The Research On Output-cavity Of Ka-band Gyroklystron And Design Of New Output-taper

As a member of gyrotrons,the gyroklystron has a certain bandwidth,high power,high gain, high efficiency. Gyroklystron is a new high power microwave-soures, andhas been widely applied to radar systems,communications,electronic counterwork,Ultra long distance space exploration, RF plasma heating and material disposals．In this dissertation, the new output-taper section of Ka-band TE01modegyroklystron had been designed using the mode-matching technique and method offitting a function of sine and cosin. The output cavity of Ka-band TE01mode or TE02mode high power gyrotron is studied innovativly.In the second chapter, the mode-matching technique and Radius mutation theoryare introduced. On the basis of the theory, a single-stage mutation matrix equation isdetailed deduced and established, and then thereby draw the processing method in thecase of multistage mutant cascade or radius-tapered.In the third chapter, the studies and design of Ka-band TE01mode new outputtaper are show. Radius-tapered waveguide cascaded scattering matrix is builded by usedof the mode-matching technique, and the code of Matlab are compiled to analysis theeffect of the taper’s length and starting radius on transmission, reflection coefficient andthe coupling coefficient to TE02mode or TE03mode. Through numerical calculationand analysis, the Ka-band TE01mode new output tapered section is formed. The newtapered section’s mode coupling and mode purity ared calculated in axes of taper. Theresults show it has the above purpose and match with the data by HFSS. When thetaper’s length is80mm and diameter changed from14mm to32mm, the resultsindicates its transmission coefficient>-0.006dB, reflection coefficient <-60dB, modepurity>0.965, the coupling coefficient to TE02mode <-35dB.and TE03mode <-80dBin29GHz-35GHz.In the fourth chapter, the output cavity with the new taper of34GHz, TE01modegyroklystron and the output cavity with the sine taper of35GHz, TE02modegyroklystron are researched and designed. The open resonator with sinusoidal taperedsection and abrupt changes in radius for gyroklystron is studied using the mode-matching technique to build scattering matrix. A MATLAB code is developed tocalculate the scattering matrix. The effects of the cavity’s length and radius, thecoupling aperture’s radius and thickness, the taper’s length and starting radius on theresonance characteristics of output cavity for gyroklystron are analyzed. And the effectof the taper’s length and starting radius on transmission, reflection coefficient and thecoupling coefficient to parasitic mode are counted.Through the analysis an calculation,the design parameters of the output cavity is given, the simulated in HFSS. The resultsof HFSS and Matlab are bacically identical. TE01mode output-cavity‘s centerfrequency is34GHz, the quality factor is61.8. TE02mode output-cavity‘s centerfrequency is35GHz, the quality factor is66.