accelerator physics
DESCRIPTION
Accelerator Physics. Samuel Krinsky NSLS-II Accelerator Physics Group Leader NSLS-II Accelerator Systems Advisory Committee February 1-2, 2012. Outline. Accelerator Physics Group Progress Conclusions. Accelerator Physics Group. G. Bassi, J. Bengtsson, A. Blednykh, W. Cheng, J. Choi, - PowerPoint PPT PresentationTRANSCRIPT
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Accelerator Physics
Samuel KrinskyNSLS-II Accelerator Physics Group Leader
NSLS-II Accelerator Systems Advisory Committee February 1-2, 2012
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Outline
• Accelerator Physics Group
• Progress
• Conclusions
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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
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Interface with Engineering Groups
Magnet Design: J. Bengtsson, W. Guo, Y. Li, Diagnostics: A. Blednykh, W. Cheng, P. Ilinski, I. Pinayev, S. SeletskiyControls: J. Choi, Y. Hidaka, L. Yang, L.H. Yu, Insertion Device: J. Bengtsson, O. Chubar (ESD), W. Guo, Safety: S. Kramer, Y. LiVacuum: A. Blednykh, IlinskiRF: A. Blednykh, G. Bassi
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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
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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
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Physics input to the magnet production-1
• Trend study of the field quality, and make suggestions on shimming.• Monitor the field quality of all the magnets before approving the shipment.
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.
10-pole
14-pole
IHEP tune the harmonics by replacing the ironpins with stainless steel pins. The magnetsfrom production have a large b5 (4-8 units), afterpinning, b7 grows to ~ 2 units. We suggest themretract the two movable center poles by 20-40 μm.
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Physics input to the magnet production-2• Identified the design defects in the skew quadrupole coils, and proposed a solution.
• Analyze the dipole field mapping data, and determine the nose piece parameters.
+
+
--
--
x
y
0 .3 0 .2 0 .1 0 .1 0 .2 0 .3
0 .03
0 .02
0 .01
0 .01
0 .02
0 .3 0 .2 0.1 0 .1 0.2 0.3
0.02
0.04
0.06
0.08
z
z
A4=1000 units, equivalent to ~15 units in a normal quad. We use a four-current model, and calculatedthe a4 component from the present dimension (center plot). If the dimension is symmetrized, the integratedstrength becomes negligible. The conclusion is verified by a more advanced tool.
A4 A4
Name Nose θ /100(mr)
L(m)
∫b1*102 Left
∫b2 *104
Left
35mm SN01
no 9.7996 2.44227 1.90 6.7
35mmSN01
#2 nose 1.0367 2.60567 1.8 6.15
90mmSN01
no 1.0409 2.62573 1.9 1.69
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.
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Compensating APPLE-II (EPU49) Dynamic Focusing Effects
by Current StripsAPPLE-II RADIA Model with Strips Idea: I. Blomqvist
Implementation at BESSY: J. Bahrdt
Verti
cal (
Equi
vale
nt)
Fie
ld In
tegr
al [G
.cm
]
Horizontal Position [mm]
Curre
nt [A
]
Horizontal Position [mm]
in Linear Vertical Polarization Mode
Equivalent Vertical Field Integrals from Dynamic Focusing and from the Current Strips
Compensating Currents in Lower Strips
Electron Trajectory in 3D Magnetic FieldWithout and With Correction
Horizontal Trajectory
Longitudinal Position [mm]
x0=0, y0=0 before Undulator
Vertical Trajectory
Horiz
. Pos
ition
[μm
]Ve
rtica
l Pos
ition
[μm
]
Horizontal Trajectoryx0= -4 mm, y0=0 before Undulator x0= 4 mm, y0=0 before Undulator
Longitudinal Position [mm]
Horiz
onta
l Pos
ition
[μm
]
Longitudinal Position [mm]
Horiz
onta
l Pos
ition
[μm
]
Efficient Solving for CurrentsUsing Least-Squares Linear Fit
QJI
Field Integral from Current Densities:
IQQQJ T1T )(
Current Densitiesfrom Field Integral:
Number of Strips used: 2 x 20Strip Dims: 2 mm x 0.3 mm x 2 mHorizontal Gap bw Strips: 1 mmVertical Gap bw Strips: 10.7 mmMax. Current obtained: ~ 2.3 AAPPLE-II Vertical Gap: 11.5 mm
)()( xx lowerupper JJ
Since the Dynamic Effectsare Anti-Symmetric vs X:
Matrix calculated using RADIA
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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.
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HLA Progress 1
1. Lattice (Magnet) mapping to channel access is done by Channel Finder Service (developed in Controls group)
2. 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)
3. 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)
4. 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)
5. Graphical User Interface(GUI) applications are in progress. Orbit display GUI is done. Beam Based Alignment (BBA) script version is done.
6. Linear Optics Modeling (LOCO) is in progress. (J. Choi)7. Misc: Data storage (Input/Output) related routines and unit conversion are in
progress.
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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.
