WG3b since Snowmass

S. Guiducci

LNF-INF

On behalf of ILC Working Group WG3b

GDE meeting

LNF 7-9 December 05

Baseline Configuration recommendation

Coordination of DR activity started at 1st ILC Worksop, KEK, November 2004

Injector conveners: G. Dugan, M. Kuriki, S. Guiducci

Progress was reviewed at the 2nd ILC Workshop at Snowmass, in August 2005. We were not ready at that time to make any recommendations.

Final results were reported at the damping rings meeting at CERN, November 2005.

Damping Ring conveners: J. Gao, S. Guiducci, A. Wolski

Participants in the meeting agreed recommendations on the DR configuration.

Baseline Configuration recommendation

Nearly 50 participants Contributions from more than a dozen institutions in all the three regions.

D. Alesini* (INFN)A. Babayan (YPI)I. Bailey (CI)K. Bane (SLAC)D. Barber* (DESY)Y. Cai* (SLAC)W. Decking (DESY)A. Dragt* (UM)G. Dugan (Cornell)E. Elsen* (DESY)L. Emery* (ANL)J. Gao* (IHEP)G. Gollin* (UIUC)S. Guiducci* (LNF)S. Heifets* (SLAC)J. Jones (ASTeC)E.-S. Kim* (POSTECH)

H. S. Kim* (CHEP)K. Kubo (KEK)M. Kuriki (KEK)S. Kuroda (KEK)O. Malyshev* (ASTeC)L. Malysheva* (CI)F. Marcellini* (LNF)C. Mitchell* (UM)T. Naito (KEK)J. Nelson* (SLAC)K. Ohmi* (KEK)Y. Ohnishi* (KEK)K. Oide (KEK)T. Okugi* (KEK)M. Palmer* (Cornell)M. Pivi* (SLAC)P. Raimondi (LNF)

T. Raubenheimer (SLAC)I. Reichel* (LBNL) M. Ross* (SLAC)D. Rubin* (Cornell)D. Schulte* (CERN)G. Stupakov* (SLAC)A. Tomonori* (KEK)J. Urakawa* (KEK)J. Urban* (Cornell)M. Venturini* (LBNL)L. Wang (SLAC)R. Wanzenberg* (SLAC)A. Wolski* (LBNL)M. Woodley (SLAC)G. Xia* (DESY)A. Xiao (ANL)F. Zimmermann (CERN)

* 34 participants in the DR meeting at CERN, November 9-11, 2005

Status of the debate…

The injection/extraction kickers should be strip-line (or similar) devices powered by fast pulsers.

“Conventional” kicker technology has developed so that 17 km or 6 km damping rings are feasible. 3 km rings may also be possible, but at present have higher technical risk.It is still important to document thoroughly the work that has been done on alternative kicker technologies.

Further studies are needed to make a firm decision on the circumference. However, a very promising option appears to be a 6 km circumference ring, possibly using rings in pairs to provide adequate bunch spacing (for electron cloud, bunch number increasing…)

Other options need further information and debate.We have an organized international effort to produce the necessary information.We have a plan for presenting a well-documented recommendation to the GDE.

Snowmass - WG3b Summary

Seven representative lattices were assembled by end of April 2005

The goal was to apply analysis tools and procedures systematically to each of the seven reference lattices.

An “arbitrary” naming scheme was chosen to promote objectivity.

We did not set out to choose one of the lattices. Our goal was to understand the issues based on the results of studies of these reference lattices, and use that understanding to make a recommendation for a configuration, not a design.

Lattice Name Energy [GeV] Circumference [m] Cell Type

PPA 5.0 2824 PI

OTW 5.0 3223 TME

OCS 5.0 6114 TME

BRU 3.7 6333 FODO

MCH 5.0 15935 FODO

DAS 5.0 17014 PI

TESLA 5.0 17000 TME

DR Configuration Study Task Forces were formed to co-ordinate activities

1: Acceptance IssuesY. Cai and Y. Ohnishi

2: Vertical Emittance TuningJ. Jones and K. Kubo

3: Classical InstabilitiesK. Bane, S. Heifets, G. Stupakov

4: Space-Charge EffectsK. Oide and M. Venturini

5: Electron-Cloud EffectsK. Ohmi and M. Pivi

6: Fast-Ion EffectsE.-S. Kim, D. Schulte, F. Zimmermann

7: PolarizationD. Barber

8: Kicker TechnologyM. Ross and T. Naito

9: Cost EstimatesS. Guiducci, J. Urakawa and A. Wolski

10: AvailabilityJ. Nelson

An enormous amount of work was completed in a little over six months.

