MG - MTE Workshop 24/09/2010 MG - MTE Workshop 24/09/2010 1 Measurements’ analysis Measurements’ analysis S. Gilardoni, M. Giovannozzi, M. S. Gilardoni, M. Giovannozzi, M. Newman Newman Introduction Introduction Techniques, tools Techniques, tools Results (selected) Results (selected) Outlook Outlook Acknowledgements Acknowledgements : G. Arduini, H. Damerau, E. : G. Arduini, H. Damerau, E. Métral, and Métral, and OP-PS crew!!! OP-PS crew!!!
Aim of these studies:Aim of these studies:Optimisation of various parameters Optimisation of various parameters Identification of sources (beam dynamics) of trapping Identification of sources (beam dynamics) of trapping fluctuationsfluctuations
Instruments used:Instruments used:Mainly transformers in TT2 to evaluate extraction and Mainly transformers in TT2 to evaluate extraction and trapping efficiency trapping efficiency
BCTFI212: spill shape and total intensityBCTFI212: spill shape and total intensityBCT372: total intensityBCT372: total intensity
Wire scanner to evaluate islands’ parameters and Wire scanner to evaluate islands’ parameters and trapping efficiencytrapping efficiencyScreens in TT2 to evaluate position fluctuations and Screens in TT2 to evaluate position fluctuations and emittance/sigma variationemittance/sigma variation
General approachGeneral approachPerform scans over selected parametersPerform scans over selected parametersEstimate trapping/extraction efficiency Estimate trapping/extraction efficiency Compute average/standard deviation of Compute average/standard deviation of trapping/extraction vs. parameter testedtrapping/extraction vs. parameter testedEvaluate correlation between trapping/extraction Evaluate correlation between trapping/extraction efficienciesefficienciesEvaluate frequencies in time-evolution of Evaluate frequencies in time-evolution of trapping/extraction efficiencytrapping/extraction efficiency
Plain FFT not always applicable (not evenly-spaced data)Plain FFT not always applicable (not evenly-spaced data)Lomb periodogramme usedLomb periodogramme used
Equivalent to fitting sine/cosine functions to measured dataEquivalent to fitting sine/cosine functions to measured dataFigure-of-merit function suitable for statistical interpretation: Figure-of-merit function suitable for statistical interpretation: significance level of fit frequencies.significance level of fit frequencies.
When are the fluctuations When are the fluctuations generated? - conclusionsgenerated? - conclusions
Taking into account thatTaking into account thatIt is not possible to collect too much statistics with It is not possible to collect too much statistics with wire scannerswire scannersThe five-Gaussian fit might be hard to perform when The five-Gaussian fit might be hard to perform when the islands are not well separatedthe islands are not well separated
Then, the fluctuations seem to be generated Then, the fluctuations seem to be generated right at the beginning of the splitting.right at the beginning of the splitting.
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Principle:Principle:It excites the beam at an harmonic (h) of the betatron It excites the beam at an harmonic (h) of the betatron frequencyfrequencyIt excites the beam at a given tune valueIt excites the beam at a given tune valueIn summary:In summary:
Kick amplitudeKick amplitudeStart and end times of excitationStart and end times of excitationOther excitation formsOther excitation forms
Broad maximum: length minimised to avoid Broad maximum: length minimised to avoid emittance blow-upemittance blow-up10
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MD4_July_12_Damper_Study
Damper On Excite On
Damper On Excite Off
Normal MTEDamper OnExcite Off
Damper OffExcite Off
Damper OffExcite On
Various Various configurations configurations of damper of damper ON/OFF: clear ON/OFF: clear impact on impact on trapping; no trapping; no impact on impact on fluctuationsfluctuations
Mild dependence of trapping on h -> Mild dependence of trapping on h -> selected selected h=8h=8Strong dependence of trapping on qx -> Strong dependence of trapping on qx -> selected qx=0.25selected qx=0.25Threshold effects on start excitation -> Threshold effects on start excitation -> selected 700 msselected 700 msBroad optimum for excitation length -> Broad optimum for excitation length -> selected 40 msselected 40 msEssentially no impact of other options (type of Essentially no impact of other options (type of modulation, slope in qx vs. time)modulation, slope in qx vs. time)
Strong impact on trapping efficiency of damper, Strong impact on trapping efficiency of damper, but no impact on fluctuations.but no impact on fluctuations.
