Commissioning of the 1 PW arm at 1 Hz repetition rate using a tape target system


P.I. M.O. Cernaianu
On the 4th of November, as part of the 1 PW commissioning of the ELI-NP HPLS, the ELI-NP team performed a TNSA experiment at high repetition rate, using a tape target. The laser shots were done up to full energy (~24 J) and at the max repetition rate of the system (1 Hz). The laser was focused down to a spot of about 3.6 ?m FWHM onto a 13 μm thick Kapton ribbon running at 11 mm/s. The tape drive system has been developed by the STFC laboratories, under the IMPULSE project collaboration. The experiment was done in partnership with ELI-Beamlines within the framework of the IMPULSE project.

An imaging plate positioned on a motorized stage was continuously running to grab the proton spectra (see in Fig 2b, 2c). We obtained a proton cutoff energy of about 7 MeV with a shot-to-shot energy variation of ±5% for 2 J laser energy. For the shots at full energy (~20 J laser energy in this case), the proton cutoff energy was 25 MeV with ±10% energy fluctuation.

Fig. 1 - The tape drive system set up in the C1 chamber of the E5 1 PW experimental area of ELI-NP

Fig. 2 - a) Sequence of shots on the tape with 2 J laser energy. b) proton traces on the image plate obtained with 33 consecutive shots for 2 J laser energy delivered at 1 Hz. c) proton traces of 7 shots delivered at 20 J and 1 Hz