An X-band magnetically insulated transmission line oscillator （MILO） is designed and investigated numerically and experimentally for the first time. The X-band MILO is optimized in detail with KARAT code. In simulat...An X-band magnetically insulated transmission line oscillator （MILO） is designed and investigated numerically and experimentally for the first time. The X-band MILO is optimized in detail with KARAT code. In simulation, the X-band MILO, driven by a 720 kV, 53 kA electron beam, comes to a nonlinear steady state in 4.0 ns. High-power microwaves （HPM） of TEM mode is generated with an average power of 4.1 GW, a frequency of 9.3 GHz, and power conversion efficiency of 10.870 in durations of 0-40 ns. The device is fabricated according to the simulation results. In experiments, when the voltage is 400 kV and the current is 50 kA, the radiated microwave power reaches about 110 MW and the dominating frequency is 9.7GHz. Because the surfaces of the cathode end and the beam dump are destroyed, the diode voltage cannot increase continuously. However, when the diode voltage is 400 kV, the average power output is obtained to be 700 MW in simulation. The impedance of the device is clearly smaller than the simulation prediction. Moreover, the duration of the microwave pulse is obviously shorter than that of the current pulse. The experimental results are greatly different from the simulation predictions. The preliminary analyses show that the generations of the anode plasma, the cathode flare and the anode flare are the essential cause for the remarkable deviation of the experimental results from the simulation predictions.展开更多
This paper puts forward a novel magnetically insulated transmission line oscillator （MILO） for the first time which takes a modified HEM11 mode as its main interaction mode. The excitation of the oscillation mode is...This paper puts forward a novel magnetically insulated transmission line oscillator （MILO） for the first time which takes a modified HEM11 mode as its main interaction mode. The excitation of the oscillation mode is made possible by carefully adjusting the arrangements of each resonant cavity in a two-dimensional （2-D） slow wave structure. The high frequency characteristics are analyzed and a PIC simulation is carried out; the detailed results are discussed to get a better understanding of this new MILO. Employing an electron beam of about 441 kV and 39.7 kA, it finds that the modified HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz. The power conversion efficiency is about 8.4% and the generated microwave is in a TEll-like circularly polarized mode; its polarization direction is decided by the rotation direction of the SWS.展开更多
A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation...A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure. The special feature of such a device is that in the slow-wave-structure region, the interaction mode is HEM11 mode which is a TM-like one that could interact with electron beams effectively; and in the coaxial output region, the microwave mode is TE11 mode which has a favourable field density pattern to be directly radiated. Employing an electron beam of about 441 kV and 39.7 kA, the HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation. The power conversion efficiency is about 8.4 % and the generated microwave is in a TEll-like circular polarization mode. In a preliminary experiment investigation, high power microwave is detected from the device with a frequency of 1.46 GHz, an output energy of 43 J 47 J, and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV450 kV, and the diode current is 37 kA-39 kA.展开更多
Abstract The magnetically insulated line oscillator （MILO） is a gigawatt-class, coaxial crossed-field microwave tube, which is at present a major hotspot in the field of high-power mi- crowaves （HPM） research. In ...Abstract The magnetically insulated line oscillator （MILO） is a gigawatt-class, coaxial crossed-field microwave tube, which is at present a major hotspot in the field of high-power mi- crowaves （HPM） research. In order to improve the power conversion efficiency and eliminate or at least minimize anode plasma formation in the load region and radio frequency （RF） breakdown in the slow wave structure （SWS） section, an X-band MILO is presented and inyestigated nu- merically with KARAT code. The design idea is briefly presented and the simulation results are given and discussed. In the simulation, HPM is generated with peak power of 3.4 GW, maximum electric field of about 1 MV/cm, and peak power conversion efficiency of 14.0%, when the voltage is 559.1 kV and the current is 43.2 kA. The microwave frequency is pure and falls in the X-band of 9.0 GHz. The theoretical investigation and the simulation results are given to prove that the anode plasma formation and the RF breakdown can be effectively avoided or at least minimized, respectively.展开更多
