The high-gradient X-band test facility (left-side view) at CERN (Image: Matteo Volpi)

The Xboxes are klystron-based X band test stands located at CERN in Geneva, Switzerland. The test stands are dedicated to the testing and development of high-gradient accelerating structures and high-power rf components.

At present there are three Xboxes: two with each powered by a 50 MW/1.5μs/50 Hz klystron and the third is powered by four 6 MW/5 μs/400 Hz klystrons combined in pairs.

These Xboxes were constructed and are being used to high-power test the main linac accelerating structures and novel rf components for the Compact Linear Collider (CLIC). The test stands are just as useful for developing high gradient and power structures for X-band FELs, Compton/Thomson sources and as potential RF units in linacs.


  • 3 x klystron-based X-band (11.994 GHz) test stands
  • 6 x fully powered and instrumented testing slots
  • Support infrastructure eg: radiation shielding, water cooling, vacuum etc

Support offered

Access to the Xboxes will be granted in two modes: Primary access will be given to accelerating structures and RF components powered by RF directly. Parasitic access will be given to experiments dedicated to projects such as high gradient research and diagnostic developments.


Interested parties are encouraged to contact the Facility Coordinator before beginning the formal application process with brief details of the test campaign proposal. 

Xbox Facility Coordinator: Walter Wuensch