Results are being written up: far too many results to do justice in a short presentation.

There were close to 50 contributors, with activities co-ordinated by the Task Force leaders.

Most Task Forces carried out thorough studies of all (or nearly all) reference lattices.

Results were continually cross-checked between two or more researchers.

Configuration studies were concluded in early November

Two reports are now in preparation, containing the results of the configuration studies and the configuration recommendations:

– ILC Damping Rings Configuration Recommendation Summary Reporthttp://www.desy.de/~awolski/ILCDR/DRConfigurationStudy_files/DRConfigRecommend.pdf

Completed.

– ILC Damping Rings Configuration Studies Detailed Reporthttp://www.desy.de/~awolski/ILCDR/DRConfigurationStudy_files/DRConfigRecommendSummary.pdf

In progress (180 pages).

Nearly all contributions have been collected.

Expected completion in early 2006.

– Configuration Recommendation has been presented to the GDE Executive Committee by Andy Wolski (SLAC, November 17th)

http://cbp.lbl.gov/people/wolski/Wolski-DRConfigRecommend-2.pdf

BC recommendation meeting

CERN, November 9-11,

Thanks to Gilbert Guignard for hosting the meeting at CERN.

34 participants

21 presentations on the results of the task forces were presented. and are available on the web:

http://www.desy.de/~awolski/ILCDR/CERNDampingRingProceedings.htm

One afternoon and the following morning were devoted to discussions.

For each configuration item, the participants agreed on:– the relevant issues and their significance;– the risks associated with each issue for each of the configuration options;– a recommendation for the baseline and alternative configurations.

Nominal Parameters and performance specifications

Circumference and Layout

The critical choice for the DR was the circumference and layout recommendation

I’ll describe the options, the issues and the process which led to the recommendations.

For each issue was attributed a significance for the circumference choice (A,B,C) and a risk parameter (from 1 to 4).

Final recommendations came from the discussion, not a mathematical formula.

Classification of “Significance” and “Risk”

12

Circumference optionsfrom TESLA dogbone 17 Km to 6 & 3 Km

3 Km6 Km

3 or 6 km rings can be built in independent tunnels

“dogbone” straight sections share linac tunnel

Two or more rings can be stacked in a single tunnel

Issues for the circumference choice

KickersInjection/extraction kickers are more difficult in a shorter ring. R&D programs are proceeding fast, it is expected a demonstration for a 6 km circumference.

Electron cloud effect Shorter rings have a closer bunch spacing, which greatly enhances the build-up ofelectron cloud. Electron cloud density is dominant in the wiggler and in the dipole. Electron cloud instability could limit the stored current or increase the vertical beam size in the positron ring. R&D programs on mitigation tecniques are in progress at different storage rings.

AcceptanceGiven the high average injected beam power injection efficiency has to be ~100% for the nominal positron distribution. The dogbone damping rings have a small acceptance, while the nearly circular 6 km ring has the largest acceptance.

Ion effectsFast ion instability could limit the current in the electron ring. Fill pattern and vacuum pressure are more significant than the circumference for the severity of the effect. Gaps in the fill and very low vacuum levels will be necessary to mitigate ion effects.

Issues for the circumference choice

Space chargeThe incoherent space-charge tune shift is proportional to the ring circumference. The coupling bumps used to reduce this effect in the dogbone ring could be some risk for the vertical emittance.

Tunnel layoutSharing the linac tunnel reduces the time available for commissioning and reduces the availability.

Stray fields in the linac tunnel could adversely affect the vertical emittance

of the extracted beam.

CostSmaller rings have lower cost. Dogbone shape allows tunnel cost saving.

Issues for the circumference choice

Availability (Significance: C)

The larger number of components in a larger ring is likely to have an adverse impact on reliability.

Classical collective effects (Significance: C)

Classical collective effects as: resistive-wall instability, HOM coupled-bunch instabilities, microwave instability, and intrabeam scattering are of potential concern. Issues such as bunch charge, bunch length, momentum compaction, beam-pipe diameter etc., are determinant rather than the circumference. These effects should be manageable in any of the proposed circumference options.

