Modeling Jitter in Continuous-Time ΣΔ · • For an accurate simulation: T. step
PI laser jitter measurements
description
Transcript of PI laser jitter measurements
PI laser jitter measurements
Data taken on 11th April 2013
• 11th April 2013• Quadrant photodiode mounted on virtual
cathode table• Photodiode has ‘bandwidth’ of 150 kHz • Measured 100 μs trains @ 10 Hz, 16 MHz
within train ? pulse power (LA = 0.65)?• Measured x-y, and sum for several single
shots, on hi-res scope (1 Gsample/sec)
Sample single shot x,y, chargeRaw scope dataUnits on vertical axis are arbitraryHorizontal units are nanoseconds
20 000 40000 60 000 80 000 100 000
0.2
0.4
0.6
0.8
1.0
1.2
zoomed trace0.1 ns sample spacingindividual pulses not discernible
Data (5 shots)x
x
charge
chargey
DFTx
x
charge
chargey
REMINDER OF BPM VARIATIONS SEEN IN 2012
Nominal Lattice• FEL-like set-up. • Nominal ar1q1/4 = 2.2 A
3133 AR1
3205 INJ-BPM-01 INJ-BPM-01 fast bunch electronics RAW DATA
Note significant droop in all 3 observables
Small transient at start of train
x y charge15 pC
21 pC
30 pC
43 pC
60 pC
BPM frequency content, 0 – 1 MHz
Strong 300 kHz
100 kHz not obviously apparent
Norrmalised the x,y DFT so that the amplitudes are in mm
3205 INJ-BPM-01
INJ-BPM-03• Nominal FEL set-up. ‘Typical’ 1-shot BPM train measurement
100 KHz obvious in xy very similar to sum_pickup voltage6 Mhz present, smaller than 100 KHz‘usual’ 300 KHz present
x (mm), y (mm), sum voltageFourier transform vertical axis amplitude^2horizontal axis frequency in MHzFourier transforms done after subtracting mean values
3191 INJ-BPM-03
INJ-BPM-02 Shot to Shot Variation
Again, the low frequency (< 200 kHz) content does vary a bit shot-to-shot
After steering to get more
central y position on INJ-BPM-02
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