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
Lawrence Berkeley National Laboratory
M. Furman, HHH2004 Session 6B: “Overview of EC Simulation Codes” p. 4
Types of codes
Lawrence Berkeley National Laboratory
• 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;
Lawrence Berkeley National Laboratory
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
Lawrence Berkeley National Laboratory
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 [email protected] BNLYunhai Cai [email protected] SLACMiguel Furman [email protected] LBNLTom Katsouleas [email protected] USCKazuhito Ohmi [email protected] KEKMauro Pivi [email protected] LBNLLanfa Wang [email protected] KEKHong Qin [email protected] PPPLGiovanni Rumolo [email protected] GSITai- Sen Wang [email protected] LANLFrank Zimmermann [email protected] 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