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PI laser jitter measurements. Data taken on 11 th April 2013 . 11th April 2013 Quadrant photodiode mounted on virtual cathode table P hotodiode has ‘bandwidth’ of 150 kHz M easured 100 μs trains @ 10 Hz, 16 MHz within train ? pulse power (LA = 0.65)?

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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, charge

Raw scope data

Units on vertical axis are arbitrary

Horizontal units are nanoseconds

zoomed trace

0.1 ns sample spacing

individual pulses not discernible


Data 5 shots
Data (5 shots)

charge

x

charge

x

y


DFT

charge

x

charge

x

y


Reminder of bpm variations seen in 2012
REMINDER oF BPM variations seen in 2012


Nominal lattice
Nominal Lattice

3133 AR1

  • FEL-like set-up.

  • Nominal ar1q1/4 = 2.2 A


3205 inj bpm 01 inj bpm 01 fast bunch electronics raw data
3205 INJ-BPM-01 INJ-BPM-01fast bunch electronics RAW DATA

x y charge

15 pC

21 pC

30 pC

43 pC

60 pC

Note significant droop in all 3 observables

Small transient at start of train


Bpm frequency content 0 1 mhz

3205 INJ-BPM-01

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


Inj bpm 03

3191 INJ-BPM-03

INJ-BPM-03

  • Nominal FEL set-up. ‘Typical’ 1-shot BPM train measurement

x (mm), y (mm), sum voltage

Fourier transform vertical axis amplitude^2

horizontal axis frequency in MHz

Fourier transforms done after subtracting mean values

100 KHz obvious in x

y very similar to sum_pickup voltage

6 Mhz present, smaller than 100 KHz

‘usual’ 300 KHz present


INJ-BPM-02 Shot to Shot Variation

3243

After steering to get more central y position on INJ-BPM-02

Again, the low frequency (< 200 kHz) content does vary a bit shot-to-shot


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