Improving the spectral intensity of aluminum plasma by applied-magnetic field in laser-induced breakdown spectroscopy
Introduction
Laser-induced breakdown spectroscopy (LIBS) is one of the most effective technique which uses a powerful laser beam onto the sample material and generates the plasma that consisting of atoms, electrons, ion and excited species. The optical emission spectrum during the excitation of plasma provides necessary information about the composition of material, which can be utilized for plasma diagnostic and analytical purposes [1]. LIBS is a spectroscopic technology that has precedence over other traditional techniques since it is applicable for all types of materials [2], [3], [4]. This tool carries the ability of multi-elemental analysis, real-time response, experimental flexibility and simplicity [5]. It has ascertained its applications in the fields of biotechnology [6], environmental monitoring [7], remote sensing industry [8] and substantial analysis [9]. The performance of traditional LIBS can be improved to enhance the intensity of spectral lines from plasma. Different procedures that can be utilized to improve the sensitivity of LIBS, include in-transparent laser occurrence, double pulse, nanoparticle-enhanced LIBS, usage of purge gas, spatial and magnetic confinements [10], [11], [12], [13], [14], [15] etc.
The use of magnetic field in LIBS to enhance the plasma’s optical emission is a simple and inexpensive method. This subject has useful applications in nanoparticle production, debris dispersal, thin film removal, provision of intense ultra-violet (EUV) lithographic sources along with surface amendments [16], [17], [18], [19], [20]. The expansion of laser-induced plasma (LIP) across a magnetic field involves various physical phenomena, like, plume imprisonment, change of thermal energy of plasma to kinetic energy, ion acceleration, emission development and plasma instabilities [21]. The plasma-magnetic field interactions help to comprehend the inertial imprisonment fusion plasmas [22], [23], [24], aids in improvement of solar wind and astrophysical jets [25], benefits in promulgation of bipolar flows and charged particle beams linked to young stellar objects [26], [27]. High-intensity pulsed magnetic fields were widely used to enhance the emission in LIBS [28], [29], [30], [31]. Previously, different researchers intended to understand the enhancement effects in LIP across an-applied magnetic field. For instance, Arshad et al. [32] studied the influence of transverse magnetic field (0.5 T) on the emission spectra of graphite plasma as a function of laser fluence in background ambient gas. The laser fluence was ranged from 0.4 to 2.9 J/cm2 under two different environments of air and Ar at a pressure of 150 and 760 torr. It was found that the plasma intensity, electron temperature and electron number density were enhanced at all fluences and environmental conditions due to the application of magnetic field. This effectiveness of plasma parameters was ascribed to the joule heating effect and magnetic confinement. Rai et al. [33] explored the role of steady magnetic field (∼5 kilogauss) on LIBS emission from certain elements (Mn, Mg, Cr and Ti) in aqueous solution. Nearly 1.5 times higher enhancement in the emission intensity was seen in the presence of magnetic field. Moreover, the temporal profile for Mg line emission exhibited a significant enhancement between 2 and 7 µs time delays due to the presence of magnetic field. This enhancement in plasma emission is associated to an increase in the rate of recombination due to the existence of magnetic field. Recently, Abbasi et al. [34] reported an optical emission improvement from palladium (Pd) sample by applying magnetic field-assisted laser-induced breakdown spectroscopy (MF-LIBS). A significant enhancement (3–4 fold) in plasma emission was observed at low values of laser fluence (12.6 J/cm2) for both Pd-I and Pd-II lines. The plasma parameters; the temperature and electron density were also considerably increased in the presence of magnetic field as compared to the without case. In another study of plasma enhancement effects due to the applications of magnetic field, Liu et al. [35] employed a Nd:YAG laser to measure the optical emission from Al-alloy target at different ambient air pressures. They observed that the spectral emission from Al and Li lines was significantly improved under the variation of magnetic field strength. Further, the temporal evolution of different plasma parameters like, electron temperature, electron number density, expansion velocity and plasma lifetime were all significantly affected by the field.
In this report, we explore the role of an applied-magnetic field on the emission aspects of laser-induced Al plasma with different air pressures and several time delays, in order to optimize the spectroscopic performance, and investigate the influence of magnetic field on the plasma parameters such as Te & ne. The main objective of the study is to improve the spectroscopic performance of LIBS by utilizing a combination of magnetic field and ambient air pressures at different time delays. A Nd:YAG laser in its fundamental wavelength (1064 nm) was employed to generate the plasma plume inside the vacuum chamber and its optical emission recorded with a OES technique. The field strength of 0.5 T was generated with the help of two permanent magnets and measured with a gauss tesla meter.
