ATF2 ground motion model
Very tentative
March 20, 2007
Andrei Seryi
Global Design Effort
Goal
• To set framework for modeling of ATF2 with
ground motion and vibration
• Very tentative
• Use older LIAR (Matliar) based tools
• Adjustment of the code of Lucretia is ongoing
and studies have started – Glen White
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Ground motion C. F= 10Hz, n= 10 pulses.
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Ground motion B. F= 10Hz, n= 10 pulses
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0.1
1
10
0.1
1
10
Measured at ATF
• “Quick fix” the model
K to adjust for ATF
conditions
/5, *1.7, *1.7
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Models of coherence for dL=27m are
overlapped onto measurements at ATF
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Draft GM model for ATF
Ground motion ATF. Tentative version
K model
'Parameter A of the ATL law,
A [m**2/m/s]
'Parameter B of the PWK,
B [m**2/s**3]
'Frequency of 1-st peak in PWK, f1 [Hz]
'Amplitude of 1-st peak in PWK, a1 [m**2/Hz]
'Width of 1-st peak in PWK,
d1 [1]
'Velocity of 1-st peak in PWK,
v1 [m/s]
'Frequency of 2-nd peak in PWK, f2 [Hz]
'Amplitude of 2-nd peak in PWK, a2 [m**2/Hz]
'Width of 2-nd peak in PWK,
d2 [1]
'Velocity of 2-nd peak in PWK,
v2 [m/s]
'Frequency of 3-rd peak in PWK, f3 [Hz]
'Amplitude of 3-rd peak in PWK, a3 [m**2/Hz]
'Width of 3-rd peak in PWK,
d3 [1]
'Velocity of 3-rd peak in PWK,
v3 [m/s]
'Minimum time,
Tmin [s]
'Maximum time,
Tmax [s]
'Minimum distance,
Smin [m]
'Maximum distance,
Smax [m]
'Number of w or k harmonics,
Np
[1]
'Ampl. of peak in systmat.P,
Q1 [m**3]
'Wavenumber of peak in syst.P, rk1 [1/m]
'Width of peak in system.P,
rkk1 [1]
'linear or sqrt(t)->exp syst. iwhat_syst (0,1)
'
tau_syst [years]
'(used if ist=1) time gap tgap_syst [years]
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Global Design Effort
1.00000E-17
5.00000E-18
1.60000E-01
4.00000E-13
5.00000E+00
1.0000E+03
2.50000E+00
3.00000E-15
3.00000E+00
3.00000E+02
9.00000E+00
3.00000E-17
2.80000E+00
2.50000E+02
1.00000E-02
1.00000E+02
1.00000E+00
1.50000E+04
100
3.00000E-02
2.00000E-03
1.00000E+00
1
30.0000E+00
2.00000E+00
1.00000E-11
-1.0000E+03
1.00000E-15
-4.0000E+02
1.00000E-17
-4.0000E+02
Negative V means that this
fit is used:
V(f)=450+1900exp(-f/2), m/s
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Ground motion ATF, F= 10Hz, n= 10 pulses
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Ground motion ATF, F= 10Hz, n= 5000 pulses, no
corrections or feedback
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Modeling supports and noises
• Matliar has capabilities to model
– arbitrary “Transfer Functions” (TF) function, characterized by
complex (Re+Im) table. TF describe amplification or damping by
a support
– “Technical Noises” (TN), characterized by power spectrum. The
TN with different ID are uncorrelated. TN describe noises
produced not by ground, but e.g. by cooling water
QF1
QD0
BSM & BPM
Support
table
TF1(f)
xg(s1)
TF2(f)
xg(s2)
TF3(f)
In Freq. domain, vibration of
QF1 would be:
xg*TF1(f)+xTN
xg(s3)
Ground
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Example of model with stabilization
• Assume this perfect
stabilization curve
(phase =0)
• Assume that all FD
magnets and also the
IP BPM are placed
on support with this
TF
• Consider TF only in
vertical plane (Y)
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With and without idealized
stabilization
GM C, no stabilization
GM ATF, no stabilization
GM C, with stabilization
GM ATF, with stabilization
• Interesting that this particular stabilization curve does not
help for model C. Probably because near 1Hz in model C
there is a lot of coherence, but stabilization brakes it.
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TF and TN from measurements
• If there no TN on the table, then ground-table coherence is exactly 1
• Coherence <1 is due to noise of sensor or additional uncorrelated
vibration on the table (TN)
• Need to figure out using different sensors
• Also, to find TF, need to know Re and Im parts or amplitude & phase.
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Next to do
• Cross check and continue modeling with
other tools like Lucretia
• Verify ground motion model, by “measuring”
generated motion, comparing its spectrum
and correlation with ATF data
• Study effect of non-ideal stabilization
• Determine and use TF for table placed on
ground
• Include and study effect of additional noises
generated on the table
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