The Last Year of SLS Operation and Progress towards SLS 2.0

Felix Armborst on behalf of the SLS & SLS 2.0 Teams

31^st European Synchrotron Light Sources Workshop at DESY, Hamburg, November 21^th - 22^th, 2023

WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN

Outline

1. SLS
1. Operation Statistics
2. Outage Highlights 2023
3. Final Machine Development Week
4. Final Shutdown
2. SLS 2.0
• Milestones
• SLS Disassembly
• SLS Super-3HC Incident from 2022
• New Components Preparation
• Magnet Measurements
• First Arc String Assembly
• Arc String Installation in Magnets
• ARS10 Activation

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 2

courtesy of

Andreas Lüdeke,

Lukas Stingelin,

Christian Geiselhart,

Jonas Kallestrup

courtesy of

Romain Ganter,

Stephane Sanfilippo,

Lukas Stingelin

​

SLS - Operation Statistics 2023

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 3

SLS - Operation Statistics 2023

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 4

The year 2023 was … the worst in the entire SLS history (greytime)!

• Beam availability of 92.3 %.
• MTBF was still 92 hours.

SLS - Operation Statistics 2023

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 5

Many outages due to system upgrades, partly related to the SLS 2.0 project

• Upgrades require in-situ testing (BPM electronics, …)
• Reduced maintenance due to experts working on new systems

​

• Water-to-vacuum leak caused 73 % of downtime: more than a week!
• Feedbacks: BPMs, FPFB/Timing

​

SLS - Outage Highlights 2023

Overview

• 03.02. Flooding of diagnostic beamline (4 h)
• 18.02. Water leak at LINAC quadrupole (17 h)
• 04.04. Water leaks at booster RF-cavity (2 h)
• 13.05. Water to UHV leak in absorber (> 1 week)
• 15.07. Issue with Super-3HC Cryoplant (17 h):
• Some others:
• Defective water-leak sensor
• Issue with Circulator Temperature Compensation Unit (drifting reflected power)
• Broken charging-unit in LINAC → broke power contactor and tripped fuse.

​

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 6

SLS - Outage Highlights 2023

Flooding of the diagnostic beamline

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 7

February, 1st: The Front End X09DA was isolated from ring due to bad vacuum

• Two days later 100 l cooling water were missing
• Investigations showed that the front end had been flooded
• End of life for the diagnostic beamline (no repair before SLS2)
• No beam size measurement for user operation
• Shared beamline available only for MD�with FZP beam size measurement

SLS - Outage Highlights 2023

Water leak at LINAC quadrupole

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 8

Incident in 2023

• Pressure drop in water cooling for ring RF initialized investigations
• 300 l cooling water lost
• 17 hours of downtime

​

Possibly a general maintenance issue for SLS

• 10 QT-type quadrupoles, manufactured in 1991, installed in LINAC
• Obtained from the Dutch National Institute for Subatomic Physics, Nikhef.
• Previously installed in the Amsterdam Pulse Stretcher (AmPS) ring.
• In recent years, several of these quadrupoles have had water leaks.

SLS - Outage Highlights 2023

Water leak at booster RF-cavity

​

​

• Investigations initiated after “Tunnel Leak” Interlock at SSA
• Tunnel access showed water puddle under booster cavity
• Temporary “fix” 1: bridged leak sensor and bucket enabled operation until next day
• Temporary “fix” 2: closing water valve of the affected circuit enabled operation until following shutdown
• 40 l cooling water lost

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 9

SLS - Outage Highlights 2023

Water to UHV leak in SLS Absorber

• May 13th 2023: �> 20 mbar in whole Arc12 !
• Leak due to corrosion from water with X rays
• 10 days to recover UHV !

​

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 10

Leaking Absorber

Only 3 mm of copper

SLS - Outage Highlights 2023

Water to UHV leak in SLS Absorber

• May 13th 2023: �> 20 mbar in whole Arc12 !
• Leak due to corrosion from water with X rays
• 10 days to recover UHV !

