A. G. Shkvarunets

A calorimetric spectrometer measuring single pulses of relativistic microwave generators

A calorimetric spectrometer measuring individual pulses radiated by wideband relativistic microwave oscillators is described. The calorimetric spectrometer comprises two calorimeters and a set of low-pass filters. In the development of such a spectrometer, the basic feature consists in the high radiation power (∼108 W) and low pulse energy (∼1 J). To prevent the microwave surface discharge, the calorimeters have a rather large area (∼0.1 m2). The calorimeters’ sensitivity is 0.05 J. Frequency responses of the filters were measured experimentally and calculated with the help of a three-dimensional version of the KARAT computer code. The experimental spectrum of a wideband relativistic microwave plasma oscillator measured in a frequency range of 5–40 GHz is presented.

Calorimetric spectrometer for measuring single microwave pulses in relativistic microwave electronics devices

Broadband plasma relativistic microwave oscillators fabricated at the General Physics Institute of the Russian Academy of Sciences have the following output parameters: microwaves are generated in a frequency band on the order of the mean frequency, the output power is -100 MW, the mean microwave frequency is 10-20 GHz, the duration of a single pulse is 20-800 ns, and the diameter of the emitting horn window is no less than 15 cm (because of the possible microwave breakdown). The spectrum of high-power broadband emission from the plasma in the course of a REB-plasma interaction was studied in experiments in a number of experiments but accuracy of measurement has been low. The authors describe a calorimetric spectrometer that has very high accuracy. The main advantage of the spectrometer is that it can measure the spectrum of the total microwave energy flux in absolute units, while the spectrometers used previously were capable of measuring only a small fraction of the total energy flux. The spectrum of the total energy flux from oscillators is the fundamental characteristic calculated theoretically and used to estimate the possible applications.

Electron Beam Generated Plasmas: Theory, Experiments, Applications

The review of results of investigations, carried out during last 30 years in GPI, on fundamental physical processes and applications of plasmas generated by long-pulse non-relativistic electron beams, as well as by high-current, short pulse relativistic electron beams (REB) is presented. The applications in the case, when low-density plasmas are generated, deal with using such plasmas in high-power plasma microwave electronics, whereas in the case, when high-density plasmas are created, the applications in laser physics are discussed.

Measurement of spectrum and power of microwave radiation from relativistic plasma microwave oscillator

Experimentally studied microwave radiation from plasma waveguide when relativistic electron beam (600 keV, 2 divided by 4 kA, 100 ns) propagate axially the plasma waveguide. Spectrum of microwave radiation was measured by multi resonator spectrometer power was measured by broadband calorimeter. The calorimeter measured the total microwave energy emitted from output horn. Emitting microwave power strongly depended on plasma density, interaction length and gap between annular tube beam and annular tube plasma column. Spectrum of radiation was approximately 50%.