Jawla Sudheer K, Griffin Robert G, Mastovsky Ivan A, Shapiro Michael A, Temkin Richard J
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
Department of Chemistry and the Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
IEEE Trans Electron Devices. 2020 Jan;67(1):328-334. doi: 10.1109/ted.2019.2953658. Epub 2019 Dec 10.
We report the design and experimental demonstration of a frequency tunable terahertz gyrotron at 527 GHz built for an 800 MHz Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance (DNP-NMR) spectrometer. The gyrotron is designed at the second harmonic ( = 2 ) of the electron cyclotron frequency. It produces up to 9.3 W continuous microwave (CW) power at 527.2 GHz frequency using a diode type electron gun operating at V = 16.65 kV, I = 110 mA in a TE mode, corresponding to an efficiency of ~0.5%. The gyrotron is tunable within ~ 0.4 GHz by combining voltage and magnetic field tuning. The gyrotron has an internal mode converter that produces a Gaussian-like beam that couples to the HE mode of an internal 12 mm i.d. corrugated waveguide periscope assembly leading up to the output window. An external corrugated waveguide transmission line system is built including a corrugated taper from 12 mm to 16 mm i.d. waveguide followed by 3 m of the 16 mm i.d. waveguide The microwave beam profile is measured using a pyroelectric camera showing ~ 84% HE mode content.
我们报告了一款为800兆赫动态核极化增强核磁共振（DNP-NMR）光谱仪制造的527吉赫频率可调太赫兹回旋管的设计与实验演示。该回旋管设计为电子回旋频率的二次谐波（ = 2 ）。它使用二极管型电子枪，在V = 16.65千伏、I = 110毫安的条件下，以TE模式在527.2吉赫频率产生高达9.3瓦的连续微波（CW）功率，效率约为0.5%。通过结合电压和磁场调谐，该回旋管在约0.4吉赫范围内可调。该回旋管有一个内部模式转换器，可产生类似高斯光束，耦合到内径12毫米的内部波纹波导潜望镜组件的HE模式，直至输出窗口。构建了一个外部波纹波导传输线系统，包括从内径12毫米到16毫米的波纹渐变，接着是3米内径16毫米的波导。使用热释电相机测量微波束轮廓，显示HE模式含量约为84%。
