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Christou, C.

Paper Title Page
MOPC033 Sapphire - A High Peak Brightness X-Ray Source as a Possible Option for a Next Generation UK Light Source 142
 
  • R. P. Walker, C. Christou, J. H. Han, J. Kay
    Diamond, Oxfordshire
  • R. Bartolini
    JAI, Oxford
  
  In the UK there is increasing interest in a radiation source which would provide ultra-fast (from 100 fs down to a few fs and potentially below) multi-keV X-ray pulses with high peak brightness, in order to study rapid dynamical processes in electronic and molecular systems, complementary to the newly operational Diamond Light Source which has been designed principally for high time-averaged X-ray brightness. In this paper we present the results of our initial studies for one option for a cost-effective, staged, linac based source suitable as a national facility which can act additionally as a portal to larger X-ray free-electron laser facilities in Europe, the US and Japan.  
TUPP020 Analysis of Collective Effects at the Diamond Storage Ring 1574
 
  • R. Bartolini, C. Christou, R. T. Fielder, M. Jensen, A. F.D. Morgan, S. A. Pande, G. Rehm, C. A. Thomas
    Diamond, Oxfordshire
  
  The Diamond storage ring has achieved its nominal operating current of 300 mA in multi-bunch mode and up to 10 mA in single bunch mode. Several collective instabilities have been observed and their dependence on machine parameters such as chromaticities, RF voltage and fill pattern have been investigated. We report here the analysis of the observed current thresholds and rise times of the instabilities compared with analytical estimates and tracking simulations. We also present the results of the MAFIA simulations performed with the aim of understanding the main contribution to the impedance of the ring and establishing a machine impedance database.  
WEPC057 Preparation for Top-up Operation at Diamond 2121
 
  • R. P. Walker, P. T. Bonner, F. Burge, Y. S. Chernousko, C. Christou, J. A. Dobbing, M. T. Heron, V. C. Kempson, I. P.S. Martin, G. Rehm, R. J. Rushton, S. J. Singleton, M. C. Wilson
    Diamond, Oxfordshire
  • R. Bartolini
    JAI, Oxford
  
  We report on progress towards top-up operation of Diamond. We describe the extensive safety assessment that has carried out, including the measurements and simulations to assess the potential radiation doses in the case of poor injection efficiency or a top-up "accident", and the various levels of safety measures - procedures, software limits and personnel safety system interlocks - that have been implemented. We describe the top-up control algorithm, the technique used to maintain a given arbitrary filling pattern and the performance in practise. The work carried out to reduce the effect of the injection kickers on the stored beam is described, and the effect of the residual disturbance on user operation is discussed. The modifications to the timing system to provide hardware and software gating signals, and experience with the use of these, are also described.  
WEPC070 Further Optimisation of the Diamond Light Source Injector 2157
 
  • C. Christou, J. A. Dobbing, V. C. Kempson, A. F.D. Morgan, B. Singh, S. J. Singleton
    Diamond, Oxfordshire
  
  The Diamond Light Source injector consists of a 100MeV linac and a 3GeV full-energy booster, and has been providing beam to the storage ring since September 2006. System optimisation has continued throughout the first year of user operation at Diamond. Beam losses on injection into both the booster and storage ring have been minimised by optimisation of operating parameters and the stabilisation of injection elements, particularly the elimination of a linac energy beat. High level software has been developed to monitor turn-by-turn BPM data, allowing booster chromaticity to be measured. The same software generates an automatic log of storage ring frequency spectra on injection, enabling the parasitic measurement of storage ring tune, and can be used to provide information on storage ring impedance and chromaticity. Further optimisation of single bunch injection has been carried out in preparation for top-up operation, and top-up capability has been extended to provide a single bunch filling mode for the storage ring. Injection into the booster at low energy has been demonstrated, providing a mode of operation for the injection system in the event of a linac klystron failure.