Magnicon amplifier operated at the second harmonic of the cyclotron frequency

Abstract

A high power, highly efficient, phase-stable frequency-multiplying magnicon microwave amplifier is disclosed having efficiencies that exceed 60%. The magnicon amplifier has an output cavity that receives an electron beam that is deflection modulated by the drive, gain and penultimate cavities of the magnicon amplifier. The output cavity is dimensioned so as to operate in a TMm10 mode, where m is an even integer greater than two. The output cavity is selected to preferably have an operating frequency fo which is twice the cyclotron frequency fc of the output cavity.

What we claim is: 
     
       1. A microwave amplifier comprising: (a) a generator of an electron beam;   (b) an input coupler having first and second ends with the first end receiving a microwave signal having a frequency, f s  ;   (c) a drive cavity connected to the second end of the input coupler and receiving said microwave signal at frequency f s , said drive cavity having means at one end of said drive cavity for accepting said electron beam, said microwave signal exciting a first microwave field at said frequency f s  in said drive cavity, said microwave field deflection modulating said electron beam which exits from a second end of said drive cavity;   (d) at least one gain cavity having means for receiving the deflection modulated electron beam at a first end that excites a second microwave field at the frequency f s  in said at least one gain cavity, said microwave field further deflection modulates said electron beam which exits at a second end of said at least one gain cavity;   (e) a penultimate cavity having means for receiving said deflection modulated electron beam that had exited from said at least one gain cavity at a first end of said penultimate cavity, which excites a third microwave field at said microwave frequency f s  in said penultimate cavity that still further deflection modulates said electron beam which exits at a second end of said penultimate cavity;   (f) an output cavity being configured to have means for receiving the deflection modulated electron beam output of said penultimate cavity and having a predetermined cyclotron frequency f c  and a predetermined operating frequency, f c  ; said output cavity having dimensions and excited by said deflection-modulated electron beam so as to operate in a TM m10  mode, where m is an even integer greater than 2 so that said operating frequency, f o , is equal to m times the microwave frequency f s  and is equal to at least two (2) times said cyclotron frequency f c , said deflection-modulated electron beam exciting a fourth microwave field to produce an output which exits from said microwave amplifier;   (g) magnetic means producing a magnetic field encompassing all of said drive, gain, penultimate, and output cavities; said,drive, gain and penultimate cavities being dimensioned so as to operate in a TM 110  mode.     
     
     
       2. The microwave amplifier according to claim 1, wherein said frequency, f s , is about 2.85 GHz, said operating frequency, f o , is about 11.4 GHz, and m is 4 so that said output cavity operates in a TM 410  mode, and said operating frequency f o  is about twice said cyclotron frequency f c . 
     
     
       3. The microwave amplifier according to claim 1, wherein each of said penultimate and said output cavities includes a respective iris. 
     
     
       4. The microwave amplifier according to claim 1, wherein said output cavity is operated in the TM 410  mode and said output cavity has a preselected cyclotron frequency f c  said electron beam having a voltage of about 500 kV and a current of about 172 amperes (A), and having a velocity ratio α of about 1.5 entering said output cavity and said output cavity and said output cavity having dimensions to operate at the second harmonic of the cyclotron frequency, said cyclotron frequency being determined by a magnetic field of 3.25 k Gauss (G) produced by said magnetic means. 
     
     
       5. A method of operating a magnicon amplifier having a drive cavity, at least one gain cavity, a penultimate cavity and an output cavity operatively connected together, said magnicon amplifier having a magnet supplying a magnetic field to said drive, at least one gain, penultimate and output cavities, said drive, at least one gain and penultimate cavities having a microwave signal at frequency f s  serving as an operating frequency therefor, and said output cavity being configured to have a predetermined cyclotron frequency f c  and an operating frequency f o , said method comprising the steps respectively associated therewith of: (a) dimensioning said drive, at least one gain and penultimate cavities to provide an operating mode TM 110  ; and   (b) dimensioning said output cavity to provide an operating mode TM m10 , where m is an even integer which is greater than two (2).   
     
     
       6. The method of operating a magnicon amplifier according to claim 5, wherein said step (b) further comprises selecting m as being equal to four (4) so that the operating frequency f o  is equal to twice that of the cyclotron frequency f c . 
     
     
       7. The method of operating a magnicon amplifier according to claim 6 further comprises the step of: (c) adjusting the magnetic field so that said cyclotron frequency f c  is about 15% less than one-half of said operating frequency f o .