Design of a Vlasov mode converter of 263 GHz gyrotron oscillator for DNP-NMR

The Journal of Engineering

Zhiliang Li¹  Jinjun Feng² 

[1] Vacuum Electronics National Laboratory , Beijing Vacuum Electronics Research Institute , Beijing 100015 , People's Republic of China

关键词: frequency 263.0 GHz;    elliptical reflector;    nuclear magnetic resonance;    quasioptical mode converter system;    wave beam-shaping reflectors;    Gaussian mode;    vector diffraction theory;    circular TE03 mode gyrotron oscillator;    dynamic nuclear polarisation;    efficiency 85.23 percent;    Vlasov stepped-cut launcher;    DNP-NMR;    Vlasov mode converter;    parabolic reflector;    geometric optics theory;   

DOI  :  10.1049/joe.2018.0124

学科分类：工程和技术（综合）

来源: IET

【 摘 要 】

This paper presents design and simulation of a quasi-optical mode converter of 263 GHz gyrotron oscillator operating in the circular TE03 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 TE03 mode gyrotron oscillator. The simulated results show that a good fundamental Gaussian mode is converted at the output window from the TE03 mode, and that the power conversion efficiency and the vector correlation are 90.11 and 85.23%, respectively.

【 授权许可】

CC BY