The theory of slow backward-wave amplifications is developed based on electron cyclotron maser （ECM） mechanism employing an initially rectilinear beam, A nonlinear evolution equation is derived to describe the elect...The theory of slow backward-wave amplifications is developed based on electron cyclotron maser （ECM） mechanism employing an initially rectilinear beam, A nonlinear evolution equation is derived to describe the electron energy. Numerical calculations show that the saturated interaction efficiency in this system may exceed 20~, and the saturated interaction length spans 3-6 centimeters. The distinctive interaction mechanism is promising for the design of compact backward microwave amplification devices, Numerical studies are also presented for the slow-wave ECM efficiency with inclusion of Gaussian beam electron velocity spread. It is shown that the velocity spread reduces the interaction e^ciency.展开更多
Based on the principle of electron cyclotron maser(ECM),gyrotrons are among the most promising devices to generate powerful coherent terahertz(THz)radiation and play a vital role in numerous advanced THz applications....Based on the principle of electron cyclotron maser(ECM),gyrotrons are among the most promising devices to generate powerful coherent terahertz(THz)radiation and play a vital role in numerous advanced THz applications.Unfortunately,THz ECM systems using a conventional high-Q cavity were theoretically and experimentally demonstrated to suffer from strong ohmic losses,and,accordingly,the wave output efficiency was significantly reduced.A scheme to alleviate such a challenging problem is systematically investigated in this paper.The traveling-wave operation concept is employed in a 1-THz third harmonic gyrotron oscillator,which strengthens electron-wave interaction efficiency and reduces the ohmic dissipation,simultaneously.A lossy belt is added in the interaction circuit to stably constitute the traveling-wave interaction,and a down-tapered magnetic field is employed to further amplify the forward-wave(FW)component.The results demonstrate that the proportion of ohmic losses is nearly halved,and output efficiency is nearly doubled,which is promising for further advancement of high-power continuous-wave operation of the ECM-based devices.展开更多
In recent years, much attention has been paid to the free-electron laser (FEL). Especially, Madey provided an important theorem, the first part of which expresses the stimulated emission as the derivative of the spont...In recent years, much attention has been paid to the free-electron laser (FEL). Especially, Madey provided an important theorem, the first part of which expresses the stimulated emission as the derivative of the spontaneous emission, and the second part gives an expression for the spontaneous emission in terms of the firstorder perturbation to the energy of the electron expressed in powers of the optical field. Subsequently, Kroll Morton et al. and Groven et al. rewrote the Madey theorem as the following form:展开更多
The cyclotron autoresonace masers with a large-orbit electron ring in a dielectric-loaded waveguide have been analyzed.The stability properties are investigated self-consistentlyon the basis of the linearized Vlasov-M...The cyclotron autoresonace masers with a large-orbit electron ring in a dielectric-loaded waveguide have been analyzed.The stability properties are investigated self-consistentlyon the basis of the linearized Vlasov-Maxwell equations.The numerical results show that thedielectric liner can greatly reduce the energy of the electron beam,and a novel effective radiationdevice with low electron beam energy in the millimeter and submillimeter wave region have beenproposed.展开更多
The spike radiation in the microwave region has been known for a long time as a special radiation which comes from the interaction of waves and nonthermal electron beams in the source region of corona. Many solar radi...The spike radiation in the microwave region has been known for a long time as a special radiation which comes from the interaction of waves and nonthermal electron beams in the source region of corona. Many solar radio astronomers, such as Melrose and Dulk, Zhao and Shi, have studied the physical reason of spike radiation. It is generall believed that the lose cone distribution of the nonthermal electrons in a flaring loop is unstable, and if the beam particle distribution develops a positive gradient, i.e. (?)f/(?)p】0, some electron-magnetic waves are excited.展开更多
To develop 200 GHz electron cyclotron maser(ECM)in University of Electronic Science and Technology of China,a magnetron injection gun(MIG)with 60 kV/5 A has been designed.The behavior of the designed magnetron injecti...To develop 200 GHz electron cyclotron maser(ECM)in University of Electronic Science and Technology of China,a magnetron injection gun(MIG)with 60 kV/5 A has been designed.The behavior of the designed magnetron injection gun with variations of relevant parameters is given in detail by means of computer simulations.The preliminary and operation parameters of the gun are reported.The optimization by using the EGUN code shows that the ratio of the perpendicular velocity to the parallel velocity of the electron beam is 1.63,and the perpendicular and parallel velocities spread are 2.62%and 6.63%,respectively.展开更多
基金supported by National Natural Science Foundation of China(Nos.11275007 and 11175023)the Program for Liaoning Excellent Talents in University(LJQ2012098)
文摘The theory of slow backward-wave amplifications is developed based on electron cyclotron maser （ECM） mechanism employing an initially rectilinear beam, A nonlinear evolution equation is derived to describe the electron energy. Numerical calculations show that the saturated interaction efficiency in this system may exceed 20~, and the saturated interaction length spans 3-6 centimeters. The distinctive interaction mechanism is promising for the design of compact backward microwave amplification devices, Numerical studies are also presented for the slow-wave ECM efficiency with inclusion of Gaussian beam electron velocity spread. It is shown that the velocity spread reduces the interaction e^ciency.
