Interaction of High-Intensity Femtosecond Radiation With Gas Cluster Beam: Effect of Pulse Duration on Joint Terahertz and X-Ray Emission

Abstract

This paper studies the phenomenon of joint generation of terahertz (THz) and X-ray radiation in the argon nanocluster jet under the action of high-power femtosecond laser pulse in both the single-color and dual-color regimes. It was discovered that in a gas cluster beam the pulse duration affects the properties of THz and X-ray emission differently. For the same given total energy of optical pulse in the dual-color excitation regime of cluster medium, more than a five times increase of THz radiation power was observed in comparison with the single-color regime, while the conversion efficiency to the argon X-ray K-line reached 7 × 10 −6 and remained unchanged. The possibility of separation of contributions of different beam components into the THz signal was demonstrated experimentally, using contributions from clusters and nonclustered gas as an example. We suggest an interpretation of experimental results based on a theoretical model of cluster ionization that self-consistently predicts the level and dynamics of ionization and electron temperature in the clusters.Index Terms-Femtosecond laser pulses, gas cluster beam/jet, high-intensity radiation, nanoplasma, quadrupole radiation, terahertz (THz) and X-ray emission.

Giant Enhancement of THz Wave Emission under Double-Pulse Excitation of Thin Water Flow

“…Finely-synchronized THz wave and X-ray radiation is required for their complimentary usage, for instance, for imaging [42]. This study explores the enhancement of THz wave radiation from the simultaneous THz/X-ray emission source which were first reported in gas, glass, and water [32,43,44].…”

Dual THz Wave and X-ray Generation from a Water Film under Femtosecond Laser Excitation

“…Gases [ 15 , 16 , 17 , 18 ], atomic clusters [ 19 , 20 , 21 ] and solids [ 22 , 23 ] have been used as targets for THz wave emission from the laser-induced plasmas. Fast electron motions accelerated by laser ponderomotive forces [ 15 , 18 , 19 ] and the four-mixing process induced by two-colour excitation [ 17 ] have been proposed as THz emission mechanisms from laser-induced plasmas.…”

“…Simultaneous emission of the THz wave and X-ray and combined usages of THz wave and X-ray pulses have recently been introduced as readily-available table-top realisations [ 41 ]. To date, experiments on such simultaneous emission with a Al-coated glass substrate [ 15 ] and gas targets, He [ 15 ] or Ar [ 20 ], in vacuum chambers were reported. This type of work, though the numbers of such reports are still quite limited, will be the first step for the discussion of the conversion of near-IR (eV) laser photon energy into photons at the two ends of the spectrum, several-keV (X-ray) and meV (THz wave), and will contribute well to other fields like material sciences.…”

Enhancement of X-ray emission from nanocolloidal gold suspensions under double-pulse excitation

“…Recently, similar experiments with narrowly focussed fs-laser pulses for terahertz-wave emission from water flow were reported [ 51 ], while terahertz emission from various solutions under broad focusing was already known [ 52 ]. Simultaneous emission of X-ray and terahertz waves from gas clusters in vacuum [ 53 – 54 ], Al-coated glass substrates in vacuum [ 54 ], or a distilled water flow in air under double-pulse excitation [ 16 ] were independently reported. A simultaneous emission of X-ray and terahertz wave radiation is highly expected for novel pump–probe experiments [ 55 ].…”