Electron Accelerator (IMAGE) DOE/SLAC National Accelerator Laboratory Caption This is an illustration of the electron accelerator of SLAC's future rapid-fire LCLS-II X-ray laser. Very cold, superconducting niobium cavities (not visible) inside a series of underground cryomodules (red tubes) boost the energy of a rapid sequence of electron bunches as they fly through the accelerator. The necessary energy for this process comes from high-power radiofrequency fields (blue) that are generated by klystrons above ground (structures at the top) and transferred to the cryomodules underground. Credit SLAC National Accelerator Laboratory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.