Plasma wakefield acceleration is nowadays very attractive in terms of accelerating gradient, able to overcome conventional accelerators by orders of magnitude. However, this poses very demanding requirements on the accelerator stability to avoid large instabilities on the final beam energy. In this study we analyze the correlation between the driver-witness distance jitter (due to the RF timing jitter) and the witness energy gain in a plasma wakefield accelerator stage. Experimental measurements are reported by using an electro-optical sampling diagnostics with which we correlate the distance between the driver and witness beams prior to the plasma accelerator stage. The results show a clear correlation due to such a distance jitter highlighting the contribution coming from the RF compression.

Plasma wakefield acceleration is nowadays very attractive in terms of accelerating gradient, able to overcome conventional accelerators by orders of magnitude. However, this poses very demanding requirements on the accelerator stability to avoid large instabilities on the final beam energy. In this study we analyze the correlation between the driver-witness distance jitter (due to the RF timing jitter) and the witness energy gain in a plasma wakefield accelerator stage. Experimental measurements are reported by using an electro-optical sampling diagnostics with which we correlate the distance between the driver and witness beams prior to the plasma accelerator stage. The results show a clear correlation due to such a distance jitter highlighting the contribution coming from the RF compression.

RF photo-gun are the electron beam sources of FELs or Compton facilities. They are key components and, presently, the RF technology mostly used for these devices is the S band (3 GHz) with typical cathode peak fields of 80-120 MV/m and repetition rates lower than 100-120 Hz. An innovative C-Band (5.712 GHz) RF gun aiming at reaching cathode peak field larger than 160 MV/m, with repetition rates exceeding the 400 Hz, has been designed, realized and high power tested in the context of the European I.FAST and INFN Commission V projects. It is a 2.5 cell standing wave cavity with a four-port mode launcher, designed to operate with short RF pulses (300 ns). Its realization is based on the new brazed-free technology developed and successfully tested at INFN. In the paper, after a short overview of the design and RF gun capabilities, we illustrate the realization procedure and the results of the high power RF tests that have been done at the high power C band test facility at PSI (Switzerland).