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12717

Role of Loss Mechanisms in the Breakdown of Argon Irradiated with IR Laser Radiation

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Last updated: 23 Dec 2024

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Abstract

Threshold intensity measurements of the breakdown of argon are numerically analyzed. The breakdown is induced by a Nd: YAG laser radiation at wavelength of  1064 nm and pulse duration of 8.5  ns.The investigation considered argon over pressure range extended from 25 torr- 760 torr.The measured threshold intensity corresponding to this pressure range is found to vary between 5.4xl011 W/cm2 and 1.1xl011 W/cm2. These are the experimental conditions given by Davis et al. [1]. The analysis considers an electron cascade model given previously by Evans and Gamal (1980) [2] and modified by Gamal and Shafik [3]. The model solves the time dependent energy equation numerically in addition to a set of equations describing the rate of change of the formed excited states population.  For realistic results, most of the physical processes that might take place during the interaction of laser radiation with the gas are included in the modified model. The calculated threshold intensity showed reasonable agreement with the measured values over the tested pressure range. The obtained values of the electron energy distribution function as well as the time variation of the electrons density  for selected gas pressures,  revealed that photo-ionization of the formed excited states plays a minor role for electron generation and  plasma formation over the studied gas pressure range. Collisional ionization is the main mechanism responsible for the breakdown process.  The loss process, due to electron diffusion, is found to have significant contribution only at pressures ≤ 40 torr. On the other hand, the recombination process is acting in a pronounced manner for the higher pressure regime.

DOI

10.21608/ajnsa.2018.12717

Keywords

Laser induced argon plasma, inverse Bremsstrahlung absorption, electronic excitation, electron recombination

Authors

First Name

O.

Last Name

Nassef

MiddleName

-

Affiliation

National Institute of Laser Enhanced Sciences, Cairo University, Giza, Egypt

Email

onassef@niles.edu.eg

City

-

Orcid

-

First Name

Yosr

Last Name

Gamal

MiddleName

-

Affiliation

National Institute of Laser Enhanced Sciences, Cairo University, Giza, Egypt

Email

ygamal@niles.edu.eg

City

-

Orcid

-

Volume

51

Article Issue

4

Related Issue

875

Issue Date

2018-10-01

Receive Date

2017-06-14

Publish Date

2018-10-01

Page Start

118

Page End

125

Print ISSN

1110-0451

Online ISSN

2090-4258

Article File

AJNSA_Volume 51_Issue 4_Pages 118-125.pdf

PDF . 332.7kB

Link

https://ajnsa.journals.ekb.eg/article_12717.html

Detail API

https://ajnsa.journals.ekb.eg/service?article_code=12717

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13

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Original Article

Type Code

455

Publication Type

Journal

Publication Title

Arab Journal of Nuclear Sciences and Applications

Publication Link

https://ajnsa.journals.ekb.eg/

MainTitle

Role of Loss Mechanisms in the Breakdown of Argon Irradiated with IR Laser Radiation

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Article

Created At

22 Jan 2023