Transcript The Octopus T-map

3 June 2012 BE-KT Innovation Day Prevessin, CERN, Switzerland
BE-KT Innovation Day
Octopus Temperature Mapping System
for Cavity Diagnostics
Kitty Liao
BE-RF-SRF
[email protected]
Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Presentation Structure
1.
2.
3.
4.
Background : Cavity diagnostics for quench
Mainstream (Existing) systems
NEW- The Octopus Temp. Mapping system
Outlook & Summary
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Temperature Mapping System
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Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Temperature mapping background
• Goal
- achieve high accelerating gradient 704 MHz
cavities for the SPL @ CERN (244 x 5-cell β
=0.6 & β =1 cavities)
- quality control
• Limitation
Superfluid He (2 K)
H bulk
Niobium
Tc =9.2 K
- cavity quench: at a defective (quench spot)
- thermal breakdown
• Solution
- the first system: in CERN (1981) for 500 MHz
LEP cavities
- 120 Ω , ¼ W Allen-Bradley carbon
resistors , rotating motor
Field
emission
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Quench Loss
distribution
source: G. Ciovati, et al.,” Temperature mapping system for
single cell cavities”, Fermilab, internal report (2005)
Precursor
BE-KT innovation day Octopus
Temperature Mapping System
source: Ph. BERNARD, Nuclear Instruments and Methods
190 (1981), ‘Temperature Mapping on a Superconducting
RF Cavity in Subcooled Helium by H. Piel & R.3Romijn,
CERN/EF/RF 80-2 (1980)
Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Mainstream systems
scan time
sensor
accuracy
flexibility
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Fixed
slow
fast
few
many
better
BE-KT innovation day Octopus
x
x
Temperature Mapping System
source: T. Tajima,
LA-UR-09-02723, PAC09
source: D. Reschke et al.,
THP016, LINAC08
source: J. Knobloch et. al, Rev.
Scientific Instru. 65 (11)
Rotating
β↑
β↓
4
Octopus Temperature Mapping System
Design Concept & Features
• For SPL type cavities (=0.6, =1)
• Octopus inspired
- Flexibility, time saving  good contact and use on different
beta cavities
- Allen-bradley sensor package
(100 Ω, 1/8W, raw resistor ΔR/ΔT≈ 758 Ω/K)
 75.8Ω/100 mK
- Fixed sensor pattern more accurate
- Multiplexer IC on printed circuit board
 reduce cross talk
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Temperature Mapping System
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Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Octopus Temperature Mapping System
Prototype
• 1/3 Octopus flexible polymide (Kapton) PCB
- sensor res. 20 (equator) ~ 34 mm
- pre carved space for second sound travel
- multiplexers IC
H. Piel & R. Romijn,
CERN/EF/RF 80-2 (1980)
• Allen-Bradley sensor package
- dedicated glass fiber holder
- concealed manganin wires in stycast
- stable pins on the sides
- ~3000 (5 cell)
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Temperature Mapping System
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Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Octopus Temperature Mapping System
Prototype
• Acquisition board outside the cryostat
- calibration (at 4 K and 2 K)
- measure resistance, process data
- send to PC, show map
- post process (real time) to see quench development
PC
Temp
maps
12 ribbon cables BE-KT
for innovation
a single
cell
day Octopus
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Temperature Mapping System
1 cell
5 cell
Resist MUX µc
ors
boards
576 144
6
7
2880 720
30
Background
Mainstream systems
The Octopus T-map
Outlook & Summary
Outlook & Summary
• Temperature mapping system is essential for quench localisation &
understanding cavity performance.
• The octopus Tmap is designed with features to solve problems with shape
difference and with better performance – now at the prototyping stage.
• The first 1/3 prototype hoped to be tested by end of July.
• Further adjustment and modification for full 5 cell SPL structure/ LHC
cavities/ Crab cavities
• Possibilities outside CERN in HEP: replacement for old style non-flexible
temperature mapping systems?
• Man-power needed and manufactures for making the sensors! The
needs you! Stephane Rey BE-RF (microprocessor programme and circuits)
and me (end of July)!
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