​

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 11

Leaks

May 13th

Pressure (mbar)

• Drying period
• N2 rinsing
• Crotch exchange

Leak source found: May 17th

Turbo pumping

6 bar He stress test

Ion pumping

Ti sublimation

May 24th: 2E-9 mbar without beam

Leaking Absorber

SLS - Outage Highlights 2023

Water to UHV leak in SLS Absorber

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 12

24 h

Vacuum conditioning with beam:

< 20 Ah to get 10 hours lifetime!

SLS - Outage Highlights 2023

Issue with Super-3HC Cryoplant

• Incident detection due to Helium loss at broken connections from vibrations
• Bearing damage on the compressor screws of the compressor
• Such strong vibrations that approaching the plant was impossible without hearing protection due to noise levels way above pain threshold
• Compressor screws beyond repair after just 61000 h of operation
• Screws were grinding into each other and scraping the housing
• Metal abrasion in oil
• Motor power went up from 100 kW to maximum of 131 kW during incident
• Reduced cooling power due to impurities in Helium

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 13

SLS - Final Machine Development Week (5 days)

• BD Collaboration with BESSY / HZB on Coupling
• Tests of SLS 2.0 MBFB and FPFB
• Tests of New SLS 2.0 FOFB
• Machine Learning for SLS 2.0: Train Model
• Investigation of the Super-3HC failure and impedance of the vacuum-components
• Robinson stability measurements at lower current
• SLS 2.0 Injection Chain Setup for 2.7 GeV
• 50 mA Storage Ring Kicker Matching
• Software Development for BPM TbT Data
• Tests on influence of ELM brake for servo motor on stored beam with/without FOFB
• Tests of the booster inj/ext with the upgraded timing system and fine delay feature
• Tests of the timing master software with beam
• Machine Learning for SLS 2.0: Test Model
• Optimizing the Beam Size to Lifetime Ratio
• Beam Size Minimization Measurements
• Software Development for Emittance Measurement
• Tests of Spare PCT Hardware
• Ceremonial Beam Dump

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 14

SLS - Final Shutdown / Beginning of the Darktime

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SLS 2.0 - Milestones

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 16

3

Funding Secured

01.01.2021

5

Dark Time

30.09.2023

6

Close Tunnel

16.12.2024

7

Nominal Beam

01.05.2025

8

First User Operation

01.08.2025

22.11.2023

1

Lattice Defined

30.06.2020

2

Beamline Geometry Defined

30.09.2020

4

Dark Time Ready

17.10.2022

9

Shutdown Phase 2

21.12.2025

10

User Operation

01.06.2026

22 months without user operation

SLS 2.0 - SLS Disassembly�Weekend after SLS has been switched OFF→ Start of Dismantling

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 17

Dismantling is going according to plan

1st half of October

• Removal of tunnel roof bars
• Removal of cable trays and cooling distribution along Ring

2nd half of October

• Removal of to be reused components: Super-3HC, Kickers, Undulators, …
• Removal of RF modulator & Klystron and most electrical cabinets

November

• Removal of girders�with magnets

​

SLS 2.0 - SLS Disassembly

Arc Section 09

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 18

03.10.2023

02.11.2023

SLS 2.0 - SLS Dismantling

Post Mortem Pictures from SLS Components

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 19

Bellow in front of the Super-3HC

• Molten, welded and bent RF finger

Absorber in front of the Super-3HC

• Scorch marks on vacuum chamber and absorber-block
• Needs closer inspection.

SLS 2.0 - SLS Super-3HC Incident from 2022

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 20

Orbit problems, current drops

Vacuum increase, voltage asymmetry starts

Operator tries to increase voltages

Beam-loss (CBI)

Vacuum-controller did not interlock the beam!

Orbit off by several mm!

