The Ion Beams for Energy Applications Model (IBEAM) is a systems-level, source-to-target code for heavy-ion drivers for inertial fusion energy (IFE). The heavy-ion fusion programs at Lawrence Livermore National Laboratory and Lawrence Berkeley National Laboratory have been collaborating on the development of this computer model for systems analysis of heavy ion drivers based on induction linac technology. Work has focused on drivers for future heavy-ion fusion (HIF) power plants, but the tools being developed will also be used to evaluate candidates for more near-term experimental facilities. The model is an integrated source-to-target model that includes the key interdependencies of the major subsystems in terms of cost, performance and constraints.
The computer model is written using the commercial scientific/engineering software package Mathcad* that incorporates text and graphics in an easily readable and user-friendly format. Options for induction linac driver architecture includes a multi-beam injector feeding an optional electrostatic-focusing accelerator section, which is followed by a magnetic-focusing accelerator section at some higher energy (typically ~100 MeV). The electrosatic-focusing section is optional, as is four-to-one beam merging. Final transport and final-focus sections follow the main accelerator. The final-transport section provides the distance needed for drift compression (to get the required pulse length on target) and re-alignment of the beams for two-sided illumination. The final-focus section includes the final-focus quadrupoles that are used to first expand the beam radially and then focus it to a small spot on target. Calculation of the spot size on target is included.
The heart of the model is the set of transport, component sizing, and cost scaling algorithms that describe the components in each section of the driver. Numerous inputs, assumptions and constraints for the models of the various components are defined throughout the program. Typical assumptions are cost scaling dependencies and component unit costs (e.g., $/kg of various materials). Examples of constraints include the source current density limit (A/m2) and the acceleration gradient limit (V/m) in the accelerator. A key input is the specification of beam characteristics that the driver must deliver to the target.
* Mathcad is a registered trademark of MathSoft, Inc., 101 Main St. Cambridge, MA 02142, USA.
W. R. Meier, R. O. Bangerter, and A. Faltens, "An Integrated Systems Model for Heavy Ion Drivers," Nucl. Instr. Meth. Phys. Res. A415, 249 (1998).
For comments or questions contact WMSharp@lbl.gov or DPGrote@lbl.gov. Work described here was supported by the Office of Fusion Energy at the US Department of Energy under contracts DE-AC03-76SF00098 and W-7405-ENG-48. This document was last revised June, 2002.