advanced photon source upgrade project: injection design and … · 2018. 11. 21. · advanced...
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Advanced Photon Source Upgrade Project:The World’s Leading Hard X-ray Light SourceInjection design and
beam test results for the APS-MBA upgrade
Aimin XiaoAccelerator physicistArgonne National Laboratory
For the Fast Injection Kickers Task Group
Topical Workshop on Injection and Injection Systems28th - 30th August 2017, BESSY, Germany
2A. Xiao, TWIIS, August 2017, BESSY, Germany
Group members*
J. Carwardine – group leaderF. Lenkszus (retired) – previous group leaderPhysics Team –
M. Borland, C-Y. Yao (retired), A. Xiao
Engineering Team – A. Barcikowski, A. Brill, T. Clute, A. Cours, Z. Conway, R. Keane,L. Morrison, X. Sun, J. Wang, F. Westferro, M. Abliz
Oversees by managementG. Decker (associate project manager- accelerator), J. CarwardineH. Cease, U. Wienands
* System is highly integrated with other systemsInput, comments, … from many colleagues outside the group
3A. Xiao, TWIIS, August 2017, BESSY, Germany
Outline
Introduction Specifications Simulation study* Beam testing results Other pulser technology Summary
* Simulation study used ANL/LCRC blues cluster
4A. Xiao, TWIIS, August 2017, BESSY, Germany
Reasons to choose on-axis swap-out vertical injection
APSU is a 42-pm1 low emittance storage ring (M. Borland and Y. Sun)– Strong nonlinear effects – limited machine acceptance– Use current APS injector system
• Large injected beam emittance• Delivers one bunch per cycle
→ On-axis injection only, the weakest stored bunch is swapped out
Minimum required beam separation (D) at septumD = R(stored chamber) + 2mm(Septum sheet) + 3σ(inj) + MarginD(H) = 4 mm (R) + 2 mm + 2.15 mm (3σ) + MarginD(V) = 3 mm (R) + 2 mm + 0.66 mm (3σ) + Margin ← less kick strength
→ Vertical injection
5A. Xiao, TWIIS, August 2017, BESSY, Germany
Extraction/Injection region layout
Stripline Kicker
Magnets
S38 S40
…
S39
LambertsonA:M1 Beam Dump
Stored Beam
Injected BeamExtracted Beam
Side View
HHC
High stored bunch power density would damage swap-out dump:pre-kicker required to inflate the projected beam size (see J. Dooling's talk)
6A. Xiao, TWIIS, August 2017, BESSY, Germany
Layout of the on-axis injection section
Injection kickers (4)
Injected beam trajectory
Septum
Q2 Q1
Horizontal Plane
Vertical Plane
7A. Xiao, TWIIS, August 2017, BESSY, Germany
Q1 cross section (Courtesy A. Donnelly)
95 mm
Gap: ±8 mmBSC: ±6.5mm
Tilting of Septum magnetInjected beam chamber
8A. Xiao, TWIIS, August 2017, BESSY, Germany
Specification – Septum
Septum (1T, 1.78 m)
BTS dipole
BM1 Q2 Q1
9A. Xiao, TWIIS, August 2017, BESSY, Germany
Optimization of stripline kickers
S
IK1
Septum
IK2 IK3 IK4
M2 M1
PA (8 cm)
5 cm 10 cm
y
Beam size: ±3σ @εy=20 nm (sketched plot)
Aperture clearence– M1: +3σ of injected beam to top blade of IK1– M2: -3σ of injected beam to bottom edge of injection beam chamber in
septum Stripline: voltage / gap / length – optimization objects
– Optimal condition: M1=M2
10A. Xiao, TWIIS, August 2017, BESSY, Germany
Blade voltage – Septum strengthBlade length
M1 (positive slope): clearance at kicker
M2 (negative slope): clearance at Septum
Optimal point(same clearance)
Scan parameters
11A. Xiao, TWIIS, August 2017, BESSY, Germany
Optimization results – balance risk/challenge between stripline kicker and septum design Blade voltage –
Septum strength
L: 0.54 m (high E field)
L: 0.72 m(Low E field)
M1,
M2
12A. Xiao, TWIIS, August 2017, BESSY, Germany
Pulser timing requirements
Flat top – provide uniform kick to injected/extracted bunch– T_top > 2L/c + 6σinj/stored + Δt
Rise/fall time – no excessive kick to neighboring stored bunch– Minimum bunch spacing 11.4 ns (324 bunch fill)– T_rise (T_fall) < 11.4 - 2L/c - 6σstored – Δt
Total waveform width– T_full < 22.8 – 2L/c – 6σstored – Δt
L = 0.72 m; σinj = σstored =100 ps; Δt (max peak to peak) = 0.5 ns
T_top > 5.9 ns; T_rise (T_fall) < 5.5 ns; T_full < 16.9 nsL
T_topT_rise T_fall
T_full
13A. Xiao, TWIIS, August 2017, BESSY, Germany
Injected beam loss simulation (1)
Include optical mismatch: BTS line Quad strength error 1% Longitudinal mismatch: energy and timing (very conservative) Trajectory error: simulation and measurement
(rms)
14A. Xiao, TWIIS, August 2017, BESSY, Germany
Injected beam loss simulation (2) 50 storage ring post-commissioning ensembles (V. Sajaev) Injected beam parameters: σδ=0.12%, σt=100 ps
– εx=60 nm, εy=16 nm
– εx=75 nm, εy=20 nm
– εx=90 nm, εy=24 nm
Uniformly distributed bunch with weight from Gaussian distribution Tracking for 1000 turns
HSCU (6x6 mm) HGSCU (6x6 mm)
COLCOL
15A. Xiao, TWIIS, August 2017, BESSY, Germany
Beam test with FID pulser1,2,3,4
1 C. Yao et al., IPAC 15,3286.2 C. Yao et al., NAPAC16, 9523 X. Sun et al., NAPAC16, 943.4 A. Xiao et al., AOP-TN-2017-027
y
Cosmotec Inc.
