October 09, 2015

Wakefield accelerators can make accelerators vastly more powerful and compact and could power Xray free electron lasers

CERN approved a boost in funding for a planned experiment called the Advanced Wakefield Experiment, or AWAKE. Due to switch on next year, AWAKE will accelerate particles by ‘surfing’ them on waves of electric charge created in a plasma, or ionized gas. It is a method that could allow future accelerators to probe matter and the forces of nature at ever-higher energies, without the usual accompanying increase in the instruments’ size and therefore cost.

Plasma wakefield accelerators send a pulse of charged particles or laser light through a plasma, which sets electrons and positively charged ions oscillating in its wake. The resulting regions of alternating negative and positive charge form waves that accelerate further charged particles. Injected at just the right time, these particles effectively surf the waves (see ‘Wakefield acceleration’). Crucially, as the electric fields are much stronger than those in a conventional collider, the acceleration can be as much as 1,000 times greater over the same distance.

Estimates indicate a wakefield machine just a few kilometres long could produce electrons with 6 times the energy of those that would be produced by the next planned conventional accelerator, the 31-kilometre-long Inter-national Linear Collider.

Wakefield-accelerated electrons could drive X-ray free-electron lasers, which probe matter using powerful bursts of light that are short enough to capture the motions of molecules. These are currently kilometres long — but using wakefield technology might allow them to fit into labs or hospital basements.

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