A tunable magnetically insulated transmission line oscillator（MILO） is put forward and simulated. When the MILO is driven by a 430 k V, 40.6 k A electron beam, high-power microwave is generated with a peak output po...A tunable magnetically insulated transmission line oscillator（MILO） is put forward and simulated. When the MILO is driven by a 430 k V, 40.6 k A electron beam, high-power microwave is generated with a peak output power of 3.0 GW and frequency of 1.51 GHz, and the relevant power conversion efficiency is 17.2%. The 3-d B tunable frequency range（the relative output power is above half of the peak output power） is 2.25–0.825 GHz when the outer radius of the slow-wave structure（SWS） vanes ranges from 77 mm to 155 mm, and the 3-d B tuning bandwidth is 92%, which is sufficient for the aim of large-scale tuning and high power output.展开更多
<div style="text-align:justify;"> A high-efficiency ridged magnetically insulated transmission line oscillator (RMILO) is proposed and investigated theoretically and numerically in this paper. In the R...<div style="text-align:justify;"> A high-efficiency ridged magnetically insulated transmission line oscillator (RMILO) is proposed and investigated theoretically and numerically in this paper. In the RMILO, ridge-disk vanes are introduced to enhance the power efficiency. Theoretical investigation shows that the ridge-disk can enhance the coupling impedance of the slow-wave structure (SWS), and so enhance the power efficiency. Moreover, the ridge has a weak influence on frequency, so, it influences little on the tunability of the MILO. In simulation, when the applied voltage is increased to 807 kV, the RMILO can get the 3 dB tunable frequency range with 7.6 - 13.9 GHz and the 3 dB tuning bandwidth with 58.6% which has an increase of 27.6% compared with the conventional MILO. So, the tuning performance of the RMILO is more superior. Besides, the RMILO gets the maximum output power of 7.1 GW, the corresponding power efficiency is 22.6% and the frequency is 1.400 GHz. Furthermore, when the applied voltage is increased to 807 kV, high-power microwave with a power of 13.5 GW, frequency of 1.400 GHz, and ef?ciency of 24.5% is generated, which has an increase of 20.2% compared with the conventional MILO. The simulation results con?rm the ones predicted by theoretical analysis. </div>展开更多
基金supported by the Chinese National Natural Science Foundation (Grant No 10675168)Innovation Fund of Graduate School of the National University of Defense Technology of China
文摘An X-band magnetically insulated transmission line oscillator （MILO） is designed and investigated numerically and experimentally for the first time. The X-band MILO is optimized in detail with KARAT code. In simulation, the X-band MILO, driven by a 720 kV, 53 kA electron beam, comes to a nonlinear steady state in 4.0 ns. High-power microwaves （HPM） of TEM mode is generated with an average power of 4.1 GW, a frequency of 9.3 GHz, and power conversion efficiency of 10.870 in durations of 0-40 ns. The device is fabricated according to the simulation results. In experiments, when the voltage is 400 kV and the current is 50 kA, the radiated microwave power reaches about 110 MW and the dominating frequency is 9.7GHz. Because the surfaces of the cathode end and the beam dump are destroyed, the diode voltage cannot increase continuously. However, when the diode voltage is 400 kV, the average power output is obtained to be 700 MW in simulation. The impedance of the device is clearly smaller than the simulation prediction. Moreover, the duration of the microwave pulse is obviously shorter than that of the current pulse. The experimental results are greatly different from the simulation predictions. The preliminary analyses show that the generations of the anode plasma, the cathode flare and the anode flare are the essential cause for the remarkable deviation of the experimental results from the simulation predictions.
基金Project supported by the Science Foundation of the China Academy of Engineering Physics (Grant No 2008B0402046)
文摘This paper puts forward a novel magnetically insulated transmission line oscillator （MILO） for the first time which takes a modified HEM11 mode as its main interaction mode. The excitation of the oscillation mode is made possible by carefully adjusting the arrangements of each resonant cavity in a two-dimensional （2-D） slow wave structure. The high frequency characteristics are analyzed and a PIC simulation is carried out; the detailed results are discussed to get a better understanding of this new MILO. Employing an electron beam of about 441 kV and 39.7 kA, it finds that the modified HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz. The power conversion efficiency is about 8.4% and the generated microwave is in a TEll-like circularly polarized mode; its polarization direction is decided by the rotation direction of the SWS.
