Perez, F.; Alvarez, J.; Bellafont, I.; Bravo, B.; Ocampo, J.; Salom, A.; Solans, P.; Ebert, M.; Fröhlich, N.-O.; Hülsmann, P.; Onken, R.; Anders, W.; Dürr, V.; Löwner, T.; Matveenko, M.; Ries, M.; Shi, L.; Tamashevich, Y.; Tsakanian, A.; De Gersem, ; Müller, W.: Active harmonic EU cavity: Commissioning and operation with beam. Nuclear Instruments & Methods in Physics Research A 1072 (2025), p. 170195/1-15
10.1016/j.nima.2024.170195
Open Accesn Version
Abstract:
ALBA is a 3rd generation synchrotron light source located in Spain, in operation since 2012. In preparation for its upgrade to a 4th generation facility, which requires addressing the significantly reduced Touschek lifetime, ALBA has designed and constructed a higher-order mode (HOM) damped active 3rd harmonic RF cavity. This cavity is designed to longitudinally lengthen the electron bunches, thereby reducing their density and enhancing the beam lifetime. The design is based on the EU HOM-damped cavity currently employed in ALBA’s main radio frequency (RF) system. The cavity prototype was installed in the BESSY II ring under a collaborative agreement between ALBA, HZB, and DESY, institutions that operate at the same main RF frequency, 500 MHz. This paper presents the first commissioning results, including bead-pull measurements, high-power conditioning and initial beam tests in both single and multi-bunch operation modes. The results confirm that the cavity parameters are consistent with the design specifications, the HOMs are effectively mitigated, and the anticipated beam lifetime enhancement is achieved, demonstrating the feasibility of the designed cavity.