Vacuum
Elettra Vacuum system
The Elettra facility consists of three main parts:- a 1.0 GeV injection system Linac;
- a 90 m long transfer line;
- a storage ring 260 m in circumference, which is divided into six vacuum sectors.
Each vacuum sector contains two achromats composed of one normal bending magnet (BM) vacuum chamber and of one straight section with an insertion device (ID) BM vacuum chamber.
The status of the Insertion Device Vacuum Chambers is reported in the following table:
| I.D. | Material of the I.D. Vacuum Chambers | Beamlines |
|---|---|---|
| 1 | Aluminum (no ante-chamber) | FEL / NanoSpectroscopy |
| 2 | Aluminum (no ante-chamber) | SuperESCA / ESCAMicroscopy |
| 3 | Stainless Steel (with ante-chamber) | VUV Phot. / SpectroMicroscopy |
| 4 | Stainless Steel (no ante-chamber) | Circularly Polarised Light |
| 5 | Stainless Steel (with ante-chamber) | XRD1 / SAXS |
| 6 | Stainless Steel (with ante-chamber) | Gas Phase / SPELEEM |
| 7 | Stainless Steel (with ante-chamber) | ALOISA |
| 8 | Aluminum (no ante-chamber) | BACH |
| 9 | Aluminum (no ante-chamber) | APE |
| 10 | Aluminum (no ante-chamber) (*) | IUVS |
| 11 | Stainless Steel (no ante-chamber) (*) | XRD2 |
(*) To be installed.
The electron beam chamber has a rhomboidal cross section to fit all of the magnetic elements. Coupling the rhomboidal chamber to the antechamber via a 1 cm high slot makes the BM vacuum chamber.
The status of the Light Port Vacuum Chambers is reported in the following table:
|
B.M. Light Port |
Material | Beamlines |
|---|---|---|
| 1.1 | Aluminum | Back FEL |
| 2.1 | Stainless Steel | |
| 3.1 | Stainless Steel | |
| 4.1 | Stainless Steel | |
| 5.1 | Stainless Steel | |
| 6.1 | Stainless Steel | SYRMEP / Materials Science |
| 7.1 | Stainless Steel | |
| 8.1 | Stainless Steel | LILIT / XMOSS |
| 9.1 | Stainless Steel | |
| 10.1 | Stainless Steel | Deep Lithography / ___ |
| 11.1 | Stainless Steel | XAFS / ___ |
| 12.1 | Stainless Steel | |
| 12.2 | Stainless Steel | Diagnostic |
|
I.D. Light Port |
Material | Beamlines |
|---|---|---|
| 1.2 | Aluminum | FEL / NanoSpectroscopy |
| 2.2 | Stainless Steel | SuperESCA / ESCAMicroscopy |
| 3.2 | Stainless Steel | VUV Phot. / SpectroMicroscopy |
| 4.2 | Stainless Steel | Circularly Polarised Light |
| 5.2 | Stainless Steel | XRD1 / SAXS |
| 6.2 | Stainless Steel | Gas Phase / SPELEEM |
| 7.2 | Stainless Steel | ALOISA |
| 8.2 | Aluminum | BACH |
| 9.2 | Aluminum | APE |
| 10.2 | Aluminum (*) | IUVS |
| 11.2 | Stainless Steel | XRD2 |
(*) To be installed.
More details about the Elettra vacuum system can be found in ref. [1].
A new approach for storage ring vacuum system design, based on three years experience with Elettra vacuum system, was published in ref. [2].
The pumping system allows to measure total pressures according to the current absorbed in the sputter-ion pumps. It has been designed at home, calibrated and tested during Elettra commissioning. It was observed that the real experimental conditions, e. g. the presence of the radio frequency, radiation and strong external magnetic fields can change and affect total and partial pressure measurements. This experience and the possible cure of these undesired effects are described in ref. [3].
Elettra has been built especially for the use of the high brilliance radiation from insertion devices (ID). Experience with the first five ID vacuum chambers with and without central pumping is published in ref. [4] and [5], respectively.
Operational experience with the BM and ID vacuum chambers fabricated from machined and extruded aluminum respectively, is reported in ref. [6].
The wall conditioning in Elettra has been very rapid and even a non bake out start up can be considered. Some theoretical aspects of beam cleaning efficiency and results of gas injection experiment can be found in ref. [7] and [8], respectively.
[1] Daclon F., Giacuzzo F., Miertusova J., "Elettra Vacuum System - Part I", Internal Report, Sincrotrone Trieste, ST/M-92, (1992)
[2] Miertusova J.: "New Aspects on the Design of the Vac. Syst. for Future Synchr. Light Sources", Vacuum, vol. 48, No. 7-9, p. 751 (1997)
[3] Miertusova J.: "Reliability and Accuracy of Total and Partial Pressure Meas. in the UHV under Real Exp. Conditions", Vacuum, vol. 51, No.1, p.61 (1998)
[4] Miertusova J., Pangos N.: "Insertion Device Vacuum Chamber for Elettra Storage Ring, Proc. of the PAC'95", Dallas (1995)
[5] Miertusova J.: "Vacuum Performance Char; 5m-Long Pump Free ID Vac. Chamber, Proc. EPAC'98", Stockholm, (1998)
[6] Miertusova J.: "Elettra Status - Operational Experience with the Aluminium Vacuum Chambers", Vacuum 60 p. 101 (2001)
[7] Miertusova J.: "New Approach on the Design of Pumping, Measuring and Baking Systems for Synchr. Light Sources", Vuoto vol. XXVII, No. 2, p.3 (1998)
[8] Karantzoulis E., Casarin K., Miertusova J., Pradal F., Richter F., Tromba G., Vascotto A.: "Lifetime Measurements at Different Pressure Conditions", Proc.EPAC 2000, Wien (2000)
