Influence of the Kinetic Energy Spectrum of Pulsed Beam Electrons on the Effective Absorbed Dose Distribution Over the T
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QUANTUM ELECTRONICS INFLUENCE OF THE KINETIC ENERGY SPECTRUM OF PULSED BEAM ELECTRONS ON THE EFFECTIVE ABSORBED DOSE DISTRIBUTION OVER THE TARGET DEPTH I. S. Egorov, A. A. Isemberlinova, M. A. Serebrennikov, A. V. Poloskov, and G. E. Remnev
UDC 621.384.6, 539.1.047
The analysis of the efficiency of the absorbed dose depth distribution as a function of the kinetic energy spectrum of a submicrosecond electron beam showed that the use of two operating modes of a submicrosecond electron accelerator, which differ in the amplitude of the accelerating voltage pulse (200 and 300 kV), under irradiation of various materials can provide different effects determined by different depth distributions of absorbed energy. For the constructed spectra of the beam electron kinetic energies, we used a model sample that takes into account the structure and penetration of the material, which determines the conditions for the electron beam absorbed energy distribution over the depth. Based on the experimental data, the absorbed dose in the structural parts of the object was estimated using the example of a wheat seed, and conclusions were drawn about the efficiency of using irradiation modes with different kinetic energy spectra of electrons in the beam. Keywords: pulsed electron beam, electron kinetic energy spectrum, depth distribution of absorbed dose.
INTRODUCTION The intensive development of pulse circuits for generating the accelerating voltage has led to the emergence of compact pulsed accelerators with performance characteristics suitable for solving practical problems [1–3]. Pulsed electron accelerators can compete with continuous electron beam sources at their average power of the order of several kilowatts and voltage levels up to 1 MeV due to more compact dimensions and lower requirements for vacuum conditions in an electron diode. For monoenergetic beams of continuous accelerators, the absorbed energy distribution of electron beam has a characteristic maximum at a certain depth from the surface of the object [4–6], which makes it impossible to uniformly distribute the absorbed dose over the depth and requires the use of additional means of positioning the objects to be treated during irradiation [7, 8]. For pulsed beams with a wide spectrum of kinetic electron energies, the maximum absorbed dose is achieved, as a rule, in the near-surface layer [9]. This must be taken into account when solving applied problems, primarily those associated with surface treatment by an electron beam, when the irradiation depth does not exceed the geometric size of the sample in the direction of the beam propagation. This is important, in particular, when processing biological materials, for example, grain crops with an electron beam [10, 11]. When planting, radiation exposure is necessary mainly on the surface coat of the seed. The indicated absorbed energy (J/kg) characterizes the operating mode of the setup, but does not reflect the real values of absorbed doses (kGy), which
National Research Tomsk Polytechnic University, Tomsk, Russia, e
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