C.M. Celata

Highly Compressed Ion Beams for High Energy Density Science

The Heavy Ion Fusion Virtual National Laboratory is developing the intense ion beams needed to drive matter to the High Energy Density regimes required for Inertial Fusion Energy and other applications. An interim goal is a facility for Warm Dense Matter studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target “foils,” which may in fact be foams with mean densities 1% to 10% of solid. This approach complements that being pursued at GSI Darmstadt, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the beam requirements for Warm Dense Matter experiments. We discuss neutralized drift compression and final focus experiments and modeling. We describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally. Finally, we discuss plans toward a user facility for target experiments.

Modeling the muon cooling channel using moments

Using a moment formalism, we model beam transport in the muon collider cooling channel. This model contains much of the physics we believe to be relevant to muon cooling such as ionization energy loss and multiple scattering. Space-charge forces are currently neglected but can, in principle, be added to the model. Previously, this model has been shown to closely agree with particle tracking while being significantly less computationally intensive. Presently our simulation is limited to the six-dimensional dynamics of the transverse cooling section. A matrix representation of an emittance exchange section is presented. This formulation of emittance exchange can either be ideal (conserving 6-d emittance) or can include energy loss and heating representative of the effects expected in a realistic emittance exchange section. These elements should give our model sufficient generality to enable the preliminary, yet realistic, design of a complete muon cooling channel.