Suppression and enhancement of coherent synchrotron radiation in the presence of conducting boundaries

The suppression effect of coherent synchrotron radiation due to conducting boundaries has been studied using the Tohoku University 300‐MeV electron linac. It has been experimentally observed that emission of coherent synchrotron radiation is not only suppressed but also enhanced with nearby metallic plates. The variation of the relative intensity of coherent synchrotron radiation with the gap between the metallic plates is well explained by the theory of Nodvick and Saxon. The emission of coherent synchrotron radiation in the long‐wavelength region is suppressed more than predicted by the theory, which indicates that there may be other effects suppressing the emission.