M. E. Balezin

High-current electron beam generation by a metal–ceramic cathode

We present results of the investigation of a metal–ceramic cathode suitable for technological applications. The cathode was tested in electron diodes powered by two different high-voltage generators (500 kV, 50 ns, 300 Ω, ⩽200 Hz and 300 kV, 250 ns, 84 Ω, ⩽5 Hz). The metal–ceramic cathode which was made in a form of a disk was composed of TiO2 ceramics with stainless steel spherical particles uniformly inserted inside. It was shown that already at relatively low accelerating fields (E⩽5 kV/cm) fast cathode plasma formation occurs as a result of surface flashover. This surface flashover is initiated in triple points located in micropores which were formed during the process of cathode preparation due to the different thermal expansion coefficients of the ceramic and the metal. Experimental data concerning the uniformity of the light emission from the cathode surface and inside the anode–cathode gap and divergence of the generated electron beams are presented. Also, it is shown that the uniformity of the ge...

YPT-0.5 repetitive-pulse nanosecond electron accelerator

An YPT-0.5 repetive-pulse nanosecond electron accelerator designed according to the thyratron-pulse transformer-semiconductor opening switch scheme is described. Its accelerating voltage reaches 0.5 MV, the FWHM pulse duration is 50 ns, and the pulse repetition rate is 200 Hz. A metal-dielectric cathode allows for obtaining an electron beam with a diameter of 30–100 mm at a maximum pulse current density of 40 A/cm2. Operating in the bremsstrahlung generator mode, the accelerator provides an absorbed dose rate of 30.4 Gy/min at a distance of 5 cm from the target.

A review of possible applications of nanosecond electron beams for sterilization in industrial poultry farming

Elaboration of principles of technologies for radiation sterilization employing nanosecond electron accelerators in the industrial poultry farming was studied. The obtained results suggest that the URT-0.5 accelerator may be used to sterilize a bone meal. It is possible to create the processing line providing an output of 1500 kg per hour at the estimated cost amounting to

Application of nanosecond electron beam for production of silver nanopowders

0.01/kg. Was found that consumer properties of the melange changed little up to an absorbed dose of 50 kGy and approached the measurement error. So, it is possible to use the URT-0.5 accelerator as the basis of a process line with an output of about 800 l/h at the estimated cost of nearly 0.14

Properties of a metal-ceramic cathode

/l, which accounts for not more than 5% of the melange cost. Consequently, the use of nanosecond electron beams for sterilization in industrial poultry farming is technically possible and economically reasonable.

Metal-Ceramic Cathodes for Electron Accelerators

Experiments on the irradiation of silver nitrate solutions in various liquids by the nanosecond electron beam of a URT-0.5 (0.5 MeV, 50 ns, 1 kW) accelerator facilitated the development of technology for producing silver nanopowders. The powder yield and particle size as a function of the irradiation mode has been established. An increase in the adsorbed dose results in an increased powder yield; however, the particle size decreases and the powder agglomeration rate increases. Therefore, the targeted production of silver nanopowders with a mean particle size in the range of 90 ÷ 1100 nm is possible.

AУPT-1M accelerator for radiation technologies

The characteristics of a metal-ceramic (MC) cathode designed for nanosecond electron accelerators are studied in relation to the size of metal particles, their density on the ceramic surface, and the type of ceramics. A high emissivity of the MC cathode at a moderate electric field in the diode tube is demonstrated. This allows one to significantly sharpen the electron beam and increase its current (power). The possibility of controlling the emissivity of the MC cathode by varying the composition of the MC plate is established.

Production of Nanopowders Using Nanosecond Electron Beam

Institute of Electrophysics, Ural Division, Russian Academy of Sciences, Komsomol’skaya ul. 34, Yekaterinburg, 620219 Russia 1. Nanosecond pulse generators with the pulse recurrence frequency as high as 1 kHz and the resource up to 1010–1011 pulses and electron accelerators with such generators [1, 2], which are of considerable promise for technological applications [3, 4], have been developed on the basis of semiconductor current switches. In connection with this, the problem of creating simple, inexpensive, and high-resource cathodes with high and stable emissivity in the course of the exploitation becomes urgent. Metal–dielectrics–metal cathodes [5], in which electrons are emitted from plasma arising at a point of contact of special electrodes with ceramics (triple points), most fully conform to these requirements. Among disadvantages of these cathodes are a complexity of the structure and limited number of emitting points. This causes the erosion of igniting electrodes and the ceramics under them, a inhomogeneity in the current distribution at the output foil of a vacuum diode, and a reasonably high impedance of the diode for small dimensions of the cathode unit.

Accelerator URT-1M-300 for mobile installation

AУPT-1M modernized electron accelerator with an accelerating voltage up to 1 MV, a 1-kW electron beam power, and a 100-ns pulse duration is described. As compared to the prototype (УPT-1 accelerator), the layout of assemblies is changed in it, allowing one to place it in rooms with heights up to 2.5 m. It uses Murata capacitors and a ТQPи1–10k/75 thyratron with a cold cathode for switching. The computer-aided parameter-monitoring system is created. A metal-ceramic cathode consisting of several elements with ∼15% nonuniform current density distribution of the electron beam on the exit foil was used to obtain an electron beam with a width of up to 400 mm. The accelerator can be used in radiation technologies in layers with a thickness of up to 0.3 g/cm2.

Using Nanosecond Electron Beam to Produce Silver Nanopowder

Frequency nanosecond electron accelerators type URT has been developed for use in radiation technologies. The accelerator includes a thyratron, a pulse transformer and a semiconductor opening switch. The accelerating voltage is up to 0.9 MV, FWHM pulse length is up to 60 ns, and the repetition rate is up to 250 Hz. A metal ceramic cathode, which is used in the accelerator, provides an electron beam cross section up to 16 cm in diameter or rectangular with the dimensions of 45 * 5cm2 at a maximum density of the pulse current equal to 2 A/cm2. Thus, a family of nanosecond electron accelerators has been developed for use in radiation technologies applied to layers up to 0.4 g/cm2 thick, such as production of nanopowders from gas and liquid precursors. Experiments on the irradiation of silver nitrate solutions in various liquids by a URT-0.5 accelerator facilitated the development of technology for producing silver nanopowders (NPs). The powder yield and particle size as a function of the irradiation mode has been established. An increase in the adsorbed dose results in an increased powder yield; however, the particle size decreases and the powder agglomeration rate increases. Therefore, the targeted production of silver NPs with a mean particle size in the range of 90–1100 nm is possible. Besides to produce TiO2 and SiO2 NPs the gas precursors were used.