Small and Powerful Tabletop Particle Accelerator Created by Texas Physicists

Physicists at the University of Texas at Austin have made a breakthrough when it comes to particle accelerators. They've built a tabletop particle accelerator that can generate energies and speeds previously reached only by major facilities that are hundreds of feet long and cost hundreds of millions of dollars to build. This "portable" accelerator is a huge step into making the technology more affordable and usable in research facilities and universities across the nation.

The current 2 gigaelectronvolt (GeV) accelerator can actually be converted into "hard" X-rays as bright as those from large-scale facilities. With further refinement, it may be even possible to drive an X-ray free electron laser, the brightest X-ray source currently available to science.

"We have accelerated about half a billion electrons to two gigaelectronvolts over a distance of about one inch," said Mike Downer, professor of physics in the College of Natural Sciences, in a news release. "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."

In order to actually generate the energetic electrons capable of producing these X-rays, the researchers used an acceleration method known as laser-plasma acceleration. This involves firing a brief, but powerful, laser pulse into a puff of gas. The laser ionizes the gas and makes plasma, but also imprints structure in it. It separates electrons from the ion background and creates enormous internal space-charge fields. Then the charged particles emerge from the plasma, are trapped in these fields and accelerate in them.

What makes this 2 GeV accelerator so special is that researchers have been stuck at a maximum energy of 1 GeV for years. In order to overcome this issue, the researchers employed the Texas Petawatt Laser, one of the most powerful lasers in the world. More specifically, the laser allowed the scientists 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 electrons 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."

The researchers were successfully able to demonstrate the workability of the 2 GeV accelerator. Now, they're looking forward to the next step. They hope that they'll be able to construct 10 GeV accelerators, which would be able to do the X-ray analyses that scientists want.

The findings are published in the journal Nature communications.