Model of charge-state distributions for electron cyclotron resonance ion source plasmas

• Main Authors: D. H. Edgell, J. S. Kim, S. K. Wong, R. C. Pardo, R. Vondrasek
• Format: Article
• Language: English
• Published: American Physical Society 1999-12-01
• Series: Physical Review Special Topics. Accelerators and Beams
• Online Access: http://doi.org/10.1103/PhysRevSTAB.2.123502

A computer model for the ion charge-state distribution (CSD) in an electron cyclotron resonance ion source (ECRIS) plasma is presented that incorporates non-Maxwellian distribution functions, multiple atomic species, and ion confinement due to the ambipolar potential well that arises from confinement of the electron cyclotron resonance (ECR) heated electrons. Atomic processes incorporated into the model include multiple ionization and multiple charge exchange with rate coefficients calculated for non-Maxwellian electron distributions. The electron distribution function is calculated using a Fokker-Planck code with an ECR heating term. This eliminates the electron temperature as an arbitrary user input. The model produces results that are a good match to CSD data from the ANL-ECRII ECRIS. Extending the model to 1D axial will also allow the model to determine the plasma and electrostatic potential profiles, further eliminating arbitrary user input to the model.