Traveling wave tube devices

Abstract

In a microwave tube of the type wherein an electron beam emitted by an electron gun is focused and caused to interact with an input high frequency wave at a high frequency circuit unit by magnetic flux generated by a periodic permanent magnet assembly, and the electron beam after the interaction is collected by a collector unit, the portion connected to the output unit of the high frequency circuit unit comprises a column-shaped waveguide member having an end surface comprising a portion of the wall of a cavity at the end of the high frequency circuit unit, the member being bored with a central aperture at the center axis to allow electron beam to pass from the electron gun to the collector unit. A waveguide for guiding the electromagnetic waves from the end surface to the output unit is also provided, and the end surface is shaped like a fan.

What is claimed is: 
     
       1. In a traveling wave tube of the type provided with an electron gun, a high frequency circuit unit connected thereto and comprising a cavity resonator type delay circuit unit, a collector unit disposed on the output side of the said high frequency circuit unit and adapted to receive an electron beam sent via said high frequency circuit unit, a beam focusing unit disposed adjacent to said high frequency circuit unit and adapted to cause a periodic magnetic field to act upon the electron beam passing through the high frequency circuit unit, and input/output units connected to the electron gun side of said high frequency circuit unit and the end portion of the collector unit side, a waveguide portion connected to the output unit of said high frequency circuit unit comprises a column-shaped waveguide member having an end surface forming a portion of the wall of a cavity at the end of the high frequency circuit unit, said member being bored with a central aperture at a central axis to allow the passage of the electron beam from the electron gun to the collector unit, said central aperture is tapered and its diameter increases towards the collector unit, and a waveguide for transmitting the electromagnetic waves from said end surface to the output unit, said end surface of the waveguide being shaped like a fan. 
     
     
       2. The traveling wave tube according to claim 1 wherein said beam focusing unit is composed of ring shaped permanent magnets magnetized in the axial direction and ring shaped pole pieces, said magnets and pole pieces being alternately disposed, and wherein the pole piece disposed at the end closest to the collector unit includes the waveguide which connects an opening of the fan-shaped waveguide which is opened on the side face of said waveguide member with the output unit. 
     
     
       3. The traveling wave tube according to claim 1 wherein a rectangular waveguide is provided within the pole piece, said rectangular waveguide being inversely tapered toward the direction of the output unit from the opening of said fan-shaped waveguide. 
     
     
       4. The traveling wave tube according to claim 1 wherein a waveguide portion joined to the input unit of said high frequency circuit unit comprises a second column-shaped waveguide member having an end surface forming a portion of the wall of a cavity at the end of the high frequency circuit unit, said second waveguide member being bored with a central aperture through which the electron beam passes from the electron gun toward the collector unit, and wherein there is further provided a waveguide to guide the electromagnetic waves from the input unit to the end surface of said second waveguide member, said end surface of said second waveguide member being shaped like a fan. 
     
     
       5. The traveling wave tube according to claim 1 wherein the said column-shaped waveguide member comprises a first column part disposed adjacent to the end of the PPM assembly, and a second column part having an end surface that forms a portion of the wall of a cavity at the end of the high frequency circuit unit, said first column part having a larger diameter than said second column part, a fan-shaped waveguide formed on the first and the second column parts, the output unit being connected to the opening of a fan-shaped waveguide bored on the side face of the second column part. 
     
     
       6. The traveling wave tube according to claim 2 or 3 or 5 wherein the fan-shaped waveguide provided on said waveguide member comprises a first part having a fan-shaped cross section that is formed in a direction parallel to the axis from the wall of a cavity at the end of said high frequency circuit unit and a second part connected to the end of the first portion and reaching the side face of the waveguide member as it extends in the direction perpendicular to the axis. 
     
     
       7. The traveling wave tube according to claim 6 wherein the second portion has a cross section which is rectangular and inversely tapered toward the side face of the waveguide member. 
     
     
       8. The traveling wave tube according to claim 1 or 2 or 3 or 4 or 5 wherein the outer radius of the end surface facing a cavity of the fan-shaped waveguide is equal to the inner diameter of the cavity, and the width of the said fan-shaped waveguide is equal to the height of the cavity. 
     
     
       9. The traveling wave tube according to claim 8 wherein the length of the fan-shaped waveguide in the circumferential direction is equal to the lateral width of the rectangular waveguide comprising the output device in the operation frequency range of the traveling wave tube. 
     
     
       10. The traveling wave tube according to claim 1 including a second waveguide portion connected to the input unit of said high frequency circuit unit, said second waveguide portion including a column-shaped waveguide member having an end surface forming a portion of the wall of a cavity at the end of the high frequency circuit unit, said column-shaped waveguide member of said second waveguide portion is formed with a tapered central aperture through which the electron beam passes from the electron gun toward the collector unit, the diameter of said central aperture of said second waveguide portion increasing toward the collector unit.