Particle accelerator that can fit on a tabletop opens new chapter for science research

Jun 20, 2013
This tabletop set-up accelerated approximately half a billion electrons to 2 gigaelectronvolts over a distance of about 1 inch. It's a feat that previously required a conventional accelerator that stretches more than the length of two football fields. Credit: Courtesy of Rafal Zgadzaj

Physicists at The University of Texas at Austin have built a tabletop particle accelerator that can generate energies and speeds previously reached only by major facilities that are hundreds of meters long and cost hundreds of millions of dollars to build.

"We have accelerated about half a billion electrons to 2 gigaelectronvolts over a distance of about 1 inch," said Mike Downer, professor of physics in the College of Natural Sciences. "Until now that degree of energy and focus has required a conventional accelerator that stretches more than the length of two football fields. It's a downsizing of a factor of approximately 10,000."

The results, which were published this week in Nature Communications, mark a major milestone in the advance toward the day when multi-gigaelectronvolt (GeV) laser plasma accelerators are standard equipment in research laboratories around the world.

Downer said he expects 10 GeV accelerators of a few inches in length to be developed within the next few years, and he believes 20 GeV accelerators of similar size could be developed within a decade.

Downer said that the electrons from the current 2 GeV accelerator can be converted into "hard" as bright as those from large-scale facilities. He believes that with further refinement they could even drive an X-ray , the brightest X-ray source currently available to science.

A tabletop X-ray laser would be transformative for chemists and biologists, who could use the bright X-rays to study the of matter and life with atomic precision, and femtosecond , without traveling to a large national facility.

The interior of the vacuum chamber in which the acceleration occurs. The laser beam arrives from the right. The gas cell, within which the acceleration of electrons occurs, is in the center of the chamber. The actual acceleration occurs over a distance of about an inch. Credit: Neil Fazel

"The X-rays we'll be able to produce are of femtosecond duration, which is the on which molecules vibrate and the fastest take place," said Downer. "They will have the energy and brightness to enable us to see, for example, the of single in a living sample."

To generate the energetic electrons capable of producing these X-rays, Downer and his colleagues employed an acceleration method known as laser-plasma acceleration. It involves firing a brief but intensely powerful laser pulse into a puff of gas.

"To a layman it looks like low technology," said Downer. "All you do is make a little puff of gas with the right density and profile. The laser pulse comes in. It ionizes that gas and makes the plasma, but it also imprints structure in it. It separates electrons from the ion background and creates these enormous internal space-charge fields. Then the charged particles emerge right out of the plasma, get trapped in those fields, which are racing along at nearly the speed of light with that laser pulse, and accelerate in them."

Downer compared it to what would happen if you threw a motorboat into a lake with its engines churning. The boat (the laser) makes a splash, then creates a wave as it moves through the lake at high speed. During that initial splash some droplets (charged particles) break off, get caught up in the wave and accelerate by surfing on it.

"At the other end of the lake they get thrown off into the environment at incredibly high speeds," said Downer. "That's our 2 GeV electron beam."

Former UT Austin physicist Toshiki Tajima and the late UCLA physicist John Dawson conceived the idea of acceleration in the late 1970s. Scientists have been experimenting with this concept since the early 1990s, but they've been limited by the power of their lasers. As a result the field had been stuck at a maximum energy of about 1 GeV for years.

Downer and his colleagues were able to use the Texas Petawatt Laser, one of the most powerful lasers in the world, to push past this barrier. In particular the petawatt laser enabled them to use gases that are much less dense than those used in previous experiments.

"At a lower density, that laser pulse can travel faster through the gas," said Downer. "But with the earlier generations of lasers, when the density got too low, there wasn't enough of a splash to inject into the accelerator, so you got nothing out. This is where the petawatt laser comes in. When it enters low density plasma, it can make a bigger splash."

Downer said that now that he and his team have demonstrated the workability of the 2 GeV accelerator, it should be only a matter of time until 10 GeV accelerators are built. That threshold is significant because 10 GeV devices would be able to do the X-ray analyses that biologists and chemists want.

"I don't think a major breakthrough is required to get there," he said. "If we can just keep the funding in place for the next few years, all of this is going to happen. Companies are now selling petawatt lasers commercially, and as we get better at doing this, companies will come into being to make 10 GeV accelerator modules. Then the end users, the chemists and biologists, will come in, and that will lead to more innovations and discoveries."

