TUCO-C  —  Theory, Modeling & Plasma Diagnostics   (16-Sep-08   14:00—15:20)

Chair: D. Leitner, LBNL, Berkeley, California

Paper Title Page
TUCO-C01 Three-Dimensional Simulation of Electrons and Ions in ECRIS 154
 
  • J. H. Andrä
    Westfaelische Wilhelms-Universität Muenster, Muenster
  
  Electron-Cyclotron-Resonance-(ECR)-Heating (ECRH) is known to produce non-equilibrium plasmas with the total non-Maxwellian energy in the electrons while the ions stay below 1 eV. Theories based on Maxwell distributions are thus unable to correctly describe ECR-Ion Sources (ECRIS). Particle In Cell (PIC)-techniques are feasible only with significant approximations in the extremely complicated magnetic structure of an ECRIS. This is the reason to concentrate all efforts on the calculation of various electron distributions in an ECRIS taking into account all three-dimensional static fields, dynamic microwave fields, and all collisions of the electrons. To this end the Boris-algorithm is introduced which is shown to be very efficient and precise for all conditions in an ECRIS including the resonance transitions. The electron distributions clearly show the low efficiency of ECRH in a standard ECRIS with a central minimum of the axial magnetic field compared to the high ECRH-efficiency in a plateau-ECRIS with a flat central minimum. A non-relativistic version of the code is used to demonstrate the positive effects of ion-CRH on the confinement of the ions with far reaching consequences.  
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TUCO-C02 Towards Kinetic Modeling of Ion Transport in an ECRIS Plasma 155
 
  • P. J. Mullowney, Y. Choi, D. W. Fillmore, P. Messmer, D. S. Smithe
    Tech-X, Boulder, Colorado
  
  Funding: Work supported by DOE Office of Science, Office of High Energy Physics, and Office of Nuclear Physics, Grant #'s DE-FG02-06ER84484 (HighZ) and Tech-X Corporation.

Next generation heavy ion beam accelerators require intense, high charge state ion currents of exotic materials. ECRIS devices can generate these currents however detailed kinetic simulations are needed to optimize the loading of these materials into the plasma. Full Particle-In-Cell simulations of the plasma are highly challenging due to the large discrepancy between length and time scales. However separation of time-scales provides a means of making progress. Electrostatic simulations on ion timescales, though demanding, are capable of modeling the kinetic behavior of the ions. Similarly, electromagnetic simulations on electron time scales can provide the non-thermal kinetic properties of the electron population. In this work, we treat the electrons as a simplified fluid for the longer time-scale evolution of the ions. We characterize and diagnose the electron distribution for use in the ion simulations. Ionization and recombination processes are then modeled in a hybrid fluid-electron / kinetic-ion formulation using the prescribed electron distribution as one of the interaction partners. Progress in the electrostatic modeling of the ion dynamics is also presented.

 
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TUCO-C04 Far-Tech's ECR Charge Breeder Optimization Simulation Toolset - MCBC, GEM, and IonEx 156
 
  • J. S. Kim, I. N. Bogatu, B. Cluggish, S. Galkin, L. Grubert, L. Zhao
    Far-Tech, Inc., San Diego, California
  
  Funding: This work is supported by the US DOE SBIR program.

FAR-TECH has been developing ECR charge breeder optimization toolset. It consists of three computational modules: [1] the GEM (General ECRIS Model) code, [2] the MCBC (Monte Carlo Beam Capture) code, and [3] the IonEx (Ion extraction) code. The GEM code simulates ECR plasmas via Fokker-Plank electrons and ion fluids. MCBC is a particle tracking code to trace the injected charge breeder beam ions, and IonEx simulates the ion extraction region accurately by resolving the plasma sheaths at the extraction region. Current status of the work will be presented along with examples.

[1] J. S. Kim, L. Zhao, B. P. Cluggish, I. N. Bogatu, and R. Pardo, 'Electron cyclotron resonance charge breeder ion source simulation by MCBC', Rev. Sci. Instrum. 79, 02B906 (2008) [2] D. H. Edgell, J. S. Kim, S. K. Wong, R. C. Pardo and R. C. Vondrasek, Rev. Sci. Instrum. 71, 666 (2000) [3] B. P. Cluggish, S. A. Galkin, and J. S. Kim, 'Modeling Ion Extraction from an ECR Ion Source', Proceeding of the 2007 Particle Accelerator Conference, Albuquerque, NM, June 25-29, 2007

 
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