Advanced Accelerator
Simulation
Panagiotis Spentzouris
Fermilab Computing Division (member of the SciDAC AST project)
Accelerators are essential for the advance of science. In DOE’s “Facilities for the Future of Science”
13 of the 28 facilities are accelerators!
SciDAC AST project(Accelerator Science & Technology)
UC DavisVisualization, multi-resolution techniques
FNALSoftware Integration, Lie methods, space charge in rings, Booster simulation& experiment
UCLAParallel PIC Frameworks
SLACEllectromagnetic component modeling
LBNLBeam-beam modeling, space charge in linacs & rings, parallel Poisson solvers, collisions
U. Maryland Lie Methods in
Accelerator Physics, MaryLie
LANL High order optics,
beam expts, collisions, multi-language
support, statistical methods
M=e:f2: e:f3: e:f4:…N=A-1 M A
BNLWakefield effects,Space charge in rings,BNL Booster simulation
SciDAC AST project goals
Develop and apply an advanced, comprehensive, high-performance simulation environment to solve
challenging problems and to enable new discoveries in accelerator science & technology.
maximize performance of existing and optimize design of future accelerators
Synergia• Multi-language, extensible, parallel PIC framework
• Incorporates multi-physics; state-of-the-art numerical libraries,
solvers, physics modules
Humane user interface and job creation/monitoring tools
Multi-bunch capability Multiple Poisson solvers
FFT, multigrid (PETSc) Multi-turn injection Ramping rf and magnet modeling Active feedback modeling
From test suite: comparison w/ analytical result (J. Comp. Phys, 211,1, 2005)
Synergia used in international space charge benchmark effort
lead by I.Hofmann (PAC'05)
Unique capabilities for synchrotrons, boosters, and storage rings
Longitudinal phase space shows halo & space-charge “drag” during bunch merge
Synergia performance
● Utilized NERSC SP3 and Linux clusters
Millions of macro-particles on
hundredths of processors
Fermilab’s accelerator complex
Main Injector
Booster
Tevatron
The Fermilab Booster
The Booster is a rapid cycling machine (15Hz) accelerating protons from 400 MeV to 8 GeV
The success of the quest to understand the nature and properties of neutrino masses at Fermilab depends on the Booster.
Multi-particle dynamics effects, such as space charge are responsible for machine losses which limit performance
High intensity proton driver modeling
● Problem: optimize accelerator performance
● Problem size (FNAL Booster example):
6×1012 protons circulating for 20,000 turns
~100 electromagnetic elements in accelerator
● Need to model the beam's self-interaction
● Need to understand observed beam characteristics and losses➔ simulation requires 106 to 107 macro-particles
Booster simulation details
● Self-consistent 3D space-charge ● High order magnetic optics● 33x33x257 grid, ~5M particles● boundary conditions
longitudinal periodic transverse closed
● Realistic model multi-turn injection machine ramping with position feedback
Multi-bunch modelling in 3D➔ follow 5 200 MHz Linac
micro-bunches in a
37.8 MHz PhS slice.
● Synergia to study and optimize beam quality on normal operating conditions compare to turn-by-turn
beam profiles ● 3D model enables study of
phase space correlations
Space charge effects on resonances
Synergia simulation
Data, machine running on resonance
Less charge more charge
Beam evolution on resonance:how close to a resonance can we
operate?
Requirements for end to end Booster simulation
● Computational effort:
~ Nturns× Nbunches
× Nkicks × {parameters}
for 20,000 turns → 20 days for multi-bunch simulation with smoothing,
effective Nbunches
~10
need ~100× current capability and improved scalability
continuing R&D for solvers with better performance and scalability
As the beams pass through each other, each beam’s charge affects the other beam, reducing performance. We need to study and understand these
“Beam-Beam” effects to maximize Tevatron luminosity.
The Tevatron is the highest energy particle accelerator in the world; it accelerates protons and antiprotons up to 1 TeV (trillion electron volt). The two beams circulate together and
collide at the detector locations.
BeamBeam3D: a 3D, self consistent code
Can model multiple bunches!
1e-06
1e-05
1e-04
0.001
0.01
0.1
0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15
pow
er (
arbi
trar
y un
its)
tune
sigma modesynchro mode 1
beam-beam pi mode
But first verify model: beam-beam force couples transverse and
longitudinal dynamics, so effect can be tested by comparing to FFT of the
bunch motion in dedicated experiments.
VEP-II accelerator, dedicated to beam measurements
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