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Ruan, J.

Paper Title Page
TUPTPF062 Initial Synchroscan Streak Camera Imaging at the A0 Photoinjector 258
 
  • A.H. Lumpkin, J. Ruan
    Fermilab, Batavia
 
 

The Fermilab A0 photoinjector facility consists of an L-band photocathode (PC) gun and a 9-cell SC rf accelerating structure which combine to generate up to 16-MeV electron beams. The drive laser operates at 81.25 MHz, although the micropulse structure is usually counted down to 9 MHz. Bunch length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a single-sweep module of the Hamamatsu C5680 streak camera system with an intrinsic shot-to-shot trigger jitter of 10 to 20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz and a phase-locked delay box to provide synchronous summing capability with less than 1.5 ps FWHM trigger jitter. This allows us to measure both the UV laser pulse train at 244 nm and the e-beam via optical transition radiation (OTR). Due to the low OTR signals, we typically summed over 50 micropulses with 1 nC per micropulse. We also identified a significant e-beam micropulse elongation effect from 10 to 30 ps (FWHM) as the charge was varied from 1 to 5 nC. This is attributed to space-charge effects in the PC gun as reproduced by ASTRA calculations.