Low-emittance tuning (Significance: C)

Achieving the specified vertical beam emittance in the damping rings is important for producing luminosity. However, there is an additive emittance dilution in all the systems downstream of the damping rings. There is little evidence that the circumference of the damping ring in itself has an impact on the emittance sensitivity to misalignments and tuning errors.

Polarization (Significance: C)

Studies suggest that depolarization should not be a major issue in any of the configuration options under consideration.

Kickers

The length of the TESLA DR and the idea of the dogbone shape (to save tunnel length) were originated by the anavailability of ultra fast kickers. 17Km were needed to accommodate ~3000 bunches with 20 ns bunch distance.

Three different type of fast pulsers have been tested on a strip line kicker at ATF(KEK). All of them have very short rise/fall time (~3ns) and fulfil nearly all of the requirements for the damping ring injection. R&D programs are in progress in various laboratories both on the pulser and on the electromagnetic design of the electrode. With the ATF kickers’ strength, nearly 10 stripline electrodes are needed to reach the required injection/extraction angle. R&D programs are rapidly proceeding and the task force participants are confident that:

- kickers for a 6 Km (i.e. 6 ns bunch spacing) are a “low risk” issue

- kickers for the 3 Km ring are considered at present a high risk.

Injection/extraction kickers beam test at ATF

J. Urakawa, for ATF collaboration

0

20

40

60

80

100

0 5 10 15 20 25 30

Pulse timing v.s. kick angle(FID FPG-3000M)

Delay(ns) Timekick timing [ns]

kick

ang

le [r

ad]

0

20

40

60

80

100

10 12 14 16 18 20

Pulse timing v.s. kick angle(FID FPG-3000M)

Delay(ns) Timeki

ck a

ngle

[r

ad]

kick timing [ns]

Rise/fall time < 3ns

a tail of a few percent extends for ~7ns:

•R&D on the pulser

•Cancellation with two kickers at

1) General considerations: kicker length and pulse length

t

VIN

Tf

Tr

Generator pulse shape

Tr

ILC DR DANE

E [GeV] 5 0.51

TB [ns] 6.15 2.7

B [mm] 6 35

Defl. [mrad] 0.5 5

L [cm] 87 73

Tf [ns] 5.9 5.3

x [mm] @ septum and kicker 5 2

y [mm] @ septum and kicker 1 1

L=kicker length

Tr=rise time length

Tf=flat top length

B=bunch length

TB=bunch spacing

assuming Tr=300ps

t

2L/c+Tr

Tf-2L/c=4B/c

2L/c+Tr

2TB

t

VT

2TB

VT ILC

DANEInjectionupgrade

t

VT

2L/c

Kicker impulse response(ideal case)

Injected bunch

Stored bunches

VT=2.5 MV

19

Design completed

Y. Cai

Single bunch instability threshold and simulated electron cloud build-up density

Single-bunch instability thresholds

1.0E+10

1.0E+11

1.0E+12

1.0E+13

TESLA MCH DAS 2 xBRU

2 xOCS

OCS BRU OTW PPA PEP-IILER

KEKBLER

cloud density [m^-3]

Instability thresholdSEY=1.2SEY=1.2 + solenoidSEY=1.4SEY=1.4 + solenoid17 km range 2 x 6 km 6 km

3 km

arc vacuum pipe round 22mm; wigglers design as TESLA TDR;

photon reflectivity 80%

M. Pivi, K. Ohmi, F. Zimmermann, R. Wanzenberg, L. Wang, T. Raubenheimer, C. Vaccarezza, X. Dong

22

The instability limit is more likely to be exceeded in smaller rings.

Larger bunch spacing Damping Rings with a larger synchrotron tune and/or momentum compaction are preferable.

In order of preference: MCH, DAS, TESLA, BRUx2, OCSx2, BRU, OCS.

It’s a technical challenge to stably reduce the SEY below 1.1-1.2

Redflag: KEKB Annual Report 2005 “The electron cloud effect still remains the major obstacle to a shorter bunch spacing, even with the solenoid windings” [1].

If the SEY can be reduced in magnets, the 6 km BRU and OCS can be feasible.

Promising cures as microgrooves and clearing electrodes need further R&D and full demonstration in accelerator.

Larger wiggler apertures may be helpful to reducing the cloud density below threshold in 6km rings

In the short bunch spacing 3 km DR, multipactoring arises even at low SEY~1, developing the highest cloud densities (see Snowmass 05 talks) therefore should be discarded as possible candidates.