ODEs are used to compensate the non-linear ODEs are used to compensate the non-linear coupling between H/V plane. coupling between H/V plane. Sextupoles should not generate negative Sextupoles should not generate negative chromaticity (increasing their strengths reduces chromaticity (increasing their strengths reduces chromaticity)!chromaticity)!
Sextupoles/octupoles – results - ISextupoles/octupoles – results - I
ODEs are used to compensate the non-linear ODEs are used to compensate the non-linear coupling between H/V plane. coupling between H/V plane. Sextupoles should not generate negative Sextupoles should not generate negative chromaticity (increasing their strengths reduces chromaticity (increasing their strengths reduces chromaticity)!chromaticity)!
Change of frequency of Change of frequency of fluctuations (rarely seen in the fluctuations (rarely seen in the whole measurement campaign)!whole measurement campaign)!
Limit of negative Limit of negative chromaticitychromaticity
Sextupoles/octupoles – results - IISextupoles/octupoles – results - II
ODEs are used to compensate the non-linear ODEs are used to compensate the non-linear coupling between H/V plane. coupling between H/V plane. Sextupoles should not generate negative Sextupoles should not generate negative chromaticity (increasing their strengths reduces chromaticity (increasing their strengths reduces chromaticity)!chromaticity)!
Mild dependence of trapping on OMTs strength Mild dependence of trapping on OMTs strength at top energyat top energyMild dependence of trapping on OMTs flat top Mild dependence of trapping on OMTs flat top lengthlengthBroad optimum of h11 around 0.Broad optimum of h11 around 0.Clear impact of XMT39 strength on trapping Clear impact of XMT39 strength on trapping and frequenciesand frequencies
No strong impact of sectupoles/octupoles on No strong impact of sectupoles/octupoles on amplitude of fluctuations.amplitude of fluctuations.
It changes the beam energyIt changes the beam energyVia feed-down tunes and local chromaticities Via feed-down tunes and local chromaticities are changedare changedTo fix ideas:To fix ideas:
1 mm is equivalent to about 6×101 mm is equivalent to about 6×10-4-4 p/pp/pNegative position -> Negative position -> p/pp/p
Radial position effect - resultsRadial position effect - results
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MD4_September_11_Vary_Radial_Position
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Radial Position @ +2.0 mmRadial Position @ +1.5 mmRadial Position @ +1.0 mmRadial Position @ +0.5 mmRadial Position @ +0.0 mmRadial Position @ -0.5 mmRadial Position @ -1.0 mmRadial Position @ -1.5 mmRadial Position @ -2.0 mmRadial Position @ -2.5 mm
Horizontal chromaticity is Horizontal chromaticity is shifted towards negative valuesshifted towards negative values
Similar change of Similar change of frequency as for XMT39!frequency as for XMT39!
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 210
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Average Trapping EfficiencyAverage Extraction Efficiency
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 280
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Some reduction of Some reduction of fluctuations amplitude fluctuations amplitude for radial position for radial position outside maximum of outside maximum of trappingtrapping
Amplitude of fluctuations is about 3-4%.Amplitude of fluctuations is about 3-4%.From the results of the measurements this From the results of the measurements this could be generated by: could be generated by:
Fluctuation in the start timing of the damper -> 20 msFluctuation in the start timing of the damper -> 20 msFluctuation in the quadrupoles’ settings to generate Fluctuation in the quadrupoles’ settings to generate a jitter of 20 ms in the resonance crossing timinga jitter of 20 ms in the resonance crossing timingFluctuation in the qFluctuation in the qxx value of the damper -> ~2×10 value of the damper -> ~2×10-3-3
Fluctuation in the quadrupoles’ settings to generate Fluctuation in the quadrupoles’ settings to generate a tune fluctuationa tune fluctuationFluctuation in the reference of fFluctuation in the reference of frevrev for the damper -> for the damper -> ~2×10~2×10-4-4 (assuming h=8) (assuming h=8)Fluctuation of the radial position -> ~1 mmFluctuation of the radial position -> ~1 mmFluctuation in beam energy/BFluctuation in beam energy/Bfieldfield -> 0.6×10 -> 0.6×10-3-3
To assess the impact of intensity on splitting To assess the impact of intensity on splitting behaviour:behaviour:
MD1: initial beam used for SPS setting up. Total MD1: initial beam used for SPS setting up. Total intensity of about 3-4×10intensity of about 3-4×101212 ppp. ppp.MD4: intermediate intensity about 1.7-1.8×10MD4: intermediate intensity about 1.7-1.8×101313 ppp. ppp. MD4: high intensity about 2.1×10MD4: high intensity about 2.1×101313 ppp. ppp.
