10-4-06 ap department meeting 1 ilcdr06 workshop highlights e. gianfelice
TRANSCRIPT
10-4-06 AP Department Meeting 1
ILCDR06 WorkshopHighlights
E. Gianfelice
https://wiki.lepp.cornell.edu/ilc/bin/view/Public/DampingRings/CornellWorkshopTalks
Date Event ILCTA@NML 2
ParticipantsCornell University:• Michael Billing, James Crittenden,
Gerry Dugan, Don Hartill, Robert Meller, Mark Palmer, David Rice,David Rubin, David Sagan, Levi Schachter, Eugene Tanke, Jeremy Urban
SLAC:• Karl Bane, Craig Burkhart, Yunhai Cai,
Anatoly Krasnykh, Cho Ng, Mauro Pivi, Gennady Stupakov, Lanfa Wang
LBNL:• Christine Celata, Stefano De Santis,
Ina Reichel, Marco Venturini, Michael Zisman
ANL:• Michael Borland, Louis Emery,
Katherine Harkay, Aimin Xiao
KEK:• Kazuhito Ohmi, Yusuke Suetsugu,
Junji Urakawa
INFN-LNF:• Susanna Guiducci, Fabio Marcellini
DESY:• Ferdinand Willeke, Guoxing Xia
FNAL:• Panagiotis Spentzouris, Eliana
Gianfelice-Wendt
• Gerald Codner (CLASSE), Robert Macek (TechSource/LANL), Thomas Mattison (Univ. of British Columbia), Art Molvik (LLNL), George Gollin (University of Illinois), Andy Wolski (University of Liverpool/Cockcroft Institute).
Date Event ILCTA@NML 3
Goal
Opening talk by A. Wolski:• Not justified double addressed topics worry
funding agencies. • The GDE R&D Board has charged a 10
members task force (S3, chair: A.Wolski)
for coordinating efforts. • S3 suggested meetings focused on the most
design affecting issues (kickers, e-clouds, impedance driven instabilities) and comparisons between codes and possibly with measurements.
Date Event ILCTA@NML 4
Two major changes wrt November 2005 baseline:
• one e+ DR (instead of two)• 650 MHz RF frequency (instead of 500)
Under re-consideration:• length• one tunnel for both DRs
Date Event ILCTA@NML 5
Impedance driven instabilities Experiments
K.Harkay showed results from APS (impedance computations + simulations vs. measurements). Agreement between theory and measurement is evaluated as ``70 %'', but for the microwave instability 80% larger than computed impedance was needed to get order of magnitude right! Not comforting for the design of new components.
Time demanding 3D-codes going to be used for a better estimate of APS components impendance. J.Urakawa summarized the past years attempts of bunch length
measurement and microwave instability detection at ATF in presence of IBS.
Large discrepancies between some theoretical (Bane) and experimental evaluations of the machine impedance. With new detectors (Silicon Bolometer, Schottky Barrier Diode) CSR
has been detected, but no microwave instability.
K.Bane reported briefly on the “puzzling” experience with the 3 SLC DR designs.
Date Event ILCTA@NML 6
SLC damping ring summarySLC damping ring summary
original 1.1e10 1.5e10
old 2.0e10 3.0e10
new 2.0e10* 1.5e10
threshold version calculated measured
“sextupole” mode
quadrupole mode
*if add 2nH (0.1) inductance• How to understand: from old to new ring reduced the impedance and threshold dropped? old, inductive ring—strong mode—tune spread—weak modes Landau damped new, resistive ring—weak mode—little tune spread—no Landau damping
• Note: old ring, SLC operation limited to 3e10, new ring—5e10
Date Event ILCTA@NML 7
Current dependence
Date Event ILCTA@NML 8
Impedance driven instabilities
Code developments
M. Borland presented the capabilities of elegant for ``integrated modeling'': one code for (almost) all.
The current DR design does not meet the Boussard (crude) criterion (for long bunches)!
