Efficient, highly linear traveling wave tube using collector with high backstreaming current under saturated drive

A method for operating a traveling wave tube provided with a slow wave structure (SWS) having an input end for receiving a microwave input signal having a power level and an output end for supplying a microwave output signal having a power level, the traveling wave tube further provided with a collector assembly having at least five electrodes, the method comprising:

• injecting electrons at the input end of the SWS to form an electron beam through the SWS, wherein the electron beam has a power level;
• applying the microwave input signal to the input end of the SWS, wherein the power level of the microwave input signal is selected such that the power level of the microwave output signal is at least twenty five times lower than the power level of the electron beam and such that the power level of the microwave output signal is at least 3 dB lower than a power level of the microwave output signal when the traveling wave tube is operating at saturation;
• and
• collecting the electrons in the electron beam at the output end of the SWS with the collector assembly, wherein a geometry of the collector electrodes is dimensioned and respective bias voltages applied to the corresponding collector electrodes are selected to optimally handle the electron beam when the traveling wave tube is operating at least 3 dB backed off from saturation so as to maximize the collection efficiency, and wherein the geometry is dimensioned and the respective bias voltages are selected such that the collector assembly generates a backstreaming current greater than 5% of a cathode current in the traveling wave tube when the traveling wave tube is operating at saturation.

A method for operating a traveling wave tube provided with a slow wave structure (SWS) having an input end for receiving a microwave input signal having a power level and an output end for supplying a microwave output signal having a power level, the traveling wave tube further provided with a collector assembly having at least ive electrodes, the method comprising:

• injecting electrons at the input end of the SWS to form an electron beam through the SWS;
• applying the microwave input signal to the input end of the SWS, wherein the power level of the microwave input signal is selected such that the power level of the microwave output signal is at least 3 dB lower than a power level of the microwave output signal when the traveling wave tube is operating at saturation;
• and
• collecting the electrons in the electron beam at the output end of the SWS with the collector assembly, wherein a geometry of the collector electrodes is dimensioned and respective bias voltages applied to the corresponding collector electrodes are selected to optimally handle the electron beam when the traveling wave tube is operating at least 3 dB backed off from saturation so as to maximize the collection efficiency, and wherein the geometry is dimensioned and the respective bias voltages are selected such that the collector assembly generates a backstreaming current greater than 5% of a cathode current in the traveling wave tube when the traveling wave tube is operating at saturation.