European Spallation Source, ESS

The accelerator of the European Spallation Source (ESS) in Lund includes a section with 26 superconducting double spoke resonators (also called spoke cavities) that accelerate a proton beam from 90 to 216 MeV. This type of superconducting cavities has never before been used in an accelerator. FREIA assists in the development and testing of these cavities to prepare for the construction and operation of ESS.

double spoke cavity
A double spoke cavity, exploded view
inside of a double spoke cavity
The inside of a double spoke cavity with the
two crossing spokes

FREIA has a dedicated test facility for studying the performance of superconducting accelerating cavities. It is used to measure, at low and high power, the performance of double spoke cavities for the ESS linear accelerator (linac) and decide on their installation. Complete cryomodule systems consisting of a cryostat with two superconducting cavities, frequency tuning control and radio-frequency high power amplifiers and controllers will be evaluated to measure the system performance. The project focuses on the development of high power radio-frequency generation and control technology, and development of superconducting spoke cavities and their application in particle accelerators.

Assembled spoke cavity
Assembled spoke cavity