In a traveling wave tube (TWT) using an interaction circuit of the helix-derived type, the gain of the tube normally varies significantly over the passband. The invention provides a simple method of reducing the gain variation together with a reduction in the noise power density produced at the output of the tube. This is accomplished by affixing a nonresonant terminated transmission line such as a meander line on at least one of the dielectric rods used to support the helix.

Helix traveling wave tubes with reduced gain variation

A traveling wave tube and method of operation is disclosed. The traveling wave tube includes a slow wave structure such as a helix member provided with input and output ends and located within a tube member. An electron gun assembly is adjacent the input end for injecting electrons as an electron beam along an axial path through the helix member. A magnetic focusing device generates a magnetic field having a given strength to confine the beam to the axial path. The given strength of the magnetic field is sufficient to confine the beam only when the power level of the microwave input signal is selected such that the given power level of the microwave output signal is at least 6 dB lower than the power level of the microwave output signal at saturation. Boron Nitride (BN) supporting rods are engaged between the tube and helix members for supporting and transferring heat away from the helix member.

Optimally designed traveling wave tube for operation backed off from saturation

A traveling wave tube apparatus and method is disclosed. The traveling wave tube includes a slow wave structure such as a helix member. The helix member has an input end for receiving a microwave input signal having a selected power level and an output end for supplying a microwave output signal having a given power level. A microwave source is connected to the input end of the helix member for applying the microwave input signal to the helix member. An electron gun assembly is adjacent the input end of the helix member and has a cathode for injecting electrons as an electron beam through the helix member. A collector assembly is adjacent the output end of the helix member and has at least four collector electrodes for collecting the electrons in the electron beam. The power level of the microwave input signal is selected such that the given power level of the microwave output signal is at least 3 dB lower than the power level of the microwave output signal at saturation. The geometry of the electrodes and bias voltages applied to the electrodes are selected to optimally handle an electron beam of a traveling wave tube operating at least 3 dB backed off from saturation so as to maximize the collection efficiency. The geometry of the electrodes and bias voltages applied to the electrodes are selected such that the collector assembly generates a high level of backstreaming current when the traveling wave tube operates at saturation.

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

A delay line for travelling wave tubes, particularly travelling wave tube whose gain and whose output power are independent of frequency over a plurality of octaves and contain a helix (9) in an electrically conductive cylinder (5). The helix is fixed and adjusted by retaining rods (8). Loading webs (4) are arranged parallel to the axis of the adjoining electrically conductive cylinder (5) and a small gap (12) is left free adjacent the helix (9). The extremely high requirement for mechanical dimensional accuracy and reproducibility of the dimensions in such delay lines are obtained by using loading webs (4) which are integrally formed in the electrically conductive cylinder (5).

Espinosa Robert J

Papers

Non-resonant stub supports for slow wave circuits