The dynamics of the dimensions of the electron beam generated by the magnetron gun in the particle transport channel and the efficiency of focusing the tubular electron beam in the gradient magnetic field are investigated. The experiments were carried out with magnetron guns with secondary-emission cathodes (cathode diameters 36 and 16 mm, anodes diameters 78 and 36 mm) at cathode voltage of 20...80 kV. Magnetic fields were created both by the solenoid and jointly by the solenoid and the permanent magnet. The dependence of the radial distribution of the beam on metal targets on the amplitude and gradient of the magnetic field along the axis of the system is investigated. The possibility of controlling the beam diameter by varying the magnetic field is shown. The imprints of collimated beams were obtained experimentally on targets located at selected distances. The obtained experimental data agree with the results of numerical simulation. It is shown that with an increase in the amplitude of the gradient magnetic field, the effect of radial focusing of the beam is more pronounced.

An assessment of the energy efficiency of pulse modulators of technological accelerators at the NSC KIPT. The influence of the parameters of a pulse transformer on a voltage pulse at a load is investigated. The possibilities of increasing the energy efficiency of plants are considered. Studies of losses in high-voltage pulse modulator systems were conducted and it was shown that the main elements that require replacement or improvement are forming lines and pulse transformers.

The results of a study on the formation of an electron beam by a magnetron gun with a secondary-emission cathode (cathode diameter 36 mm, an anode 78 mm) in the voltage range 25...90 kV are presented. The secondary-emission process in the gun is triggered by a voltage pulse with an amplitude of up to 16 kV applied to its anode. The generation of an electron beam is investigated as a function of the voltage of the incoming pulse. The dependence of the onset of electron beam generation on the beginning of the decay of the triggering pulse with its positive and negative polarity is studied. The dependence of the formation of the electron beam on the time of the secondary emission on the flat part of the voltage pulse was investigated.

A small-sized nanosecond generator was developed to trigger a magnetron gun. A voltage pulse of amplitude up to 20 kV is applied to anode for gun triggering. Rise and fall fronts of high-voltage pulse are 20 and 70 ns consequently. Thyratron TGI1-500/16 with a low-inductive storage capacitance was used as a switch. The capacitance is discharged to the cable transformer (input wave impedance 25 Ohm, transformation ratio n = 2) operating at a load of 500 Ohm (the capacitance of the magnetron gun anode to ground is 40 pF). Using this resistance transformer on RF cables makes it possible to change rapidly the polarity of the trigger pulse.

Results are reported from the experimental and model investigations of the formation of a radially-directed electron beam, which is generated by a secondary-emission cathode magnetron gun in the electron energy range between 30 and 65 keV, as the beam is transported in the decreasing magnetic field of the solenoid. The beam transport was realized in the system consisting of copper rings with an internal diameter of 66 mm; the system was at a distance of 85 mm from the magnetron gun edge. The radial beam current and its distribution along the length of the measuring ring system were investigated versus the amplitude and gradient of the magnetic field. Studies were made into the mode of electron current bunch formation. Numerical simulation data on the tubular electron flux motion in the decreasing magnetic solenoidal field are presented.

The problem of regulating the gradient of the solenoidal magnetic field decrease has been investigated in a wide range of values. The results of developing two methods of regulation are reported. With the first method, the field decrease of the main solenoid is regulated through the use of the stray magnetic field, which was produced by SmCO5 permanent magnets. According to the second method, the regulation was realized with the use of an additional solenoid. The rate of field decrease was regulated within 50...400 Oe/cm. The electron beam formed by the magnetron gun was transported in the decreasing magnetic field of the solenoid. Measuring systems have been created to investigate the beam current distribution in the radial direction.

Modulators performed according to linear circuit with PFN depletion via pulse transformer are used in NSC KIPT active electron accelerators. Switch and its components determine the reliability of a plant. Hydrogen thyratrons providing the current switching up to 2.3 kA at anode voltage up to 40 kV are used as a switch in modulators of technological accelerators. The results of study of operational reliability of switches in active accelerators are reported in this article.

