Pi laser jitter measurements
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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

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Pi laser jitter measurements

PI laser jitter measurements

Data taken on 11th April 2013


Pi laser jitter measurements

  • 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)


Pi laser jitter measurements

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


Pi laser jitter measurements

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


Pi laser jitter measurements

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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