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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
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Demonstrated Loss Control in Xray Ring-1Xray Ring has 5mm Cu scraper near dispersion maximum in SP=3
0.91m CBLM in dipole end
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Demonstrated Loss Control in Xray Ring-2
-40 -35 -30 -25 -20 -150
1000
2000
3000
4000
5000
6000
X15 Scan proCBLM Hi Gain
Lifetimex100CBLM*20 (mV)b2bm2 (raw)b1bm2 (raw)b1bm1 (raw)
X15 Inner Scraper Position [mm]
Life
time
hr*1
00],C
BLM
[mv*
20],B
LMs
BLM monitors decrease and CBLM increase showing change in beam loss locations by the scraper scan on the momentum apertureBeam loss at CBLM after scraper, charge loss rate used to calibrate CBLM
As the scraper reduces momentum aperture:
__ CBLM show increaseEven before the
__ LIFTIME starts decrease__ b2bm2 BLM1 decrease__ b1bm1 BLM2 decrease__ b1bm1 BLM1 decrease
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Transverse BxB Feedback
16
• 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
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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
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500MHz PETRA-III 7-Cell Structure
500MHz PETRA-III 7-cell structure
• Normal Conducting Structure w/o HOM’s - Dampers
0.860 14.7 55700
0.867 17.5 56800
0.869 56.1 58200
0.871 19.7 59400
1.043 83.6 40400
1.046 26.2 40900
1.089 17 49400
1.465 15.5 54600
1.545 26.8 44300
• Transverse Higher Order Modes
• Longitudinal Higher Order Modes
0.722 1.1 32200
0.728 3 33600
0.733 0.7 35000
0.738 0.5 35500
0.739 0.5 36000• Mode frequencies provided by R. Wanzenberg
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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
Self consistent simulations of head-tail effect + coupled-bunch interaction with the OASIS code
Fastest growing mode μ=74 Slow head-tail effect: damping at ξ=2
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)
Working Points (ξ,ΔΩ)
).(Re)/(4
)Im(100
0
px
b pMZeE
McI
vs. at
ΔΩ ,𝑘𝐻𝑧
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Summary Results of Calculated Impedance (s=3mm) Number of occur. V/pC
(ImZ||/n) V/pC/m V/pC/m
Photon Absorbers
Multipole Stick ABS (20mm) 2 2.8x10-2 1.2x10-4 TBD TBD
Multipole Stick ABS. (22mm) 28 0.2 0.7x10-3 TBD TBD
Multipole Stick ABS (25mm) 96 0.2 7.7x10-4 TBD TBD
Dipole Crotch ABS (21mm) 60 0.2 0.9x10-3 TBD TBD
Flange ABS (64mmx21mm) 100 2.1 TBD 143 269
Bellows Regular Bellows (r=12.5mm) 200 4.4 1.2x10-2 TBD TBD
RF Bellows (r=120mm) 1 TBD TBD TBD TBD
Diagnostic Regular BPM (7mm, r=12.5mm) 180 1.62 4.1x10-3 90 90
ID BPM (4.8mm, r=5.75mm) 60 0.53 1.8x10-3 TBD TBD
Stripline Kicker (4e60, 15cm) 2 1 0.04 42 42
Vertical Kicker (2e90, 30cm) 1 0.4 0.04 22 23
Horiz. Kicker (2e90, 30cm) 1 TBD TBD 23 22
RF Cavity transitions/straight 2 7 28x10-3 50.8 114
500 MHz CESR-B cavity 4 1.24 ------- 0.68 0.68
1500 MHz CESR-B cavity 4 2.08 ------- 10.4 10.4
Scrapers Scraper (Horizontal) 3 0.44 2.8x10-3 44 4
Scraper (Vertical) 2 TBD TBD TBD TBD
Vat Valves Elliptical Vat Valve 60 0.54 TBD TBD TBD
RF1 Vat Valve (r=120mm) 2 0.08 TBD TBD TBD
RF2 Vat Valve (r=61.4mm) 1 TBD TBD TBD TBD
Number of occur. V/pC
(ImZ||/n) V/pC/m V/pC/m
Resistive wall 578.9m Al (VC, r=12.5mm) 1 6.3 --- 292 584
10m Al (Far-IR, r=23mm) 1 0.06 --- 0.8 1.6
45m Cu (IVU, r=2.5mm) 1 1.9 --- 2082 4164
43m StSt (S4, r=12.5mm) 1 2.1 --- 21.7 43.4
3.8m Inc (S4, r=12.5mm) 1 0.3 --- 12 24
56m Al (DW, r=5mm) 1 1.6 --- 442 884
15.6m Cu (Blw, r=14mm) 1 0.1 --- 4.1 8.2
14m StSt (Blw, r=13mm) 1 0.7 --- 30 60
15.5m StSt (3PW, r=12.5mm) 1 0.9 --- 43.5 87
10.2m Inc (Corr., r=12.5mm) 1 0.7 --- 32.5 65
loss x y loss x y
Vacuum Chambers
DW Chamber 8 0.16 TBD 128 456
Dipole Chamber 60 2x10-3 4.2x10-6 0.27 0
Multipole Chamber 90 4.5x10-4 9x10-7 0.06 0
Mid-IR Chamber TBD TBD TBD TBD TBD
Far-IR Chamber 4 0.34 2.8x10-3 20.4 TBD
Septum Chamber 1 6x10-3 TBD TBD TBD
S4 Stainless Steel Cham. 30 TBD TBD TBD TBD
IVU geom. (5mm gap) 15 0.46 TBD 1020 4350
EPU Chamber (10mm) 1 0.02 TBD 16 57
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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
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Backup Slides
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Technical Requirements & SpecificationsEnergy 3.0 GeVCircumference 792 mNumber of Periods 30 DBALength Long Straights 6.6 & 9.3mEmittance (h,v) <1nm, 0.008nmMomentum Compaction .00037Dipole Bend Radius 25mEnergy Loss per Turn <2MeV
Energy Spread 0.094%RF Frequency 500 MHzHarmonic Number 1320RF Bucket Height >2.5%RMS Bunch Length 15ps-30psAverage Current 500maCurrent per Bunch 0.5maCharge per Bunch 1.2nCTouschek Lifetime >3hrs
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Lattice Functions for One Cell