Author: Longhi, E.C.
Paper Title Page
MOPRO101 Transparent Re-alignment of the Diamond Storage Ring 325
 
  • M. Apollonio, R. Bartolini, W.J. Hoffman, E.C. Longhi, A.J. Rose, A. Thomson
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
 
  72 out of the 74 girders on which the Diamond Storage Ring magnets are mounted, can in principle be moved along 5 degrees of freedom (sway, heave, yaw,pitch, roll) potentially allowing a thorough re-alignment of the machine. Previously conducted tests improved our knowledge of the system both in terms of simulations and comprehension of the control system we rely upon. In this report we present the results of more detailed tests which now give us full confidence in our ability to predict the results of any given set of girder moves. We also discuss possible ways of increasing the speed of the procedure, and a strategy to mitigate the impact of girder moves involving nearby beam lines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO101  
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TUPRI081 Feed-forward and Feedback Schemes applied to the Diamond Light Source Storage Ring 1757
 
  • M.T. Heron, M.G. Abbott, M.J. Furseman, D.G. Hickin, E.C. Longhi, I.P.S. Martin, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh
    DLS, Oxfordshire, United Kingdom
 
  Since initial operation for users in Jan 2007, Diamond Light Source has developed to support a suite of 22 experimental stations. These stations have resulted in the installation of 24 undulators and two superconducting wigglers in the storage ring. To preserve optics, tune and coupling with the operation of these devices has necessitated the implementation of a number of feed-forward and feedback schemes. The implementation and operation of these correction schemes will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI081  
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TUPRI082 Active Optics Stabilisation Measures at the Diamond Storage Ring 1760
 
  • I.P.S. Martin, R. Bartolini, R.T. Fielder, M.J. Furseman, E.C. Longhi, G. Rehm, W.A.H. Rogers, A.J. Rose, B. Singh
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
 
  The Diamond storage ring is currently operated with 26 insertion devices (IDs), including 14 in-vacuum IDs, 7 APPLE-II type helical undulators and 2 superconducting wigglers. Differences in the design, construction and operation of these devices, combined with different Twiss parameters at the source point, mean each has a different impact on tune stability and beta-beat. In turn, these parameters affect the on and off-momentum dynamic aperture and ultimately impact on the injection efficiency and lifetime. Another source of optics variation arises from the coherent tune shift with current, which when injecting from zero current causes the tune to span the available good-tune region. In this paper we discuss the difficulties of operating the Diamond storage ring in top-up mode with these effects, and present the various measures taken to stabilise the storage ring optics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI082  
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WEPRO047 A New Cooling System for Cryocooled Permanent Magnet Undulators at Diamond Light Source 2047
 
  • E.C. Longhi, A.G. Miller, E.C.M. Rial, A.J. Rose, J.C. Schouten, C.W. Thompson, A. Thomson, J.H. Williams
    DLS, Oxfordshire, United Kingdom
  • C. Monroe
    Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom
 
  Cryocooled permanent magnet undulators (CPMUs) using NdFeB magnets around 150K were first proposed by Hara*. These are cooled by using either GM cryocoolers or circulating sub-cooled liquid nitrogen. Due to the heat load from radiation and wakefield heating from the electron beam, temperature gradients can develop along the length of the magnet girders which could be as large as several degrees for the Diamond Light Source (DLS) storage ring operating parameters. Some grades of the magnetic material (NdxPr1-x)2Fe14B have remanence curves versus temperature which increase significantly for temperatures below 150K with peaks below 80K**. This means that the operating temperature of a CPMU using this material can be close to the boiling point of liquid nitrogen. The proposed cooling system for the new DLS CPMU is based on a thermosiphon allowing nitrogen to boil inside the cooling channels without a circulating pump. This has the advantage of absorbing large amounts (>250W) of heat with very small temperature gradients. We report here the results of a prototype magnet beam cooled with a thermosiphon producing a temperature gradient of less than 0.05K along a 2m beam at ~77K.
* T. Hara et al., Phys Rev Spec Top. Accelerator & Beam, Vol 7, 2004.
** J. Bahrdt et al., AIP Conf. Proc., SRI 2009, Melbourne Australia, vol. 1234, pp. 499-502, 2010.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO047  
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WEPRI095 Modelling of a Short-period Superconducting Undulator 2716
 
  • B.J.A. Shepherd, J.A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • V. Bayliss, T.W. Bradshaw
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • E.C. Longhi
    DLS, Oxfordshire, United Kingdom
 
  STFC, in collaboration with Diamond Light Source, are designing and building a 15.5 mm period, 1.26 T superconducting undulator. This paper describes the modelling of the undulator, using Radia and Opera. Extensive numerical modelling has been carried out to simulate the effect of manufacturing tolerances on the quality of the magnetic field, in order to meet the demanding 3° rms phase error specification.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI095  
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