M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 1

Overview of Electron-Cloud Simulation CodesSession 6B

Miguel A. Furman

LBNL

First CARE-HHH APD Workshop on

Beam Dynamics in Future Hadron Colliders and

Rapidly Cycling High-Intensity Synchrotrons

CERN, 8-11 November 2004

HHH 2004

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 2

Acknowledgments

My gratitude for collaboration or education over time to:

A. Adelmann, G. Arduini, V. Baglin, M. Blaskiewicz, O. Brüning, Y. H. Cai, R. Cimino, I. Collins, O. Gröbner, K. Harkay, S. Heifets, N. Hilleret, J. M. Jiménez, R. Kirby, A. Kulikov, G. Lambertson, R. Macek, K. Ohmi, M. Pivi, G. Rumolo, D. Schulte, F. Zimmermann.

I stole many slides from the ECLOUD’04 talks

http://icfa-ecloud04.web.cern.ch/icfa-ecloud04/

Lawrence Berkeley National Laboratory

My apologies for the incompleteness of this talk• please bring omissions to my attention

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 3

Summary

• List of codes and features; contact persons, status,…• Code features, sample results• The CERN e-cloud comparisons center• Current and future directions

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M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 4

Types of codes

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• EC buildup codes:– beam is prescribed (not dynamical, except possibly for multibunch dipole

motion)– electrons are dynamical (macroparticles)– vacuum chamber geometry, various electron sources

• Instability codes:– e-cloud is prescribed, at least initially; either lens or particle cloud– beam is dynamical (macroparticles)

• Self-consistent codes:– various degrees of self-consistency– both beam and e-cloud are dynamical– typically 3D ; may accept an input lattice description– may or may not describe e-wall collisions (SEY)– ultimately: model gas desorption, photoelectric effect, ionization, stray

particles/wall collisions, secondary ionization

• Map code (MEC) (later)

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 5

Code table (incomplete; possible errors)code contact dim e- model features Parallel

(max CPU)PEI K. Ohmi, KEK SR, SE build- up; dipole inst.EPI K. Ohmi, KEK SR, SE build- up; dipole inst.CLOUDLAND L. Wang, BNL 3 SE, build- up; NECLOUD G. Rumolo, GSI,

D. Schulte, F.ZimmermannCERN

2- 3 SR, SE, IZ buildup; multibunch dipoleinst.

N

POSINST M. Furman,LBNL; M. Pivi,SLAC

2.5 SR, SE, IZ,BPL

buildup; multibunch dipoleinst.

N

CSEC M. Blaskiewicz,BNL

2- 3 SE, IZ, BPL build- up; single-bunchinstability

N

HEADTAIL D. Schulte, F.Zimmermann,G. Rumolo

2 build- up; single-bunchinstability

PEHT K. Ohmi, KEK head- tailPEHTS K. Ohmi, KEK head- tail; SCCLOUD_MAD T.

Raubenheimer,SLAC

MAD-t racking particles withecloud "lenses"

PARSEC A. Adelmann,PSI

3 SE; IZ; SR;BPL

SC; lattice description Y (4048)

ORBIT J. Holmes,ORNL

2- 3 SE; IZ SC; lattice description Y

WARP+POSINST J. L. Vay, LBNL 3 SE; IZ; SR;BPL

SC; lattice description Y

QUICKPIC W. Mori, UCLA 2- 3 PIC plasma code; initially-prescribed ecloud

Y (128)

BEST H. Qin, PPPL 3 SC; Vlasov-M axwell; no e- wallcollisions

Y (512)

MEC U. Iriso, BNL empirical maps

SR=synchrotron rad. photoelectrons; SE=secondary electron emission; IZ=ionization of resid. gas; BPL=beam-particle lossesSC=self-consistent;

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M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 6

Sample build up simulation: e vs. time

K. Ohmi, T. Koyama and C. Ohmori, PRSTAB 5, 114402 (2002)

JPARC

PSR ISIS

SNS AGS

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 7

E-cloud sample simulation in a quad (CLOUDLAND)

L. Wang, ECLOUD’04

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 8

HEADTAIL simulation setup

M. Pivi, ECLOUD’04

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 9

QUICKPIC and HEADTAIL results: vs. time

0

0.2

0.4

0.6

0.8

1

1.2

1.4

No. of Turns

Red : QuickPIC(Single Kick Mode)Blue : HEAD-TAIL

• Benchmarking: Single Kick QuickPIC vs. HEAD-TAILBenchmarking: Single Kick QuickPIC vs. HEAD-TAIL (LHC params.)• For accurate benchmarking, QuickPIC is modified to be in single kick regime• Good agreement between the two codes.• LHC parameters have been used for benchmarking purpose.

A. Ghalam, ECLOUD’04

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 10

QUICKPIC and HEADTAIL: more

• Growth rate changes with the number of kicks!

QuickPIC Results for LHC

HEAD-TAIL results for LHC

Green : 4 Kicks/TurnBlue : 2 Kicks/TurnRed : 1Kick/TurnAqua : 16Kicks/Turn

2

3

4

5

6

7

8

No. of Turns

A. Ghalam, ECLOUD’04

Lawrence Berkeley National Laboratory

QuickPIC and HEADTAILresults for vs. timeE. Benedetto

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 11

Contemporary developments• Do we need self-consistency?

– Yes, in some cases:

• At PSR, electron-cloud signal is 10-100 times larger for unstable beam than for stable

• Do we need the 3rd dimension?– Yes, for long bunches (PSR) (see PSR quad movie)

– Probably yes for long bunch trains and long/complicated machine lattices

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M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 12

PSR EC instability measurements

R. Macek

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 13

PSR EC instability measurements

R. Macek

Lawrence Berkeley National Laboratory

“For high intensity unstable beams the electrons saturate our electronics. Setting up unstable beam at lower beam intensities allows us to see the electrons without saturation.”

