ESRF Friday Lecture Top-Up ?? J. L. Revol On behalf of the Accelerator & Source Division With the contribution of: JF Bouteille, L Farvacque, T Perron, E Plouviez, J Jacob, L Hardy, M Hahn, Lin Zang, P Berkvens A Chumakov P Clotens, G Monaco, T Mairs, O Mathon S Pascarelli, A Rogalev L Emery (APS) , T Nakamura(SPring8), P Kuske (Bessy), E Karentzoulis (Elettra), V Kempson (Diamond), M Bieler (Petra), A Luedeke (SLS), A Loulergue (Soleil), G Benedetti (ALBA)
What is Top Up? Compensate for beam decay induced by the finite lifetime originating from the different loss processes (vacuum, Touschek, physical aperture, ...) By Frequent injections Which Top Up do we need at the ESRF? Which Top Up could we provide at the ESRF? 2 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Petra Top-Up Top-Up Top-Up Bessy II Top-Up Top-Up SLS Top-Up APS Top-Up Decay mode Top-Up Top-Up Top-Up every 12h 3 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Pro: Reduced heat load variation on the beamline optics. � Improves stability Con: Increased number of injections . � Disturbs stability Survey of Top Up operation at ESRF/ APS/ SPRing8/ PETRA/ SOLEIL/ DIAMOND/ BESSY/ ELETTRA/ ALBA /SLS Top Up is multi parameters with discrepancies between institutes! 4 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Stability in current Stability in current at SPring8: 0.03 % "If this level of stability is impossible to achieve, constant decay in ~ a few minutes is preferable.“ said spring8 operation physicist. 5 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Stability in current Current (mA) Delta I (mA) % SPring 8 100 0.03 0.03 Bessy 300 0.4 0.13 Lower variation is Elettra 300 1 0.3 the best, ALBA 400 1 0.25 but what is really APS 100 0.5 0.5 needed for optics SLS 400 2 0.5 stability ?? Soleil 400 2 0.5 Diamond 250 2 0.8 Petra 100 1 1 ESRF 200 40 20 6 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
� Heat load effects depends on electron beam current but also on: Photon energy, slit aperture,... and optics and beamline design � Two issues in terms of optic stability at ESRF: � Short term stability Long term stability � � ESRF has developed a lot of expertise in the design of the optics and in the layout of beamlines to manage heat load variation, especially for the UPBLs, which should be less sensitive to refills. � Could we still gain (a lot) by reducing the current variation ? � What would be the (maximum) current variation which would make a refill transparent? Difficult to get a single answer from the ESRF experts !! Beamlines have already made a lot of efforts to be less sensitive to heat load variation, solution optimized for the different techniques........ Only experimental data would really give precise information .. 7 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Short term stability Displacement field at UPBL06 Inelastic scattering- TDR the beam spot of the first crystal (7 keV) Heat-load on the Si(111) monochromator Thermal slope error on the first crystal Power on the crystal: 5 mA → 10 W Change the beam divergence 100 mA → 200 W � corrected by vertically deflecting white beam 200 mA → 400 W mirror mounted on a bender 240 mA → 475 W 8 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Short term stability Setup: 10 mA 50 mA narrow vertical slit 100 mA 150 mA 2 Slit 2 x 1 mm at various vertical 200 mA ID18 Measurement of 250 mA positions 300 mA crystal curvature 15 Si(333) at 43.236 keV 15 Surface height (nm) 2 ) slits, Δ Hx Δ V (mm 10 7/8+1 2.0 x 1.0 Rocking curve FWHM ( μ rad) Bragg angle 5 16 Bunch 10 Optics optimized for 200 mA 0 � Ideal collimation between 160 and 200 mA, crystal flat -4 -3 -2 -1 0 1 2 3 4 5 due to the power deposit Horizontal position (mm) � But crystal too cold to be 16 Bunch 7/8+1 ideally flat between 60 and 90 mA 0 � More disturbance in 0 50 100 150 200 250 300 16bunch than in 7/8+1 Storage ring current (mA) 9 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Long term stability ID24/ UPBL11 Time resolved and Extreme conditions X-ray Absorption Spectroscopy Stability on a long timescale 130 Sensitive to short term and 2008 Horizontal 120 2008 Vertical long term thermal effects. 