turbulence and noise –results 2000/2001
DESCRIPTION
Turbulence and noise –results 2000/2001. Pk. Det. BCT. Pk. Det. Pk. Det. V RF. V RF. 10/2001 1 PS batch, 72 bunches 4.0*10 12 total : 5.6 *10 10 / bunch 10.8 s before voltage rise 0.7% /s reduction in peak detected signal. Instability removed by coupled-bunch feedback which - PowerPoint PPT PresentationTRANSCRIPT
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Turbulence and noise –results 2000/2001
VRF
Pk. Det
Pk. Det
BCT
08/2000Hardware noise improvements.1 PS batch, 48 bunches0.8*1012 total : 1.7 *1010 / bunch7.2 s before voltage riseMinimal reduction in peak detected signal.
Pk. Det
VRF
08/2000
4.0*1012 total : 8.3 *1010 / bunch
1.7%/s reduction in peak detectedsignal for slow decay plus instability
10/2001
1 PS batch, 72 bunches4.0*1012 total : 5.6 *1010 / bunch10.8 s before voltage rise 0.7% /s reduction in peak detectedsignal. Instability removed by coupled-bunch feedback which also introduces noise.Turbulence reduced.
Max. intensity restricted in 2001 by pressure rise due to electron cloud effect. Bunches shorter on the flat bottom.
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Emittance growth during cycle 11/2001
Cycle 537. t = 22.8 4 batches injected, 1.64 * 1013 total, ~ 90% transmission At 450 GeV/c, 1.48 * 1013 total, 3.7 * 1012 / batch, 5.14* * 1010 / bunch.
Individual RF feed-back and feed-forward on each cavity.Coupled bunch feedback on main cavity pass-band, (two cavities)High voltage cycle, 6.7 MV, with 800 MHz on 650 kV.Noise introduced by coupled bunch feedback and 800 MHz system – to be improved!
After capture, 1200 ms 0.4 eVsEnd flat bottom 26 GeV (Pk detected 10% height) 0.48 eVsTop energy 1) from bunch length: HHFW 0.6 – 0.69 eVs Baseline 0.7-0.9 eVs
2) from peak detected cf analytic 0.67 eVs
Bunch rotation: Drop adiabatically from 6.8 MV to 650 kV. Jump to 6.8 MV (0.5 ms) (J.Tuckmantel)(Using fast counterphasing, T.Bohl) Can gain 40% in bunch length – deduced from peak detected.dp/p increases proportionally.
50 ms /div.
0.5 ms /div.
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B train – cycle 537 -2001
start rise join of new parabola to old9800 ms
Peak in Bdot caused by adjustmentof injection energy. (E. Shaposhnikova,T. Bohl, G. Arduini)
Increase from 0.0198 T/s to 0.0296 T/sGives ~ 5% reduction in bucket area for 2 –3 MV
Capture loss should occur ~ 11125 ms or earlierObserved loss may come from peak in Bdot
Suggestion: re-calculate whole B slope or ar leastspread it over a > 4 times longer time-scale
BCT
Bdot
Variation in Bdot caused by errors insaturation tables?
Bdot varies 0.35 T/s 0.02 T/sEffect on bucket area greatest withmatched emittance cycle.0.6 eVs becomes 0.56 eVs at overshoot.Less important to correct but ...
16800 ms / 350 GeV