Plasma Diagnostics I

Typical E-FISH measurements are extremely time consuming due to a large number of accumulations required to achieve a high signal-to-noise ratio and due to the low repetition rate of commercially available lasers (10 Hz). A method to accelerate the measurement speed of the E-FISH measurements was demonstrated in [1]. There, beam splitters and delay lines were used to produce several consecutive laser pulses from a single laser shot. In the present work, an alternative approach is used. The laser pulse is recycled by trapping it in an optical laser loop. It allows to achieve high repetition rates of the laser pulses with high energy using a much simpler optical arrangement. Test measurements [2] demonstrate that 8 sub-pulses can be generated easily, meaning 8 times faster measurements. An optimized setup would allow to accelerate the measurements even further. In addition, it has been shown that the polarization sensitive nature of the E-FISH technique allows to tailor the strength of the signal within the pulse train. This option is suggested to rationally use the available bit-depth of the detector in case of a high dynamic range of the electric field time trace.

 

[1] Chen T Y et al. 2024 Appl. Phys. Lett. 125 054102

[2] N. D. Lepikhin et al.  2025 J. Phys. D: Appl. Phys. 58 205206

Funding acknowledgement

The work is supported by the DFG funded SFB1316 Project 'Transient atmospheric plasmas—from plasmas to liquids to solids'.