ILC DR Task Force 6 Recommendation Summary

M.Pivi, K. Ohmi, R. Wanzenberg, Zimmermann, SLAC, Nov 2005

*

Microgrooves.

Groove spacing comparable with e- Larmor radius.

R&D status: laboratory tests at SLAC very successful in magnetic free

regions, measured reduction to SEY < 0.7. Building

chamber for installation in dipole region in PEP-II.

Clearing electrodes: simulations show that likely electrodes can suppress

electron cloud in magnetic field regions, but need further R&D and

studies (Impedance, support …).

R&D at KEKb.

Photon absorbers to reduce reflectivity

Suppressing e- cloud in magnetic field regionsSuppressing e- cloud in magnetic field regionsSuppressing e- cloud in magnetic field regionsSuppressing e- cloud in magnetic field regions

• Possible solution: need laboratory and accelerator tests in dipole field

Simulated secondary yield of a rectangular grooved surface in a dipole field compared with a smooth surface (field free reference).

Groove dimensions in wiggler ~10-100 um. 1cm wide stripe with grooves.

Rectangular grooves in BEND: SEYRectangular grooves in BEND: SEY

Rectangular groove surface

smooth surface

By=0.19T

Parameters rectangular groove: period = 250 um depth = 250 um width = 25 um

DAS/PITESLA/S-Shape17 kmz=6mm

17 kmz=6mm

ACCEPTANCE: Dynamic Aperture with Multipole Errors and Single-Mode Wigglers

MCH OCS16 kmz=9mm

6 kmz=6mm

Y. Cai, Y. Ohnishi, I. Reichel, J. Urban, A. Wolski

Comparison of different wiggler models and tracking codes

DA for TESLA DR with CESRc or one-mode wiggler model

DA for TESLA DR with CESRc or one-mode wiggler model

M. Venturini, ILC DR Meeting - CERN 10 Nov 05

One-mode is an ideal, infinite pole width, wiggler

28

Topics of Acceptance Study

• Dynamic aperture– Items to be considered:

• Ideal lattice, Multipole errors, Nonlinear wigglers, (Machine errors)

– Output:

• 2Jy0-2Jx0 plot, 2Jx0-0 plot, Tune scan

• Physical aperture– Aperture of wiggler section

• Frequency map analysis (already reported at Snowmass)

– Resonance structures

• Injection efficiency– Input: Positron distribution

– Output: Survived particle distribution

29

Risks Associated the Acceptance Studies

• Lack of margin in acceptance especially for the off-momentum particles

• Uncertainty of dynamic aperture in tracking compare to measurement, at best 20% agreement at SPS

• Wiggler model is the best could be achieved. This inexplicitly assumes that we need large aperture and super conducting wigglers

• Magnetic errors are also at the best can be achieved no room for any mistake

• No misalignments and linear optical errors in the simulations yet.

• Margin of acceptance is necessary for an adequate efficient collimation system in the damping ring.

• Uncertainty in the actual distribution for the positron source

Y. Cai

Circumference recommendation: Ion effects

Mini-gap can reduces the growth rate of FII and tune-shift up to a factor of 10~20

Ion-density reduction factor (IRF) depends on fill-pattern, optics and the time during the damping. IRF=10 is guaranteed.

The growth time with mini-gaps will be longer than 1 turn.

Detail study is under the way to get a maximum IRF.

Growth Time with IRF=10

0

1

2

3

4

5

6

7

8

9

PPA OTW OCS 2OCS BRU MCH DASTESLA

Growth time in turn

With Coupling Bump

Without Coupling Bump

Tun-shift with IRF=10

0

0.02

0.04

0.06

0.08

0.1

0.12

PPA OTW OCS 2OCS BRU MCH DAS TESLA

Tune shift

With Bump

Without Bump

L. Wang, T. Raubenheimer, Y. Cai, E.-S. Kim

Conclusions - Space charge

• The winner is the OCS lattice [medium-size circumference (6.1Km), good symmetry properties]

• The lattices shorter than 6km have not been analyzed in detail but they should be as good or better

• The dogbone lattices are more vulnerable to space charge (as expected) but they still seem to offer patches of usable tunespace• Choice of working point may get in conflict with other requirements

• Risk is higher

• Augmented symmetry helps (‘S-shaped’ TESLA DR is better than the ‘C-shaped’ version)

• Coupling bumps come at a cost as they excite new resonances and restrict region of usable tunespace• Effectiveness of coupling bumps seems dependent on lattice design

• In general, they do not necessarily offer a decisive advantage

• Still, installation may be recommended to add flexibility

M. Venturini

Circumference recommendation: Space-charge effects

Vertical (left) and horizontal (right) emittance growth from tracking MCH (16 km lattice) using Marylie-Impact.

