TUOCMH  —  Beam Instrumentation and Feedback   (25-May-10   15:00—16:00)

Chair: T. Nakamura, JASRI/SPring-8, Hyogo-ken

Paper Title Page
TUOCMH01 Pulse-to-pulse Beam Modulation and Event-based Beam Feedback Systems at KEKB Linac 1271
 
  • K. Furukawa, T.T. Nakamura, M. Satoh, T. Suwada
    KEK, Ibaraki
 
 

Beam injections to KEKB and Photon Factory are performed with pulse-to-pulse modulation at 50Hz. Three very different beams are switched every 20ms in order to inject those beams into KEKB HER, LER and Photon Factory (PF) simultaneously. Human operators work on one of those three virtual accelerators, which correspond to three-fold accelerator parameters. Beam charges for PF injection and the primary electron for positron generation are 50-times different, and beam energies for PF and HER injection are 3-times different. Thus, the beam stabilities are sensitive to operational parameters, and if any instability in accelerator equipment occurred, beam parameter adjustments for those virtual accelerators have to be performed. In order to cure such a situation, beam energy and orbit feedback systems are installed that can respond to each of virtual accelerators independently.

 

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TUOCMH02 Stabilization and Fine Positioning to the Nanometre Level of the CLIC Main Beam Quadrupoles 1274
 
  • K. Artoos, C.G.R.L. Collette, P. Fernandez Carmona, M. Guinchard, C. Hauviller, S.M. Janssens, A.M. Kuzmin, F. Lackner, R. Leuxe, A. Slaathaug
    CERN, Geneva
 
 

The CLIC main beam quadrupoles need to be stabilized to 1.5 nm integrated R.M.S. displacement at 1 Hz. The choice was made to apply active stabilization with piezoelectric actuators in a rigid support with flexural guides. The advantages of this choice are the robustness against external forces and the possibility to make fast incremental nanometre positioning of the magnet with the same actuators. The study and feasibility demonstration is made in several steps from a single degree of freedom system (s.d.o.f.) with a small mass, a s.d.o.f. with a large mass, leading to the demonstration including the smallest (type 1) and largest (type 4) CLIC main beam quadrupoles. The paper discusses the choices of the position and orientation of the actuators and the tailored rigidities of the flexural hinges in the multi degree of freedom system, and the corresponding MIMO control system. The compatibility with the magnet support and micrometer alignment system is essential. The status of the study and performed tests will be given.

 
TUOCMH03 Initial Experience with the Machine Protection System for LHC 1277
 
  • R. Schmidt, R.W. Assmann, B. Dehning, M. FERRO-LUZZI, B. Goddard, M. Lamont, A.P. Siemko, J.A. Uythoven, J. Wenninger, M. Zerlauth
    CERN, Geneva
 
 

Nominal beam parameters at 7TeV/c will only be reached after some years of operation, with each proton beam having a stored energy of 360MJ. However, a small fraction of this energy is sufficient to damage accelerator equipment or experiments in case of uncontrolled beam loss. The correct functioning of the machine protection systems is vital during the different operational phases already for initial operation. When operating the complex magnet system, with and without beam, safe operation relies on the protection and interlock systems for the superconducting circuits. For safe injection and transfer of beam from SPS to LHC, transfer line parameters are monitored, beam absorbers must be in the correct position and the LHC must be ready to accept beam. At the end of a fill and in case of failures beams must be properly extracted onto the dump blocks, for some failures within less than few hundred microseconds. Safe operation requires many systems: beam dumping system, beam interlocks, beam instrumentation, equipment monitoring, collimators and absorbers, etc. We describe the commissioning of the LHC machine protection system and the experience during the initial operation.

 

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