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PDF 11.29 MB
master's thesis
19
2
Effect of nanosecond laser pulses on atmospheric pressure plasma jets
Nikola Šegedin (2017)
University of Zagreb
Faculty of Science
Department of Physics
Cite this item:
https://urn.nsk.hr/urn:nbn:hr:217:111673
Metadata
Title
Utjecaj nanosekundnih laserskih pulseva na atmosferske plazmene mlazove
Author
Nikola Šegedin
Mentor(s)
Slobodan Milošević
(thesis advisor)
Maja Planinić
(thesis advisor)
Abstract
U ovom radu je promatran spektar laserske plazme na atmosferskom zraku, u heliju i helijevom plazmenom mlazu (jetu) u svrhu određivanja interakcije između laserske plazme, plinske mete i helijevog jeta. Pritom smo laserske snopove fokusirali na navedene plinske mete te promatrali interakciju pomoću LIBS spektrometra i vremenski razlučive spektroskopije. Laserski snop energije pulsa od 63.2 mJ i frekvencije 5Hz je fokusiran na plinsku metu ispred optičkog vlakna spojenog na LIBS spektrometar i monokromator s rešetkom. LIBS spektrometar je korišten za analiziranje spektara laserske plazme u heliju i na atmosferi. Pritom su uspješno određeni i navedeni prijelazi unutar atoma i iona koji tvore lasersku plazmu. Posebno je laserski snop fokusiran na helijev jet, a dobivena svjetlost je analizirana preko fotomultiplikatora čiji signal je bilježen i promatran u vremenu na računalu. U daljnjim analizama smo odredili spektralni profil helijeve linije valne duljine 388.86 nm za različite pomake u vremenu integracije. Također je određena ekscitacijska temperatura elektrona za različita vremena od početka laserskog pulsa. Poznavanjem eksitacijske temperature i Starkovog širenja odredili smo koncentraciju elektrona u volumenu interakcije. Pokazano je da prisustvo jeta ne utječe značajno na ekscitacijsku temperaturu elektrona i njihovu koncentraciju unutar laserske plazme, ali utječe na helijev emisijski spektar u kojem je smanjen intenzitet helijeve 388.86 linije u prisustvu jeta.
Keywords
nanosecond laser pulses
atmosferic pressure plasma jets
Parallel title (English)
Effect of nanosecond laser pulses on atmospheric pressure plasma jets
Committee Members
Maja Planinić
(committee chairperson)
Slobodan Milošević
(committee member)
Mirko Planinić
(committee member)
Davor Horvatić
(committee member)
Emil Tafra
(committee member)
Granter
University of Zagreb
Faculty of Science
Lower level organizational units
Department of Physics
Place
Zagreb
State
Croatia
Scientific field, discipline, subdiscipline
NATURAL SCIENCES
Physics
Study programme type
university
Study level
integrated undergraduate and graduate
Study programme
Physics; specializations in: Education
Study specialization
Education
Academic title abbreviation
mag. educ. phys.
Genre
master's thesis
Language
Croatian
Defense date
2017-07-12
Parallel abstract (English)
In this paper, we were examining the spectrum of laser plasmas in atmospheric air, helium gas target and helium jet while our objective was to determine interactions between laser plasmas and named targets. To do this we were focusing laser pulses on mentioned targets and observing interactions using LIBS spectrometer and method of time - resolved spectroscopy. A laser pulse of energy 63.2 mJ and repetition rate of 5 Hz was focused on the gas target in front of optical fiber that was connected to LIBS spectrometer and monochromator with the optical grating. LIBS spectrometer was used to analyze laser plasmas spectrum in helium and atmospheric gases. We were successful in determining laser plasmas spectrum and identifying atoms and ions inside the plasma. Furthermore, we were focusing laser pulses on atmospheric pressure helium plasma jet, and monitoring interactions using photomultiplier whose signal was recorded in time on the computer. In addition to this, spectral line profile of helium line 388.86 nm was observed in different time delays. By determining the width of line it was possible to calculate excitation temperature of electrons within laser plasmas. By knowing excitation temperature of electrons and Stark width we successfully calculated concentrations of electrons within laser plasmas. In our results, we showed that the presence of the jet didn’t have a significant effect on excitation temperature of electrons or their concentration within laser plasma, however it does effect the helium emission spectrum by reducing the intensity of helium 388.86 nm line in the presence of helium jet.
Parallel keywords (Croatian)
nanosekundni laserski pulsevi
atmosferski plazmeni mlazovi
Resource type
text
Access condition
Open access
Terms of use
URN:NBN
https://urn.nsk.hr/urn:nbn:hr:217:111673
Committer
Iva Čizmin