High-power Magnetically Insulated Transmission Line Oscillator Study

Magnetically insulated line oscillator(MILO) is gigawatt-class coaxial crossed field microwave device which operates at low impedance.It requires no externally applied magnetic field to insulate the electron flow in the slow-wave structure(SWS). This self-insulating property enables the tube to handle extremely large input power at modest applied voltage without ensuing electrical breakdown of the anode-cathode gap(AK gap).Thus it allows the design and operation of a relatively compact and lightweight source.It is a major hotspot in the field of high power microwave(HPM) research.This dissertation is mainly about the numerical simulation and experimental investigation of high power MILO based on theoretical analyses.The main research contents include:1.The research background of HPM,the history,actual state,trends and principle of MILO are introduced.2.The beam-wave interaction principle of MILO is analyzed according to its working mechanism.The principles to select the parameters of a MILO device are presented.3.Simulation and experimental investigations of L-band high power MILO are carried out.The existed L-band ladder cathode MILO is optimized by numerical simulation.Employing an electron beam of 568 kV,53.3 kA,a high power microwave with output power of 5.5 GW,frequency of 1.2 GHz is obtained.The power conversion efficiency is 18.2%.Experimental research of high power MILO is carried out.The experimental investigation results of L-band high power MILO is presented.Employing an electron beam of 675 kV,59 kA,a high power microwave with output power of 2.59 GW,frequency of 1.23 GHz is obtained.The power conversion efficiency is about 6.5%.The pulse length of microwave is 15 ns.The output microwave power is relatively low contrast to the simulation results,and the pulse length is rather short.It is figured out that the power handling capability of the radiation antenna is the main reason.A newly TEM-TM₀₁ mode converter and antenna are designed which allows high power microwave radiation of our device.A high power microwave with output power of 3.1 GW,pulse length(full wave at half Maximum,FWHM) of 50 ns is obtained in the end.4.The four-cavity ladder-cathode MILO and its primary investigation are presented.The simulation investigation of L-band four-cavity ladder-cathode MILO is carried out.The results reveal that this tube can work at a single frequency on its fundamental mode.It also has a high power conversion efficiency which can be over 20%when employing a beam of 667 kV.The primary experiment of the L-band four-cavity ladder-cathode MILO is briefly introduced.The primary experimental results show that this device can work at a single frequency on its fundamental mode. A P-band four-cavity MILO is also investigated which works at the frequency of 0.88 GHz.Employing an electron beam of 596 kV,50 kA,a high power microwave with output power of 5.6 GW is obtained.The power conversion efficiency is 18.7%.