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Article
Laser-Based Measurements in Non-Equilibrium Plasmas

Authors: E. bin Selima --- R. Fortier --- A. Elmahdi
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2012 Volume: 8 Issue: 1 Pages: 3-10
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this article, advanced laser diagnostics have been used in combination with modeling to study fundamental non-equilibrium low temperature Plasma Assisted Combustion kinetics. We also discuss recent advances in ultra-high frame rate imaging, which provides new capability for capturing the dynamic evolution of high speed, unsteady flow fields, and/or increasing the data collection rate in short run time “impulse” facilities.


Article
Detection of Trace Explosive Materials by Standoff Raman Spectroscopy System

Authors: Haider G. Abdulzahraa --- Naseer M. Hadi --- Mohammad R. Mohammad
Journal: Al-Nahrain Journal of Science مجلة النهرين للعلوم ISSN: (print)26635453,(online)26635461 Year: 2017 Volume: 20 Issue: 1 Pages: 91-98
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

Standoff Raman spectroscopy SRS technique is one of the most powerful technologies that can identify trace amount of explosive materials. The Raman scattered signal collected by reflective telescope and a spectrograph is used to analyze the Raman scattered light. In order to view the spectrum, the spectrograph is equipped with charge coupled device CCD detector which allows detection of very weak stokes line. In order to test the capability of SRS system of detecting explosives trace, detection of C4 and AN explosives have been achieved with limit of detection (LOD) about 20 µg for C4 and 40 µg for AN. [DOI: 10.22401/JNUS.20.1.13]


Article
Standoff Raman Spectroscopy of C4 Explosive and Study the Effect of Integration Time and Laser Power

Authors: Naseer M. Hadi --- Haider G. Abdulzahraa --- Mohammad R. Mohammad
Journal: Al-Nahrain Journal of Science مجلة النهرين للعلوم ISSN: (print)26635453,(online)26635461 Year: 2017 Volume: 20 Issue: 2 Pages: 82-89
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

In this paper standoff Raman spectroscopy SRS system for explosive materials is developed. Standoff Raman detection of C4 substance under dark laboratory condition at 4 m distance is achieved. A frequency doubled Nd:YAG laser at 532 nm excitation is used. The Raman scattered light is collected by a telescope and then transferred via fiber optics cable to spectrograph and finally into CCD detector. Notch filter used to reject Rayleigh scattering light. Carbon tetrachloride CCL4 and Acetone (CH3)2CO are used as a calibration standard for the Raman measurements because of their strong and intensive scattering capability. Raman measurement of C4 explosive is also acquired using conventional Raman microscopy for verification of standoff Raman measurements. The effects of integration time and laser power on Raman cross section under dark condition were studied. Standoff Raman detection of C4 substance at 4 m distance under partially illuminated condition has been achieved and hence the effect of higher integration time was studied under the same condition.


Article
Advanced Laser Diagnostics for Non-Equilibrium Plasma Assisted Combustion Kinetics

Authors: Ali El-Mahdi --- Imad bin Selima --- Roger Fortier
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2018 Volume: 14 Issue: 2 Pages: 3-10
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

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Abstract

In this article, advanced laser diagnostics have been used in combination with modeling to study fundamental non-equilibrium low temperature Plasma Assisted Combustion kinetics. We also discuss recent advances in ultra-high frame rate imaging, which provides new capability for capturing the dynamic evolution of high speed, unsteady flow fields, and/or increasing the data collection rate in short run time “impulse” facilities.


Article
The effect of Helium dilution of silane on the structural, optical and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by HW-CVD method
تأثير تخفيف السايلان بالهيليوم على الخواص التركيبية والضوئية والكهربائية للاغشية الرقيقة للنانو سليكون البلوري (nc-Si:H) المهدرج المحضرة بطريقة HW-CVD

Author: Nabeel A. Bakr نبيل علي بكر
Journal: Diyala Journal For Pure Science مجلة ديالى للعلوم الصرفة ISSN: 83732222 25189255 Year: 2012 Volume: 8 Issue: 3 - part 2 Pages: 355-374
Publisher: Diyala University جامعة ديالى

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Abstract

Structural, optical and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) films, deposited from silane (SiH4) and helium (He) gas mixture without hydrogen by hot wire chemical vapor deposition (HW-CVD) method were investigated as a function of helium dilution of silane (RHe). We observed that the deposition rate is much higher (4-33 Å/s) compared to conventional plasma enhanced chemical vapour deposited (PE-CVD) nc-Si:H films. Raman spectroscopy revealed that the crystalline volume fraction decreases with increasing He dilution of silane whereas the crystallite size remains almost constant (~ 2 nm) for the entire range of He dilution of silane studied. Furthermore, an increase in the structural disorder in the nc-Si:H films has been observed with increasing He dilution of silane. The hydrogen content was ~ 9 at. % for the film deposited at 60 % RHe and decreases rapidly as RHe increases further. The photoresponse decreases by order of 1 with increasing helium dilution of silane from 60 to 97 %. It has been concluded that adding helium gas to the silane induces the structural disorders in the hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by HW-CVD method.

تمت دراسة الخواص التركيبية والضوئية والكهربائية للاغشية الرقيقة للنانو سليكون البلوري المهدرج (nc-Si:H) والمرسب من مزيج غازي السايلان (SiH4) والهيليوم (He) بدون استخدام الهيدروجين بطريقة الترسيب بالبخار الكيميائي باستخدام السلك الساخن (HW-CVD) كدالة لنسبة تخفيف السايلان بوساطة غاز الهيليوم . لقد وجد بان معدل الترسيب اعلى بكثير(4-33 Å/s) مقارنة بالطريقة التقليدية للترسيب بالبخار الكيميائي باستخدام التعزيز بالبلازما (PE-CVD) . طيف رامان بين بان الجزء الحجمي البلوري يقل مع زيادة نسبة التخفيف في حين ان قياس البلورات يبقى ثابتا تقريبا (~ 2 nm) في مدى التخفيف المدروس . كما وجد ان عدم الانتظام التركيبي للاغشية الرقيقة المحضرة بهذه الطريقة يزداد بزيادة نسبة التخفيف . وقد كانت كمية الهيدروجين المحتوى في الغشاء المرسب بحدود (9%) باستخدام نسبة تخفيف مساوية لـ 60% ويقل بشكل سريع بزيادة نسبة التخفيف مما يؤدي الى تدهور في مواصفات الغشاء . كما وجد ان الاستجابة الضوئية تقل بزيادة نسبة التخفيف . تم التوصل من خلال هذه الدراسة الى ان اضافة غاز الهيليوم الى غاز السايلان يؤدي الى زيادة عدم الانتظام التركيبي للاغشية الرقيقة للنانو سليكون البلوري المهدرج والمحضر بطريقة (HW-CVD).

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