Density oscillations in laser produced plasma decelerated by external magnetic field

N, V; Shukla, Mayank; Pant, H. C.

doi:10.1007/s12043-000-0044-y

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…21,22 The average energy of laser produced ion at I = 10 8 Wcm −2 is in the range of KeV. Torrisi et al 23 reported average energy of laser produced charge state 1 + are increased ranging from 18% to 161% in the presence of external magnetic field.…”

Section: A Ion Energy and Dose Measurementsmentioning

confidence: 99%

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Modifications in surface, structural and mechanical properties of brass using laser induced Ni plasma as an ion source

et al. 2016

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Laser induced Ni plasma has been employed as source of ion implantation for surface, structural and mechanical properties of brass. Excimer laser (248 nm, 20 ns, 120mJ and 30 Hz) was used for the generation of Ni plasma. Thomson parabola technique was employed to estimate the energy of generated ions using CR39 as a detector. In response to stepwise increase in number of laser pulses from 3000 to 12000, the ion dose varies from 60 × 1013 to 84 × 1016 ions/cm2 with constant energy of 138 KeV. SEM analysis reveals the growth of nano/micro sized cavities, pores, pits, voids and cracks for the ion dose ranging from 60 × 1013 to 70 × 1015 ions/cm2. However, at maximum ion dose of 84 × 1016 ions/cm2 the granular morphology is observed. XRD analysis reveals that new phase of CuZnNi (200) is formed in the brass substrate after ion implantation. However, an anomalous trend in peak intensity, crystallite size, dislocation line density and induced stresses is observed in response to the implantation with various doses. The increase in ion dose causes to decrease the Yield Stress (YS), Ultimate Tensile Strength (UTS) and hardness. However, for the maximum ion dose the highest values of these mechanical properties are achieved. The variations in the mechanical properties are correlated with surface and crystallographical changes of ion implanted brass.

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Section: A Ion Energy and Dose Measurementsmentioning

confidence: 99%

“…As a result plume confinement occurs. 28 There is extensive collision of plasma species because of confinement of plasma through the magnetic field. As a result more plasma constituents are formed in the confinement region.…”

Section: A Ion Energy and Dose Measurementsmentioning

confidence: 99%

Modifications in surface, structural and mechanical properties of brass using laser induced Ni plasma as an ion source

et al. 2016

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“…A saturation in the x-ray emission was also noticed in the form of change in the slope with an increase in the laser intensity. However this saturation was found to be correlated with the loss of plasma energy in form of the generation of an instability and high energy particles in the plasma along with emission of high energy x-rays (Rai et al, 2000a, Rai et al, 2000b.…”

Section: Laser Absorption and Shielding Effect In Plasmamentioning

confidence: 99%

Theoretical aspect of enhancement and saturation in emission from laser produced plasma

N.¹

2012

Laser Part. Beams

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This paper presents a simplified theoretical model for the study of emission from laser produced plasma to better understand the processes and the factors involved in the onset of saturation in plasma emission as well as in increasing emission due to plasma confinement. This model considers that plasma emission is directly proportional to the square of plasma density, its volume and the fraction of laser pulse absorbed through inverse Bremsstrahlung in the pre-formed plasma plume produced by the initial part of the laser. This shows that plasma density and temperature (that means the electron-ion collision frequency ν ei ) decide the threshold for saturation in emission, which occurs for ν ei ≥ 10 13 s -1 , beyond which plasma shielding effects become dominant. Any decrease in plasma sound (expansion) velocity shows drastic enhancement in emission supporting the results obtained by magnetic as well as spatial confinement of laser produced plasma.The temporal evolution of plasma emission in the absence and presence of plasma confinement along with the effect of laser pulse duration are also discussed in the light of this model.

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External magnetic field effect on plume images and X-ray emission from a nanosecond laser produced plasma

et al. 2008

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The plume images of the laser produced silver plasma in the absence and presence of 0.45 T transverse magnetic field has been investigated under vacuum ~10−4 torr and in air. An Nd:YAG laser (1.064 µm, 1.1 MW, 9 ns) with intensity ~1012 Wcm−2 was used to generate plasma. A CCD image capture system was used for plasma imaging to explore the plume. A magnetic probe was employed to measure the variation in internal magnetic field of plasma with as well as without 0.45 T external transverse magnetic field. The X-ray emission from plasma in both the cases (with and without B field) was also monitored using two PIN photodiodes filtered with 24 µm Cu and 24 µm Al. The plume images in both the cases were then correlated with the time resolved soft X-ray emission. It was found that the self generated magnetic field of the plasma increases in the presence of magnetic field. Plume images reveal that the confinement of the plume takes place in the presence of magnetic field both in the cases of air and vacuum. Jet and spikes like structures were also observed due to plasma instabilities. Lobe formation in the plume at latter stages of plasma evolution was more prominent in air than under vacuum. X-ray emission signals exhibited an enhancement in the emission under transverse magnetic field. An increased rate of recombination due to high density as a result of plasma confinement across the applied magnetic field was found to be the main reason behind emission enhancement.

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Density oscillations in laser produced plasma decelerated by external magnetic field

Cited by 5 publications

References 10 publications

Modifications in surface, structural and mechanical properties of brass using laser induced Ni plasma as an ion source

Modifications in surface, structural and mechanical properties of brass using laser induced Ni plasma as an ion source

Theoretical aspect of enhancement and saturation in emission from laser produced plasma

External magnetic field effect on plume images and X-ray emission from a nanosecond laser produced plasma

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