Adapting of energy of accelerated ions for irradiation of materials of interest for fusion reactors

Andričević, Pavao Roko (2015) Adapting of energy of accelerated ions for irradiation of materials of interest for fusion reactors. Diploma thesis, Faculty of Science > Department of Physics.

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Abstract

One of the major steps towards building a fusion nuclear power plant is finding materials able to withstand prolonged and intensive 14.1 MeV neutron radiation, without it changing their physical and chemical properties. To be able to understand and master the phenomenas which define the time of life and the integrity of the material under such neutron radiation, it is necessary to expose the material to conditions as simmilar as possible to the ones in fusion reactors. One of the ways to achieve that is irradiation using two or three ion beams of MeV energy range, all falling at the same spot. As the ion beam energy deposition loses is very unhomogenuous on its path in the material, achieving its maximum at a maximum depth, it is necessary to install a system for adjusting and varying the energy of accelerated ions. The aim is to get a homogenuous distribution of ion energy deposition in the material along the entire path, from the surface to maximal ion range in the material. This master thesis includes designing a so-called ”ion beam degrader” ie. a simple system for the mechanical variation of energy of accelerated ions, using metal foils of various thickness. The ion beam degrader would be shaped as a circle that contains 8 trapezoid like foils. The thickness of different groups of foils are calculated for irradiation of iron with heavy ions i.e. iron ions of energy 20, 30 and 40 MeV, and light ions of the same range in iron, i.e. protons of energies 600 and 700 keV and alpha-particles of energy 2000 and 2500 keV. In addition to calculating the energy deposition of ions in the material, ions’ small angle multiple scattering distributions were also calculated for the purpose of determination of irradiated areas at the sample, and to confirm that both ion beams will irradiate the same matching area. The position of the ion beam degrader inside the chamber was determined, and its speed of rotation is proposed to be no less than 600 revolutions per minute. At that speed there will be no overheating of the thin foils and it is not difficult to stop spinning because of the need to measure current.

Item Type: Thesis (Diploma thesis)
Keywords: fusion, fusion reactors, accelerated ions
Supervisor: Tadić, Tonči
Date: 10 July 2015
Number of Pages: 51
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 08 Sep 2015 14:02
Last Modified: 05 Sep 2016 15:33
URI: http://digre.pmf.unizg.hr/id/eprint/4228

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