New tools for studying microwave instabilities has been presented by
G. Stupakov (linearized Vlasov-FP equation solver in time domain, accurate but time consuming), S.Heifets and K.Bane (tracking, fast but prone to noise)
and M.Venturini (Vlasov equation).
Date Event ILCTA@NML 9
Impedance driven instabilities
Date Event ILCTA@NML 10
Impedance driven instabilities
• Consistent with Heifets macroparticle simulationsfor Broad-Band resonator model (Venturini).
Current Threshold
Vlasov calculationVlasov calculation
Macroparticlesimulation
Macroparticlesimulation
No
rmal
ized
cu
rren
t
Macroparticle simulation includes radiation effects
Date Event ILCTA@NML 11
Impedance driven instabilities
• Coasting beam: Oide-Yukoya frequency domain VFP solver indicates instability when there is none
Eigenvalue spectrum below (theory) threshold
• Theory says all eigenvalues should be on real axis…
Eigenvalue spectrum
above (theory) threshold
only this eigenvalue
corresponds to a reallyunstable mode
Date Event ILCTA@NML 12
Compare options: simulations recent historyCompare options: simulations recent historyCompare options: simulations recent historyCompare options: simulations recent history
Cloud density near (r=1mm) beam (m-3) before bunch passage, values are taken at a cloud equilibrium density. Solenoids decrease the cloud density in DRIFT regions, where they are only effective. Compare options LowQ and LowQ+train gaps. All cases wiggler aperture 46mm.
e- clouds
Date Event ILCTA@NML 13
e- clouds
To be addressed:
e- production suppression through clever vacuum chamber design
surface material and conditioning to reduces SEY
clearing electrodes design compatible with
heat load and beam stability
Date Event ILCTA@NML 14
e- clouds• Some past experience• Laboratory measurements: conditioning: SEY~1. In vacuum de-conditioning brings up SEY ~ 1.3• KEKB tests: conditioning in situ. [Cross-benchmarking with simulations gives low SEY~1]• SPS-CERN: • conditioning in situ in the SPS. Minimum measured conditioned surface
SEY~1.5. De-conditioning effect. Electron cloud effects decreased in time• PSR-LANL: conditioning slow in time and de-conditioning. Still an issue. Measuring electron
cloud since 1989! • Dafne: Luminosity reach is limited. (Aluminum SEY ~2.0 after conditioning)• Bfactories: KEKB: smaller bunch spacing is limited by electron cloud. Still after years PEP-II: no problem up to 2.7A. • Ongoing tests KEKB (effect of solenoid and fill pattern, see Ohmi presentation), CESRc (no effect of solenoids &wigglers observed, see Rice presentation), Dafne, PEP-II, PSR (e- production and trapping at quads, see Macek presentation).
Date Event ILCTA@NML 15
Ongoing chamber projects at SLAC:
e- clouds
CLEARING ELECTRODES
BEND PEP-II LER PR12 2007 Design
FINS TRIANG. BEND PEP-II LER PR12 2007 Design
TEST in LOCATION Ready for INSTALLATION
Status
SEY TESTS STRAIGHT PEP-II LER PR12 November 2006Ready
FINS RECTANG. STRAIGHT PEP-II LER PR12 November 2006
Coating of extruded Al chambers
Next chamber projects:
M. Pivi, SLAC
Date Event ILCTA@NML 16
e- clouds
• Model for MWS • Head (W:8 mm,T:7 mm, L:90 mm)– Copper, 10 mm from beam
• Support – BN (W: 4 mm, T: 6mm)
• r = 4.0, tan= 0.0008– Al2O3 (W: 4 mm, T: 4mm)
• r = 9.0, tan = 0.0001– Thin layer (t = 0.1mm) with
conductivity (), as a coating• Duct
– 94, L: 300 - 500 mm• SiC
– Deby first-order dispersion– s= 110, = 14, = 110-9s
Port 1
Port 2
Beam duct SupportHead
SiC
SiC
• Calculation– S11between Port 1 and Port 2
• Antenna: 10 mm– Frequency mode
is
r
1
)()(
Debye type
Date Event ILCTA@NML 17
e- clouds SimulationsEfforts of improving the e- clouds simulations.
