Quasi-3D Model of an Electron Cyclotron Resonance Ion Source

The production of high-quality, high-charge-state ion beams is an area of intensive research and development worldwide for particle accelerators, atomic physics experiments, and industrial applications. Electron cyclotron resonance ion sources (ECRIS) generate multiply charged ions through electron impact ionization in a confined plasma. These sources reduce the cost to produce ion beams by reducing the accelerating voltage needed to achieve the desired beam energy. However, the three-dimensional (3D) geometry of the ECRIS magnetic field generates 3D structures in the extracted beam, which increases their emittance and reduces the efficiency with which they can be delivered to an accelerator. The complicated 3D geometry also makes numerical modeling a difficult task. FAR-TECH, Inc. proposes to use a mapping technique to develop a sophisticated modeling tool that can simulate the 3D ECRIS plasma in a reasonable amount of computation time. The tool will aid ECRIS users in operating existing ion sources and designing and building new ones. During Phase I, FAR-TECH developed a mapping technique to provide a useful means of estimating the electron distribution function (EDF) in 3D without the computational expense of a 3D calculation. This quasi-3D modeling technique (Quasi3D) predicts successfully the 3D nature of ECRIS properties as observed in experiments such as the triangular cross sections of extracted beam ions. Our Quasi3D mapping technique eliminates the most time consuming part of the computation. The quasi-3D mapping is only valid for electrons. The complete 3D model requires proper treatment of gas and ions. In phase II, we will develop a Monte-Carlo Particle-In-Cell (MC-PIC) simulation module for support gas tracking. The electrons from our Quasi3D mapping will be integrated with the MCC-PIC gas and ion simulations. The completed code will treat electrons and ions self-consistently and provide 3D ECRIS modeling capability, within a practical computation time, up to steady states of an ECRIS (tens of milliseconds). Simulation results will be validated against measurements on ECRIS devices. Commercial Applications and Other Benefits: Numerical modeling of ECRISs will improve the efficiency of rare isotope ion beam facilities as well as industrial applications using highly charged ions, such a materials processing and hadron therapy.