Comparison of extraction and beam transport simulations with emittance measurements from the ECR ion source venus

Abstract

The versatility of ECR (Electron Cyclotron Resonance) ion sources makes them the injector of choice for many heavy ion accelerators. However, the design of the LEBT (Low Energy Beam Transport) systems for these devices is challenging, because it has to be matched for a wide variety of ions. In addition, due to the magnetic confinement fields, the ion density distribution across the extraction aperture is inhomogeneous and charge state dependent. In addition, the ion beam is extracted from a region of high axial magnetic field, which adds a rotational component to the beam. In this paper the development of a simulation model (in particular the initial conditions at the extraction aperture) for ECR ion source beams is described. Extraction from the plasma and transport through the beam line are then simulated with the particle-in-cell code WARP. Simulations of the multispecies beam containing Uranium ions of charge state 18+ to 42+ and oxygen ions extracted from the VENUS ECR ion source are presented and compared to experimentally obtained emittance values.

Ion beam properties for ECR ion source injector systems

“…However, increasing the pressure in the beam line also increases the charge exchange rate of highly charged ions, and is therefore not an option for high charge state ion injectors. Simulations show that using a 70 to 80% neutralization level agrees well with experimental emittance and beam profile measurements [25] but further measurements will be necessary to determine the degree of neutralization along the beam line and in various beam line components (in particular inside the analyzing magnet).…”

Preliminary simulation of beam extraction for the 28-GHz ECR ion source

“…The simulation is started with an equal number of 3 Uranium 238 atoms (40000) and the charge state of +33.5 which are homogeneously distributed in the ECR zone. The initial conditions of these studies are summarized on table 2 which is on the basis of VENUS ECR ion source study [5].…”

Ion Beam Emittance for an Ion Source with a Conical Hot Cavity

“…by beam divergence (or convergence) and its spread. Computer simulations are a commonly used tool widely applied to design efficient ion sources, ion guns, injectors, or transmission lines characterized by low transverse emittance [1][2][3][4][5][6].…”