  Laser-driven (LD) ion acceleration has been explored in a newly constructed
short focal length beamline at the BELLA petawatt facility (interaction point
2, iP2). For applications utilizing such LD ion beams, a beam transport system
is required, which for reasons of compactness be ideally contained within 3 m.
The large divergence and energy spread of LD ion beams present a unique
challenge to transporting them compared to beams from conventional
accelerators. This work gives an overview of proposed compact transport designs
that can satisfy different requirements depending on the application for the
iP2 proton beamline such as radiation biology, material science, and high
energy density science. These designs are optimized for different parameters
such as energy spread and peak proton density according to an application's
need. The various designs consist solely of permanent magnet elements, which
can provide high magnetic field gradients on a small footprint. While the field
strengths are fixed, we have shown that the beam size and energy can be tuned
effectively by varying the placement of the magnets. The performance of each
design was evaluated based on high order particle tracking simulations of
typical LD proton beams. A more detailed investigation was carried out for a
design to deliver 10 MeV LD accelerated ions for radiation biology
applications. With these transport system designs, the iP2 beamline is ready to
house various application experiments.