Section snippets
Experiment and procedures
The setup for the LIBS experiment is shown in Fig. 1. A Nd:YAG laser (Q-switched) was employed to ablate the Al sample in a stain-less steel chamber, with the repetition rate of 10 Hz, pulse width of 8 ns and 1064 nm wavelength. The size of Al sample was 3 mm and 1.5 mm in length and thickness, respectively. For smooth movement inside the magnetic field, sample’s width was chosen to be of small size. The laser beam energy of 200 mJ was concentrated on the target sample by using simple quartz
Discussion and results
Fig. 2(a) & 2(b) illustrates the influence of applied-magnetic field on signal strength of laser-induced Al plasma at air pressure of 100 Pa and 500 Pa, respectively. Both LIBS spectra were recorded at a delay time of 100 ns and 200 ns in the absence and presence of magnetic field. The significant number of emission peaks were obtained in each spectrum of Al plasma. It was observed that the optical intensity of emitted lines was higher at 500 Pa as compared to the 100 Pa. At high pressure
Conclusions
In conclusion, we studied the influence of external magnetic field (0.5 T) on LIBS emission in order to improve the spectroscopic performance from a solid aluminum target. The enhancement factors based on the emission intensity were calculated by varying the ambient pressures at several delay times. It was found that intensities of spectral lines in a magnetic field increased at low pressure and shorter delay time. For instance, at lower pressure (100 Pa) and shorter delay time (100 ns), the
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We thank Dr. Haroon Asghar (National center for Physics) for useful support during the study.
References (47)
Analysis of environmental lead contamination: comparison of LIBS field and laboratory instruments
Spectrochim. Acta B
(2001)- et al.
Wavelength-shift investigation of optical emission from nanosecond pulsed laser ablated metal Al
Optik
(2013) - et al.
Determination of colloidal iron in water by LIBS
Anal. Chim. Acta
(1995) - et al.
Ultrashort double pulse laser ablation of metals
Thin Solid Films
(2004) - et al.
Effects of cross-magnetic field on thin film preparation by pulsed Nd:YAG laser deposition
Thin Solid Films
(2000) - et al.
Enhancement of optical signal and characterization of palladium plasma by magnetic field-assisted laser-induced breakdown spectroscopy
Optik
(2020) Laser-induced breakdown spectroscopy of gas mixtures of air, CO2, N2, and C3H8 for simultaneous C, O, H, and N measurement
Appl. Opt.
(2003)- et al.
Combined effects of magnetic field and ambient gas condition in the enhancement of laser-induced breakdown spectroscopy signal
Optik
(2018) - A. Hussain, H. Asghar, M. Tanveer, M. Zafard, Qura-Tul-Ain, and Z. Nawaz, Spectral emission improvement by combining...
- et al.(2013)
Femtosecond time resolved laser induced breakdown spectroscopy for detection and identification of bacteria: a comparison to the nanosecond regime
J. Appl. Phys.
Laser induced breakdown spectroscopy for the environmental determination of total C and N in soils
Appl. Opt.
Limitations of signal averaging due to temporal correlation in laser remote-sensing measurements
Appl. Opt.
Effect of sampling geometry on elemental emission in LIBS
Appl. Spectrosc.
Nanoparticle-enhanced laser- induced breakdown spectroscopy of metallic samples
Anal. Chem.
LIBS using dual and ultra-short laser pulses
Fresenius J. Anal. Chem.
Collimation of laser produced plasmas using axial magnetic field
Laser Part. Beams
Development of laser-induced breakdown spectroscopy for microanalysis applications
Laser Part. Beams
Plasma physics and radiation hydrodynamics in developing an extreme ultraviolet light source for lithography
Phys. Plasmas
Laboratory experiments on Alfvén waves caused by rapidly expanding plasmas and their relationship to space phenomena
J. Geophys. Res. Space Phys.
Debris mitigation in a laser-produced tin plume using a magnetic field
J. Appl. Phys.
Confinement and dynamics of laser produced plasma expanding across a transverse magnetic field
Phys. Rev. E
Inertial fusion energy target output and chamber response: calculations and experiments
Phys. Plasmas
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