orbit stabilization at the advanced photon source · horizontal: 5.0 microns / 1.0 microradians p-p...
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Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Orbit Stabilization at the AdvancedPhoton Source
Glenn DeckerDOE-BES Review
May 24, 2005
DOE-BES ReviewGlenn DeckerMay 24, 2005
er Distortion”)
tion upgrade
Argonne National Laboratory
Beam Stability Outline
• New beam stability specification
• Orbit control system overview
• DC Beam stability status and plans- Completion of girder displacement project (“deck- “Gold standard” hard x-ray bpm project
• AC Beam stability status and plans- Monopulse rf beam position monitor data acquisi
DOE-BES ReviewGlenn DeckerMay 24, 2005
cation
s rmsns rms
nce / low coupling lattice
dians rms <----dians rms
f the source point in the
citly stated in the past.)
cification, PAC ‘95§
Argonne National Laboratory
APS AC Beam Stability Specifi
Original Stability SpecificationEquivalent to 5% of Particle Beam Dimensions*:
Vertical: 4.4 microns / 0.45 microradianHorizontal: 16 microns / 1.2 microradia
Translating this 5% requirement to the present low-emittaresults in**:
Vertical: 0.42 microns / 0.22*** microraHorizontal: 3.0 microns / 0.53 microra
This specification gives the allowable rms beam motion ofrequency band 0.016 to 200 Hz.
(Note: The frequency band has typically never been expli
* Y.C. Chae, G. Decker, “APS Insertion Device Field Quality and Multipole Error Spe
** http://www.aps.anl.gov/asd/oag/SRSourceParameters/sourcePointResults/*** Includes photon angular divergence contribution, 7th harmonic, APS Undulator A
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Data from Monochromatic X-ray BPM, 13ID
DOE-BES ReviewGlenn DeckerMay 24, 2005
cationith period ranging from
adians p-p <----adians p-p
ory reproducibility speci-
--------------------------------ser at the 2004 user’s
Argonne National Laboratory
APS DC Beam Stability SpecifiThe allowable amount of peak-to-peak source point drift w1 minute to 1 week (168 hours) is
Vertical: 1.0 microns / 0.50 microrHorizontal: 5.0 microns / 1.0 micror
This is also to be interpretted as the week-to-week trajectfication, e.g. following a machine studies period.----------------------------------------------------------------------------Compare this with dc stability “goals” stated by an APS umeeting:• Short term:
angular: vertical 1 µrad, horizontal 2 µrad,position: 5 µmover duration of run;
• Mid-term:angular: vertical 0.3 µrad, horizontal 1 µradposition: 3 µmover 1 year
DOE-BES ReviewGlenn DeckerMay 24, 2005
C C
2 X2
X1
e-ID
C
x x
in One Sector
16m
20m
x
) (Turn-by-Turn)4) (~ 300 Hz)ical Only) (~165 Hz)Hz)
Argonne National Laboratory
C C CCBMBM
X
X1
FC
Beam Position Monitors and Magnets
11m
18m
x
Q
x : Broad-band RF Beam Position Monitors (7 : Narrow-band RF Beam Position Monitors (
: BM X-ray Beam Position Monitors (2 - Vert : ID X-ray Beam Position Monitors (2) (~165 FC : “Fast” Corrector Magnet (1) (~ 1000 Hz)C : “Slow” Corrector Magnets (7) (few Hz)Q : Quadrupole Magnets
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
DC Beam Stability
• All sectors have now been realigned to reduce id x-bpm stray radiation back-ground, completing a 7-year effort.
• Photon bpm’s are used in DC feedback at all 19 bending magnet beamlines,and 17 out of 29 insertion device beamlines.
• Every insertion device straight section has 4 channels of narrowband rf bpmelectronics. Two have very high resolution using pickup electrodes mounted onsmall aperture ID vacuum chamber, the other pair are used for the missteeringinterlock.
DOE-BES ReviewGlenn DeckerMay 24, 2005
ID photons
from down- quadrupoles,d correctors
er Alignment*
Argonne National Laboratory
77 mrad
1 mrad
Stray radiation from upstreamdipole, quadrupoles, sextupolesand correctors
Stray radiationstream dipole,sextupoles an
Re-direction of Stray Photons by Gird
Phys. Rev. ST Accel. Beams 2, 112801 (1999)*
DOE-BES ReviewGlenn DeckerMay 24, 2005
Argonne National Laboratory
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
µrad
One-Week Angular Drift, ID Source Point*
Local Steering
* angles calculated from vertical ID xbpm readbacks, fixed gap.
500 nradSpecification
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Correction of Residual ID Photon BPM Gap-dependent Systematic Errors
ID 20 Gap (mm) ID 20 Gap (mm)
ID 20 Gap (mm) ID 20 Gap (mm)
Background Subtraction Only Background + Exponent Corrections
∆x / Σ(Absolute)
∆x / Σ(Relative)
100 microns
approx. 40 microns
∆x / Σ(Absolute)
∆x / Σ(Relative)
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Insertion Device Field Integrals vs. Gap(Rotating Coil Data)
500 nrad
DOE-BES ReviewGlenn DeckerMay 24, 2005
Pointing Stability
rs
non-colinearity
used to generate lookup
tion, causing significant
problems, e.g. electron
particle beam is indeter-
ary to solve this problemesign to be tested at
to follow in 2006.
