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Romasko, V.P.

Paper Title Page


 A Pulsed Modulator To Energize The Secondary-Emission Electron Source Of The Technological Accelerator 

  • A.N.Dovbnya, V.V.Zakutin, N.G.Reshetnyak, V.P.Romasko, I.A.Chertishchev
    Kharkov Institute of Physics and Technology, Kharkov, Ukraine

Experiments were made to investigate a pulsed modulator intended to energize the electron accelerator based on the secondary-emission electron source. The accelerator with a great pulse length (8 - 40 mks) and a pulse repetition rate up to 10 Hz is designed for material-surface treatment. To form long pulses in the modulator (with reservoir capacitor discharge through a step-up transformer), the nonlinear properties of the pulse-transformer core material are used, while the top of the pulse is formed through summation of a short spike and a flat-topped long-duration pulse. At a load resistance of 4300 Ohm; a voltage pulse with a spike amplitude of ~ 150 kV and a flat-topped pulse with an amplitude of ~ 130 kV of ~ 16 mks duration and a repetition frequency of 3 Hz were obtained. During formation of the beam with a current of ~ 100A the amplitude of the flat part of cathode voltage made ~ 100 kV.




 The Electron Accelerator Based on the Secondaryemission Electron Source for Material-Surface Treatment 

  • N.I.Ayzatskiy, A.N.Dovbnya, V.V.Zakutin, V.N.Boriskin, N.G.Reshetnyak, V.P.Romasko, N.A.Dovbnya
    Kharkov Institute of Physics and Technology, Kharkov, Ukraine

The paper reports the results of experimental studies on formation of electron beams in three types of secondary-emission sources. Experiments were carried out with a magnetron gun having a cylindrical anode (70 mm in diameter): 1) with a smooth cathode (40 mm in diameter) and a modified cathode: 2) with 4 longitudinal seams and 3) composed of 8 copper rods (5 mm in diameter). Parameters of beams were studied and beam indentations were obtained. In the first case the beam formation occurs with a current of ~40 A (at a cathode voltage of 40 kV) and an azimuthal uniformity of 5 %. In the second case, at a field nonuniformity of ~30%, the azimuthal nonuniformity is ~15 A. In the third case, at a field nonuniformity of ~60% there occurs formation of 8 separate beams having the form close to the half-ring and with a total current of ~10A (at a cathode voltage of 30 kV). The beam current amplitude stability in all the cases was 2 ... 5 %.



 Electron Beam Forming In The Magnetron Gun With Secondary-Emission Cathodes Of Different Materials 

  • A.N.Dovbnya, V.V.Zakutin, N.G.Reshetnyak, V.P.Romasko
    Kharkov Institute of Physics and Technology, Kharkov, Ukraine

A magnetron gun with a cold secondary-emission cathode in crossed fields is used as an electron source in the high-energy RF-devices. Experiments were carried out using the secondary-emission cathodes made of different metals: copper, aluminum, titanium, stainless-steel (cathode diameter of 40 mm, gun length of 140 mm). In experiments the electron beam production was observed. It has been established that the beam current dependence on the voltage obeys to the 3/2 law. Experiments demonstrated that despite the fact that the coefficient of secondary emission in the case of aluminum and titanium is less than unity, the processes of secondary-emission multiplication take place, apparently, on the cathode surface oxide layers formed in technical vacuum below 10-5 - 10-6 Torr and with the presence of organic materials inside the chamber.




 The Electron Accelerator Based On The Secondary-Emission Electron 

  • N.G.Reshetnyak, A.N.Dovbnya, M.I.Ayzatskiy, V.N.Boriskin, V.V.Zakutin, V.P.Romasko, I.A.Chertishchev, N.A.Dovbnya
    Kharkov Institute of Physics and Technology, Kharkov, Ukraine

The electron accelerator for radiation technology purposes is being created at the NSC KIPT. The accelerator is designed to have a particle energy up to 200 keV and a beam power up to 5 MWt/cm2 at a voltage pulse duration between 8 and 40 mks and a pulse repetition rate up to 10 Hz. A magnetron gun with a cold secondary-emission cathode in cross fields is used as an electron source. Results are reported from the experiments on electron beam production in the magnetron gun (the diameters of the cathode and anode being 40 mm and 78 mm, respectively). The longitudinal magnetic field was measured to range from 1500 to 2300 Oe. In one of the modes of operation, an accelerated electron energy of ~ 100 keV was obtained (beam current 110 A, duration ~ 16 mks), the power density on the target was ~ 4 MW/cm2. Targets made from different materials (stainless steel, aluminum, etc.) were exposed to radiation.