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CERN DQW TESTS SUMMARYAlejandro Castilla
on behalf of
BE-RF-SRF section and the crab cavity project.
Testing team: K. Artoos, S. Barriere, I. Ben-Zvi, G. Burt, M. Coly, B. Frere-Bouniol, M. Gourragne, K. Hernandez-Chahin, A. Macpherson, J. Mitchell, N. Shipman, J. Swieszek, K. Turaj, M. Wartak1, A. Zwozniak1
7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017
1IFJ PAN, PL-31342 Krakow, Poland
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Cavity Validation Campaign
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 2
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CERN Vertical Cryostat
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 3
Photo: CERN archives
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CERN Vertical Cryostat
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 4
Photo: CERN archives
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Bare Cavity 001 History Line
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 5
1. Reception
2. HPWR
3. ISO4 Assy.
4. Bake out
5. RF Test
6. Slow Vent
7. Warm Antenna Assy.
8. Send to Workshop
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Bare Cavity DQW_SPS_001
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 6
VALIDATION:
• Characteristic multipacting
barriers seen at low gradients
• Multipacting was processed
after some conditioning
• Dynamic load at LHC nominal
transverse voltage < 5W
• Field Emission onset > 3.6MV
• Quench limit ~ 5MV
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Other Results DQW_SPS_001
Surface Resistance Surface RRR
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 7
K. Hernandez-Chahin, UGto/CERN-BE-RF-SRF
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Bare Cavity 002 History Line
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 8
Field Emission
🤦 🤦 ♂🤦
Light BCP
👨🤦 🔬
On Spec !
😎
1. Reception
2. HPWR
3. ISO4 Assy.
4. Bake out
5. RF Test
10. Slow Vent
11. Warm Antenna Assy.
12. Send to Workshop6. Etching
9. RF Test7. HPWR
8. ISO4 Assy.
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Bare Cavity DQW_SPS_002After He-Processing
No Scaling
Fowler-Nordheim
Higher Field Enhancement
in He-Atmosphere
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 9
K. Hernandez-Chahin, UGto/CERN-BE-RF-SRF
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Bare Cavity Results Summary
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 10
VALIDATION:
• Multipacting barriers at low
gradients observed and
processed in both cavities
• Dynamic load at nominal
transverse voltage ≤ 5W
• Minimum field emission
onset > 3.6MV
• Quench limit ≤ 4.8MV
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Cavity Bulk RRR Measurements
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 11
N. Shipman, Lancaster University/CERN-BE-RF-SRF
• A four wire measurement was used to determine the bulk RRR of
the CERN DQW cavities during the vertical cryostat testing
• Current and voltage leads are attached to opposite beam pipes to
maximise the voltage drop
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Cavity Bulk RRR Measurements
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 12
N. Shipman, Lancaster University/CERN-BE-RF-SRF
• DQW_SPS_001
• Made of 3 Nb sources.
• RRR given by the supplier shown in red
• In-situ cavity measurements shown in green
• DQW_SPS_002
• Made of 1 Nb source
• RRR given by the supplier shown in red
• RRR measurements of 3 samples that followed the same heat treatment as the cavity shown in orange
• In-situ cavity RRR measurements shown in green
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Cavity Bulk RRR Measurements
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 13
N. Shipman, Lancaster University/CERN-BE-RF-SRF
• Results suggest that detrimental effects of the heat treatment on the bulk RRR are less severe for the cavity than for the samples, this is under investigation
• Finite element models are being developed to investigate the effects of sample sizes on the measurement of RRR
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Partially Dressed Cavity
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 14
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Partially Dressed Cavity 001 History Line
