Advanced Photon Source Upgrade Project: Injection design and … · 2018. 11. 21. · Advanced...

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


Outline

Introduction Specifications Simulation study* Beam testing results Other pulser technology Summary

* Simulation study used ANL/LCRC blues cluster


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


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)


Layout of the on-axis injection section

Injection kickers (4)

Injected beam trajectory

Septum

Q2 Q1

Horizontal Plane

Vertical Plane


Q1 cross section (Courtesy A. Donnelly)

95 mm

Gap: ±8 mmBSC: ±6.5mm

Tilting of Septum magnetInjected beam chamber


Specification – Septum

Septum (1T, 1.78 m)

BTS dipole

BM1 Q2 Q1


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


Blade voltage – Septum strengthBlade length

M1 (positive slope): clearance at kicker

M2 (negative slope): clearance at Septum

Optimal point(same clearance)

Scan parameters


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


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


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)


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



Uniformly distributed bunch with weight from Gaussian distribution Tracking for 1000 turns

HSCU (6x6 mm) HGSCU (6x6 mm)

COLCOL


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


Measured FID* pulser waveform * FID Gmbh, www.fidtechnology.com

Flattop: main kick and width

Waveform tail: residual kick

After pulses: residual kick


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


Other pulser technology?

Sydro (Kentech) Technologies Inc. proposed pulser w/pseudo-Gaussian waveform*

*Waveform courtesy Sydro Tech.

V0MaxV0Spread

V1Max


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


Distribution of maximum kick strength to injected beam


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


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


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


Required nominal kick strength

Measured maximum kick strength of FID pulser


Measured flattop width of FID pulser


Measured tail strength of FID pulser


Residual kick tolerance

Measured after pulse kick strength


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

Advanced Photon Source Upgrade Project: Injection design and … · 2018. 11. 21. · Advanced...

Documents

Transcript of Advanced Photon Source Upgrade Project: Injection design and … · 2018. 11. 21. · Advanced...