Research On 263GHz Frequency Tunable Terahertz Gyrotron

In recent years,terahertz(THz)science and technology has become a research hot area,and the research on terahertz is developed rapidly.It has been applied in nuclear magnetic resonance(NMR),controlled thermonuclear fusion,radar detection,etc.Among them,NMR has been applied in many scientific fields such as biology,medicine,physics,chemistry,geology,materials.The substances can be investigated by NMR accurately and rapidly without any damage.The dynamic nuclear polarization(DNP)technology driven by high-frequency millimeter wave or terahertz wave radiation makes electrons interact with nuclei and transfer a large number of highly polarized electron spins to nuclear spins.It increases the sensitivity of NMR by 1 to 2 orders of magnitude,which greatly shortens the time to obtain information.To obtain higher resolution spectra,modern NMR spectroscopy has been pushed to much higher magnetic fields,it requires high-power and high-frequency THz radiation source.Gyrotron is the best choice for THz radiation sources.Based on the requirements of the DNP-NMR system,this paper investigates the 263GHz continuously frequency-tunable gyrotron for400MHz DNP-NMR system.The main work is as follows:1.Based on the requirements of the gyrotron,TE₅₂mode was selected as a suitable operation mode.The cavity structure of the gyrotron is designed.The effect of the cavity size parameters of the resonant cavity on the operation frequency and the quality factor of the gyrotron is investigated based on the cold cavity simulation.2.The beam-wave coupling coefficient and the starting current of the 263GHz gyrotron are analyzed based on the linear theory,an appropriate guiding center radius is selected,and the preliminary size parameters of the gyrotron was designed.3.The Beam-wave interaction is investigated based on the self-consistent nonlinear theory.The effect of electromagnetic parameters such as the voltage,the current and the magnetic field on the output power and the beam-wave interaction efficiency is studied by electromagnetic simulation software.At the same time,the operating parameters of the gyrotron is optimized.4.Magnetron injection gun(MIG)of the 263 GHz continuously frequency-tunable gyrotron is optimized to meet the basic requirements of the electron beam of the263GHz continuously frequency-tunable gyrotron.5.The thickness of the required output window is designed and optimized by electromagnetic simulation software.The parts of the components of 263GHz continuously frequency-tunable gyrotron were manufactured.