Initiation of air ionization by ultrashort laser pulses: Evidence for a role of metastable-state air molecules

A. V. Bulgakov; I. Mirza; N. M. Bulgakova; V. P. Zhukov; R. Machulka; O. Haderka; E. E.B. Campbell; T. Mocek

doi:10.1088/1361-6463/aac56a

Initiation of air ionization by ultrashort laser pulses: Evidence for a role of metastable-state air molecules

A. V. Bulgakov, I. Mirza, N. M. Bulgakova, V. P. Zhukov, R. Machulka, O. Haderka, E. E.B. Campbell, T. Mocek

Department of Physics

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

Transmission measurements for femtosecond laser pulses focused in air with spectral analysis of emission from the focal region have been carried out for various pulse energies and air pressures. The air breakdown threshold and pulse attenuation due to plasma absorption are evaluated and compared with calculations based on the multiphoton ionization model. The plasma absorption is found to depend on the pulse repetition rate and is considerably stronger at 1 kHz than at 1-10 Hz. This suggests that accumulation of metastable states of air molecules plays an important role in initiation of air breakdown, enhancing the ionization efficiency at high repetition rates. Possible channels of metastable-state-assisted air ionization and the role of the observed accumulation effect in laser material processing are discussed.

Original language	English
Article number	25LT02
Journal	Journal of Physics D: Applied Physics
Volume	51
Issue number	25
DOIs	https://doi.org/10.1088/1361-6463/aac56a
State	Published - 1 Jun 2018

Bibliographical note

Publisher Copyright:
© 2018 IOP Publishing Ltd.

Keywords

femtosecond laser pulses
laser-induced air breakdown
metastable-state molecules
multiphoton ionization

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10.1088/1361-6463/aac56a

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title = "Initiation of air ionization by ultrashort laser pulses: Evidence for a role of metastable-state air molecules",

abstract = "Transmission measurements for femtosecond laser pulses focused in air with spectral analysis of emission from the focal region have been carried out for various pulse energies and air pressures. The air breakdown threshold and pulse attenuation due to plasma absorption are evaluated and compared with calculations based on the multiphoton ionization model. The plasma absorption is found to depend on the pulse repetition rate and is considerably stronger at 1 kHz than at 1-10 Hz. This suggests that accumulation of metastable states of air molecules plays an important role in initiation of air breakdown, enhancing the ionization efficiency at high repetition rates. Possible channels of metastable-state-assisted air ionization and the role of the observed accumulation effect in laser material processing are discussed.",

keywords = "femtosecond laser pulses, laser-induced air breakdown, metastable-state molecules, multiphoton ionization",

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T2 - Evidence for a role of metastable-state air molecules

AU - Bulgakov, A. V.

AU - Mirza, I.

AU - Bulgakova, N. M.

AU - Zhukov, V. P.

AU - Machulka, R.

AU - Haderka, O.

AU - Campbell, E. E.B.

AU - Mocek, T.

PY - 2018/6/1

Y1 - 2018/6/1

N2 - Transmission measurements for femtosecond laser pulses focused in air with spectral analysis of emission from the focal region have been carried out for various pulse energies and air pressures. The air breakdown threshold and pulse attenuation due to plasma absorption are evaluated and compared with calculations based on the multiphoton ionization model. The plasma absorption is found to depend on the pulse repetition rate and is considerably stronger at 1 kHz than at 1-10 Hz. This suggests that accumulation of metastable states of air molecules plays an important role in initiation of air breakdown, enhancing the ionization efficiency at high repetition rates. Possible channels of metastable-state-assisted air ionization and the role of the observed accumulation effect in laser material processing are discussed.

AB - Transmission measurements for femtosecond laser pulses focused in air with spectral analysis of emission from the focal region have been carried out for various pulse energies and air pressures. The air breakdown threshold and pulse attenuation due to plasma absorption are evaluated and compared with calculations based on the multiphoton ionization model. The plasma absorption is found to depend on the pulse repetition rate and is considerably stronger at 1 kHz than at 1-10 Hz. This suggests that accumulation of metastable states of air molecules plays an important role in initiation of air breakdown, enhancing the ionization efficiency at high repetition rates. Possible channels of metastable-state-assisted air ionization and the role of the observed accumulation effect in laser material processing are discussed.

KW - femtosecond laser pulses

KW - laser-induced air breakdown

KW - metastable-state molecules

KW - multiphoton ionization

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Initiation of air ionization by ultrashort laser pulses: Evidence for a role of metastable-state air molecules

Abstract

Bibliographical note

Keywords

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