Cyclotron resonance maser amplifier and waveguide window

Coupling apparatus for transferring microwave power between a given mode in a first waveguide and a given mode in a second waveguide, said coupling apparatus comprising first and second coaxial hollow metallic circularly cylindrical members, said first member forming a first waveguide section for coupling to said first waveguide, said first and second members forming a second waveguide section surrounding said first waveguide section and coaxial therewith, said first waveguide section being bounded externally by said first member, and said second section being bounded internally by said first member and externally by said second member, said first and second members having respective radii at which a given mode in said first waveguide section propagates at substantially the same velocity as a given mode in said second waveguide section, and said first member having a plurality of apertures therethrough for transferring microwave power between said first and second waveguide sections, said apertures in said first member being small relative to the radius of said first member and spaced around the circumference of said first member, said coupling apparatus further comprising third and fourth hollow metallic circularly cylindrical members coaxial with said first and second members and axially displaced from said first and second members, said third and fourth members forming a third waveguide section for coupling to said second waveguide section to transfer microwave power between said second waveguide section and said third waveguide section, said third waveguide section being bounded externally by said third member and internally by said fourth member, said fourth member forming a fourth waveguide section coaxially within said third waveguide section for coupling to said second waveguide, said fourth waveguide section being bounded externally by said fourth member, said third and fourth members having respective radii at which a given mode in said third wave guide section propagates at substantially the same velocity as a given mode in said fourth waveguide section, said fourth member having a plurality of apertures therethrough for transferring microwave power between said third and fourth waveguide sections, said apertures in said fourth member being small relative to the radius of said fourth member and spaced around the circumference of said fourth member.

A cyclotron resonance maser microwave amplifier comprising:

• an assembly of components disposed successively along a common axis and including successively and coaxially an annular source of electrons, circularly cylindrical walls forming an input waveguide section, circularly cylindrical walls forming a first interaction waveguide section, circularly cylindrical walls forming a drift tube section, circularly cylindrical walls forming a second interaction waveguide section, circularly cylindrical walls forming an output waveguide section, and an annular collector of electrons;
• means for forming electrons from said source into an annular beam of electrons having substantial transverse energy and directing said beam of electrons successively through said input waveguide section, said first interaction waveguide section, said drift tube section, said second interaction section and said output waveguide section to said collector, said means including magnetic means for producing magnetic lines of flux extending substantially parallel to said axis at least through said first and second interaction sections and said drift tube section;
• an input waveguide extending coaxially through said annular source of electrons for introducing input microwave energy into said amplifier;
• first coupling means for transferring input microwave energy from said input waveguide into said annular beam of electrons in said input waveguide section, said input waveguide providing means for transmitting microwave energy to said first interaction waveguide section, said first interaction section and said magnetic means providing means for causing said microwave energy and said electrons in said beam to interact to initiate phase bunching of said electrons, said drift tube section providing means for substantially decoupling said first interaction section from said second interaction section in respect to microwave energy while passing said bunching electrons to said second interaction section, and said second interaction section and said magnetic means providing means for causing the bunched electrons to radiate microwave energy and transfer the radiated energy to said output waveguide section, said walls forming at least one of said first and second interaction sections and said drift tube section including means for dissipating axial wall currents therein;
• an output waveguide extending coaxially through said annular collector for transmitting the microwave output from said amplifier;
• and
• second coupling means for transferring output microwave energy from said output waveguide section to said output waveguide.