A new home for the generators of the Multi-Turn Extraction (MTE) kickers

By M. Fraser (SY-ABT), L. Ducimetiere (SY-ABT), Vasco Namora (SY-ABT)

The Multi-Turn Extraction kicker system has been in development since 2008 for the proton beam extraction from PS towards the SPS, via TT2, entering operation in 2015 to produce fixed target beams for the North Area. The circulating beam is first prepared for extraction and split in two by pushing its tune through a ¼ integer resonance in the presence of strong non-linear sextupolar and octupolar fields. The “magnetic” splitting creates a second beam, which populates regions of stability in phase space at large amplitude and is wrapped around the core with a periodicity of four times the beam core remaining on-axis, i.e. the second beam is continuous, connected to itself over four turns of the PS and observed as four distinct beamlets. Splitting the beam in this way has significantly reduced the beam loss during extraction in comparison to shaving and cutting the beam directly on the thin blade of an electrostatic septum. Once the beam is split, fast pulsed kicker magnets, located in straight sections (SS) 13 and 21 (KFA13 and KFA21), create a closed bump to extract the second beam in the first four turns. Once the beamlets making up the second beam are extracted, the beam core is extracted on the fifth turn. The beam core needs to be moved out by more than twice the distance of the other four beamlets that were located at large amplitude from the core. Two additional kickers located in SS4 (KFA4) and SS9 (KFA9) are used to kick out the core beam in the fifth turn, in conjunction with the existing fast extraction kicker KFA71-79 system. Two existing fast dipoles (DFAs) in the TT2 transfer line correct the trajectory of the beamlets to reduce the beam emittance in the SPS.

To free up space for the new building, two barracks were demolished (B.6573 and B.149). The new B.369 is composed of a main hall of approximately 235m² and a technical room of 30m². The main hall will host the three Pulse Forming Network (PFN) for the KFA13 and KFA21, the 2 generators for the KFA4 and the controls racks.

Figure 5 – 3D model of building interior

After the conclusion of the Civil Engineering works in April 2024, the installation of general services (EN-CV, EN-EL, EN-HE, EN-AA, IT-CS) are foreseen to be concluded during the first quarter of 2025. The equipment displacement and the re-routing of High-Voltage cables, from the old location to the new building, will be initiate once LS3 starts.