• MD shift with experimental orbit bumps
• BPM system failure → large orbit excursion
• 1E-5 mbar vacuum at absorbers before and after Super-3HC
• Asymmetry in detuning is permanent
• Always observed during accumulation with drifts over 10s of minutes until new equilibrium reached

SLS / SLS 2.0 - Super-3HC Incident from 2022

Investigation of Observed Detuning

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 21

After the incident: detuning of the Super-3HC changed by -5.5 kHz (cav 1) and -10 kHz (cav 2) for the same voltage with

no obvious change in LHe consumption.

​

Could quality factor degradation explain the observed detuning?

• Only for values around 2E4 with 100 kW loss, whereas the cooling can only sustain 50 W → No!

SLS / SLS 2.0 - Super-3HC Incident from 2022

Reconstruction of distorted orbit and Synrad Calculation

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 22

Reconstructed orbit during the first incident:

• Bending magnet is around s=137 m
• Super-3HC starts at s=141 m with flange-to-flange length: 1.1 m

​

Synrad

Increased power at tapers before and after the cavity for reconstructed orbit�

Orbit data: M. Boege, Synrad template: L. Schulz, Locations: N.Kirchgeorg

Heating during incident due to what ?

• Wakefield at valve/bellow
• Synchrotron-radiation

RF Fingers

Absorber

SLS / SLS 2.0 - Super-3HC Incident from 2022

Investigations: Measurement of Flange Temperature and Movement

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 23

View from outer wall, beam indicated by blue arrow

Temperature change 0 …400mA:

ΔT₁=+4.3°C ΔT₂=+3.2°C�ΔT₃=+0.4°C ΔT₄=+0.3°C

View from inner wall

Longitudinal position of the flange changes with same time-constant as the voltage-drift �(after accumulation 0…400mA)

​

Driving offset-bumps with up to 0.5mm horizontally and 1.6mm vertically did not show any significant effect. → Damage likely caused by synchrotron radiation and not wakefields.

Installation by D. Kunz

SLS 2.0 - New Components Preparation

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 24

• Girders and racks are assembled in large external storage and assembly hall
• 1100 Power supplies – 10 A ready at PSI

• One 500 MHz HOM-Damped RF Cavity conditioned to 600 kV
• Two more cavities passed the FAT
• Delays with Solid State Amplifiers

BPM Electronic tested including FOFB test in last shifts of SLS

30 nm RMS position noise* reached

(~1% of minimum beam size) !

SLS 2.0 - Magnets Measurements

• 7 benches to measure 950 magnets
• 3 months delays with Permanent Magnets measurements: critical path of project !

• Quadrupole Series: 112 /112 ready
• Steerers: 117 / 117 ready
• Sextupoles: 59 / 270 ready
• Octupoles: 16 / 268 ready

​

• Triplet Bending magnet: 1 / 60 ready

BN 22/60 ready

VB 2/120 ready (rotating coil bench not ready)

• Reverse Bends: 0 / 150 ready

Yokes to be delivered in october

​

Rotating coils benches

Vibrating wires benches

Hall Probe bench

Moving wire benches

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 25

SLS 2.0 - First Arc String Assembly

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 26

18 m long arc assembly

Successful transport of arc

Arc transport & storage frame

(fits baking oven)

Status November 2023:

• 3 Arc vacuum string assembled and activated => pressure around 1E-11 mbar

​

SLS 2.0 - Arc String Installation in Magnets

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 27

• Vacuum arc fits in the magnets apertures !
• Installation Procedure is validated !
• … minor corrections of cooling pipes.

Sept. 12^th , 2023

SLS 2.0 - ARS10 Activation

31st ESLS@DESY | Status SLS & SLS 2.0 | 21.11.2023 Page 28

Bake out 130 deg

> 48 h

IP flashing

NEG cartridges

activation

NEG activation

200 deg

> 24 h

IP ON

Valves closed (13H)

& Arc Gauges ON (16H)

2.e-11 mbar

4.e-11 mbar

3.e-10 mbar

18/08/2023

25/08/2023

Arc Gauges:

Swiss Light Source

Thank you for your attention

And thanks to the many colleagues

who provided slides and input

for this presentation