Specialization: 011200 Physics
Profile: 01 Wave processes and methods of their investigation
Profile manager: head of department, prof. N.N. Zernov 
Department of Radiophysics  
Supervisor: prof. A.V. Tyukhtin
Referee: prof. M.A. Bisyarin

The electromagnetic field in a circular waveguide with the boundary between a vacuum area and an area having a cylindrical dielectric layer
A.A. Grigoreva

We consider a mode transformation in the circular waveguide with a vacuum part and a part consisting of cylindrical dielectric layer and vacuum channel. Two situations are analyzed: a mode falls from the vacuum part and a mode falls from the partially dielectric part. The incident mode can be both propagating and evanescent. 
Analytical investigation is performed by crosslinking method. In two dedicated cases, the case of a narrow channel and a thin dielectric layer, the approximate solution has been obtained. In order to analyze the mode transformation in general case the numerical algorithm has been constructed. 
Typical behavior of the reflection and transmission coefficients depending on channel radius is presented. In particular, it is shown, that the evanescent incident mode can excites propagating modes in reflected and transmitted fields.  

The list of the publications
1.	Григорьева, А. А. Трансформация мод в круглом волноводе с вакуумной частью и частью, содержащей слой диэлектрика / А. А. Григорьева // XVIII Всероссийская научная конференция студентов-радиофизиков: тезисы докладов, СПб, 21–23 апреля, 2015 – с. 10–12.
2.	Grigoreva, A. A. Mode transformation in circular waveguide with transversal boundary between vacuum and partially dielectric area. / A. A. Grigoreva, A. V. Tyukhtin, S. N. Galyamin. // Int. Conf. “Days on Diffraction 2015”: abstracts, Saint–Petersburg, May 25 – 29, 2015. – P. 58 – 59.
3.	Grigoreva, A. A. Mode transformation in waveguide with transversal boundary between vacuum and partially dielectric area. / A. A. Grigoreva, A.V. Tyukhtin, T. Yu. Alekhina, S.N. Galyamin. // Proceedings of IPAC’15, Richmond, USA, May 3-8, 2015. In press.