Surface properties of graphite and LaB₆ materials used for laser heated emissive probe diagnostic

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• 作者：P. Mehta ; A. Sarma ; A. D. Sivagami ; N. HariPrakash ; S. Gopi…
• 关键词：Laser heated ; Emissive ; Material ; Surface ; EDAX analysis ; Image
• 刊名：Indian Journal of Physics
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：91
• 期：2
• 页码：225-234
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics, general; Astrophysics and Astroparticles;
• 出版者：Springer India
• ISSN：0974-9845
• 卷排序：91

文摘

Laser heated emissive probe (LHEP) has been used as an alternative diagnostics to measure direct plasma potential. In this case, surface properties of LHEP materials have been studied before and after exposing it to high power laser. A high density small diameter (0.5 mm) laser light of variable power density is used to heat the probe tip. Two types of probe tip material are used in this experiment, viz, Graphite (Coarse grain and HOPG) and LaB₆. Purity of material is dependent on the constituents of the same. Surface properties of these materials before and after laser exposure and plasma conditions have been characterized by scanning electron microscopy (SEM) and the energy dispersive X-ray spectroscopy. In order to achieve higher sensitivity on carbon surface and other layers the low-energy probing (~1.0 keV), the energy dispersive spectroscopy is used. Data of the energy dispersive X-ray spectroscopy allows us to obtain the structure of the materials as well as different elements present in these materials. To understand the surface morphology more critically, open source software named Gwyddion (version 2.35) has been used for processing of the SEM images. The 3-D visualization of the probe tip at different experimental conditions has been made using the Interactive 3-D surface plot plug-in of Gwyddion. Optical properties are also analyzed using diffusion reflectance spectroscopy and from which band gap energy of the same has been estimated.