Chapter 3 : Upgrading of BESSY I - SESAME

More documents

Recommendations

Info

In an upgrading process the length of the quadrupoles and sextupoles can be changed in order to get longer straight sections. Furthermore a mini beta section can be introduced (version SES_4_2). The parameters of these versions are summarized in Table (3.3) and (3.4). Table 3.3: Main parameters of the versions upgraded to 2 GeV. SES_2_1 has 6 fold, SES_3_1 and SES_4_1 have 8-fold symmetry. SES_4_1 uses gradient bending magnets and BESSY I quads and sextupoles. Parameter SES_2_1 SES_3_1 SES_4_1 Energy (GeV) 2.0 2.0 2.0 Emittance (nmrad) 62.2 23.7 18.7 Number of straights 6 8 16 Useable wiggler straights and length (m) 4 / 4.64 6 / 3.20 8 / 2.43 Useable undulator straights and length (m) 6 / 1.80 Circumference (m) 112.0 116.0 120.0 16.5 20.6 35.7 x, bending / wiggler) (mm) 0.283/1.484 0.136/0.847 0.167/0.613 y, bending / wiggler) (mm) 0.120/0.108 0.074/0.025 0.078/0.032 x y) Bending magnet (mm^2) 0.214 0.063 0.082 Wiggler/ Undulator (mm^2) 1.007 0.133 0.123/0.092 Critical photon energy Bending magnet (keV) 4.00 4.00 3.60 Wiggler (2.25Tesla) (keV) 6.00 6.00 6.00 Undulator (keV) Wavelength shifter (7.5Tesla) (keV) 20.0 20.0 20.0 Table 3.4: Main parameters of the versions upgraded to 2 GeV with a mini beta section. SES_2_2 has 6 fold, SES_3_2 and SES_4_2 have 8-fold symmetry. SES_4_2 uses gradient bending magnets. Parameter SES_2_2 SES_3_2 SES_4_2 Energy (GeV) 2.0 2.0 2.0 Emittance (nmrad) 76.0 25.6 12.9 Number of straights 6 8 16 Useable wiggler straights and length (m) 3 / 3.84 4 / 3.20 8 / 2.60 Useable undulator straights and length (m) 1 / 4.64 2 / 3.20 6 / 1.70 Circumference (m) 116 122.0 124.0 13.9 19.6 34.6 x, bending / wiggler) (mm) 0.336/0.322 0.149/0.145 0.097/0.254 y, bending / wiggler) (mm) 0.139/0.033 0.083/0.029 0.062/0.0073 Beam size area (2* x y) Bending magnet (mm^2) 0.241 0.077 0.038 Wiggler/Undulator (mm^2) 0.067/1.24 0.026/0.295 0.012/0.081 Critical photon energy Bending magnet (keV) 4.0 4.0 3.6 Wiggler (2.25Tesla) (keV) 6.0 6.0 6.0 Undulator (keV) Wavelength shifter (7.5Tesla) (keV) 20 20 20 3.4 Comparison of the Different Versions 3.4.1 Magnets For the different upgrading versions the needed magnets are summarized in Table (3.5). To upgrade the storage ring to 1 GeV (version: SES_1_2) the bending magnets have to be modified in 17
order to reach a field of 1.87 Tesla. Furthermore 8 quadrupoles and 8 sextupoles are needed. For this version a DBA lattice is foreseen and the symmetry of the machine is 6 fold. For a 2 GeV storage ring (version SES_2_1) 12 new bending magnets and 8 new sextupoles are needed. In order to increase the brilliance of the radiation from the wiggler a “mini beta section” should be introduced. This is possible with the version SES_2_2 for which 6 additional quadrupoles with a length of 0.7 m are requested. Table 3.5: Number of magnet elements needed for the different upgrading versions for SESAME. The lengths of the elements are given in brackets. *) This is a combined quadrupole / sextupole magnet Version Bendings Quadrupoles Sextupoles New bends New quads New sextup. 16 16 16 (0.23) BESSY I 12 32 (0.44) 16 (0.25) 4 (0.25) SES_1_1 12 30 (0.44) 16 (0.25) 8 (0.15) 8 (0.15) SES_1_2 12 30 (0.44) 16 (0.25) 12 modified (Green book) 12 (0.25) 8 (0.15) 8 (0.25) 8 (0.15) SES_2_1 12 30 (0.44) 16 (0.25) 12 8 (0.15) 8 (0.15) SES_2_2 12 30 (0.44) 16 (0.25) 12 6 (0.70) 8 (0.15) 6 (0.70) 8 (0.15) SES_3_1 16 32 (0.44) 16 (0.25) 16 8 (0.25) 16 (0.15) 8 (0.25) 16 (0.15) SES_3_2 16 32 (0.44) 16 (0.25) 16 8 (0.22) 16 (0.15) 8 (0.22) 16 (0.15) 8 (0.60) 8 (0.60) SES_4_1 16 32 (0.44) 16 (0.25) 32 (0.20) *) 16-32 (0.20) *) 16 (0.15) 16 (0.15) SES_4_2 16 16 (0.23) 32 (0.15) 32 (0.15) 16 (0.45) 16 (0.35) 32 (0.20) *) 16 (0.45) 16 (0.35) 32 (0.20) *) For an eight fold symmetry (SE_3_1) 16 new bending magnets, 8 quadrupoles and 16 sextupoles are needed. In order to get 4 mini beta sections in the storage ring (SES_3_2) 8 more quadrupoles with a length of 0.6 m are needed. The version SES_4_1 needs 16 new bending magnets, 16 sextupoles with a length of 0.15 (m) and 16 to 32 combined sextupole / quadrupole magnets. In order to increase the length of the straight sections it is possible to change on a later stage the BESSY quadrupoles and sextupoles by more compact magnets. Furthermore by introducing 16 new quadrupoles it is possible to make in each cell a mini-beta-section (version SES_4_2). 3.4.2 Performance of the Different Upgrading Versions Performance of the radiation of a synchrotron light source is given by the brilliance of the beam, the spectral range of the radiation and the overall length (or the number) of insertion devices that can be installed. The spectral range is given by the so-called critical photon energy, which is proportional to the magnetic field and proportional to the square of the beam energy. Hence by changing the energy from 1 GeV to 2 GeV, the useable spectrum is a factor of 4 broader. As already discussed in chapter 2 the spectrum is broader by a factor of 10. To avoid a super-conducting wiggler has two more advantages: 1) The high field of the wiggler has a strong influence of the behavior of the beam. 2) The operation of a super-conducting wiggler needs a special knowledge, which at present is not available at SESAME. 3) The superconducting wiggler is much more expensive. 18
Page 1 and 2: 3. Upgrading of BESSY I 3.1 Introdu
Page 3: size) SES_1_2 can’t compete with
Page 7 and 8: 3.4.2.1 With a “Mini-Beta-Section
Page 9 and 10: 3.6 Characteristics of the Radiatio
Page 11 and 12: Bending Flux Density SE_1_2 SE_3_2
Page 13 and 14: esult that the flux from the 2 GeV
Page 15 and 16: Wiggler Flux SE_1_2 SE_2_2 SE_4_2 1

Chapter 3 : Upgrading of BESSY I - SESAME

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?