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4Joint generation of THz radiation and electron flow in gas-cluster media under laser excitation
A.V. Balakin1*, N.A. Kuzechkin2, P.M. Solyankin2, A.P. Shkurinov1
1-Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia 2- National Research Centre "Kurchatov Institute", Moscow, Russia
Complex study of interaction of high intense femtosecond laser pulses with gas-cluster targets is of a great interest to reveal fundamental features of the process and to next implementation of the results in plenty of applications, such as efficient generation of radiation in an extremely wide spectral range from X-ray through deep-UV to THz, as well as generation and acceleration of flow of fast charged particles [1-6]. Usually, an adiabatic expansion of gas into vacuum through a special supersonic nozzle is applied to form gas-cluster nanoscale targets. The resulted gas-cluster jet inherits a unique feature as high local and relatively low average density of matter, and effectively interacts with high-intensity femtosecond laser pulses.
Here we present and discuss our recent results on study the processes of generation of THz radiation and electron flow occurring jointly in gas-cluster jet under laser excitation. Ti:Sapphire laser system produced pulses at 1 kHz repetition rate with 35 fs duration and energy of up to 6 mJ per pulse was used as an excitation source in our experiments. A variety of gases and gas mixtures were examined to form gas-cluster target, and SF6:Ar gas mixture (molar ratio 1:8) was selected finally, as it demonstrated the better electrons yield. We have investigated properties and measured base characteristics of generated electron beam and THz radiation under various conditions of the gas-cluster target excitation and parameters of the laser radiation. In particularly, it was found that optimal position of laser focus in the gas-cluster jet differs significantly for the effective generation of electron flow and THz radiation. Another remarkable result is that varying of polarization state of laser radiation from linear to circular results in decrease of electrons yielding whereas the THz yielding increases under the same change.
This work was funded partly within the state assignment of NRC "Kurchatov Institute" and in part by the Ministry of Science and Higher Education of the Russian Federation in framework of Agreement № 075-15-2022-830 from 27 May 2022.
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