Argonne National Laboratory
Summary of Factors Limiting Long-term
• Tunnel temperature +/- 0.1 degrees C is mandatory.
• ID photon bpm residual gap-dependent systematic erro
- Internal trajectory errors cause particle / x-ray beam
- RF bpm’s (measuring particle beam trajectory) aretables for ID photon bpm offset vs. gap
- Photon bpm’s are sensitive to bending magnet radiabackground signal, important at large ID gap.
- Sensitivity to ultraviolet radiation halo causes othercloud effects.
• The direction of the x-ray beam centroid relative to the minate at the few-µrad level using present technology.
- A diagnostic sensitive only to hard x-rays is necess- Funding has been approved to move forward on a d19ID in CY05, with a refined first production article
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Beam-definingAperture
Water-cooledMoveable Scrapers
Shielded X-ray Detectors (4),Beryllium Filter
(Target: Cu or W)
X-rayFluorescence
Plan View of Hard X-ray Beam Position Monitor Concept
White ID X-ray Beam
InsertableFilter Array(C)(Fixed)
Above and Below Plane of Beam
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
AC Beam Stability
• The real time feedback system has been in operation since 1997.
• Makes use primarily of original monopulse rf bpm electronics.
• Provides powerful diagnostic of ac beam motion - 1.5 kHz sample rate, withaccess to virtually all beam position monitors and corrector magnet power sup-plies.
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
0.01 - 767 Hz
0.01 - 100 Hz
0.01 - 30 Hz
Horizontal RMS Motion Vertical RMS Motion
µmrms
µmrms
βx = 22 m βy = 6.9 m
~4 days
Long Term Stability of AC Beam Motion
Top-up operation, 24 singlet fill pattern
0.4 µmSpec.
3 µm H. Spec.
APS Real-time feedback system allows simultaneous acquisition of 40 waveforms
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Power Spectral Density Sqrt[Integ[PSD]] Sqrt[ReverseInteg[PSD]]
µrad2/Hz
µrad2/Hz
Horz.
Vert.
µradrms
µradrms
µradrms
µradrms
with Feedback
Frequency (Hz)
AC Pointing Stability
without Feedback
Frequency (Hz)
Frequency (Hz) Frequency (Hz)Frequency (Hz)
Frequency (Hz)
DOE-BES ReviewGlenn DeckerMay 24, 2005
s
rocessing technologies.5 kHz), a larger
tion of BH4 corrector toctor of two according to
re ongoing.
e narrowband and pho-precludes their effectiveed (CY05). ID photonn a user opens his gap).
l processing is archaic.enhance functionalityoise. Strategy is tokaged separately from
Argonne National Laboratory
AC Beam Stability Plan
• A lot of relatively inexpensive fast network and signal pare available. This could allow a faster update rate (> 1response matrix, or some optimal combination.
• The addition of a second fast feedback corrector (relocaG3 spool piece) could improve noise rejection up to a fasome older simulation results. Further investigations a
• An over-aggressive design in the analog front end of thton beam position monitors (6-pole anti-aliasing filters)use in realtime feedback. These filters are being modifibpm gap dependence still an issue (e.g. what to do whe
• The monopulse rf bpm data acquisition and digital signaFunding has been approved to upgrade one sector, to (e.g. fast beam history feature), and reduce electronic nretain existing monopulse receiver front ends, to be pacthe new data acquisition (VXI format).
DOE-BES ReviewGlenn DeckerMay 24, 2005
ary
/ week demonstrated,together with ID photon
d to overcome residualrad p-p / week goal.
rade options are underunds.
. Tunnel temperature iser the dominant source, e.g. low-level mechani-
Argonne National Laboratory
APS Beam Stability - Summ
• DC beam stability is world-class, with sub-microradian and not unusual. High-resolution narrowband rf bpm’s,bpm’s have been critical in this effort.
• New technology (“gold standard hard x-bpm”) is needegap-dependent systematic errors, to achieve true 500 n
• AC beam stabilization hardware is showing its age, upginvestigation, with some efforts proceeding with ARIM f
• Passive source identification and mitigation will continuebecoming a limiting factor. Power supplies are no longof ac noise. Search for other mechanisms will continuecal vibration.
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Backup Viewgraphs
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Air Temp (deg. F)
8ID V. Angle (µrad)
8ID H. Angle (µrad)
Local Tunnel Air Temperature Impacts Pointing Stability
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Variation of Particle Trajectory Through Insertion Device vs Gap
(Derived from Second Field Integral of Magnetic Measurement Data)
X (
mic
rons
)X
(m
icro
ns)
X (
mic
rons
)X
(m
icro
ns)
Argonne National Laboratory DOE-BES ReviewGlenn DeckerMay 24, 2005
Power Spectral Density Sqrt[Integ[PSD]] Sqrt[ReverseInteg[PSD]]
µm2/Hz
µm2/Hz
Horz.
Vert.
µmrms
µmrms
µmrms
µmrms
APS
APS,SPring-8*
Frequency (Hz)
Normalized toβx = 20 meters
Normalized toβy = 5 meters
AC Beam Stability
(No Feedback)
Frequency (Hz)
Frequency (Hz) Frequency (Hz)Frequency (Hz)
Frequency (Hz)
*Spring-8 DataCourtesy H. Tanaka