IWBS2004 was a very exciting and fruitful workshop. Most of the represented operating or future ring based light sources are using or proposing very similar techniques to achieve high orbit stability as there is firstly careful source suppression by means of:
hall/tunnel/cooling-water temperature stabilization including simulations of tunnel temperature distributions,
careful FEM based structural analysis of girders (ensuring an excellent element-to-element alignment) and whole assemblies including magnets and vacuum systems,
a tight magnetic and mechanical error budget,
low power supply noise (often digital control),
utilization of beam-based alignment techniques in order to reduce on quadrupole-to-BPM misalignments,
linear encoder based systems which allow the mechanical stability of girders, BPMs and other accelerator components to be judged and monitored,
``top-up'' operation to ensure a constant synchrotron radiation heat load, thus allowing a thermal equilibrium and therefore excellent stability to be achieved.
Secondly high resolution/BW BPM systems (often digital) allow an excellent orbit measurement on the sub-micron level over a range of a few kHz. Sophisticated FF schemes utilizing BPMs and X-BPMs can make ID operation nearly transparent while keeping the photon beam position constant at the X-BPMs of the ID. Together with global/local SOFBs and FOFBs based on high resolution BPMs/X-BPMs and correctors orbits can be stabilized to the sub-micron level on time scales ranging from ms to several days allowing also for a completely transparent operation of the installed IDs.
The stability requirements of linac based 4th generation light sources (``archery'') are on the micron to sub-micron level, but are much more difficult to achieve than in ring based sources (``spinning top''). Noise source suppression (particularly RF related) becomes extremely important. High precision single-pass BPM diagnostics, which at present have not yet met the requirements, are necessary in order to implement high BW FF schemes between micro-/macro-pulses at the XFEL. It became apparent that these machines pose a real challenge to the accelerator community.
Next:ACKNOWLEDGEMENTS Up:SUMMARY OF THE 3RD Previous:STABILITY REQUIREMENTS IN 4THMichael Boege 2005-01-25