Top:Particles/bunch = 0

Middle:Particles/bunch = 2×1010

Coupling bumps OFF

Bottom:Particles/bunch = 2×1010

Coupling bumps ON

Errors will further reduceusable area of tune space

K. Oide and M. Venturini

Preliminary Cost estimates

A 3 km ring would have rather a lower cost than 6 km or 17 km rings.

The additional tunnel in the 6 km rings makes the costs comparable to the 17 km rings.

Two 6 km rings in a single tunnel is a higher cost than a 17 km ring.

An example from the Summary Report: the Circumference (4)

The significance of each issue and the risk associated with each option are based on results from the configuration studies, which will be presented in the Detailed Report.

Recommendation for the circumference (baseline configuration)

Positrons: two rings of ~ 6 km circumference in a single tunnel.

Two rings are needed to reduce e-cloud effects unless significant progress can be made with mitigation techniques.

Preferred to 17 km due to:Space-charge effects

Acceptance

Tunnel layout (commissioning time, stray fields)

Electrons: one 6 km ring.

Preferred to 3 km due to:Larger gaps between minitrains for clearing ions.

Injection and extraction kickers ‘low risk’

Estimated cost for 3x6 km rings is lower than 2x17 km.

Recommendations for the circumference (alternative configurations)

1. If techniques are found that are sufficiently effective at suppressing the electron cloud, a single 6 km, or possibly smaller, ring can be used for the positron damping ring. This will save costs.

2. If electron cloud mitigation techniques are not found that are sufficient for the baseline positron ring, then a 17 km ring is a possible alternative; this would require addressing space-charge, acceptance and stray fields issues. This will increase costs.

Recommendations summarized

Item Baseline Alternatives

Circumference (e+) 26 km(e-) 6 km

1. (e+) 6 km2. (e+/e-) 17 km

Beam energy 5 GeV

Injected emittance and energy spread Ax+Ay<0.09 m-rad||<1%

Ax+Ay<0.045 m-rad||<2%

Train length @ bunch charge 2800 @ 21010 >2800

Extracted bunch length 6 mm - 9 mm

Injection/extraction kicker technology Fast pulser/stripline kicker 1. RF separators2. Fourier pulse compressor

Wiggler technology Superconducting 1. Normal-conducting2. Hybrid

Main magnets Electromagnetic Permanent magnet

RF technology Superconducting Normal conducting

RF frequency 500 MHz

Vacuum chamber diameter,arcs/wiggler/straights

50 mm/46 mm/100 mm

Vacuum system technology …

Energy recommendation

Options: 3.7 GeV, 5 GeV, 6.8 GeV

Issues:

Baseline recommendation 5 Gev

Lower energy increases risk for collective effects, higher energy makes more difficult to tune for low emittance

39

Wigglers for ILC DR• Parameters

• Bpeak 1.6 T w 0.4 m• Total length 165 m• Radiated energy 9.3 MeV

• A high quality field is needed to achieve the dynamic aperture necessary for good injection efficiency:

• Physical aperture A large gap is needed to achieve the necessary acceptance for the large injected positron beam:

– a full aperture of at least 32 mm is highly desirable for injection efficiency

– a full aperture of at least 46 mm is highly desirable to mitigate e-cloud effects

40

Technology Options• Field requirements have led to 3 suggested options:

– Hybrid Permanent Magnet Wiggler– Superferric Wiggler– Normal Conducting Wiggler

• Design Status– Hybrid PM based on modified TESLA design

• Basic modified TESLA design (Tischer, etal, TESLA 2000-20)– 6 cm wide poles– Tracking simulations in hand

• Next generation design (see note from Babayan, etal)– New shimming design– Improved field quality – field maps available at end of last week– Field fitting now underway, but no tracking studies yet

– Superferric design based on CESR-c wiggler (Rice, etal, PAC03, TOAB007)

