5, “Low-Voltage Operation of the Retarding- Field Oscillator at X-Band and the Mil& meter Wavelength Region”

C. J. CARTER AND W. H. CORNETET, JR. Electron-Tube Laboratory, Ohio State University

Columbus, Ohio The retardingfield oscillator is similar to the reflex

klystron except that the repeller (the reflector of the reflex klystron) is an integral part of the resonant cavity and the rf power is coupled to the load in a different manner. The basic difference between the operation of the tubes lies in the fact that the regions for bunching, drift- ing, and working of the electron beam are not distinct in the retardingfield oscillator as they are in the reflex klystron.

This paper concerns the partial development of two low- voltage designs of the Retarding-Field Oscillator. These two designs differ fundamentally in the method of coupling the rf power to the load. The X-Band model has coarial- line coupling to a waveguide while the millimeter wave- length model has double cavity coupling to a waveguide.

The design developed at X-Band allows operation at a voltage as low as 200 volts with an output power of 20 milliwatts. In the millimeter wavelength range, an output power of 5 milliwatts has been obtained at a wavelength of 6.5 millimeters with an anode voltage of 400 volts. If the millimeter tube is operated at 600 volts, it may be mechanically tuned over a wavelength range of 5.25 to 6.5 millimeters with output power ranging between 5 and 20

4.3 and 5.8 millimeters wavelength with starting voltages milliwatts. One tube has been designed to operate between

ranging between 400 and 700 volts. None of these designs use grids in the interaction gap.

Both low-voltage oscillator designs use high perveance electron guns. The millimeter tube uses a gun with a

of 0.009 inch, while the X-Band model uses a gun with perveance of 3.5 x 10-6 amp/volt3/2 and a beam diameter

a perveance of approximately 6 x 10-6 amp/volt3/2 and a beam diameter of 0.020 inch. The latter gun gives a beam transmission of nearly 80 percent at 300 volts. The use of both sprayed and matrix cathodes in these guns is dis- cussed.

These oscillators are versatile in that they may be oper- ated at higher anode potential with correspondingly great- er output power. The X-Band model can be operated at voltages up to 600 volts with an output power up to 1 watt being available. The millimeter tube can be operated upto 1000 volts with an available output power up to 300 milliwatts. Other characteristics are also discussed,

6. “Efiect of Collector Potential on the E f i - ciency of Traveling-Wave Tubes”

H. J. WOLKSTEIN Radio Corporation of America

Harrison, New Jersey This paper describes methods by which the over-all effi-

ciency of traveling-wave tubes can be increased through a

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