Author: Qian, B.L.
Paper Title Page
MOPC132 Influences of the Inner-conductor on Microwave Characteristics in an L-band Relativistic Backward-wave Oscillator* 388
 
  • X.J. Ge, L. Liu, B.L. Qian, J. Zhang, H.H. Zhong
    National University of Defense Technology, Changsha, Kaifu District, People's Republic of China
 
  Funding: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, People’s Republic of China. *gexingjun230230@yahoo.com.cn
The influences of the inner-conductor on microwave characteristics in an L-band relativistic backward-wave oscillator (RBWO) are investigated theoretically and experimentally. The numerical results show that the resonance frequency decreases obviously with the increase in the inner-conductor radius. To verify the above conclusions, an L-band coaxial RBWO is investigated in detail with particle-in-cell (PIC) code. It is shown that the frequency is lowered from 1.63 GHz to 1.51 GHz when the inner-conductor radius increases from 0.5 cm to 2.5 cm. And the efficiency varies in the range of 35.4-27.7%. Furthermore, experiments are carried out at the Torch-01 accelerator. When the diode voltage is 887.6 kV and the current is 7.65 kA, the radiated microwave with frequency of 1.61 GHz, power of 2.13 GW and efficiency of 31.3% is generated. It is found that the frequency decreases from 1.64 GHz to 1.58 GHz when the inner-conductor radius increases from 0.5 cm to 1.5 cm. And the efficiency varies in the range of 31.3-29.8%.
 
 
WEPC071 The Motion of an Electron in the Periodic Cusped Magnetic Fields 2184
 
  • G. Du, B.L. Qian, H. Wang
    National University of Defense Technology, Changsha, Kaifu District, People's Republic of China
 
  Funding: National High Technology Research and Development Program of P. R. China
The motion and its stability of an electron in the periodic cusped magnetic fields have been analyzed theoretically and calculated numerically, as the stability could not be well predicted by the Mathieu’s equation to guide the design of the magnetic focusing system for the propagation of the sheet electron beams in the waveguides. The precise solution to the motion equations of the electron has been obtained by iteration. To validate the analytical solution and to evaluate the stability of the motion, numerical calculations have been carried out. And the results show that the analytical solution is reliable, and there is only one stable region in the (p0, B0) space, where the parameter p0 is the period of the magnetic fields, and B0 is the magnitude of the magnetic fields. Besides, the stability of the electron motion would become weaker while the initial distance between the electron and the axis becomes larger. These results are interesting to the area of the sheet-electron-beam microwave sources focused by the periodical cusped magnetic fields.