  Particle accelerators are among the largest, most complex devices. To meet
the challenges of increasing energy, intensity, accuracy, compactness,
complexity and efficiency, increasingly sophisticated computational tools are
required for their design and optimization. It is key that contemporary
software take advantage of the latest advances in computer hardware and
scientific software engineering practices, delivering speed, reproducibility
and feature composability for the aforementioned challenges. A new open source
software stack is being developed at the heart of the Beam pLasma Accelerator
Simulation Toolkit (BLAST) by LBNL and collaborators, providing new
particle-in-cell modeling codes capable of exploiting the power of GPUs on
Exascale supercomputers. Combined with advanced numerical techniques, such as
mesh-refinement, and intrinsic support for machine learning, these codes are
primed to provide ultrafast to ultraprecise modeling for future accelerator
design and operations.