The software tool has been developed for computing the electron beam formation by means of the secondary-emission cathode magnetron gun in the electron energy range between 30 and 65 keV at beam transport in a decreasing magnetic field of the solenoid. Numerical simulation data on the tubular electron flow motion and visualization are presented. The beam current was investigated versus the amplitude and gradient of the field decrease, and also, versus the initial beam particle distribution in the phase space. It has been found that for the given simulation conditions, the magnetic field reconfiguration has an effect only on the total displacement of the electron beam, without causing a noticeable change in the shape of the final flow distribution along the longitudinal coordinate.

An electron accelerator in which magnetron guns with secondary-emission cathodes of two types are used as a particle source is described. The electron-beam parameters are investigated in an electron energy range of 20–150 keV at a pulse length of 10–50 μs. Results of target irradiation by an electron beam are represented. The target surface structure is studied by the metallographic method, and the microhardness and strength of zirconium materials are measured. The possibility of beam current control by factors of 2.5–3.5 with various methods is shown.

Various techniques have been investigated for forming a high-voltage pulse to energize magnetron guns with secondary-emission cathodes. To generate a powerful beam, it was necessary that the storage element in the modulator should have a low wave impedance. A capacitor and a low-impedance forming line were used as a storage element. The flat part of the pulse was formed by means of different correction circuits. The influence of correction circuit elements on the pulse form has been investigated. Consideration has been given to the circuits of spike control by means of the driving generator, and also, by including the correction circuits in the discharge circuit. Spike formation through the use of pulse-transformer parasitic parameters was also considered. The undertaken studies have demonstrated the possibility of creating a modulator for energizing the accelerator with electron energy up to 150 keV.

Data are reported on electron beam generation and beam current control in two types of secondary-emission cathode magnetron guns. The influence of the magnetic field value and field distribution on the formation of the beam and its parameters has been investigated in the electron energy range between 20 and 150 keV. The influence of local magnetic field variations on the cathode and the electron beam characteristics has been studied. The possibility to control the electron beam current in various ways has been demonstrated.

Results of metallographic investigation of the surface of KhVG, Kh18N10T steels and VT-1 titanium after irradiation with a pipe electron beam of the accelerator based on the magnetron gun with a copper secondary-emission cathode are presented. It has been shown that this accelerator can provide an electron beam with parameters required for a purposeful modification of the surface of metals and alloys.

The report is concerned with the possibility of monitoring the parameters of the beam in the magnetron gun with a secondary-emission cathode by using magnetic fields of permanent ring-shaped magnets. The measured magnetic-field distributions of permanent magnets are presented. Consideration has been given to the possibility of controlling the beam current and size on the Faraday cup. The experimental results are reported.

The reliability and service life of accelerating installations are substantially determined by the lifetime of electron sources. The accelerator under consideration has a magnetron gun with a channel-free cold secondary-emission cathode in crossed fields as an electron source [1, 2]. In the present work, the data of the electron beam parameters obtained in the accelerator based on the magnetron gun with a secondary-emission cathode are given, and possible secondary uses are suggested.

The investigation of forming high voltage pulses for feeding power magnetron gun was made. Use of LC-circuit stop the discharge current across thyratron and give ability step over from full discharge accumulation element to partial discharge. Efficiency of modulator will be above.

The need to control a high-current pulsed arc with the aim of raising the efficiency of current-induced heating of a gas is theoretically substantiated. A computational formula for the length of the discharge gap in devices where a pulsed arc is initiated in a gas is derived. The effect of arc voltage control on the current dynamics and variation of the voltage across the gap is studied experimentally. It is shown how pulsed arc control influences the propagation rate of the leading edge of a discharge jet generated in a pulsed plasma jet former.

Results are reported from the studies on the electron beam parameters of the accelerator based on a secondary emission source. The accelerator forms the electron beam with an electron energy of up to 100 keV, a current up to I 10 A, a pulse duration between 10 and 20 mu s with a repetition rate of 3 to 5 Hz, the power density on the target surface being similar to 2 MW/cm(2). Targets from various materials were exposed to radiation.