Yu. G. Yushkov

Generation of multicomponent ion beams by a vacuum arc ion source with compound cathode

This paper presents the results of time-of-flight mass spectrometry studies of the elemental and mass-to-charge state compositions of metal ion beams produced by a vacuum arc ion source with compound cathode (WC-Co(0.5), Cu-Cr(0.25), Ti-Cu(0.1)). We found that the ion beam composition agrees well with the stoichiometric composition of the cathode material from which the beam is derived, and the maximum ion charge state of the different plasma components is determined by the ionization capability of electrons within the cathode spot plasma, which is common to all components. The beam mass-to-charge state spectrum from a compound cathode features a greater fraction of multiply charged ions for those materials with lower electron temperature in the vacuum arc cathode spot, and a smaller fraction for those with higher electron temperature within the spot. We propose a potential diagram method for determination of attainable ion charge states for all components of the compound cathodes.

Note: Resonant microwave compressor with two output ports for synchronous energy extraction

The brief theoretical analysis shows the resonant microwave compressor provides the output pulse power higher than the traveling wave power in the storage cavity. The experimental study was made with the model of the S-band microwave compressor. The power of pulses generated by the device reached the value three times as much as the value of the traveling wave power in the storage cavity at the maximum amplification 23 dB, peak power 400 MW, and pulse width 4-5 ns.

The influence of microwave radiation on the thermal stability of aluminum nanopowder

The influence of microwave radiation with a power flux density of 80 W/cm2 and carrier frequency of 9.4 GHz on the thermal stability of aluminum nanopowder after irradiation in air is studied. It is established that, after irradiation, the chemical activity of aluminum nanopowder increases, the temperature for the beginning of its oxidation decreases by 40°, while the thermal effect of oxidation decreases by 13.5%.

Formation of pulses with controlled parameters in a resonance microwave compressor employing oscillation-mode transformation

Results of an experimental study of the formation of rf pulses with controlled power, duration, repetition rate, and envelope parameters in a resonance compressor employing oscillation-mode transformation are presented. The pulse parameters are varied by using tuned intermodal coupling elements. A possibility of the formation of a series of subsecond and nanosecond rf pulses in the partial extraction of energy and nanosecond pulses of various durations in single complete extraction of energy from the compressor resonator is shown.

Electron beam evaporation of boron at forevacuum pressures for plasma-assisted deposition of boron-containing coatings

We describe the use of a plasma-cathode electron source for electron beam evaporation of boron at forevacuum pressures (∼10u2009Pa) with subsequent deposition of boron-containing coatings on a titanium substrate. We analyze the process of electron beam heating and evaporation of boron, study the mass-to-charge composition of the gas and boron beam-produced plasma, apply such plasma for coating deposition, and investigate the elemental composition of the deposited film and its microhardness.

Modified quadrupole mass analyzer RGA-100 for beam plasma research in forevacuum pressure range

The industrial quadrupole RGA-100 residual gas analyzer was modified for the research of electron beam-generated plasma at forevacuum pressure range. The standard ionizer of the RGA-100 was replaced by three electrode extracting unit. We made the optimization of operation parameters in order to provide the maximum values of measured currents of any ion species. The modified analyzer was successfully tested with beam plasma of argon, nitrogen, oxygen, and hydrocarbons.

Controlling output pulse and prepulse in a resonant microwave pulse compressor

A resonant microwave pulse compressor with a waveguide H-plane-tee-based energy extraction unit was studied in terms of its capability to produce output pulses that comprise a low-power long-duration (prepulse) and a high-power short-duration part. The application of such combined pulses with widely variable prepulse and high-power pulse power and energy ratios is of interest in the research area of electronic hardware vulnerability. The characteristics of output radiation pulses are controlled by the variation of the H-plane tee transition attenuation at the stage of microwave energy storage in the compressor cavity. Results of theoretical estimations of the parameters tuning range and experimental investigations of the prototype S-band compressor (1.5u2009MW, 12u2009ns output pulse; ∼13.2u2009dB gain) are presented. The achievable maximum in the prepulse power is found to be about half the power of the primary microwave source. It has been shown that the energy of the prepulse becomes comparable with that of the sh...

Synchronous extraction of the microwave energy from two resonators through a waveguide bridge

Results of the experimental investigation of the resonant microwave pulse compression system operating in a 10-cm wavelength region are presented. The system contains two multimode resonators for storing high-frequency energy and a waveguide bridge for the fast and synchronous energy extraction. When powered from a magnetron generator having a radiation power of 5 MW and pulse duration of 4 μs, microwave pulses with an output power of ∼0.8 GW, duration of ∼5 ns, and pulse repetition rate up to 100 Hz were obtained in this compression system.

Compression of microwave pulses in a resonant system based on two waveguide T-joints

Research results for a resonant microwave compressor consisting of two waveguide T-joints are presented. When feeding the compressor with the help of a pulse magnetron with 2 MW power and 3.2 μs duration of microwave pulses the maximum power gain of 23 dB and the peak power of 400 MW is obtained in S-band for the 4 μs long pulses.

Parameters of Iron and Aluminum Nano- and Micropowder Activity upon Oxidation in Air under Microwave Irradiation

Iron nanopowders and iron and aluminum micropowders exposed to microwave radiation with a frequency of 9.4 GHz and a power density of 80 W/cm2 at a pulse repetition rate of 400 Hz have been investigated. According to the results of differential thermal analysis, the microwave radiation caused nonmonotonic changes in the thermal properties of the A1 and Fe powders. After irradiation of the iron nanopowder, the temperature of the onset of its oxidation increased from 150.01 to 158.75°C; in the case of the micropowder, the temperature nonmonotonically changed from 150.00 to 275.38°C. The specific heat of oxidation of the Fe nanopowder increased by 17.3% at maximum, while in the Fe micropowder the maximum attained increase was 13%. For the Al micropowder, the maximum increase in the specific heat of oxidation was found to be 59.7%. Microwave irradiation leads to the formation of electron avalanches, which reduce metal ions in their oxides. At the same time, at certain irradiation doses the generated electron flows oxidize the reduced metals, which is reflected in the nonmonotonic variation in the properties of a material. The increase in the specific heat of oxidation is related to the participation of energy-saturated states of the metals in the oxidation processes.