PXL vibration and stability
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Transcript of PXL vibration and stability
PXL vibration and stability
1/7/2014
Measurements of:
• Cooling air induced vibration of the PXL sensors as a function of air flow
• DC position change as a function of air flow• Position change between power on, warm sector and
power off cold sector
Radial sector motion measured with capacitive probe inserted through hole in PST
North half sectors populated with operating ladders. South half populated with empty sector tubes. System operated with full cooling air
Probe position 1
Probe position 2
Sector 3, ladder position out3 Sector 3, ladder position out2
Probe faces the carbon tube flat just west of the ladders
Typical screen shot at full air flow
Probe signal
FFT, see next page for more detail
Stdev = 5 m
Probe conversion = 1 m/0.04 V
Fourier transform of sector vibration
40 Hz
70 Hz
230 HzMain resonance of the carbon sector tube
Measured sector radial vibration as a function cooling air flow for position 1
More precisely this shows measured vibration as a function of blower RPM since flow has been obtained in this case by scaling linearly with RPM. It has been shown, however, that the flow does indeed scale very closely to the blower RPM.
The measured vibration with no air flowing: 35 nm RMS
Radial displacement of the sector at position 1 as a function of vibration amplitude
An arbitrary offset has been applied to give a 0 intercept since a displacement value was not recorded at zero flow for this series of measurements.
The linear dependence demonstrates that the displacement like the vibration amplitude scales as the flow squared. This is not so surprising since the dynamic pressure scales as air velocity squared.
Sector displacement scales as cooling air flow squared.
Sector moves toward the center with increased flow.
Radial movement between power on and power off with full flow, i.e. Blower RPM = 5940
3 to 8 mSector moves in toward the center when heating applied.
Summary
Sector vibration in the radial direction scales as: flow2
Sector vibration at full flow: 5 µm RMS
Sector DC displacement scales as: flow2
Sector moves in at full flow: 25 µm - 30 µm
Sector moves in when ladders powered: 3 µm - 8 µm
Sources:OneNote logbook: work>sector vibration>Vibration test full with MSCAnalysis: As>AHFT1>cHFT>m>vibration wind>vibration measured full detector.xmcd