A. S. Stepchenko

X-Band Relativistic BWO-RR With Controlled Microwave Pulse Duration

The effective 1-s batch of 100-Hz pulse repetition rate mode of an X-band relativistic backward-wave oscillator with a resonance reflector (RBWO-RR) was realized using the “SINUS” pulse-periodic nanosecond accelerator allowing mechanically installed high voltage pulse length of 13 and 42 ns. Magnetic held about of 2 T was produced by two-section solenoid to transport the electron beam along RBWO-RR electrodynamic system. T M01 to T E11 mode converter connected to the oscillator output allowed Gaussian radiation pattern. The microwave oscillator allowed producing the microwave pulse length of 4.7 and 29 ns. The energy of the microwave pulse measured by the X-band aperture calorimeter was 1.4 or 6.3 J corresponding to the mentioned above microwave pulse length of 4.7 or 29 ns, respectively. That allowed estimations of the microwave peak power as high as 280 ± 30 MW and 210 ± 20 MW related to the pulse lengths. The efficiency of the oscillator was 23-25%. A possibility of the microwave pulse length fine tuning within 25 to 34 ns range in the “long pulse mode” by changing the solenoid magnetic held conhguration was shown.

Measuring the Parameters of an Electron Beam

A technique for determining the amplitude and time parameters of pulsed electron beams is proposed. Using this technique, it is possible to measure weak currents. It is based on the non-self-sustained discharge initiated by the electron beam under investigation. The experimental results are presented for two electron beams formed in a gas-filled diode at the atmospheric pressure of air, nitrogen, a mixture of CO2 : N2 : He = 1 : 1 : 3, or helium and ejected through a foil or grid.

A Nanosecond High-Voltage Periodically Pulsed Generator Based on a Helix Forming Line

A nanosecond high-voltage periodically pulsed generator based on a helix forming line is described. The line is charged from a high-coupling Tesla transformer. Compared with a conventional coaxial line, the helix line provides a fourfold increase in the generator impedance and pulse width without a significant increase in the generator dimensions, with the energy stored remaining the same.

Compact source of high-power microwaves

This paper deals with the theoretical and experimental study of BWO using a high current electron beam. The dependencies of start length and the oscillation increments on the space charge parameters are obtained from the numerical analyze of the linear stage of transient process. For the actual experimental parameters in X-band, the duration of linear stage may be about 2 ns. The established oscillations in the nonlinear stage are steady-state over a wide range of beam current (varied by factor of 20). The further increase of current results in non-sinusoidal self modulation. The efficiency of the generator rises monotonously with the current and reaches approximately 25%. In the experiment, a compact nanosecond generator with the cathode voltage of up to 350 kV was used capable of operation at a repetition rate of up to 1,000 p.p.s. The pulsed magnetic system in which the coaxial magnetically insulated diode and the BWO slow wave structure are placed can be operated at 1 p.p.s. The microwave power was approximately 200 MW with the pulse duration of approximately 1 ns.

On the radiation phase stability of a relativistic coaxial backward-wave oscillator at decimeter wavelengths

The stability of the microwave radiation phase of A relativistic coaxial backward-wave oscillator with a modulating reflector relative to a fixed voltage at a rising edge of the feeding high-voltage pulse is shown. At a carrying frequency of 1.3 Ghz, the standard phase deviation in a series of 50 consecutive pulses was not more than 20 ps for the microwave pulse duration of 80 ns.

Repetitive

This paper presents the results of an experimental study of a relativistic traveling wave oscillator with a tubular electron beam of enlarged cross section. Repetitively pulsed (30 Hz) generation of 10.1-GHz, 80-ns microwave pulses in 1-s batches is realized. The microwave pulse power a level of quasi-steady-state oscillation was 220 ± 44 MW. The driving electron beam (370-keV, 2.4-kA, 107-ns pulsewidth) was transported along the interaction space by a quasi-constant (few seconds in duration) external magnetic field with an induction of 0.6 T. The power efficiency of the generator is 25% ± 5%. The energy in a single microwave pulse is about 15 J as measured with an aperture calorimeter.

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The design and research results for a high-power source of ultra-wideband radiation with a nineelement array excited by a bipolar high-voltage pulse with 2-ns duration are presented. The radiation pulses with an effective potential of 1 MV at a pulse repetition rate of 100 Hz were obtained.