Open AccessDesign of a Vlasov mode converter of 263 GHz gyrotron oscillator for DNP‐NMR
Author(s) -
Li Zhiliang,
Feng Jinjun
Publication year - 2018
Publication title -
the journal of engineering
Language(s) - English
Resource type - Journals
ISSN - 2051-3305
DOI - 10.1049/joe.2018.0124
Subject(s) - gyrotron , reflector (photography) , physics , optics , mode (computer interface) , backward wave oscillator , beam (structure) , power (physics) , parametric oscillator , computer science , cathode ray , quantum mechanics , light source , electron , operating system
This paper presents design and simulation of a quasi‐optical mode converter of 263 GHz gyrotron oscillator operating in the circular TE 03 mode for dynamic nuclear polarisation enhanced nuclear magnetic resonance (DNP‐NMR). The converter consists of a Vlasov stepped‐cut launcher, and additional wave beam‐shaping reflectors, including an elliptical reflector and a parabolic reflector. First, the preliminary parameters of the launcher are designed with the geometric optics theory. Next, both geometric optics and vector diffraction theory are used to simulate the propagation of wave beam in the mode converter system. Finally, operation of the mode converter was simulated, based on the physical model of Vlasov mode converter for 263 GHz TE 03 mode gyrotron oscillator. The simulated results show that a good fundamental Gaussian mode is converted at the output window from the TE 03 mode, and that the power conversion efficiency and the vector correlation are 90.11 and 85.23%, respectively.