator diagram [Image credit]
For now, SLAC’s plasma wakefield accelerator is fairly useless as far as actual particle physics research goes — rather, it’s just just one of a very long line of lab-sized prototypes that need to be built so that we can fully understand how plasma wakefields work. As you can probably appreciate, decades of research went into electromagnetic acceleration before CERN even thought about building the LHC — and likewise, we probably won’t see a useful plasma wakefield accelerator for years, or maybe even decades.
In the long run, though, plasma wakefields could allow for cheap, lab-sized accelerators that massively increase the global scientific community’s throughput of particle physics research. Or alternatively, we could spend billions of dollars and build a giant plasma wakefield accelerator that (probably) reveals the universe’s deepest, darkest secrets. That’s the great thing about accelerators: Until you actually get up to speed and start smashing subatomic particles together, you have no idea what you might learn.
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