Synchroscan streak camera imaging at a 15-MeV photoinjector with emittance exchange

Abstract

At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the ebeam micropulse have been done in the past with a fast single-sweep module of the Hamamatsu C5680 streak camera 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 to provide synchronous summing capability with less than 1.5-ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of ~1 ps over 10s of minutes. These steps allowed us to measure both the UV laser pulse train at 263 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 0.25-1 nC per micropulse. The phase-locked delay box allowed us to assess chromatic temporal effects and instigated another upgrade to an all-mirror input optics barrel. In addition, we added a slow sweep horizontal deflection plug-in unit to provide dual-sweep capability for the streak camera. We report on a series of measurements made during the commissioning of these upgrades including bunch-length and phase effects using the emittance exchange beamline and simultaneous imaging of a UV drive laser component, OTR, and the 800-nm diagnostics laser.

Submicropulse electron-beam dynamics correlated with short-range wakefields in Tesla-type superconducting rf cavities

“…Images were captured from the streak camera using the Prosilica 1.3-Mpixel readout camera with 2=3 "format, and these were analyzed both online and with an offline MATLAB-based ImageTool processing program based on fitting the slice and projected experimental profiles to Gaussian profiles [9]. Bunch-length measurements using these techniques have been reported previously from the A0 facility [10] and FAST streak-camera system commissioning at 20 MeV [11]. Here, the focus is on the observation of the electron distribution's centroid shift within a micropulse and the projected transverse (spatial) and longitudinal (temporal) sizes.…”

Advanced Beamline Design for Fermilab's Advanced Superconducting Test Accelerator

“…At ASTA the availability of a superconducting linac coupled with a non-interceptive radiation-generation mechanism (e.g., diffraction radiation [47], [48]) could lead to the production of single-cycle THz pulses repeated at 3 MHz over 1-ms. As an example we consider the worst-case scenario of a fully compressed 3.2-nC bunch; the dependency of the BFF over frequency appears in Figure 4.22 (left plot). The BFF starts to take off at frequency lower than f ≃ 1 THz, thereby supporting the generation of coherently-enhanced radiation at these frequencies.…”

Synchronization and characterization of an ultrashort pulse laser for photoemission and electron-beam diagnostics studies at a radio frequency photoinjector

“…The streak camera is equipped with synchroscan and phase lock loop (PLL) electronics to maintain synchronization with the 81.25-MHz subharmonic of the A0PI master oscillator [12]. This can be operated at four sweep rates to adjust temporal range and resolution.…”