Author: Lidia, S.M.
Paper Title Page
TUIYB1 Diagnostics for High Power Accelerator Machine Protection Systems 239
 
  • S.M. Lidia
    FRIB, East Lansing, Michigan, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Modern hadron accelerators create and transport beams that carry MW-scale power or store GJ-scale energy. The Machine Protection Systems (MPS) that guard against both catastrophic failures and long-term performance degradation must mitigate errant beam events on time scales as short as several microseconds. Measurement systems must also cope with detection over many orders of magnitude in beam intensity to adequately measure and respond beam halo loss. Other issues, such as radiated signal cross-talk, also confound and complicate delicate measurements. These requirements place enormous demands on the MPS beam diagnostics and beam loss monitors. We will review the current state of MPS diagnostic systems for this class of accelerator, including SNS, ESS, FRIB, LHC, J-PARC, and SPIRAL-II. Specific designs and key performance results will be presented and discussed.
 
slides icon Slides TUIYB1 [7.425 MB]  
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TUPF16 FRIB Beam Position Monitor Pick-Up Design 355
 
  • O. Yair, J.L. Crisp, G. Kiupel, S.M. Lidia, R.C. Webber
    FRIB, East Lansing, Michigan, USA
 
  Due to the different beam diameters and the inclusion of superconducting cavities, different Beam Position Monitor (BPM) types with welded buttons are to be used in the Facility for Rare Isotope Beams (FRIB). The varying BPM sizes include the following apertures: 40 mm, 50 mm, 100 mm, and 150 mm. The 40 mm BPMs include both warm and cold types where the cold BPMs are located in cryomodules next to SRF cavities. Steel-jacketed SiO2 coaxial cables with sealed SMA connectors have been selected as signal cables in the cryomodule insulating vacuum. These will connect to the BPM assembly at roughly 4 K temperature at one end and to the feedthrough flange in the vacuum vessel wall at 300 K at the other end. The 40 mm and 50 mm BPMs will include 20 mm custom-made buttons. The 100 mm and 150 mm aperture BPM buttons will be larger, anywhere from 30 mm to 40 mm. This paper will specify the mechanical and electrical design challenges and the resolutions associated with FRIB operations in the following areas: varying BPM conditions, changes in apertures, and variants in button sizes.  
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TUPD21 AC Coupling Studies and Circuit Model for Loss Monitor Ring 455
 
  • Z. Liu, J.L. Crisp, S.M. Lidia
    FRIB, East Lansing, Michigan, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
As a follow-up study to the initial design of FRIB Loss Monitor Ring (previously named Halo Monitor Ring [1]), we present recent results of coupling studies between the FRIB CW beam and the Loss Monitor Ring (LMR). While a ~33 kHz low-pass filter was proposed to attenuate high-frequency AC-coupled signals [1,2], the LMR current signal may still contain low frequency signals induced by the un-intercepted beam, for example, by the 50μs beam notch that repeats every 10ms. We use CST Microwave Studio to simulate the AC response of a Gaussian source signal and benchmarked it to analytical model. A circuit model for beam-notch-induced AC signal is deduced and should put a ~33pA (peak) bipolar pulse on the LMR at 100Hz repetition rate. Although its amplitude falls into our tolerable region, we could consider an extended background integration to eliminate this effect.
 
poster icon Poster TUPD21 [1.201 MB]  
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WEPF17 Error Analysis for Pepperpot Emittance Measurements Redux: Correlated Phase Spaces 579
 
  • S.M. Lidia
    FRIB, East Lansing, Michigan, USA
  • K. Murphy
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Recently, Jolly et al. presented an analysis of the rms emittance measurement errors from a first principles approach [1]. Their approach demonstrated the propagation of errors in the single-plane rms emittance determination from several instrument and beam related sources. We have extended the analysis of error propagation and estimation to the fully correlated 4-D phase space emittances obtained from pepperpot measurements. We present the calculation of the variances using a Cholesky decomposition approach. Pepperpot data from recent experiments on the NDCX-II beamline are described, and estimates of the emittances and measurement errors for the 4-D as well as the projected rms emittances in this coupled system are presented.
[1] S. Jolly, et al., “Data Acquisition and Error Analysis for Pepperpot Emittance Measurements”, Proceedings of DIPAC ’09, WEOA03.
 
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