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

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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