Upgrade of ECLOUD and HEADTAIL. New 3D self consistent simulation code by W.Bruns being developed and tested against ECLOUD.
WARP-POSINST (LBNL): 3D (and 2D), any boundary, adaptive mesh size, self consistent, benchmarked by the High Current Experiment (HCX) at LLNL.
Simulations of e- clouds in wigglers with
CLOUDLAND (Lanfa Wang, SLAC).
Date Event ILCTA@NML 18
e- build-up for ILC 2(1)x6 km DR – 2 (ECLOUD)
example simulationscentre density (m-3) vs. time (s),primary photo-electron rate:d/ds= 0.001 m-1,bunch train followed by gap,arc & straight, log scale
max=1.3, 14.4 ns
max=1.5, 14.4 ns max=1.3, 7.2 ns
thr
thr thr
Date Event ILCTA@NML 19
e- clouds
WARP
POSINST
field calculator
ion mover
image forces
electron sourcemodules
kicks from beam
diagnostics
lattice description
xi, vi
interpreter&
user interface
electron mover
Date Event ILCTA@NML 20
e- clouds
1. 2D vs. 3D
2. Head-tail instability
3. Effect of gaps and resultant ecloud
4. Electron cloud & beam in wiggler
Processor hours per run
120
5600
16,000
60,000 - 270,000
CPU time is estimate-- depends on problem.
Computer Time will to be Requested (‘07) for WARP-POSINST
Date Event ILCTA@NML 21
CLOUDLAND 3D PIC code for e-cloud (PRST-AB 124402)
Simulation Key parameters(beam,ring,SEY,electrode, …) Mesh Generator
Magnetic and electric fields input
Space charge solverCharge meshUpdate particle positions
Advance particle positions using the new beam and e-cloud space charge fields
Preliminary electron generator when beam passing
Secondary electron generator
Preliminary electron generator
Wake field Instability code
Future plan --Parallelize for consistent instability study
Date Event ILCTA@NML 22
Train gap effect (2767bunches)
-200 -100 0 100 20010
8
109
1010
1011
1012
1013
Z (mm)
(
m-3
)
Bunch Train gaps reduce the electron cloud density by a factor of 10
0 20 40 60 80 100 12010
9
1010
1011
1012
Bunch ID
e (
m-3
)
average densitycentral density
0 20 40 60 80 100 12010
9
1010
1011
1012
1013
1014
Bunch ID
e (
m-3
)
One train
Short train
Date Event ILCTA@NML 23
Comparison with dipole
0 20 40 60 80 10010
9
1010
1011
1012
1013
1014
Bunch ID
e (
m-3
)
average densitycentral density
0 20 40 60 80 100 12010
9
1010
1011
1012
Bunch ID
e (
m-3
)
average densitycentral density
Dipole, B=0.194TWiggler
There is a lower electron density in Wigglers (one order)! (assuming the same initial electrons rate )
Date Event ILCTA@NML 24
e-clouds
Experimental tool at LBNL for studying
e- production and effect of clearing electrodes
(see Molvik presentation).
Date Event ILCTA@NML 25
A tool for ecloud experiments at LLNL
INJECTOR MATCHINGSECTION
ELECTROSTATICQUADRUPOLES
MAGNETICQUADRUPOLES
Focus of CurrentElectron Cloud Experiments
(2 m length)
1 MeV K+, 0.18 A, t ≈ 5 s, 6x1012 K+/pulse
low energy heavy ions
2 m
Date Event ILCTA@NML 26
ESQ injector
Marx
matching
10 ES quads
diagnostics
diagnostics
ESQ injector
10 Electrostatic quads
diagnostics
4 Magnetic quads Parameters
K+ Beam 0.2 - 0.5 Amp 1 - 1.7 MeV 4.5 s pulse
Date Event ILCTA@NML 27
MA4MA3
8 “paired” Long flush collectors (FLL): measures capacitive signal + collected or emitted electrons from halo scraping in each quadrant.
