Update of Microwave Instability Study in SuperKEKB Damping Ring Using Vlasov Fokker-Planck Solver
Overview of 6 km Damping Ring Study
description
Transcript of Overview of 6 km Damping Ring Study
![Page 1: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/1.jpg)
A U.S. Department of EnergyOffice of Science LaboratoryOperated by The University of Chicago
Argonne National Laboratory
Office of ScienceU.S. Department of Energy
Overview of 6 km Damping Ring Study
Kwang-Je Kimfor ANL-FNAL-UIUC Collaboration
ILC-Americas Work Shop
SLAC, Stanford, CAOctober 14-16, 2004
![Page 2: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/2.jpg)
2Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
6-km Damping Ring Study
• The 17-km Tesla dog-bone design assumed 20 ns rise- & fall-time kickers.
• If kickers with shorter rise & longer fall time are available, damping rings can be “small” using a injection scheme by Joe Rogers.
• Fast kickers were discussed by Frisch and Gollin.• This is an overview of work on a 6-km small damping ring by ANL-FNAL-
UIUC collaboration and J. Rogers & A. Wolski.
• Content:- Current status: linear lattice, instability estimates, & alignment
sensitivities- Plan for a next level study using tools developed for higher
brightness light sources
![Page 3: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/3.jpg)
3Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
APS, a 1 km, 7 GeV Ring at Work
![Page 4: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/4.jpg)
4Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Damping Ring Lattice Development
Initial work started at Fermilab (Amin Xiao’s talk)
• A 6-km, 5 GeV ring with TME lattice using the procedure discussed in P. Emma and T. Raubenheimer, PRSTAB,4, 021001 (2001)- 77 m of wigglers compared to 400 m in TESLA.- Higher current in smaller ring than TESLA.- Performance similar to the TESLA design.
![Page 5: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/5.jpg)
5Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
6 km17-km
DogboneEmery’s thesis
(1990) APS
Energy (GeV) 5.0 5.0 4.0 7.0
Circumference (m) 6114 17000 2229 1104
Lw (m) 77 468 360
Fw=I2w/I2A 8.5 17.3 32
Injected (m-rad) 1.010-2 1.010-2 n/a 1.310-3
Equilibrium (m-rad) 5.510-6 810-6 2.010-7 3.510-5
Extracted (m-rad) 810-6 810-6 n/a n/a
Damping time,x (ms) 27 28 13.5 9.6
rms Bunch Length (mm) 6 6 ~6 5.8
rms Energy Spread (10-3) 1.3 1.3 0.9 (2.4 with impedance)
0.96
Particles/Bunch (1010) 2.0 2.0 1.4 12.0
Average Current (mA) 443 159 0.3 100-300
Major Parameters of DRs and APS
![Page 6: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/6.jpg)
6Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Instability Estimates (Bill Ng)
• Incoherent space charge tune shift =0.026 << 0.31 for TESLA- Smaller circumference, larger beam size (larger disp.)
• Instabilities- Longitudinal: Single- & multi-bunch thresholds;safe- Transverse: Single bunch threshold; safe
multi-bunch threshold; safe with damper
- Electron cloud: Growth time about 1s with solenoids- Fast ion: Growth less than 20% with feedback
(@ 10 -10)
![Page 7: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/7.jpg)
7Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Quadrupole and Sextupole Alignment Sensitivities (A. Wolski)
• 6-km DR less sensitive than Tesla dogbone• Both 6-km DR and Tesla dogbone more sensitive than ATF
ATF TESLA Dogbone ILC Small
Quadrupole Jitter [nm] 241 80.7 198
Quadrupole Rotation [rad] 825 40.5 58.3
Sextupole Alignment [m] 45.6 11.3 40.4
![Page 8: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/8.jpg)
8Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
The “Small” DR Looks Doable. Next Step?• Further optimization of parameters
- Energy (3.7GeV), lattice,• Next-level study with tools and technology
developed for high-brightness light sources:- Impedance modelling and minimization- Beam monitoring and feedback- Wiggler development- Photon absorbers
![Page 9: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/9.jpg)
9Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Tools for Nonlinear Beam Dynamics(Louis Emery’s Talk)
• Toolkit approach combined with comprehensive tracking code elegant developed by M. Borland
• Parallel simplex optimizer being developed by H. Shang• An example of future investigation
- Trade-off in non-linearities between weaker focusing arc cell design and longer wiggler to maximize dynamic aperture
![Page 10: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/10.jpg)
10Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
RF BPM Diagnostics & Feedback
• Orbit motion is characterized by a PSD spectrum in range 0 to frev/2
• RMS orbit jitter at extraction is equal the integral of PSD spectrum
• Orbit feedback reduces beam motion only in a certain band, say, 0-60 Hz (APS) -> Orbit jitter is reduced somewhat depending on the PSD details
• For damping ring, higher-bandwidth feedback may be needed to reduce jitter sufficiently
![Page 11: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/11.jpg)
11Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Vacuum Chamber Issues• Minimizing Impedances:
- Make use “impedance database” obtained by modeling and measuring local impedance (e.g., by orbit response matrix)
• Suppress electron cloud effects:- Employ solenoids, slots, low-secondary-yield-
coefficient coatings, and/or corrugation- Based on experimental and modelling experiences at
APS (K. Harkay, R. Rosenberg, L. Loiacono)
![Page 12: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/12.jpg)
12Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Wiggler Development
• Radiation damage of PM undulator( M. Petra)• Superconducting wiggler (S.H. Kim); Useful for damping
wiggler?• The LCLS undulator under construction at APS is similar
to that used for positron production scheme.
![Page 13: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/13.jpg)
13Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Photon Absorbers
• APS dipole fan and undulator photon beam absorbers sustain high intensities ( S. Sharma)- Upto 600 mA for dipole fan, 300mA for undulator
• Damping ring absorbers can be scaled from APS designs
![Page 14: Overview of 6 km Damping Ring Study](https://reader035.fdocuments.in/reader035/viewer/2022070419/56815b14550346895dc8c39e/html5/thumbnails/14.jpg)
14Pioneering Science andTechnology
Office of Science U.S. Department
of EnergyKJK, ILC-Americas WS, SLAC, 10/14-16/04
Summary• With the development of fast kickers “small” damping rings are
a serious option for ILC.
• Preliminary study of a 6 km, 5 Gev DR look promising.
• Further optimization and next level study are planned using tools for light source improvement.
More information:
• Studies Pertaining to a Small Damping Ring for the International Linear Collider, FERMILAB-TM-2272-AD-TD
• ILC Damping Rings web site: http://awolski.lbl.gov/ILCDR/