R. Macek

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 14

Self-consistency plan

R. Cohen, ECLOUD’04

Lawrence Berkeley National Laboratory

roadmap for WARP+POSINST

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 15

Self-consistency plan

A. Shishlo, ECLOUD’04

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 16

Benchmarking ORBIT

Y. Sato, ECLOUD’04

Lawrence Berkeley National Laboratory

Theory: two-stream instability of coupled continuous beam-continuous ecloud: centroids as a f. of time(Koshkarev & Zenkevich; Keil & Zotter)

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 17

A map code (“MEC”)

Lawrence Berkeley National Laboratory

U. Iriso, ECLOUD’04Relate ecloud density at time tto density at t-t by a heuristic nonlinear map

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 18

CERN code comparisons centerhttp://wwwslap.cern.ch/collective/ecloud02/ecsim/

Contacts Persons for the Comparison of Electron- CloudSimulations

http:/ / wwwslap.cern.ch/ collective/ ecloud02/ ecsim/Mike Blaskiewicz blaskiewicz@bnl.gov BNLYunhai Cai yunhai@SLAC.Stanford.EDU SLACMiguel Furman mafurman@lbl.gov LBNLTom Katsouleas katsoule@usc.edu USCKazuhito Ohmi ohmi@post.kek.jp KEKMauro Pivi mpivi@lbl.gov LBNLLanfa Wang wanglf@post.kek.jp KEKHong Qin hongqin@princeton.edu PPPLGiovanni Rumolo G.Rumolo@gsi.de GSITai- Sen Wang twang@lanl.gov LANLFrank Zimmermann frank.zimmermann@cern.ch CERN

Lawrence Berkeley National Laboratory

• Established by F. Zimmermann after ECLOUD’02 • Input parameters for “standard” test cases are spelled out• Everybody is invited to contribute!

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 19

CERN code comparisons center contd. Comparison of Build Up Simulations

simulation results: electron line charge (total no. of e- per unit length) vs time

# ECLOUD code (eps file) FZ,GR, 23.07.2002# COUNTRYCLOUD code (eps file) Lanfa Wang, August 2002# BNL code (eps file) Mike Blaskiewicz, August 2002# PEI code (ps file) Kazuhito Ohmi, September 2002# POSINST code (eps file) Mauro Pivi and Miguel Furman, September 2002; details of the LBNL simulationLast updated 23 August 2002, FZ

Comparison of Instability Simulations

simulation result: emittances vs. time

# HEADTAIL code (ps file) Giovanni Rumolo, August 2002# PEHTS code (ps file) Kazuhito Ohmi, November 2002, comments and additional studies (pdf)# QUICKPIC code (pdf file) Ali Ghalam, Tom Katsouleas, Giovanni Rumolo, November 2002Last updated 29 November 2002, FZ

Measurements and Parametrizations of Secondary Emission

Secondary Electron Emission Data for the Simulation of Electron Cloudby N. Hilleret et al. (contribution to ECLOUD'02 Proceedings)

Excel file by N. HilleretLast updated 15 July 2002, FZ

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 20

Possible future developments• More “benchmarking”

– debugging (code should calculate what is supposed to calculate)– validation (results should agree with established analytic result for specific

cases)– comparisons (two codes should agree if the model is the same)– verification (code should agree with measurements)

• ECLOUD simulations vs. SPS measurements• POSINST simulations vs. APS and PSR measurements• Others…

• Move in 2 opposite directions:– More complete, detailed, quantitative predictions

• Ultimately requires fully self-consistent 3D calculations– Simplified descriptions, few parameters, qualitative results with broad

applicability• Identify a few basic relevant variables and input parameters (MEC code

very promising in this regard)

Lawrence Berkeley National Laboratory

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 21

Extra material

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 22

BIM in the APS (Advanced Photon Source, Argonne)

120

100

80

60

40

20

0

aver. electron-wall current [nA/cm

2]

35302520151050

bunch spacing sB [RF buckets]

measured simulated

APS, positron beam

Detector Current vs. Bunch Spacing

(10 bunches, 2 mA/bunch in all cases; measurements courtesy K. Harkay, ANL)

region of BIM

sB=d2/(reN), b<d<a

Lawrence Berkeley National Laboratory

(Furman, Pivi, Harkay, Rosenberg, PAC01)

time-averaged e– flux at wall vs. bunch spacing

measuredsimulated

• e+ beam, 10-bunch train, field-free region

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 23

BIM for long bunches: PSR• bunch length ~60 m >> t

– a portion the EC phase space is in resonance with the “bounce frequency”

– “trailing edge multipacting” (Macek; Blaskiewicz, Danilov, Alexandrov,…)

Lawrence Berkeley National Laboratory

ED42Y electron detector signal 8C/pulse beam

435 A/cm2

(simulation input)

electron signal

measured (R. Macek) simulated (M. Pivi)

(max=2.05)

M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 24

Future computer

2004: NERSC: 8000 processors (power PC3), ~8 Tflops 2004: Red Storm: ~11600 processor Opteron-based MPP [>40

Tflops] 2005: ~1280-Processor 64-bit Linux Cluster [~10 TF] 2006 Red Storm upgrade ~20K nodes, 160 TF. 2008--9 Red Widow ~ 50K nodes, 1000 TF. (?)

Lawrence Berkeley National Laboratory

Each center will get one: Sandia ORNL Pittsburgh