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Frequency tunability of axial cavity vircators and double anode vircators
KTH, School of Electrical Engineering (EES).
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This master thesis investigates the possibility of constructing a continu-ously tuneable virtual cathode oscillator (vircator), which can be used as a radiation source in high power microwave susceptibility testing carried out by the electrophysics group at the Swedish Defence Research Agency (FOI). To determine if a vircator can be made continuously frequency tuneable in a 10 %bandwidth around a central frequency lying within the S-band two vircator designs, the first an axial cavity vircator and the second a double anode vir-cator, are evaluated with electromagnetic particle-in-cell simulations using the software Magic3D. This thesis study focus on achieving continuous frequency tuning in the two vircators’ using a minimal number of tuning parameters. The axial cavity vircator is found to achieve too narrow tuning bands. Combined with issues of occasional poor frequency stability and poor radiated microwave power, the axial cavity vircator is concluded to not be a suitable radiation source for high power microwave susceptibility testing. For the double anode vircator a 10 % tuning band is observed around 2.24 GHz. The double anode vircator also has good frequency stability and radiated microwave power across the observed tuning band and is therefore concluded to be a suitable radiation source for high power microwave susceptibility testing.

Abstract [sv]

Detta examensarbete undersöker möjligheten att konstruera en kontinuerligt frekvensavstämbar virtuell katod-oscillator (virkator), som kan användas som strålningskälla vid de tester av känslighet mot med högeffektsmikrovågor som utförs elektrofysikgruppen vid Totalförsvarets forskningsinstitut (FOI). Målet är att undersöka om en virkator kan göras frekvensavstämbar, inom en bandbredd om 10 % kring en centrumfrekvens inom S-bandet. Detta görs genom att utvärdera två virkatordesigner, en axiell kavitetsvirkator och dub-belanodsvirkator, med hjälp av elektromagnetiska partikel-i-cell simuleringar i programmet Magic3D. Studien fokuserar på att uppnå kontinuerlig frekvens-avstämbarhet i de två virkatorerna med hjälp av ett minimalt antal variabla parametrar. Den axiella kavitetsvirkatorn visades ge för smala frekvensavstäm-bara band. På grund av ytterliggare problem med enstaka frekvensinstabiliteter och emellanåt svaga mikrovågsstrålningseffekter, så bedöms den axiella kavitetsvirkatorn inte vara en lämplig strålningskälla vid känslighetstester. För dubbelanodsvirkatorn observeras ett frekvensavstämbart band om 10 % runt 2.24 GHz. Dubbelanodsvirkatorn uppvisar också god stabilitet i såväl frekvens som utstrålad effekt, över hela det frekvensavstämbara bandet, och den bedöms därför vara en lämplig strålningskälla vid känslighetstester med högeffektsmikrovågor.

Place, publisher, year, edition, pages
2016. , 95 p.
EES Examensarbete / Master Thesis, TRITA-EE 2016:083
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-192463OAI: diva2:968664
External cooperation
Totalförsvarets forskningsinstitut
Available from: 2016-09-12 Created: 2016-09-12 Last updated: 2016-09-12Bibliographically approved

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