ORIGINAL PAPER Design Studies of a Multicusp Ion Source with FEMLAB Simulation Fatemeh Khodadadi Azadboni Æ Mahmood Sedaghatizade Æ Kamran Sepanloo Published online: 15 July 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Femlab simulations have been used to arrive at the first step in the design of an ion source. The goal is to optimize Magnetic multipole plasma confinement geome- tries, the increased area of constant magnetic field in the central region of the plasma volume and the increase in number of electrons which have stationary orbits within this region of the field. The confinement of electrons is essential for Multicusp ion source to produce intense beams of negative hydrogen ions (H - ). A higher electron temperature and density given by a better plasma con- finement leads to the higher efficiencies of the ionization and the production of highly charged ions. We have per- formed Femlab simulations of the magnetic flux density from permanent magnet used for a Multicusp ion source, plasma confinement and trapping of fast electrons by the magnetic field. Keywords Multicusp ion source  Radial Multicusp magnetic field  Trap of fast electrons Introduction Magnetic multipole plasma confinement geometries employing permanent magnet buckets are used extensively for a range of laboratory plasma applications [1–5]. 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 carrying out large-area ion implantation. There are, however, inherent limitations on the extent to which this approach to beam ‘‘homogenization’’ can be utilized, and even for a perfectly flat profile in the immediate post extraction region, the beam will evolve toward Gaussian as it propagates down- stream [6]. High order magnetic multipole confinement systems using permanent magnets have the additional characteristic that the magnetic field in the plasma region distant from the magnetic walls is very low. One can think of the plasma particles as being confined in a homogeneous, isotropic space with low-loss magnetic walls—a magnetic bucket. Then, not only is the plasma microscopically stable, and so of low fluctuation level (low noise), but also it assumes a more-or-less flat density profile. Thus the use of a perma- nent magnet magnetic bucket can provide a low-noise, uniform plasma for ion source application, and a large area ion beam extracted from such bucket-confined plasma can be quiescent, with a uniform current density profile, and of low divergence. This approach has been exploited well, for example, for the large ion sources developed for neutral beam injectors for fusion [7]. Many zero-dimensional (0D) [8–16] codes have been developed and successfully applied to the analysis of F. K. Azadboni (&)  M. Sedaghatizade Department of Physics, K.N. Toosi University of Technology, 41, Shahid Kavian St., P. O. Box 15875- 4416, Tehran, Iran e-mail: fatemeh@sina.kntu.ac.ir; fatemeh.khodadadiazadboni8@gmail.com F. K. Azadboni Member of Young Researchers Club, Islamic Azad University, Sari branch, P. O. Box 48161-194, Sari, Iran K. Sepanloo Head, Reactors and Accelerators Research and Development School, Institute of Nuclear Science and Technology Research, Atomic Energy Organization of Iran, Tehran, Iran e-mail: ksepanloo@aeoi.org.ir 123 J Fusion Energ (2010) 29:5–12 DOI 10.1007/s10894-009-9219-9