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The present work deals with the Argon (Ar) Thermal plasma‐induced surface modification of Cu and its correlation with the electrical and field emission (FE) properties. Polycrystalline Cu targets were treated with Ar thermal plasma under atmospheric pressure at different treatment times ranging from 5 min to 30 min. XRD patterns revealed the absence of new phase in treated samples. However, significant variation in peak intensities and shifting is observed, which is explained on the basis of thermal plasma ions induced defect generation and annihilation processes. The electrical conductivity of processed Cu targets measured by four‐probe method ranges from 1.9 MS/m to 70 MS/m and is well correlated with the crystallite size variation. Surface modification induced work function alternations investigated by employing Scanning Kelvin Probe (SKP) technique are in the range of 4.69 eV 4.97 eV. The irradiated morphology explored by optical and scanning electron microscopy analyses revealed the formation of localized melt pools, grains, hillocks, spheroids, and sputtered patches, which are explainable on the basis of Coulomb's explosion, thermal spike model, plasma‐induced sputtering, and re‐deposition. FE properties of thermal plasma‐treated Cu are measured in diode configuration by measuring I‐V characteristics of target under ultra‐high vacuum condition. The improved FE parameters such as turn‐on field (Eo), field enhancement factor (β), and maximum current density (Jmax) come out to be in the range of 3–7.5 V/μm, 1715–3223, and 284–872 nA/cm2, respectively and their correlation with plasma‐induced surface structural, morphological and work function modifications is discussed. [ABSTRACT FROM AUTHOR]

The present paper reports the investigation of surface morphology, elemental composition, phase changes and field emission properties of Si ion irradiated nickel (Ni) and titanium (Ti). The Ni and Ti targets have been irradiated with 500 keV Si ions generated by Pelletron accelerator at various fluences ranging from 6.9 × 1013 to 77.1 × 1013 ions/cm2. Stopping range of ions in matter analysis revealed higher values of electronic stopping and sputtering yield for Ni as compared with Ti. For both irradiated metals, electronic energy loss dominant over the nuclear stopping. The growth of induced surface structures have been analysed by using field emission scanning electron microscopy (FESEM) analysis. In case of Ni, as the ion fluence increases from 6.9 × 1013 to 65.8 × 1013 ions/cm2, the formation of spherical particulates, agglomers and sputtering is observed. Although in the case of Ti, with the increase of Si ion fluence from 11.6 × 1013 to 77.1 × 1013 ions/cm2, the formation of irregular‐shaped particulates along with crater and sputtered channels is observed. X‐ray diffraction (XRD) analysis shows that no new phase is identified. However, a significant increase in peak intensity is observed with increasing ion fluence. The variation in crystallite size and dislocation line density is also observed as a function of Si ion fluence. Fourier transform infrared spectroscopy analysis shows that no bands are formed after the Si ion irradiation. Field emission properties of ion‐structured Ni and Ti are well correlated with the growth of surface structures observed by SEM and dislocation line density evaluated by XRD analysis. [ABSTRACT FROM AUTHOR]

The spatial confinement effect on the laser-induced plasma parameters and surface modifications of iron (Fe) has been investigated. The Fe plasma has been generated under ultrahigh vacuum (UHV) condition by employing Nd: YAG (532 nm, 6 ns) laser at different laser irradiances ranging from 3.3 to 10 GWcm $^{-2}$. Two important Fe plasma parameters, i.e., electron temperature ranging from 13 to 27 eV and electron number density ranging from $1.92\times 10^{15}$ cm $^{-3}$ to $4.60\times 10^{15}$ cm $^{-3}$ , are evaluated by employing Langmuir probe (LP) as diagnostic technique. The probe was placed at a distance of 1 cm from target. Both plasma parameters are found to be influenced by laser irradiances and spatial confinement. They increase with the increase in laser irradiances both in the presence and absence of metallic blockers. However, it is revealed that the values of both plasma parameters are slightly higher in the presence of blocker as compared to blocker-free case. The percentage increase in electron temperature varies from 10% to 15%, whereas percentage increase in electron density varies from 11% to 25%. These percentage increase in the values of Fe plasma parameters exceeds the limits of experimental errors (±2). Therefore, the role of spatial confinement via metallic blocker for the enhancement of plasma parameters is confirmed and is attributed to the reflection of shockwaves from the blocker. The surface modifications of laser irradiated Fe have been explored by scanning electron microscopy (SEM). Various features, such as ripples, ridges, and cones, have been observed on the surfaces of ablated Fe. More pronounced, organized, and fine structures are grown on the Fe surface in the presence of blocker at lower irradiances than the blocker-free case due to spatial confinement effect. The growth of ripples is attributed to Kelvin–Helmholtz instabilities. PACS: 61.80.Ba, 52.50. −b, 52.50.Jm, 52.50.Lp, 52.35.Tc, 35 52.38., 52.38.Dx. [ABSTRACT FROM AUTHOR]