文摘A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure. The special feature of such a device is that in the slow-wave-structure region, the interaction mode is HEM11 mode which is a TM-like one that could interact with electron beams effectively; and in the coaxial output region, the microwave mode is TE11 mode which has a favourable field density pattern to be directly radiated. Employing an electron beam of about 441 kV and 39.7 kA, the HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation. The power conversion efficiency is about 8.4 % and the generated microwave is in a TEll-like circular polarization mode. In a preliminary experiment investigation, high power microwave is detected from the device with a frequency of 1.46 GHz, an output energy of 43 J 47 J, and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV450 kV, and the diode current is 37 kA-39 kA.
基金supported by National Natural Science Foundation of China(No.11075210)the Special Financial Grant from the China Postdoctoral Science Foundation(No.201104761)
文摘Abstract The magnetically insulated line oscillator （MILO） is a gigawatt-class, coaxial crossed-field microwave tube, which is at present a major hotspot in the field of high-power mi- crowaves （HPM） research. In order to improve the power conversion efficiency and eliminate or at least minimize anode plasma formation in the load region and radio frequency （RF） breakdown in the slow wave structure （SWS） section, an X-band MILO is presented and inyestigated nu- merically with KARAT code. The design idea is briefly presented and the simulation results are given and discussed. In the simulation, HPM is generated with peak power of 3.4 GW, maximum electric field of about 1 MV/cm, and peak power conversion efficiency of 14.0%, when the voltage is 559.1 kV and the current is 43.2 kA. The microwave frequency is pure and falls in the X-band of 9.0 GHz. The theoretical investigation and the simulation results are given to prove that the anode plasma formation and the RF breakdown can be effectively avoided or at least minimized, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.11075210)the Special Financial Grant from the China Postdoctoral Science Foundation(Grant No.201104761)
文摘A tunable magnetically insulated transmission line oscillator（MILO） is put forward and simulated. When the MILO is driven by a 430 k V, 40.6 k A electron beam, high-power microwave is generated with a peak output power of 3.0 GW and frequency of 1.51 GHz, and the relevant power conversion efficiency is 17.2%. The 3-d B tunable frequency range（the relative output power is above half of the peak output power） is 2.25–0.825 GHz when the outer radius of the slow-wave structure（SWS） vanes ranges from 77 mm to 155 mm, and the 3-d B tuning bandwidth is 92%, which is sufficient for the aim of large-scale tuning and high power output.
文摘<div style="text-align:justify;"> A high-efficiency ridged magnetically insulated transmission line oscillator (RMILO) is proposed and investigated theoretically and numerically in this paper. In the RMILO, ridge-disk vanes are introduced to enhance the power efficiency. Theoretical investigation shows that the ridge-disk can enhance the coupling impedance of the slow-wave structure (SWS), and so enhance the power efficiency. Moreover, the ridge has a weak influence on frequency, so, it influences little on the tunability of the MILO. In simulation, when the applied voltage is increased to 807 kV, the RMILO can get the 3 dB tunable frequency range with 7.6 - 13.9 GHz and the 3 dB tuning bandwidth with 58.6% which has an increase of 27.6% compared with the conventional MILO. So, the tuning performance of the RMILO is more superior. Besides, the RMILO gets the maximum output power of 7.1 GW, the corresponding power efficiency is 22.6% and the frequency is 1.400 GHz. Furthermore, when the applied voltage is increased to 807 kV, high-power microwave with a power of 13.5 GW, frequency of 1.400 GHz, and ef?ciency of 24.5% is generated, which has an increase of 20.2% compared with the conventional MILO. The simulation results con?rm the ones predicted by theoretical analysis. </div>
