Terahertz
accelerator modules easily fit into two fingers.
Credit:
DESY/Heiner Müller-Elsner
(October 6, 2015) Prototype
demonstrates feasibility of building terahertz accelerators
An interdisciplinary team of researchers has built the first
prototype of a miniature particle accelerator that uses terahertz radiation
instead of radio frequency structures. A single accelerator module is no more
than 1.5 centimetres long and one millimetre thick. The terahertz technology
holds the promise of miniaturising the entire set-up by at least a factor of
100, as the scientists surrounding DESY’s Franz Kärtner from the Center for
Free-Electron Laser Science (CFEL) point out. They are presenting their
prototype, that was set up in Kärtner's lab at the Massachusetts Institute of
Technology (MIT) in the U.S., in the journal Nature Communications. The authors
see numerous applications for terahertz accelerators, in materials science,
medicine and particle physics, as well as in building X-ray lasers. CFEL is a
cooperation between DESY, the University of Hamburg and the Max Planck Society.
In the electromagnetic spectrum, terahertz radiation lies
between infrared radiation and microwaves. Particle accelerators usually rely
on electromagnetic radiation from the radio frequency range; DESY’s particle
accelerator PETRA III, for example, uses a frequency of around 500 megahertz.
The wavelength of the terahertz radiation used in this experiment is around one
thousand times shorter. “The advantage is that everything else can be a
thousand times smaller too,” explains Kärtner, who is also a professor at the
University of Hamburg and at MIT, as well as being a member of the Hamburg
Centre for Ultrafast Imaging (CUI), one of Germany’s Clusters of Excellence.
For their prototype the scientists used a special
microstructured accelerator module, specifically tailored to be used with
terahertz radiation. The physicists fired fast electrons into the miniature
accelerator module using a type of electron gun provided by the group of CFEL
Professor Dwayne Miller, Director at the Max Planck Institute for the Structure
and Dynamics of Matter and also a member of CUI. The electrons were then
further accelerated by the terahertz radiation fed into the module. This first
prototype of a terahertz accelerator was able to increase the energy of the
particles by seven kiloelectronvolts (keV).