3 capacitive probes (BPM); beam capacitive pickup ((nb- ne)/ nb).
2 Short flush collector (FLS); similar to FLL, electrons from wall.
2 Gridded e- collector (GEC); expelled e- after passage of beam
2 Gridded ion collector (GIC): ionized gas expelled from beam
BPM (3)
BPM
FLS(2)
FLS
GIC (2)
GIC
Not in service
FLS
GECGEC
Date Event ILCTA@NML 28
ILC DR Test FacilitiesNew propsed DR Test Facilities:
M.Palmer presented the plan for transforming CESR in a ILC DR Test Facility (starting in 2008, 50% time sharing with SR experiments, Touschek lifetime: 7 minutes).
F.Willeke presented the plan for transforming HERA-e into a ILC DR Test Facility.
Suetsugu speculated about the possibility of transforming KEKB into a DR Test Facility (if Super KEKB get not support from the japanese HEP community?).
Date Event ILCTA@NML 29
1) What Can CESR Offer?
CESR offers:– The only operating wiggler-dominated storage ring in the
world– The CESR-c damping wigglers
• Technology choice for the ILC DR baseline design– Flexible operation with positrons and electrons– Flexible bunch spacings suitable for damping ring tests
• Presently operate with 14 ns spacing• Can operate down to 2 ns spacings with suitable feedback
system upgrades– Flexible energy range from 1.5 to 5.5 GeV
• CESR-c wigglers and vacuum chamber specified for 1.5-2.5 GeV operation
• An ILC DR prototype wiggler and vacuum chamber could be run at 5 GeV
– Dedicated focus on damping ring R&D for significant running periods after the end of CLEO-c data-taking
– A useful set of damping ring research opportunities…• The ability to operate with positrons and with the CESR-c
damping wigglers offers a unique experimental reach
Date Event ILCTA@NML 31-1
0
1
2
3
4
5
6
-5 10-9 0 5 10-9 1 10-8
FID(FPG-3000M) Waveform
Vol
tage
(kV
)
Time(s)
Pulse generator
Specifications
Amplitude at 50 ohm : 5 kVRise time : 1-1.4 nsPulse width at 50% of amplitude : 2-3 nsMaximum Pulse Repetition Frequency in burst mode : 3 MHz
FID Technology has very fast and high repetition rate pulse generators. The specification meets our requirements for the high voltage pulse source. We tested the kicker performance by using the pulse PS.
Date Event ILCTA@NML 32
Beam kick experiment at ATF DR
The kicker pulse is applied to the strip-line electrode when the beam goes through the electrode.The beam kick is observed by a turn-by-turn BPM as the amplitude of the oscillation of the betatron frequency component.The kick effect is measured by scanning the pulse timing precisely.
Date Event ILCTA@NML 33
Measurement result of FPG5-3000MThe achieved resolution is 0.2rad.
Rise time~3.2nsKick angle ~91rad(calc. 94.7rad)
Expanded horizontal scale
0
20
40
60
80
100
10 12 14 16 18 20
Pulse timing v.s. kick angle(FID FPG-3000M)
Kic
kAng
le(u
rad)
Delay(ns) Time
0
20
40
60
80
100
0 5 10 15 20 25 30
Pulse timing v.s. kick angle(FID FPG-3000M)
Kic
kAng
le(u
rad)
Delay(ns) Time
Date Event ILCTA@NML 34
• Comments (Zisman)– existing “FID” tests seem to have been DSRD
pulsers!– concerns about robustness– single-source issue
– Alternative solutions need to be studied.A working kicker design meeting impedance and
vacuum properties is still to be demonstrated. HV feed-through are critical.
– Consider use of an injection bump for relaxing kicker requirement: is it feasible?