Research On Low-Voltage Millimeter-Wave Electron Cyclotron Maser

Electron cyclotron maser device is an important millimeter and terahertz wave radiation source,which has been continuously studied by researchers around the world for its excellent high-power output capability in the millimeter and terahertz wavebands.In recent years,with the development of the millimeter wave and terahertz science technology,more and more scientific research and applications require miniaturized and highefficiency millimeter wave terahertz radiation sources with medium power,providing new opportunities for the development of electron cyclotron masers.But,in order to obtain high power and high beam-wave interaction efficiency,traditional electron cyclotron masers require cyclotron electrons to achieve a relatively high relativistic factor,and their operating acceleration voltage often reaches tens of thousands of volts,sometimes even exceeding 0.1 million volts,resulting in a large volume of system power supply,high insulated voltage requirements,and complex water cooling systems,greatly limiting the development of electron cyclotron maser device industrial applications.Therefore,lowvoltage electron cyclotron masers have become a new hotspot in the research field of electron cyclotron masers.However,when operating at low voltage,the relativistic factor of the cyclotron electrons decreases,and the space charge effect between electrons in the high current cyclotron electron beam becomes stronger,resulting in a sharp decrease in the efficiency of beam-wave interaction,limiting the improvement of the performance of low-voltage electron cyclotron masers.In order to break through this bottleneck problem,a theoretical investigation on the space charge effect in low-voltage electron cyclotron masers has been carried out.The influence of the space charge effect on the performance of low-voltage electron cyclotron masers and beam wave interactions is analyzed.The optimal operating conditions for low-voltage electron cyclotron masers are obtained.On this basis,device design and key application technology validation experiments were carried out,and engineering difficulties were analyzed,paving the way for the practical applica-tion of low voltage electron cyclotron maser device-gyrotron.The specific research contends as follows:1.The space charge effect of a gyrotron beam under low-voltage conditions has been studied,and relevant theoretical formulas have been derived.The influence of the space charge effect on the transverse and longitudinal power of the gyrotron beam has been investigated.The limit relationship between the electron beam current and voltage under different velocity transverse to longitudinal ratios has been studied,and the limit power and efficiency of the gyrotron device have been obtained.Through numerical calculation and particle simulation.It is found that the undisturbed pitch factor is 0.82 for obtaining the ultimate power capacity at extremely low operating voltages.2.On the basis of theoretical analysis,a high-performance electronic optical system under low voltage conditions is designed.Combined with the linear theory of gyrotron and the beam-wave interaction theory,the design and particle simulation of the gyrotron resonator are carried out.The 4 k V single anode compact gyrotron achieves a 100 W output at 30 GHz,and the 5 k V second harmonic gyrotron output 60 W power at 30 GHz.In order to further improve device efficiency,a miniaturized depressed collector suitable for low voltage gyrotrons was studied.Key parameters such as collector radius and collector voltage are considered.The results show that under the operating voltage of 10 k V,the overall tube efficiency can reach 50% with the single depressed collector.3.The key engineering technology research of low voltage miniaturized CW gyrotron has been carried out,including 1).Experimental investigation on the emission ability of large current long pulse and continuous wave cathodes,while improving the alignment between the electron gun and the magnet; 2).The research on 4.2 k V lowvoltage continuous wave gyrotron has been carried out,a power of 100 W in the 30 GHz is output.It verifies the feasibility of the low operating voltage in gyrotron.4.Further exploring the miniaturization of the gyrotron system,it is proposed to apply normal temperature DC electromagnets to the field of gyrotron.By optimizing the design,the power consumption of the room-temperature coil magnet is reduced,the magnetic field uniformity is enhanced,and the heat dissipation performance is improved.The room-temperature Bitter magnet is processed and measured,and the measured magnetic field distribution agrees well with the design.