Author: Zerlauth, M.
Paper Title Page
MOPPC004 Experiments on the Margin of Beam Induced Quenches for LHC Superconducting Quadrupole Magnet in the LHC 124
 
  • C. Bracco, W. Bartmann, M. Bednarek, B. Goddard, E.B. Holzer, A. Nordt, M. Sapinski, R. Schmidt, M. Solfaroli Camillocci, M. Zerlauth, E.N. del Busto
    CERN, Geneva, Switzerland
 
  Protection of LHC equipment relies on a complex system of collimators to capture injected or circulating beam in case of LHC injection kicker magnet failures. However, for specific failures of the injection kicker, the beam can graze the injection protection collimators and induce quenches of downstream superconducting magnets. This occurred twice during 2011 operation and can also not be excluded during further operation. Tests were performed during Machine Development periods of the LHC to assess the quench margin of the quadrupole located just downstream of the last injection protection collimator in point 8. In addition to the existing Quench Protection System, a special monitoring instrumentation was installed at this magnet to detect any resistance increase below the quench limit. The correlation between the magnet and Beam Loss Monitor signals was analysed for different beam intensities and magnet current. The results of the experiments are presented in this paper.  
 
THPPP009 Automated Execution and Tracking of the LHC Commissioning Tests 3743
 
  • K. Fuchsberger, V. Baggiolini, M. Galetzka, R. Gorbonosov, M. Pojer, M. Solfaroli Camillocci, M. Zerlauth
    CERN, Geneva, Switzerland
 
  To ensure the correct operation and prevent system failures, which can lead to equipment damage in the worst case, all critical systems in the Large Hadron Collider (LHC), have to be tested thoroughly during dedicated commissioning phases after each intervention. In view of the around 7,000 individual tests to be performed each year after a Christmas stop, a lot of effort was already put into the automation of these tests at the beginning of LHC hardware commissioning in 2005, to assure the dependable execution and analysis of these tests. To further increase the productivity during the commissioning campaigns and to enforce amore consistent workflow, the development of a dedicated testing framework was launched. This new framework is designed to schedule and track the automated tests for all systems of the LHC and will also be extendable, e.g., to beam commissioning tests. This is achieved by re-using different, already existing execution frameworks. In this paper, we outline the motivation for this new framework and the related improvements in the commissioning process. Further, we sketch its design and present first experience from the re-commissioning campaign in early 2012.  
 
THPPR039 Controlled Transverse Blow-Up of High-energy Proton Beams for Aperture Measurements and Loss Maps 4059
 
  • W. Höfle, R.W. Assmann, S. Redaelli, R. Schmidt, D. Valuch, D. Wollmann, M. Zerlauth
    CERN, Geneva, Switzerland
 
  A technique was developed to blow-up transversely in a controlled way high energy proton beams in the LHC. The technique is based on band limited white noise excitation that is injected into the transverse damper feedback loop. The injected signal can be gated to selectively blow-up individual trains of bunches. The speed of transverse blow-up can be precisely controlled. This opens the possibility to perform safely and efficiently aperture measurements and loss maps with high intensity bunch trains well above stored beam energies that are considered to be safe. In particular, lengthy procedures for measurements at top energy, otherwise requiring multiple fills of individual bunches, can be avoided. In this paper, the method is presented and results from beam measurements are discussed and compared with alternative blow-up methods.  
 
THPPR040 First Operational Experience with the LHC Machine Protection System when Operating with Beam Energies Beyond the 100 MJ Range 4062
 
  • M. Zerlauth, R.W. Assmann, B. Dehning, M. Ferro-Luzzi, B. Goddard, M. Lamont, R. Schmidt, A.P. Siemko, J.A. Uythoven, J. Wenninger
    CERN, Geneva, Switzerland
 
  The LHC made a remarkable progress in luminosity production during 2011 operation. This was made possible by a progressive increase of beam intensities by more than 5 orders of magnitude, reaching stored beam energies beyond 100MJ at the end of the year. The correct functioning of the machine protection systems was vital during initial operation and even more when approaching nominal beam parameters, where an uncontrolled loss of a small fraction of the beam is already sufficient to damage accelerator equipment or the large experimental detectors The machine protection system depends on the interplay of many different elements: beam dumping system, beam interlocks, beam instrumentation, equipment monitoring, collimators and absorbers, etc. The strategy applied during 2011 to allow for an efficient but yet safe increase of the beam intensities is presented along with the associated risks and drawbacks of a too aggressive approach. The experience gained with the key systems will be discussed along with possibilities to further enhance machine availability whilst maintaining the current level of safety.