Accelerator Physics

1. Accelerator Physics Samuel Krinsky NSLS-II Accelerator Physics Group Leader NSLS-II Accelerator Systems Advisory Committee February 1-2, 2012

2. Outline Accelerator Physics Group Progress Conclusions

3. Accelerator Physics Group G. Bassi, J. Bengtsson, A. Blednykh, W. Cheng, J. Choi, W. Guo, P. Illinski, S. Kramer, Y. Li, I. Pinayev (CAD), L. Yang, L.H. Yu Y. Hidaka, B. Podobedov, S. Seletskiy, X. Yang

4. Interface with Engineering Groups Magnet Design: J. Bengtsson, W. Guo, Y. Li, Diagnostics: A. Blednykh, W. Cheng, P. Ilinski, I. Pinayev, S. Seletskiy Controls: J. Choi, Y. Hidaka, L. Yang, L.H. Yu, Insertion Device: J. Bengtsson, O. Chubar (ESD), W. Guo, Safety: S. Kramer, Y. Li Vacuum: A. Blednykh, Ilinski RF: A. Blednykh, G. Bassi

5. Technical Progress • Analysis of field tolerances for ring magnet acceptance • Studies of lattice flexibility: reduced symmetry, specialized insertions • Calculation of Impedance of components • DESY 7-Cell Cavity OK for early commissioning goal of 25ma • Development of parallel computer code to simulate coupled bunch • instabilities including long and short range wakefields • Equipment Protection System Maturing • Without IDs—passively safe to 50ma • Development of high level application programs • Review in April 2012

6. Technical Progress (cont.) • Commissioning Planning • Draft report, HLA software, Focus for Accel. Phys. Group Meetings • Beam Loss Control Monitoring System • Review in July 2011 • Top-Off safety • Review in July 2011, March 2012, Fall 2012 • X-ray diagnostic beamlines and visible light monitor • Review in July 2010, • X-ray BPMs • Transverse feedback system • Insertion devices beyond baseline • Review in January 2012

7. Physics input to the magnet production-1 • Monitor the field quality of all the magnets before approving the shipment. • Trend study of the field quality, and make suggestions on shimming. 10-pole 14-pole B5 (normal 10 pole) of Danfysik sextupoles has a large current dependence. They will be used for several families with a large current span. We suggest them to shim the magnets at 60% of the full strength, rather than 100%; therefore the beam dynamics effects will be cancelled among families. IHEP tune the harmonics by replacing the iron pins with stainless steel pins. The magnets from production have a large b5 (4-8 units), after pinning, b7 grows to ~ 2 units. We suggest them retract the two movable center poles by 20-40 μm.

8. Physics input to the magnet production-2 y + -- x -- + z • Identified the design defects in the skew quadrupole coils, and proposed a solution. A4 A4 z A4=1000 units, equivalent to ~15 units in a normal quad. We use a four-current model, and calculated the a4 component from the present dimension (center plot). If the dimension is symmetrized, the integrated strength becomes negligible. The conclusion is verified by a more advanced tool. • Analyze the dipole field mapping data, and determine the nose piece parameters. The goal is to match the two types of dipoles. We first track through the dipole field map for close-orbit, Then use polynomial fitting to obtain multipoles on the curved orbit. The integrated strength is compared In the table. The length and chamfering of the nose piece are determined from these parameters.

9. Compensating APPLE-II (EPU49) Dynamic Focusing Effects by Current Strips Idea: I. Blomqvist Implementation at BESSY: J. Bahrdt APPLE-II RADIA Model with Strips in Linear Vertical Polarization Mode Efficient Solving for CurrentsUsing Least-Squares Linear Fit Field Integral from Current Densities: Equivalent Vertical Field Integrals from Dynamic Focusing and from the Current Strips Compensating Currents in Lower Strips Matrix calculated using RADIA Current Densities from Field Integral: Vertical (Equivalent) Field Integral [G.cm] Current [A] Since the Dynamic Effectsare Anti-Symmetric vs X: Number of Strips used: 2 x 20 Strip Dims: 2 mm x 0.3 mm x 2 m Horizontal Gap bw Strips: 1 mm Vertical Gap bw Strips: 10.7 mm Max. Current obtained: ~ 2.3 A APPLE-II Vertical Gap: 11.5 mm Horizontal Position [mm] Horizontal Position [mm] Electron Trajectory in 3D Magnetic FieldWithout and With Correction Horizontal Trajectory x0=0, y0=0 before Undulator Horizontal Trajectory Horiz. Position [μm] x0= 4 mm, y0=0 before Undulator x0= -4 mm, y0=0 before Undulator Vertical Trajectory Horizontal Position [μm] Horizontal Position [μm] Vertical Position [μm] Longitudinal Position [mm] Longitudinal Position [mm] Longitudinal Position [mm]

10. High Level Application Programs • Control system design provides independence of HLA from low-level details • MatLab middle layer will be available • In-house development will emphasize a python environment utilizing • services being developed by controls group • The online calculation engine uses Tracy subroutines • Documentation including programing reference and user guide available • on-line.