Impact of intensity - summaryImpact of intensity - summary
To assess the impact of intensity on splitting To assess the impact of intensity on splitting behaviour:behaviour:
MD1: initial beam used for SPS setting up. Total MD1: initial beam used for SPS setting up. Total intensity of about 3-4×10intensity of about 3-4×101212 ppp. ppp.MD4: intermediate intensity about 1.7-1.8×10MD4: intermediate intensity about 1.7-1.8×101313 ppp. ppp. MD4: high intensity about 2.1×10MD4: high intensity about 2.1×101313 ppp. ppp.
Other checks: magnets pulsing on Other checks: magnets pulsing on zero cycle zero cycle
Test to assess impact of MTE elements pulsing Test to assess impact of MTE elements pulsing on other users.on other users.Selected ZERO cycle.Selected ZERO cycle.Copied:Copied:
XMTsXMTsOMTsOMTsLow energy quadrupolesLow energy quadrupoles
No impact at all on trapping and fluctuationsNo impact at all on trapping and fluctuations
Other checks: magnets pulsing – Other checks: magnets pulsing – resultsresults
Mild dependence of trapping on OMTs strength Mild dependence of trapping on OMTs strength at top energyat top energyMild dependence of trapping on OMTs flat top Mild dependence of trapping on OMTs flat top lengthlengthBroad optimum of h11 around 0.Broad optimum of h11 around 0.Clear impact of XMT39 strength on trapping Clear impact of XMT39 strength on trapping and frequenciesand frequencies
No strong impact of sectupoles/octupoles on No strong impact of sectupoles/octupoles on amplitude of fluctuations.amplitude of fluctuations.
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Average Trapping EfficiencyAverage Extraction Efficiency
Devices normally used for MTE studies:Devices normally used for MTE studies:PS ring transformer (reference)PS ring transformer (reference)FBCT in 212 (spill and total intensity)FBCT in 212 (spill and total intensity)BCT372 (total intensity)BCT372 (total intensity)
Recently additional data should be available:Recently additional data should be available:126, 203, 372 -> spill data126, 203, 372 -> spill dataAll BCTs providing total intensityAll BCTs providing total intensity
In principle everything should be logged.In principle everything should be logged.Cross-calibration still to be improvedCross-calibration still to be improvedLogging to be verifiedLogging to be verified
Detailed studies of the dependence of the trapping on Detailed studies of the dependence of the trapping on many parameters done.many parameters done.Optimisation done for: Optimisation done for:
damper settingsdamper settingssextupolessextupolesoctupoles octupoles radial positionradial position
Still some studies to be performed with the variation of Still some studies to be performed with the variation of the tune with time.the tune with time.Fluctuations are still there:Fluctuations are still there:
They seem intrinsic to the splitting processThey seem intrinsic to the splitting processThey are not affected by the damperThey are not affected by the damperThey are generated during the splitting properThey are generated during the splitting properFluctuations amplitude: not particularly affected by the Fluctuations amplitude: not particularly affected by the parameters analysed so farparameters analysed so farFluctuations frequency: seems to be affected by chromaticity Fluctuations frequency: seems to be affected by chromaticity and intensityand intensity
