This workshop on European Synchrotron Light Sources is the 14th of a series initiated in 1993 by ESRF. In October 2006, SOLEIL was happy to host this meeting. A satellite meeting on radiation safety was also organised, prior to the ESLS meeting, on the afternoon of October 18, which was attended by 11 participants (Machine physicists and safety officers) from 6 synchrotron radiation facilities.
A total of 40 participants representing 12 laboratories could exchange and discuss the last news in the accelerator field for synchrotron radiation production. They were specially rich and exciting this time with namely:
- Many improvements in the Sources in operation: ANKA, ASTRID, BESSY, ELETTRA, ESRF, SLS.
- Tremendous results in the commissioning of new Sources: DIAMOND, MAXIII and SOLEIL.
- Decisive progresses in the construction of ALBA and PETRA III.
One session was completely dedicated to 4th generation light Source and FEL, as almost all laboratories are now making developments in this direction and at a time when significant steps have been reached on many projects. Whilst FLASH has already started operation, other projects are either starting construction or are entering into a R&D phase (E‑XFEL, SPARCX, FERMI, BESSY-FEL, MAX IV, SLS-FEL, ERLP). Ambitious projects are either in CDR phase (4GLS) or in proposal (Arc en Ciel).
Some sessions dedicated to specific topics dealt with:
- Insertions devices: Promising first results with cryogenic undulators were reported from ESRF, and SOLEIL presented good achievement using new sorting methods.
- Beam dynamics: Low alpha-optics, synchro-betatron resonances, Linear model (LOCO analysis and BBA), implications and requirements for top-up injection were discussed.
- Diagnostics: The first experiences of BPMs with the Libera module (Manufactured by Instrumentation Technology) were reported by DIAMOND and SOLEIL. Also performances of on-line emittance measurements with either visible (vertically polarised) or X-ray synchrotron light were presented.
- Instabilities: Observations of Resistive Wall & Ions instabilities and results (achieved or expected) of new multibunch transverse feedback system (using digital processing) were presented.
- New developments in Accelerator Technology: RF solid state amplifiers, IOT, HOM free cavities (superconducting or warm) and also first results of conditioning for vacuum system with generalised use of NEG coating were shown.
The main characteristics of the European 3rd generation storage rings were gathered and are shown in table1. One could highlight some peculiar points:
- The trend towards low emittance is still showing up, with the objective of reaching the symbolic value of 1 nm.rad on the 2 km long ring of PETRA III.
- The maximum intensity is still being pushed up with the planned 500 mA at SOLEIL and the goal of 300 mA at ESRF, may be even more in the far future.
- Slow and Fast Orbit feedbacks are implemented or planned in almost Sources, reaching high level of stability (SLS and ESRF around 1µm even sub-µm in the future?).
- Top-up injection already operated with success for a long time at SLS is now under test or planned at many others Sources.
- Multi-bunch digital feedback systems (bunch by bunch) are more and more generalised and are efficient to combat instabilities driven by HOM or by Resistive Wall but also to suppress ions instabilities and (why not) to minimize oscillations induced by top-up injection. On the other hand, their efficiency has still to be proven for transverse mode coupling in the single bunch mode (TMCI).
- Three sources are providing short bunches to users: X-ray pulse duration around 100 fs at SLS and BESSY using the slicing technique; X-ray pulse duration around few ps at ANKA and BESSY with low a optics (at very low current per bunch).
- Super-conducting technology, despite extra complexity is now commonly used: This began in the past with SC wigglers, then with harmonic RF SC cavities. DIAMOND and SOLEIL are now operating with main RF SC cavities. R&D on SC undulator is still being pursued at ANKA.
- Finally, for the ultra vacuum system, NEG coating is already widely used on the low gap vacuum chamber in the insertion device straight sections with very good results. SOLEIL has generalized this technology to all straight vacuum vessels and first results of conditioning are satisfying. Further experience and analysis in the following months of commissioning will allow concluding definitively on the beneficial effects.
Concluding remarks
This workshop was, once again, very interesting and fruitful. The presentations made by the different speakers were of high quality not only in term of outlook but essentially because the materials and topics presented were well focussed on the interests of our community.
DIAMOND and SOLEIL have been able to achieve very fast progress in commissioning their accelerators and storage rings, thanks to more sophisticated and powerful tools (Matlab Middle Layer, LIBERA BPMs,..), but also thanks to the experience (bad or good) reported from other existing facilities.
This demonstrates clearly the interest of these yearly ESLS meetings which contribute to the free and friendly exchanges and communications between the different European labs and enable accelerator physicists (young and senior) to meet and know each other.
The next ESLS meeting will be hosted and organized at DIAMOND in 2007.
The general feeling is that all along the past years, the demand of Users for synchrotron light from storage rings has been continuously increasing. In parallel accelerator physicists have been pushing more and more the performances of 3rd generation facilities, first to meet the ever more stringent requirements of the Users, but also sometimes to enable Users to open new research fields.
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