id:"swepub:oai:DiVA.org:uu-338158"
Search: id:"swepub:oai:DiVA.org:uu-338158" > Measurements of X-R...
- 1 of 1
- Previous record
- Next record
- To hitlist
Measurements of X-Ray Emission from Laboratory Sparks and Upward Initiated Lightning
-
- Hettiarachchi, Pasan, 1977- (author)
- Uppsala universitet,Elektricitetslära
-
- Cooray, Vernon, 1952- (thesis advisor)
- Uppsala universitet,Elektricitetslära
-
- Leijon, Mats, 1958- (thesis advisor)
- Uppsala universitet,Elektricitetslära
- show more...
- show less...
- (creator_code:org_t)
- ISBN 9789151302041
- Uppsala : Acta Universitatis Upsaliensis, 2018
- English 58 s.
- Doctoral thesis (other academic/artistic)
Abstract
Subject headings
Close
- In 1925 Nobel laureate R. C. Wilson predicted that high electric fields of thunderstorms could accelerate electrons to relativistic energies which are capable of generating high energetic radiation. The first detection of X-rays from lightning was made in 2001 and from long sparks in 2005. Still there are gaps in our knowledge concerning the production of X-rays from lightning and long sparks, and the motivation of this thesis was to rectify this situation by performing new experiments to gather data in this subject.The first problem that we addressed in this thesis was to understand how the electrode geometry influences the generation of X-rays. The results showed that the electrode geometry affects the X-ray generation and this dependency could be explained using a model developed previously by scientists at Uppsala University. The other missing information was the distribution of energy. Using a series of attenuators, we observed how the X-ray photons were attenuated as a function of barrier thickness and using a simple model we obtained the average and the maximum energy of X-rays. All the studies conducted previously was based on the lightning impulses, but in switching impulses, the voltage waveform rises very slowly compared to lightning impulses, and according to some scientists the rate of rise is an important parameter in X-ray development. Our study showed that the switching impulses were as efficient as lightning impulses in generating X-rays even though the rate of rise of voltage in switching impulses was hundreds of times slower.All the observations on X-ray generation from lightning by other scientists were based on either natural downward lightning flashes or triggered lightning in Florida. The first experiments to study the X-ray generation from upward lightning flashes systematically was conducted within this thesis work at Gaisberg Tower in Austria. The results showed that the X-ray emissions from these flashes were much weaker than the ones produced by either natural downward or triggered lightning. An attempt was made to explain this observation by invoking the possible differences in the charge distribution of leaders associated with the triggered lightning flashes in Florida and upward initiated lightning flashes at Gaisberg tower.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)
Keyword
- X-ray
- upward lighting
- laboratory discharges
- energy distribution
Publication and Content Type
- vet (subject category)
- dok (subject category)
Find in a library
- Measurements of X-Ray Emission from Laboratory Sparks and Upward Initiated Light... (Search the publication in LIBRIS)
To the university's database
- 1 of 1
- Previous record
- Next record
- To hitlist
Find more in SwePub
- By the author/editor
- Hettiarachchi, P ...
- Cooray, Vernon, ...
- Leijon, Mats, 19 ...
- Rahman, Mahbubur
- Rubinstein, Marc ...
- About the subject
-
- NATURAL SCIENCES
- NATURAL SCIENCES
- and Earth and Relate ...
- and Meteorology and ...
- By the university
- Uppsala University
Search outside SwePub
- Extend your search to:
- Google Book Search
- Google Scholar
Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.
- Copyright © LIBRIS - National Library Systems
- LIBRIS.kb.se
