Three-dimensional simulations of high-current beams in induction accelerators with WARP3d

For many issues relevant to acceleration and propagation of heavy-ion beams for inertial confinement fusion, understanding the behavior of the beam requires the self-consistent inclusion of the self-fields of the beams in multiple dimensions. For these reasons, the three-dimensional simulation code WARP3d A.Friedman was developed. The code combines the particle-in-cell plasma simulation technique with a realistic description of the elements which make up an accelerator. In this paper, the general structure of the code is reviewed and details of two ongoing applications are presented along with a discussion of simulation techniques used. The most important results of this work are presented

Developing acceleration schedules for NDCX-II

The Virtual National Laboratory for Heavy-Ion Fusion Science is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions near the Bragg-peak energy. Present plans call for using about thirty induction cells to accelerate 30 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to useful temperatures, the beam must be compressed to a millimeter-scale radius and a duration of about 1 ns. An interactive 1-D particle-in-cell simulation with an electrostatic field solver, acceleration-gap fringe fields, and a library of realizable analytic waveforms has been used for developing NDCX-II acceleration schedules. Axisymmetric simulations with WARP have validated this 1-D model and have been used both to design transverse focusing and to compensate for injection non-uniformities and radial variation of the fields. Highlights of this work are presented here

SIMULATING AN ACCELERATION SCHEDULE FOR NDCX-II

The Virtual National Laboratory for Heavy-Ion Fusion Science is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions. Present plans call for using 34 induction cells to accelerate 45 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to the desired temperatures, the beam must be compressed to a millimeter-scale radius and a duration of about 1 ns. A novel NDCX-II acceleration schedule has been developed using an interactive one-dimensional particle-in-cell simulation ASP to model the longitudinal physics and axisymmetric WARP simulations to validate the 1-D model and add transverse focusing. Three-dimensional Warp runs have been used recently to study the sensitivity to misalignments in the focusing solenoids

Critical issues for high-brightness heavy-ion beams -- prioritized

This study group was initiated to consider whether there were any ''show-stopper'' issues with accelerators for heavy-ion warm-dense matter (WDM) and heavy-ion inertial fusion energy (HIF), and to prioritize them. Showstopper issues would appear as limits to beam current; that is, the beam would be well-behaved below the current limit, and significantly degraded in current or emittance if the current limit were exceeded at some region of an accelerator. We identified 14 issues: 1-6 could be addressed in the near term, 7-10 are potentially attractive solutions to performance and cost issues but are not yet fully characterized, 11-12 involve multibeam effects that cannot be more than partially studied in near-term facilities, and 13-14 involve new issues that are present in some novel driver concepts. Comparing the issues with the new experimental, simulation, and theoretical tools that we have developed, it is apparent that our new capabilities provide an opportunity to re-examine and significantly increase our understanding of the number one issue--halo growth and mitigation