11. HLA Progress 1 Lattice (Magnet) mapping to channel access is done by Channel Finder Service (developed in Controls group) High level magnet PV control is Object-Oriented. It uses CFS to control magnets in the same Group/Family/Girder/Cell/Symmetry or whoes name matching certain pattern. (done) Low level control uses direct PV name in Python or control panels developed with Control System Studio (CSS). (contributed from HLA team, but relying on each subsystem) Physics routines are in progress. Orbit Response Matrix (ORM) library is done. Twiss measurement, global orbit correction and local bump control are done. ( more routines after Jan-Feb series of AP talks) Graphical User Interface(GUI) applications are in progress. Orbit display GUI is done. Beam Based Alignment (BBA) script version is done. Linear Optics Modeling (LOCO) is in progress. (J. Choi) Misc: Data storage (Input/Output) related routines and unit conversion are in progress.

12. HLA Progress 2 • Document including tutorial and examples for each routine/module are developed together with the code. • Communications with Diagnostics group are well established on RF BPM data acquisition. • Took advantages of tools from controls group. Raised requirements on CFS, CSS, archiver.

13. Beam Loss Control & Monitoring system Beam apertures and scraper to localize the major beam losses Verify the fraction of beam captured in shielded regions: using current monitors and beam loss monitors ( neutron and Cerenkov monitors) Principle of scraper localization demonstrated in Xray ring Thin scrapers provide high sensitivity local beam loss signal using Cerenkov detectors and reduced radiation off scraper High dynamic range Cerenkov light detector system design to detect 0.1 pC/sec lifetime losses to Injection and beam dump losses of 3mC/sec

14. Demonstrated Loss Control in XrayRing-1 Xray Ring has 5mm Cu scraper near dispersion maximum in SP=3 0.91m CBLM in dipole end

15. Demonstrated Loss Control in Xray Ring-2 As the scraper reduces momentum aperture: __ CBLM show increase Even before the __ LIFTIME starts decrease __ b2bm2 BLM1 decrease __ b1bm1 BLM2 decrease __ b1bm1 BLM1 decrease BLM monitors decrease and CBLM increase showing change in beam loss locations by the scraper scan on the momentum aperture Beam loss at CBLM after scraper, charge loss rate used to calibrate CBLM

16. Transverse BxB Feedback • 500MHz digitizer received and tested using simulated pulse • 10kHz-250MHz, 500W broadband amplifiers received and tested • First stripline kicker assembled and tested • Dedicated button BPMs free of trapped TE mode allocated • Heliax cables purchased EDM panel iGp12

17. Visible SLM • Streak camera and fast gated camera received and tested using ~ps pulse laser • Visible diagnostic beamline and experiment room design finalized. Procurement on-going. • In flange type fixed mask, defines the 3mrad*7mrad (H*V) radiation fan • Cold finger blocks the central +/- 0.5mrad x-ray • 4’’ diameter first mirror, Glidcop + optical quality coating, water cooled • Experiment rooms • Various optical components • Engineer design review Nov-2011

18. 500MHz PETRA-III 7-Cell Structure • Normal Conducting Structure w/o HOM’s - Dampers • Longitudinal Higher Order Modes 500MHz PETRA-III 7-cell structure • Transverse Higher Order Modes • Mode frequencies provided by R. Wanzenberg

19. Coupled-Bunch Stability Analysis (Iav=25mA) • Longitudinally stable : Growth time . Damping time • Transversely unstable at zero chromaticity (ξ=0): growth time • Cure: 1)Run at positive chromaticity to provide damping via slow head tail effect • 2) Frequency shift (ΔΩ) of HOM’s Slow head-tail effect: damping at ξ=2 Fastest growing mode μ=74 vs. at M=132, N=3.1x109, RBB =1MΩ/m: (1,60KHz), (2,40KHz) M=132, N=3.1x109, RBB=0.5MΩ/m : (1,110KHz), (2,70KHz) M=66, N=6.2x109, RBB=0.5MΩ/m : (1,60KHz), (2,40KHz) Self consistent simulations of head-tail effect + coupled-bunch interaction with the OASIS code Working Points (ξ,ΔΩ) ▬▬▬►

20. Summary Results of Calculated Impedance (s=3mm)

21. Conclusion Accelerator physics progress includes: A mature lattice design that meets the performance requirements of NSLS-II Incorporation of advanced IDs into lattice Careful monitoring of magnetic field quality Development of orbit feedback and bunch-to-bunch feedback systems Development of diagnostic beamlines Study of collective effects—no show-stoppers. HLA programs---using Python Top-Off Safety and LCM Systems

22. Backup Slides

23. Technical Requirements & Specifications

24. Lattice Functions for One Cell