Top-up Operation - Preservation of Bunch Pattern SPring-8 12/03/02 - - PowerPoint PPT Presentation

“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Preservation of Bunch Pattern

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Injection Oscillations

BPM in single turn mode: Horizontal Plane:

• 800 µm peak-peak over 6 µs
• Decoherence time ≈600 µs

Vertical Plane:

• Excitation <15 µm BPM noise
• 600
• 500
• 400
• 300
• 200
• 100

100 200 300 400 500 600 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 amplitude [µm] time [msec] x y 0.002 0.004 0.006 0.008 0.01 0.012 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 power spectrum [µm/√Hz] fractional tune x y

ν y =0.17 ν x =0.42 −500 µ m µ m +300 decoherent coherent injection 1.2 msec

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02 Top-up Operation - Losses @ U24

Scintillator count rates @ ID U24 –> I heard that you do not use the sys- tem of gate-signal delivery to experi- mental users during top-up injections. We would like to know how experimental users know (or don’t care about) the tim- ing of series of injections, and also how to exclude its negative contamination to their experimental data due to possible fluctuation of X-ray beam. We don’t do anything ... We plan to do a fast (ms resolution) measurement of the beam intensity during injection to get a fealing for the distortions. (C. Schulze-Briese, PX beamline re- sponsible)

1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 coincidence count rate [10^4 Hz], gap [mm], current [A] time [h] coincidence count rate gap current

7.288 mm 7.450 mm 25/4.5=5.6 45/6=7.5 37/5=7.4 7.847 mm 300 injections injection every 2.3 min @ 10h lifetime 5s 20/4.3

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02 Top-up Operation - Losses @ U24

... May be you even have some plots which illustrate the positive and negative influences of Top-up

• peration on your various experimental setups.

We don’t have plots but it can be said that the effect of Top-up on the data quality is rather positive than negative. It is believed that a small and periodic distortion is better than a continuous drift / change during the data collection. We are able to measure at least as good quality data as ESRF and a particular difficult case that was not solvable at ESRF was solved here during Top-up

• peration.

Some users told me that in SLS so far there is no experiment which requires very sever beam

• stability. I doubt this opinion. So please make clear what kind of experiment performed in SLS.

There I ask you to explicitly clarify the requirement of each experiment to beam quality. The beam stability of < 1 µm rms and < 1 µrad rms is more than sufficient for Protein Crystallography. Another nice aspect of SLS is the reproducibility of the beam position after shutdown. Typically the beam comes back to few microns and the intensity is the same as before. (C. Schulze-Briese, PX beamline responsible)

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Temperature and Pressure

Temperature 12 * 6 = 48 sensors 26 deg C 3HC arc flange 2e−8 mbar 4.5e−8 mbar 4e−8 mbar Pressure 34 gauges injection 1e−7 = Maximum Pressure 100 deg C = Maximum Temperature

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02 Top-up Operation - Gap Control and Interlocks

Gap Control:

• Set Operator/Experiment
• Status

Kicker/Septum Control:

• Set Disarm/Rearm
• Status

Orbit Autodump:

• Set Parameters
• Status

Sources Autodump:

• Orbit
• Temperature
• RF
• 3HC

Orbit Autodump Params Temp 3HC RF Orbit Sources Autodump Gap Control Kicker/Septum Control

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Controls

Top−up Control Chromaticities Tuneshifts Nominal Tunes & Chromaticities Bunch Charge SR Current 300−301 mA Gap Control Pattern Bunch Kicker/Septum Control Orbit Autodump Params Sources Autodump Orbit RF 3HC Temp Gun Trigger

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Beam Time and Faults

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Top-up Operation - Accumulated Beam Dose

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 Aug.2001 Oct.2001 Dec.2001 Feb.2002 Apr.2002 Jun.2002 Aug.2002 Oct.2002 Dec.2002

Accumulated Beam Dose [Ah]

250 Ah 1150 Ah

2002

900 Ah

Michael B¨

• ge

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“Top-up” Operation at the Swiss Light Source

SPring-8 12/03/02

Slow Orbit Feedback - Golden Orbit

vertical difference orbit ~1µm bba offsets golden orbit horizontal difference orbit ~1µm

=20.42 =8.17 νy νx 0.5mm −0.5mm

refreshrate 0.5 Hz (3 Hz) 72 BPMs µm precision

• f BPMs

~0.3 /plane 72 corrs

Michael B¨

• ge

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