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 15
1. He-Tank Weld
2. ISO4 Dressing
3. Transport to VTA
4. RF Test
5. Transport to CR
6. ISO4 FPC + Antenna
7. String Assy
8. Cryomodule Assy.
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HOM’s Measurements
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 16
J. Mitchell, Lancaster University/CERN-BE-RF
• Frequency and Q measurements of HOMs
• Mode deviation and spread wrt. simulations
The resistance ΔV/ΔI was plotted against temperature. And the RRR
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Bumps in The Way
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 17
Temp. Sensors:
• Top beam pipe
• FPC port
• He-tank bottom
• Side of HOMS2 can
• Bottom beam pipe
• EvaporatorLevel
Gauges
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Initial 2K Cooldown
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 18
A leak was seen after ~2h of passing the superfluid transition
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No Leak Above Superfluid Transition
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 19
A weekend at 2.5K and no RF power w/o a leak
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Super Leak Location
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 20
Suppressed leak onset with 50W on the heating collars
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CERN DQW Results Summary
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 21
Partially Dressed Cavity 001:
• Cool Down with ∆T < 30K across the cavity
• Multipacting slowly conditioned
with short pulses and low power
• No fast radiation monitoring
during test (pulsed mode)
• Test performed at 2.5K
• Performance degradation to be
corroborated in the cryomodule
tests
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HOMS Power Leakage and Heating
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 22
• Power transmitted through the
HOMS showed low leakage of
the fundamental (as expected)
• Micro-heating signals on the
HOMS cans observed
• No important heating detected
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DQW_SPS_001 PDC Transients
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 23
Case 1
Case 4Case 3
Case 2
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Crab Cavities’ LLRF Test
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 24
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Crab Cavities’ LLRF Test
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 25
P. Baudrenghien CERN-BE-RF
QL= 960000
• Efforts have been made to provide the crab LLRF team with “machine-like” conditions for testing the controls systems and sequences
• Further info in Philippe’s talk tomorrow
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Cryomodule Campaign
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 26
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DQW SPS Cryomodule 1
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 27
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M7 Horizontal Cavern
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 28
10/11/2017
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CERN-SM18 Tests Summary
Bare cavities validated to spec at 2K
Partially dressed cavity tested at 2.5K due to super leak
Leak was not on cavity => no issue with cooldown
Some performance degradation seen
Tests restricted to pulse mode with new LLRF system
Cavity loops and tuner loop tests ongoing in the vertical
cryostat with the DQW_PoP cavity
M7 Horizontal Cavern is ready to receive the
cryomodule this week for testing
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 29
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Thanks.
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 30
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RF Control Room Last Friday 17h31
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 31
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Work Flow
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 32
Differences
between 001
and 002
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Surface Preparation DQW_SPS_001
See next talk by S. Verdú Andrés
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 33L. Ferreira, CERN-TE-VSC
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Surface Preparation DQW_SPS_002
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 34L. Ferreira, CERN-TE-VSC
See next talk by S. Verdú Andrés
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Surface Preparation
DQW_SPS_001
Heat Treatment
DQW_SPS_002
Heat Treatment
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 35
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Surface Preparation - Degreasing
Immersion in ultrasonic bath with demineralised water with detergent (Name=1740, concentration = 20 grams/litre) Bath at 55 C
For 1hr
Liquid is gently circulated and filtered during the process
2nd immersion with replaced liquid and ultrasonic transducer on Beam port facing the transducer
Frequency = 25kHz
Power: ~1W/litre
Time: 30 -60 minute
The cavity then stays in the bath for 1 hr to allow for particulate to settle
Removed from the bath and spray rinsed with demineralised water
Last immersion in demineralised water, dipped three times
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 36
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HPR
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 37
Driven by input and waste water careful monitoring
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HPR – 1st Rinse
DQW_SPS_001
Total of 6 rinses
DQW_SPS_002
Total of 5 rinses
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 38
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HPR – Last Rinse
DQW_SPS_001
Total of ~66 hours
DQW_SPS_002
Total of ~65 hours
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 39
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V3 Vacuum Systems
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 40M. Wartak, CERN-BE-RF-SRF
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Cavity Bulk RRR Measurements
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 41
N. Shipman, Lancaster University/CERN-BE-RF-SRF
• A square wave current is applied, voltage and temperature readings are taken during the cavities’ cooldown and warm up
• The thermal gradient across the cavity is smaller during warm up, due to the fast cooldown to avoid hydrides’ precipitation on the RF surface.
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Other Measurements
DQW_SPS_001
Lorentz Force Detuning
DQW_SPS_002
Lorentz Force Detuning,
Non-Linear = measurement problem
A. Castilla, CERN-BE-RF-SRF 7th HL-LHC Collaboration Meeting 13th – 16th Nov 2017 42
K. Hernandez-Chahin, UGto/CERN-BE-RF-SRF
