Superconducting undulator device

An undulator device comprising:

• at least a first superconducting coil structure;
• and
• at least a second superconducting coil structure positioned opposite the first superconducting coil structure;
• wherein the first and second superconducting coil structures are separated by a gap dedicated to the passage of an electron beam having an electron beam trajectory around a beam axis, the beam axis being in a first direction;
• wherein each superconducting coil structure includes:
• a plurality of grooves through the thickness of said superconducting coil structure to separate it into a plurality of elementary coils;
• the grooves being configured in such a way that an electrical current flowing in the superconducting coil structure between the grooves can flow alternately in two different orientations, for example into substantially two opposite orientations, in said superconducting coil structure;
• the grooves reaching at least one side of the superconducting coil structure;
• and
• a plurality of supplementary grooves through the thickness of said superconducting coil structure, the supplementary grooves being positioned at a distance from the grooves, and being entirely contained inside the superconducting coil structure without reaching a side of the superconducting coil structure.