Terahertz rectangular corrugated transmission line with Gaussian mode filtering for DNP‐NMR. Issue 13 (3rd September 2018)

• Record Type: Journal Article
• Authors: Pu, Hong; Du, Chao‐Hai; Huang, Tie‐Jun; Pan, Shi; Liu, Pu‐Kun
• Is Part Of: IET microwaves, antennas & propagation. Volume 12:Issue 13(2018)
• Page Start: 2080
• Page End: 2084
• Publication Date: 2018-09-03
• Subjects: nuclear magnetic resonance -- filtering theory -- electromagnetic wave polarisation -- electromagnetic wave attenuation -- transmission lines -- rectangular waveguides -- gyrotrons; terahertz rectangular corrugated transmission line -- Gaussian mode filtering -- DNP‐NMR spectrometer -- gyrotron output window -- terahertz wave sources -- dynamic nuclear polarisation system -- nuclear magnetic resonance -- high‐magnetic field regime -- Gaussian beam -- terahertz transmission system -- rectangular corrugated waveguide -- back‐to‐back rectangular corrugated horn -- coupling coefficient -- electric field -- continuous wave gyrotrons; Microwaves -- Periodicals; Microwave antennas -- Periodicals; Antennas (Electronics) -- Periodicals; Radio wave propagation -- Periodicals; Microwave communication systems -- Periodicals; 621.381305
• DOI: 10.1049/iet-map.2018.5064
• Languages: English
• ISSNs: 1751-8725

Abstract

Abstract : Gyrotrons have been developed as terahertz wave sources in dynamic nuclear polarisation (DNP) system to increase the sensitivity of nuclear magnetic resonance (NMR) in the high‐magnetic field regime. However, the transmission of the Gaussian beam from the gyrotron output window to the NMR system proves to be a critical challenge. In this study, a terahertz transmission system, composed of a rectangular corrugated waveguide and a back‐to‐back rectangular corrugated horn for Gaussian mode filtering, is proposed. The attenuation in the optimised 0.33 THz corrugated waveguide remains lower than 0.01 dB/m in a broad frequency range from 280 GHz to 450 GHz. Besides, the coupling coefficient from the electric field in the 0.33 THz mode‐filtering horn to the fundamental HE11 mode in the rectangular corrugated waveguide is obtained nearly 99.5%. This terahertz transmission system is potential to be applied in DNP‐NMR spectrometer based on continuous wave gyrotrons.