In‐vacuum undulators in UVSOR electron storage ring

In‐vacuum undulators have been installed in the UVSOR‐BL3U and BL7U. Due to the improvement of the UVSOR, the insertion devices with narrow magnetic gaps such as the in‐vacuum undulators have become available. The undulators have the period length of 36/38mm and the minimum gap of 15mm, which results in wide tunability in VUV and soft X‐ray region. Influence on the stored beam, especially for the resistive wall instability, has been estimated and it has found that the disturbance for the stored beam can be negligible even in the minimum gap height.