• Tracking simulations in hand

– No active design for normal conducting option• Will scale from TESLA (TESLA TDR) and NLC (Corlett, etal, LCC-0031) proposed

designs Mark Palmer, ILCDR Meeting - CERN - 11 Nov 05

41

Field Quality• Significance: A• Primary Issue is Dynamic Aperture• 3 pole designs in hand:

– Superferric with B/B ~ 7.7 x 10-5 @ x = 10 mm (CESR-c)

• Shows acceptable dynamic aperture!• However, most designs approaching DA limit for

p/p=1%!– Modified TESLA design (60 mm pole width) B/B ~ 5.9 x 10-3 @ x = 10 mm (TESLA A)

• Dynamic aperture unacceptable!• Note that normal conducting designs (as is) are

in this ballpark– Shimmed TESLA design (60 mm pole width) B/B ~ 5.5 x 10-4 @ x = 10 mm (TESLA B)

• Detailed field map has just become available• Field fits and tracking studies not yet available• Concerned about potential impact on DA near

p/p = 1%

Lateral Field Errors

-0.007

-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0 2 4 6 8 10

x(mm)

dB/B0

CESR-c Style

TESLA A

TESLA B

Mark Palmer, ILCDR Meeting - CERN - 11 Nov 05

ILC DR Wiggler Technology

Baseline

The CESR-c wigglers have demonstrated the basic requirements for the ILC damping ring wigglers. Designs for a superconducting wiggler for the damping rings need to be optimized.

Alternatives

Designs with acceptable costs for normal-conducting (including power consumption) and hybrid wigglers need to be developed, that meet specifications for aperture and field quality.

List of R&D

International Linear Collider Damping Ring Research and Development Projects web site (Thanks to G. Gollin)http://www.hep.uiuc.edu/LCRD/ILCDR.html

• Start discussion to create a global R&D plan for the Damping Ring

• "Strawperson" list of design and engineering tasks

• Table of comments, interests and planned activities

• Categories:–Fast Kickers (HV pulsers, stripline kickers)–Feedback systems–Wiggler (design, beam dynamics)–High resolution BPMs –Fast Ion instability–Electron cloud (grooved metal surface, clearing electrodes)–Beam dynamics issues–Beam size monitors (X-SR, ODR, Laser wire) –Beam Based Alignment R&D–Feedforward system for the stabilisation of the extracted –superconducting RF cavity

List of R&D

International Linear Collider Damping Ring Research and Development Projects web site (Thanks to G. Gollin)http://www.hep.uiuc.edu/LCRD/ILCDR.html

• Laboratories, universities and industries–Diversified Technologies, Inc. (USA), University of Illinois (USA), KEK-ATF (Japan), LBNL (USA), CERN (EU), Cornell/CESR (USA), SLAC (USA), ANL (USA), DESY (EU), INFN-LNF (EU)

• Infrastructures–ATF (KEK), SPS (CERN), DAFNE (LNF), ALS (BNL), PEP-II (SLAC), KEKb, APS (ANL), CESR (Cornell)

Final Remarks

The configuration recommendations presented here represent a consensus amongst the participants at the CERN damping rings meeting.

The damping rings community has demonstrated the ability for highly collaborative and well co-ordinated effort.

Next step is to continue to work in close collaboration to coordinate the required R&D activity and to prepare the RDR.

END

Risk associated with electron cloud simulations Risk associated with electron cloud simulations (..disclaimer)(..disclaimer)Risk associated with electron cloud simulations Risk associated with electron cloud simulations (..disclaimer)(..disclaimer)

‘Build-up’ simulation codes give satisfactory agreement with experimental observation in existing accelerators.

Codes benchmarking: agreement.

‘Single-bunch’ threshold simulation codes agree qualitatively with some observations (chromaticity,..). Single-bunch simulation codes under development.

One should take a margin factor when comparing build-up and threshold.

For comparative ILC DR studies, train gaps not introduced (yet). Gaps likely reduce cloud density by certain extent.

Cloud space charge 2D: limit for wiggler simulations.

ILC DR Parameters

Energy (GeV) 5

Circumference (m) 6114

Bunch number 2820

N particles/bunch 2x10-10

Damping time (ms) 22

Emittance x (nm) 5600

Emittance x (nm) 20

Momentum compaction 1.62x10-4

Energy loss/turn (MeV) 9.3

Energy spread 1.29x10-3

Bunch length (mm) 6.0

RF Voltage (MV) 19.3

RF frequency (MHz) 650