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Scientists build 'Poor Man's Free Electron Laser'


December 23, 2010

Thijs van Oudheusden with his "poor man's X-FEL" (Photo: Bart van Overbeeke)

Thijs van Oudheusden with his "poor man's X-FEL" (Photo: Bart van Overbeeke)

If you want to obtain moving images of high-speed molecular processes at an atomic scale, one of the best facilities in the world is the X-ray Free Electron Laser (X-FEL) at Stanford University. Should you wish to use it, however, you’ll have get on a waiting list, then bring your materials to its California home once it’s your turn. If you’re thinking of building your own, you’d better start saving now – Stanford’s laser reportedly cost several hundred million dollars to build, and the cost of a new European X-FEL has been set at one billion euro (US$1.3 billion). Researchers from the Netherlands’ Eindhoven University of Technology (TU/e), however, have recently announced the development of a tabletop “poor man’s X-FEL.” It performs some of the same key functions as the big laser, but costs under half a million euro (US$656,006).

Instead of visible light, free electron lasers emit ultra-short X-ray pulses, to create a series of extremely short exposures. These pulses are generated by speeding electrons through an accelerator that’s at least one kilometer (0.6 miles) in length, then converting them to X-rays. Not only is such a facility extremely expensive to create, but it also consumes a lot of power, and requires a team to operate.

The big difference with the poor man’s X-FEL is the fact that it doesn’t convert the electrons to X-rays. “Why convert electrons into X-rays if you can use the electrons themselves?” asked the system’s creator, doctoral candidate Thijs van Oudheusden. “As well as that, you only need to give the electrons a low energy, so you can accelerate them in just a centimeter. That’s why the whole system fits on a tabletop.” 

Electrons repel one another when placed in a bunch, causing that bunch to expand to the point of making the TU/e system too slow. To get around that problem, van Oudheusden’s advisor Dr. Jom Luiten created electron bunches that were of such a shape that they could be controlled and focused by electrical fields. This allowed the bunches to be of a type and length that they could be used to create moving video footage of microscopic molecular processes.

It is estimated the the poor man’s X-FEL could be used for around half to three-quarters of the research currently conducted on traditional X-FELs. There are now plans to commercialize the technology through TU/e spin-off company AccTec BV.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth
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