I.P. Medvedkov – Head of Department, 

JSC «SPE «Almaz» (Saratov)

E-mail: medvedkovip@almaz-rpe.ru

V.I. Rogovin – Ph.D.(Phys.-Math.), Associate Professor, Deputy Director of RPC «Electronic systems»,  JSC «SPE «Almaz» (Saratov); 

Department «Bases of Micro-wave Devises Design», Saratov State University named after N.G. Chernyshevsky E-mail: rogovinvi@almaz-rpe.ru

S.O. Semenov – Ph.D.(Phys.-Math.), Associate Professor, Head of Department, 

JSC «SPE «Almaz» (Saratov);

Department «Bases of Micro-wave Devises Design», Saratov State University named after N.G. Chernyshevsky

E-mail: semenovso@almaz-rpe.ru

A method of the noise signal gain calculating in helix TWT using 2D large signal code is considered. To calculate the noise gain, the zero initial conditions for the electron beam in the interaction region entrance were replaced by conditions that take into account the initial current and velocity modulation. Accounting for the magnetic field at the cathode is introduced. The propagation of current and velocity waves in the region of the electron gun and the input part of the PPM - with a shielded cathode and with a magnetic field at the cathode, is calculated. The modulated beam data was used as input for calculate the gain of the noise signal in a helix SWS. The presence of undamped space-charge waves during the drift region in a modulated beam is shown. The introduction of a magnetic field at the cathode of the gun significantly affects to process of their propagation.

The calculation of a noise signal gain in the helix TWT was performed. The influence on the process of noise amplification of various factors is considered: the pitch of the helix, the position of the helix entrance, and the magnetic field on the cathode of the gun.

It is shown that in the case of an electron gun with a shielded cathode, the smallest noise power is achieved at the start position of the helix after the minimum of the current first harmonic, while introducing a magnetic field to the cathode leads to a correspondence the minimum of the noise power and the minimum of the first harmonic of the current at the SWS input. Thus, studies have shown the possibility of calculating the TWT noise characteristics by the method of large particles.

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