110 100 2011 Horizontal 90 2011 Vertical 80 70 60 Stability ( μ m) Optimization of the design 50 and feedback on the slits as 40 30 a function of the beam 20 10 current to maintain a 0 constant thermal load -10 -20 -30 -40 But the stability of the -50 optics is still a strong 0 10000 20000 30000 40000 50000 issue with the present time (s) Δ I, especially with the use of the 4 undulators. 10 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Stability Number of Time between Two shots injection Operating Modes SPring 8 0.03 % One ≈ 2 to 3 mn Hybrid 10 to 30 sec Bessy 0.13 % One ≈ 20 to 30 sec Soleil 0.5 % One ≈ 2 to 5 mn Injection at fixed Delta I Elettra 0.3 % 20 shots ≈ 6 mn at 2 GeV 25 mn at 2.5 GeV SLS 0.5 % 10 shots ≈ 1 to 2 mn Petra 1 % 40-50 low ≈ 8 mn charge shots 1 mn (timing mode) APS ≈ 0.5 % One 1 and 2 mn Injection at fixed Diamond ≈ 0.8 % Few 10 mn Delta ESRF ≈ 20% 400 12 hours Time 11 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Stability perturbation induced by an injection : � Injection kickers Depends on the closure of the bump and on the lattice � Injection septum Depends on the magnet design and shielding � Booster magnets field Depends on the leaking magnetic field, the shielding, the compensation field and the fast orbit feedback performances � Cleaning process Depends on the process 12 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
K4 K3 K1 K2 Typical Stored beam SR axis injection perturbation Shielding Septum For the duration of the injected beam pulse (= booster length= 1 μ s at ESRF) Stored beam is moved close to the injected beam via K 1,2,3,4 Injected beam is moved close to the stored beam via septum and K 3,4 Ideal situation : Bump is perfectly closed, even during transient Septum is perfectly shielded Never perfectly achieved in any of the machines For each shot, the stored beam is shacked and damped with the transverse damping time given by the lattice (typically a few ms) 13 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
K4 K3 K1 K2 Typical Stored beam SR axis injection perturbation Shielding Septum • Stored beam is disturbed • ± 250 um horizontally • ± 150 um vertically • Lasts 10 to 12 msec . “The issue is we have to actively maintain the tuning of the injection system kicker magnets to keep it at a minimum, then because we are pretty sure that our users can’t see the kick we have been a bit more relaxed about keeping it at a minimum and retune kickers less often leading to a higher value. We have also found the injection efficiency is not necessarily optimum at these minimum levels of stray kick”. Said Diamond Operation Manager ... 14 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
H Stability V Stability Sextupoles in the perturbation perturbation bump μ m μ m SLS Negligible 40 No Soleil 100 (peak) 70 (rms) 50 No Elettra 100 (peak) 20 No Petra 100 10 No Diamond 250 (peak) 150 No Bessy 500 (peak) 1000 No SPring 8 400 (peak);(<200 rms) 1 Yes (strength optimized) ESRF 1700 (peak) 100 Yes (4) APS 3000 (peak) 200 Yes (14) � All machines are in the μ m stability standards, injection disturbs all machines for ≈ a few ms time ! Need gating for the most demanding experiments 15 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Usage of gating trigger SLS Trigger provided, used by some Soleil Trigger provided, not used Elettra Trigger provided to 2 beamlines Petra Trigger provided, not used Diamond Trigger provided, very few use Bessy Trigger provided SPring 8 Trigger provided, not used ESRF Software trigger provided, used by a few APS Trigger provided, not used Need gating for the most Very little use of gating !! demanding experiments 16 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
Booster power Injection Number of Kicks supply type Every SPring 8 Ramping 1 Hz 2 mn One APS Ramping 2Hz 1 mn One Elettra Ramping 2Hz 6 mn Few Soleil Ramping 3Hz 2 mn One SLS Ramping 3Hz 1 mn Few Diamond Ramping 5Hz 10 mn Few Bessy Resonant 10Hz 20 sec One ESRF Resonant 10Hz 12 hours Few Petra Resonant 12Hz 8 mn Few Main issues for Top-Up: � Resonant power supply is more efficient. Reproducibility & � Ramping power supply is more flexible Switching ON sequence � Is few shots injection mode worse? 17 ISDD Friday Lecture -- Top Up ??-- Revol JL, March 23rd, 2012
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