ORIGINAL RESEARCH Trapping of Free Electrons in Multipole System Mohammad Mahdavi • Fatemeh Khodadadi Azadboni • Reza Khodadadi Azadboni Published online: 30 October 2011 Ó Springer Science+Business Media, LLC 2011 Abstract In this paper, the effective Parameters in the confinement and trapping of fast electrons in plasma source Such as; plasma pressure, wall material of plasma chamber and magnetic mirror rate have been investigated with using Comsol & Geant4 code. The calculations are shown that the Multicusp magnetic field was effective the pressure less than 5 mTor, and the confinement effect becomes stronger with decreasing pressure. It is equivalent to a higher yield of output ions of plasma source. The number of fast electrons trapped in the magnetic field increases with increasing magnetic field intensity and using aluminum for wall mate- rial. Optimum conditions of confinement plasma, leading to increased the hot electron density, and ionization efficiency is increased. The results of investigations have demonstrated good correspondence with theoretical calculations, therefore there is the adequacy of the developed approach and the possibility to build more effective source ion on this basis. Keywords Plasma pressure  Multipole field  Trapping electrons Introduction Plasma processing of materials is now becoming a critical technology not only in the electronics industry but also in the aerospace, automotive, steel, biomedical, textile, optics and paper industries. The plasma generated in a plasma source can be confined magnetically to form a plasma beam [1–6]. Magnetic confinement fusion is an approach to generating fusion energy that uses magnetic fields to con- fine the fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, the other being inertial confinement fusion. The magnetic approach is more highly developed and is usually considered more promising for energy production. Mag- netic multipole plasma confinement geometries employing permanent magnet buckets are used extensively for a range of laboratory plasma applications [7, 8]. In magnetic confinement, plasma of charged particles in a gas chamber by a powerful magnetic field is enclosed. Different configuration for confinement of hot plasma is proposed. One of the most common methods of magnetic confinement is Multicusp ion source. Electrons in the Multicusp ion source are emitted by the hot filament and with an electric arc voltage are accelerated. To increase the probability of electrons colliding with atoms (ionization), the electrons are confined by the strong magnetic field. Among the several consequences for plasma confinement is the important result that the plasma can acquire a more-or- less flat density profile, which when embodied in an ion source can lead to a flat profile for the extracted ion beam also. For many applications a uniform ion beam current density profile is quite advantageous, for example for car- rying out large-area ion implantation [9–11]. In fact, the discharge chamber is surrounded by a number of permanent magnets to prevent the diffusion of ions and high current beam be produced. Magnetic field by permanent magnets Sm–Co, Nd–Fe or NdFeB surrounding the plasma chamber produced [12, 13]. In this article by Geant 4 & Comsol simulation code, we make an analysis of confinement and trapping of fast electrons in multipolar magnetic fields. M. Mahdavi  F. Khodadadi Azadboni Department of Physics, Mazandaran University, P. O. Box 47415-416, Babolsar, Iran F. Khodadadi Azadboni (&)  R. Khodadadi Azadboni Young Researchers Club, Science and Research Branch, Islamic Azad University, P. O. Box 48161-194, Sari, Iran e-mail: F.Khodadadi@stu.umz.ac.ir 123 J Fusion Energ (2012) 31:368–373 DOI 10.1007/s10894-011-9476-2