ANL Phy. Division
16A. Xiao, TWIIS, August 2017, BESSY, Germany
Measured FID* pulser waveform * FID Gmbh, www.fidtechnology.com
Flattop: main kick and width
Waveform tail: residual kick
After pulses: residual kick
17A. Xiao, TWIIS, August 2017, BESSY, Germany
Measurement results
Results show (backup slides)– Maximum kicker angle agrees with designed value– Flattop width satisfies requirement– Waveform tail (rise/falling time) satisfies requirement– After pulse strength (~5%) is larger than specified tolerance (3%),
investigation is underway
Adjusted FID pulser trigger delay – measure beam deflection at different part of waveform
18A. Xiao, TWIIS, August 2017, BESSY, Germany
Other pulser technology?
Sydro (Kentech) Technologies Inc. proposed pulser w/pseudo-Gaussian waveform*
*Waveform courtesy Sydro Tech.
V0MaxV0Spread
V1Max
19A. Xiao, TWIIS, August 2017, BESSY, Germany
Study of voltage (kick strength) variations
Simulations assume– Injected bunch length: ±300 ps (6σ)– Stored bunch length: ±300 ps (6σ)– Stored bunch center: -11.4 ns and +11.4 ns– Timing jitters (random): σ
t=100ps, 3-σ cut-off
– Systematic error (injected bunch center relative to waveform center): 0.0 ps and 100 ps
Measures of performance shown in histograms (following slides)– V0Max: max effective voltage to injected bunch– V0Spread: effective voltage variation over injected bunch length– V1Max: max kick to the neighboring stored bunch
20A. Xiao, TWIIS, August 2017, BESSY, Germany
Distribution of maximum kick strength to injected beam
21A. Xiao, TWIIS, August 2017, BESSY, Germany
Max spread 1.8% Didn't include amplitude variation
from pulse to pulse Total kick strength variation: ≤ 2.5%
Distribution of kick strength variation to injected beam
22A. Xiao, TWIIS, August 2017, BESSY, Germany
Distribution of maximum kick strength to stored beam
Max kick strength 0.72% Specification: ≤ 3% A slightly wider pulse waveform
(giving smaller V0Spread) may be tolerable
23A. Xiao, TWIIS, August 2017, BESSY, Germany
Summary On-axis swap-out extraction/injection will be used for APS-U Injection section optimization balances risks and challenges of
different systems (kicker, septum) Injection simulation results shows good injection performance
under specified error tolerances Beam test was performed using
– A prototype stripline kicker module including feed-through– Two FID pulsers: 20kV-pulser up to 15 kV; 30 kV-pulser up to 30 kV– Measured kicker strength agrees with designed value– Measured flattop width, tails are satisfied– Measured after pulse strength higher than tolerance specifications
• Investigation is underway
A pseudo-Gaussian waveform pulser was studied– Simulation results show kick strength variations are under error
tolerance specification– Looking forward beam testing with such a pulser
Backup Slides
26A. Xiao, TWIIS, August 2017, BESSY, Germany
Required nominal kick strength
Measured maximum kick strength of FID pulser
27A. Xiao, TWIIS, August 2017, BESSY, Germany
Measured flattop width of FID pulser
28A. Xiao, TWIIS, August 2017, BESSY, Germany
Measured tail strength of FID pulser
29A. Xiao, TWIIS, August 2017, BESSY, Germany
Residual kick tolerance
Measured after pulse kick strength
30A. Xiao, TWIIS, August 2017, BESSY, Germany
Issues creating flattop
Ideally, can combine two Gaussian waveforms, one triggered at -Δt, another triggered at Δt to make a flattop
Differential mode timing errors → larger V0 variation
Conclusion: Δt=0 is preferred