Method for suppressing second and higher harmonic power generation in klystrons

An amplifier tube operating at a fundamental frequency, a cutoff frequency, and comprising in combination:

• a plurality of cavities disposed between a plurality of connecting drift tubes, said connecting drift tubes preventing the propagation of electric fields at the fundamental frequency and allowing electric fields at second and higher harmonic frequencies to propagate;
• and
• one or more external loads placed on predetermined ones of said plurality of connecting drift tubes for reducing at least partially, a second and higher harmonic power by causing the second and higher harmonic power to be loaded out,
• such that the electric fields at the fundamental frequency interact with a beam propagating through said connecting drift tubes for providing amplification of the electric fields at the fundamental frequency.

A klystron having a fundamental operating frequency, a cutoff frequency, and a second and higher harmonic frequencies, and comprising in combination:

• a plurality of cavities secured to a plurality of connecting drift tubes;
• each of said plurality of drift tubes including an inner diameter such that said cutoff frequency is above the fundamental operating frequency but below the second harmonic frequency, for preventing the propagation of electric fields at the fundamental operating frequency and for allowing electric fields at the second and higher harmonic frequencies to propagate;
• and
• one or more external loads placed on predetermined ones of said plurality of connecting drift tubes for reducing, at least partially, a second and higher harmonic power by causing the second and higher harmonic power to be loaded out as the second and higher harmonic power progresses through said plurality of connecting drift tubes.

An amplifier tube comprising in combination:

• a plurality of cavities connected to a plurality of drift tubes interconnecting a plurality of alternating cavities, said connecting drift tubes preventing the propagation of electric fields at a fundamental frequency and allowing electric fields at second and higher harmonic frequencies to propagate;
• and
• one or more external loads placed on predetermined ones of said cavities for reducing, at least partially, the second and higher harmonic power, by causing the second and higher harmonic power to be loaded out as the second and higher harmonic power progresses through said drift tubes,
• such that the electric fields at the fundamental frequency interacts with a beam propagating through said connecting drift tubes for providing amplification of the electric fields at the fundamental frequency.

A method for substantially suppressing second and higher harmonic power generation in a klystron having a drift tube connecting adjacent cavities, the method comprising the steps of:

• applying a power at a fundamental frequency to the klystron;
• selecting a drift tube diameter in order to prevent the propagation of the power at the fundamental frequency, and to allow the second and higher harmonic power to propagate within the drift tube;
• and
• loading out, at least partially, the propagating second and higher harmonic power, by means of one or more external loads, as the second and higher harmonic power progresses through said drift tube.