DESY scientists have created a miniature particle accelerator for electrons that can perform four different functions at the push of a button. The experimental device is driven by a terahertz radiation source and can accelerate, compress, focus and analyse electron bunches in a beam. Its active structures measure just a few millimetres across. The developers from the Center for Free-Electron Laser Science (CFEL) present their segmented terahertz electron accelerator and manipulator (STEAM) in the journal Nature Photonics. terahertz radiation is located between microwaves and the infrared in the electromagnetic spectrum.