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local-field-enhancement
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Hard X-Ray Generation from Copper by Ti-Sapphire Femto Second Laser Pulses
, M.Sc. Thesis Sharif University of Technology ; Sadighi Bonabi, Rasoul (Supervisor) ; Nikzad, Lida (Supervisor)
Abstract
Using plasma cluster in fusion has attracted many attentions in recent year. In this work, generating of hard X-ray with energy more than 10 keVby Ti-sapphire laser, 100 fs pulses’ duration and focal intensity of more than 1014W/cm2 has been discussed. Due to significant enhancement of X-ray production from metal nanoplasma cluster, a reasonable theoretical model is needed to describe the more than 10-fold increment of X-ray generation. Hence, the present models have been studied and a proper model based on available experimental data, has been presented. The X-ray, which is produced through this way, can be used in Inertial Fusion Confinement (ICF). One of the major obstacles in ICF is...
HTS transformer’s partial discharges raised by floating particles and nitrogen bubbles
, Article Journal of Superconductivity and Novel Magnetism ; Volume 33, Issue 10 , 6 July , 2020 , Pages 3027-3034 ; Vakilian, M ; Hekmati, A ; Fardmanesh, M ; Sharif University of Technology
Springer
2020
Abstract
Presence of defects, conducting particles, nonconducting particles, and nitrogen gas bubbles in the insulation system of high-temperature superconducting (HTS) transformers, mainly inside the liquid nitrogen as its major insulation, can create local field enhancement and consequently partial discharges which eventually lead to the catastrophic failure of the transformer. In this paper, two-dimensional (2D) axisymmetric finite element method (FEM) modeling via COMSOL Multiphysics software has been utilized for the investigation of the impact of size and shape of conducting particles and nitrogen gas bubbles on partial discharge (PD) activities in liquid nitrogen. Conducting particles of...