Time evolution of plasma afterglow produced by femtosecond laser pulses

Journal Article · Mon Nov 15 00:00:00 EST 2004 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1803920· OSTI ID:20658033

Martirosyan, A E; Altucci, C; Bruno, A; De Lisio, C; Porzio, A; Solimeno, S ^[1]

---

1. Institute for Physical Research, Armenian Academy of Sciences, Ashtarak, Armenia and Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Naples (Italy)

In this paper we investigate the time evolution of laser plasmas generated in atmospheric air by ultrashort (100 fs) laser pulses. The detected quantity is the time integrated photon yield emitted by the plasma, which monotonically depends on the amount of energy transferred by the laser pulses to the plasma. We study the effect of a preionizing pulse on the efficiency of plasma generation by a second 'probe' pulse and demonstrate that preionization results into a considerable increase of the overall photon yield emitted by the plasma. An explanation of this phenomenon relies on the fact that the larger the electron density experienced by the probe pulse, the more effective the energy transfer from the probe pulse to the residual plasma, the more intense is the light from the plasma. With this concept in mind and by relying on a pump-probe technique, we also measure the total photon yield emitted by the plasma produced by the combination of the two pulses, as a function of their relative delay time. We observe a considerable increase in the plasma brightness for delay times much longer than the laser pulse duration. This phenomenon is associated with an increase of the electron density even after the end of the pump pulse, due to secondary electron-impact ionization originating from highly-energetic primary photoelectrons, and to superelastic electron-molecule collisions. We also develop a simplified model describing the time evolution of the electron and ion densities and the electron temperature. From the calculated time evolution of these quantities produced by a single laser pulse, we can predict with a good approximation the main features of the plasma generated by an ultrashort laser pulse.

• OSTI ID: 20658033
• Journal Information: Journal of Applied Physics, Vol. 96, Issue 10; Other Information: DOI: 10.1063/1.1803920; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AFTERGLOW
AIR
BRIGHTNESS
ELECTRON DENSITY
ELECTRON TEMPERATURE
ELECTRON-MOLECULE COLLISIONS
ENERGY TRANSFER
EVOLUTION
ION DENSITY
ION TEMPERATURE
IONIZATION
LASERS
PHOTON EMISSION
PHOTONS
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA PRODUCTION
PROBES
VISIBLE RADIATION