Explore further: Novel approach to magnetic measurements atom-by-atom

More information: www.nature.com/ncomms/2013/130… /abs/ncomms2988.html

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User comments : 12

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VendicarE
3.6 / 5 (10) Jun 20, 2013
Perspective

SLAC was completed in December 1956, and reached a beam energy of 18.4 GeV in June of 1966

7 TeV for the LHC - Current upgrades should bring that to 14 TEV per nucleon
Shabs42
4.6 / 5 (9) Jun 20, 2013
Perspective

SLAC was completed in December 1956, and reached a beam energy of 18.4 GeV in June of 1966

7 TeV for the LHC - Current upgrades should bring that to 14 TEV per nucleon


Good to know. But if the smallest previous accelerator really required two acres, and this one requires a spare desk, this still seems fairly monumental.
DonGateley
2.7 / 5 (6) Jun 21, 2013
Can it be scaled up for higher energies or is the size intrinsically limited to small?
NikFromNYC
1.3 / 5 (14) Jun 21, 2013
Funding for these life saving basic science breakthroughs has now suffered long enough in competition with trillion tax dollar scams like Enron and Solyndra all cheerleaded by Phys.org and both Science and Nature journals, disgustingly, all to defend instead of condemn the most obvious and brazen scientific fraud in human history. Shame on you all for the rest of time who failed this worldwide IQ test for yours are the faces of evil.
brt
3.9 / 5 (8) Jun 21, 2013
Hey Nicky, go get me-a some meatballs and keep ya pie hole shut; kapeesh?
VendicarE
3.8 / 5 (4) Jun 21, 2013
NikkieTard has a point.

Allowing Chinese manufacturers to dump their solar cell products onto the American Market did great harm to Solyndra and caused it to go bankrupt.

But this is what free market Republicans want.

They wan't America to be slaves to Chinese economic production.

With Solyndra gone, America now has no presence in the PV manufacturing industry.

Republicans sold America down the river to slavery.
gurloc
5 / 5 (2) Jun 21, 2013
Wakefield acceleration is very promising technology but calling this a "tabletop" accelerator is pure fantasy. Its driven by the most powerful (in terms of instantaneous power) laser in the world which takes up about a 1500 square foot (139 square meter) facility when you include its power supplies.

Its the driving lasers that are the limiting factor on the size of these accelerators.
ForFreeMinds
1 / 5 (5) Jun 21, 2013
Funding for these life saving basic science breakthroughs has now suffered long enough in competition with trillion tax dollar scams like Enron and Solyndra all cheerleaded by Phys.org and both Science and Nature journals, disgustingly, all to defend instead of condemn the most obvious and brazen scientific fraud in human history. Shame on you all for the rest of time who failed this worldwide IQ test for yours are the faces of evil.


On one hand, you object to government funding for Solynda and the like, and on the other hand you object to the lack of government funding for "life saving basic science."

Perhaps, you should encourage private investment in "life saving basic science" rater than taking money, by government force, to fund it. Where those who invest in it, reap the rewards, vs. the government model where taxpayers bear the costs, and don't get the rewards because the government funded scientist does. Isn't it immoral to take from others?
Jimee
5 / 5 (2) Jun 22, 2013
Free minds know that when the government spends money for basic research the benefit comes back ten-fold because we all get to share in the benefits from discovery (unless we turn it over to private enterprise and then we pay ten-fold to help some incompetent CEO buy an island somewhere).
RealScience
5 / 5 (1) Jun 22, 2013
...Allowing Chinese manufacturers to dump their solar cell products onto the American Market did great harm to Solyndra and caused it to go bankrupt.
... With Solyndra gone, America now has no presence in the PV manufacturing industry.

@Vendicar -
Solyndra stood no chance regardless of China - a cylinder has pi times the area of a plane, and their deposition cost per area was higher inside a cylinder than on a plane (I asked them way back in 2007).
And Solyndra was only a few percent of U.S. solar capacity - U.S.-based Sunpower and First Solar are many times the size, and still some of the world's biggest solar manufacturers (although most production is overseas).

@Nick - Don't exaggerate -Solyndra was less than 0.1% of a 'trillion dollar tax scam'.
Macrocompassion
1 / 5 (1) Jun 24, 2013
Would it be possible to place a number of these accelerators in series so that at the length "of a football field" the power would exceed anything else remotely conceivable!
GSwift7
3.7 / 5 (3) Jun 24, 2013
Would it be possible to place a number of these accelerators in series so that at the length "of a football field" the power would exceed anything else remotely conceivable!


Not in this form.

The output is actually only a fraction of the input. There's a lot of waste energy here. As with the analogy in the original story, most of the energy goes into making the waves in the lake. Only a relatively small number of electrons end up getting splashed out of the lake. The rest of the energy from the blast is wasted.

This is true of the huge standard accelerators as well. You need way more input energy to get them going than you actually end up shooting out the other end.

Gurloc is correct. That 1500 square feet is only the laser itself. There is also a target room of equal size, and a pulsed power supply room of about half that size, plus clean rooms and air locks and ventilation systems rooms and such. The whole thing is the size of a house. So, yeah, tabletop in a house.