Advanced Computing for 21^st^ Century Accelerator Science and Technology

Principal Investigators

Kwok Ko^1^ and Robert Ryne^2^

^1^Stanford Linear Accelerator Center

^2^Lawrence Berkeley National Laboratory

Executive Summary

Particle accelerators have enabled remarkable scientific discoveries and
important technological advances that span all programs within the
Office of Science. In the High Energy and Nuclear Physics (HENP)
program, experiments associated with high-energy accelerators have led
to important discoveries about elementary particles and the fundamental
forces of nature, quark dynamics, and nuclear structure. In the Basic
Energy Sciences (BES) program, experiments with synchrotron light
sources and spallation neutron sources have been crucial to advances in
the materials and biological sciences. In the Fusion Energy Sciences
(FES) program, great strides have been made in developing heavy-ion
particle accelerators as drivers for Inertial Fusion Energy. Beyond
impacts to basic and applied science, accelerators have also been
proposed that address environmental, national security, and
energy-related issues through projects such as the accelerator
transmutation of waste, accelerator-based hydrodynamic imaging, and
accelerator-driven fission energy production. In summary, accelerators
play a critical role in U.S. science and technology, and are highly
beneficial to the nation's health, wealth, and security.

Given the importance of particle accelerators, it is essential that the
most advanced high performance simulation tools be brought to bear on
the development of next-generation accelerators and new accelerator
technologies. The present project will develop a comprehensive terascale
Accelerator Simulation Environment (ASE) whose components will enable
accelerator physicists and engineers to address a broad range of
important issues in next-generation accelerators and their design. These
issues, which could not be addressed without terascale resources, range
from the high accuracy requirement for modeling entire accelerating
structures of complex shapes with tight tolerances, to the high
resolution requirement needed for simulating beam halo in high-intensity
linacs, to the complexity associated with modeling the collective
interaction of intense beams, lasers and plasmas. Using terascale
resources and built on scalable algorithms, the software components and
application codes in the ASE will be able to deliver the accuracy and
resolution necessary for accelerator designs that are pushing the
envelope of machine performance and system complexity. In the important
area of accelerating structure design, for example, the new set of
electromagnetic simulators will contain the physics needed for realistic
end to end modeling so that the simulation becomes in effect a cheaper,
viable and faster alternative to the expensive, time-consuming process
of repeated fabrication and testing. New tools that are under
development have already allowed structure designers to explore novel
ideas that lead to higher acceleration gradients and lower surface
fields which otherwise would have been difficult to achieve through
traditional prototyping. Similarly, advanced accelerator modeling tools
under development have also been used to understand and interpret beam
phenomena observed in recent plasma wakefield experiments.

The creation of a new generation of accelerator simulation codes will
have an impact in three areas: (1) optimizing the design of
next-generation accelerators which may include, e.g., a linear collider
such the Next Linear Collider (NLC), a neutrino factory, a rare isotope
accelerator (RIA), a 4^th^ generation light source, and a prototype
fusion driver, (2) maximizing the DOE's investment in existing
accelerators by using simulation to help optimize their performance and
expand their operational envelopes in machines such as PEP-II, RHIC, and
the Tevatron, and (3) developing new accelerator technologies by using
simulation as a tool of discovery to explore beams under conditions like
those found in laser- and plasma-based accelerators. This new capability
will have the most impact on the DOE's HENP programs, and has the
potential to achieve a major advance in those programs, by greatly
enhancing its ability to design the next generation of high energy
accelerators and high intensity drivers for HENP facilities. Terascale
simulations will support important design decisions and feasibility
studies, helping to reduce cost and risk, and helping to ensure that
future projects are completed on schedule and within budget. The
development of state-of-the-art laser/plasma simulation codes will
furthermore enable accelerator scientists to explore new concepts that
will advance the frontiers of accelerator science and technology.

The development of the ASE will be guided by target applications that
are computationally challenging and will have maximum impact on HENP
projects. These applications will serve as the test-bed for the
simulators and the terascale simulation environment and they include:

-   Full-scale modeling of large electromagnetic accelerating systems -
    the PEP-II beamline complex around the interaction region to study
    beam heating, the entire NLC accelerator structure to calculate
    wakefields, and the proposed radio frequency quadrupole (RFQ) design
    for RIA.

-   Large-scale beam dynamics simulations for improving the performance
    of colliders (e.g. PEP-II, the Tevatron, and RHIC) and high
    intensity drivers (the FNAL booster and BNL AGS).

-   Large-scale simulation of a plasma wakefield accelerator
    (particularly with regard to the critical issues of staging and
    emittance control), and simulations of laser wakefield accelerators,
    including particle injection, capture, and acceleration.

The project's target applications and deliverables fall into three
areas: Electromagnetics (EM), Beam Dynamics (BD), and Advanced
Accelerators (AA). The EM component will involve the development of
three parallel solvers, Omega3P, Tau3P, and Phi3P, which are an
eigenmode code, a time domain electromagnetics code, and a statics code,
respectively. These codes will use unstructured grids to conform to the
geometry of complex 3D structures. The BD area will involve the
development of modules for treating multiple beam phenomena (such as
space charge effects, high-order optical effects, beam-beam collisions,
wakefields, intrabeam scattering, and ionization cooling), and their
incorporation into a parallel version of the MaryLie beam dynamics code.
The AA component will involve the development of the OSIRIS and
XOOPIC/VORPAL codes for modeling laser- and plasma-based accelerators.

The ASE will consist of a set of parallel, portable, reusable,
object-based software components that, when integrated, will enable
accelerator physicists and engineers across the country to work together
to solve the most challenging problems in accelerator design, analysis,
and optimization. The success of the ASE will require close
collaboration with computer scientists and applied mathematicians to
enable the development of high-performance software components for
terascale platforms. For all three areas of the ASE, new mathematical
models (including reduced description models) and new algorithms will be
developed to achieve high accuracy and high performance on parallel
supercomputers. The successful development of all the codes will involve
close collaboration with SciDAC/ISIC partners in areas such as applied
mathematics and numerical algorithms (eigensolvers, linear solvers),
meshing techniques (grid generation, adaptive refinement), visualization
(large data sets, multi-resolution techniques), code validation,
software interoperability (multiple language support, code component
development), and performance optimization (load balancing and
communication).