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Research On Intearaction Mechanism And Diagnosis Of Electromagnetic Pulse Generated By High Power Laser And Materials

Posted on:2016-11-25Degree:MasterType:Thesis
Country:ChinaCandidate:C X GaoFull Text:PDF
GTID:2272330473957126Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
The exploration of reaction mechanism and experimental phenomena of nuclear fusion plays a significant role in the development of nuclear technology. The interaction between high power laser pulses and metal materials may produce an extremely strong electromagnetic radiation,and will impact the electronic system and diagnostic equipment.Therefore it is necessary to understand physical laws and mechanism. This study regarding the generation mechanism of electromagnetic radiation has both theoretical and practical values. It deepens the understanding of relevant physical processes, and contributes development of lots of fields, such as inertial confinement fusion, strong-field physics, and laboratory astrophysics.In this thesis, we simulate and calibration two time-domain pulse antennas: Discone-antenna and Loop-antenna, which were based on our own design and used for the diagnosis of high power laser target coupling.The stimulation and calibration results of main parameters, including 3D gain pattern and antenna radiation efficiency are compared. The analyses suggest that, with increasing frequency, the Discone-antenna and Loop-antenna have stable gain variations and omnidirectional views.They can absorb electromagnetic pulse signals in all directions, and the beams are comparatively wide. To obtain time-domain and frequency-domain information, we measured electromagnetic pulse inside and outside the target chamber of ShenGuang III high power laser facility, and evaluated the intensity and spectrum of electromagnetic radiation from 0.1 GHz to 5 GHz frequency band by applying Discone-antenna and Loop-antenna, respectively. In the process of laser target coupling experiment, due to the obfurage target chamber, electromagnetic pulse were constantly reflected, which caused that the vibration time of electromagnetic pulse was much longer than the time of laser target coupling. The field intensity of electromagnetic pulse measured outside the target chamber was 610 V/m, and the field intensity of electromagnetic pulse measured inside the target chamber was 7200 V/m。Dipole radiation is one of the main mechanisms of radiating electromagnetic wave in the interaction between long pulse high power laser and metal target. The intensity of electromagnetic radiation is related to many factors, such as the power of laser,the way of laser shooting and angle of incidence. As for planar targets, if image and material are the same, EMP engendered by laser with different power will have the similar energy spectral density(ESD) and the identical characteristic frequency. The study is highly important for the assessment of electromagnetic pulse interference in ShenGuang III laser facility.Meanwhile, it provides the theoretical foundation for the development of electromagnetic pulse shielding and diagnostic technology. Also, it is practical and instructive for the applications related to nuclear fusion technology.
Keywords/Search Tags:Electromagnetic emissions, Time-domain pulse antenna, Dipole radiation, Time-domain distribution, Frequency-domain distribution
PDF Full Text Request
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