基金supported in part by Beijing Science Foundation for Distinguished Young Scholars(Grant No.JQ21011)the National Natural Science Foundation of China(Grant Nos.U1830201 and 61531002)Newton Advanced Fellowship from Royal Society in the United Kingdom(Grant No.NAF/R1/180121)
文摘Based on the principle of electron cyclotron maser(ECM),gyrotrons are among the most promising devices to generate powerful coherent terahertz(THz)radiation and play a vital role in numerous advanced THz applications.Unfortunately,THz ECM systems using a conventional high-Q cavity were theoretically and experimentally demonstrated to suffer from strong ohmic losses,and,accordingly,the wave output efficiency was significantly reduced.A scheme to alleviate such a challenging problem is systematically investigated in this paper.The traveling-wave operation concept is employed in a 1-THz third harmonic gyrotron oscillator,which strengthens electron-wave interaction efficiency and reduces the ohmic dissipation,simultaneously.A lossy belt is added in the interaction circuit to stably constitute the traveling-wave interaction,and a down-tapered magnetic field is employed to further amplify the forward-wave(FW)component.The results demonstrate that the proportion of ohmic losses is nearly halved,and output efficiency is nearly doubled,which is promising for further advancement of high-power continuous-wave operation of the ECM-based devices.
文摘In recent years, much attention has been paid to the free-electron laser (FEL). Especially, Madey provided an important theorem, the first part of which expresses the stimulated emission as the derivative of the spontaneous emission, and the second part gives an expression for the spontaneous emission in terms of the firstorder perturbation to the energy of the electron expressed in powers of the optical field. Subsequently, Kroll Morton et al. and Groven et al. rewrote the Madey theorem as the following form:
文摘The cyclotron autoresonace masers with a large-orbit electron ring in a dielectric-loaded waveguide have been analyzed.The stability properties are investigated self-consistentlyon the basis of the linearized Vlasov-Maxwell equations.The numerical results show that thedielectric liner can greatly reduce the energy of the electron beam,and a novel effective radiationdevice with low electron beam energy in the millimeter and submillimeter wave region have beenproposed.
基金Project supported by the National Natural Science Foundation of China amd Astronomical Committee of Chinese Academy of Sciences
文摘The spike radiation in the microwave region has been known for a long time as a special radiation which comes from the interaction of waves and nonthermal electron beams in the source region of corona. Many solar radio astronomers, such as Melrose and Dulk, Zhao and Shi, have studied the physical reason of spike radiation. It is generall believed that the lose cone distribution of the nonthermal electrons in a flaring loop is unstable, and if the beam particle distribution develops a positive gradient, i.e. (?)f/(?)p】0, some electron-magnetic waves are excited.
基金supported by the Major State Basic Research Development Program of China (No.2007CB310401)the National Natural Science Foundation of China (Grant No.10676110).
文摘To develop 200 GHz electron cyclotron maser(ECM)in University of Electronic Science and Technology of China,a magnetron injection gun(MIG)with 60 kV/5 A has been designed.The behavior of the designed magnetron injection gun with variations of relevant parameters is given in detail by means of computer simulations.The preliminary and operation parameters of the gun are reported.The optimization by using the EGUN code shows that the ratio of the perpendicular velocity to the parallel velocity of the electron beam is 1.63,and the perpendicular and parallel velocities spread are 2.62%and 6.63%,respectively.
