1. Kitty Liao BE-RF-SRF Kitty.Liao@cern.ch
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

2. Presentation Structure
Background Mainstream systems The Octopus T-map Outlook & Summary
Presentation Structure
Background : Cavity diagnostics for quench
Mainstream (Existing) systems
NEW- The Octopus Temp. Mapping system
Outlook & Summary
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System

3. Temperature mapping background
Background Mainstream systems The Octopus T-map Outlook & Summary
Temperature mapping background H
Superfluid He (2 K)
Goal
- achieve high accelerating gradient 704 MHz cavities for the CERN (244 x 5-cell β =0.6 & β =1 cavities)
- quality control
Limitation
- 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
Niobium bulk
Tc =9.2 K
Field emission
Quench
Loss distribution
Precursor
source: Ph. BERNARD, Nuclear Instruments and Methods 190 (1981), ‘Temperature Mapping on a Superconducting RF Cavity in Subcooled Helium by H. Piel & R. Romijn, CERN/EF/RF 80-2 (1980)
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System
source: G. Ciovati, et al.,” Temperature mapping system for single cell cavities”, Fermilab, internal report (2005)

4. BE-KT innovation day Octopus Temperature Mapping System
Background Mainstream systems The Octopus T-map Outlook & Summary
Mainstream systems
Rotating
Fixed
scan time
slow
fast
sensor
few
many
accuracy -
better
flexibility x
source: D. Reschke et al.,
THP016, LINAC08
LA-UR , PAC09
source: T. Tajima,
source: J. Knobloch et. al, Rev. Scientific Instru. 65 (11) β↑ β↓
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System

5. 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
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System

6. Octopus Temperature Mapping System Prototype
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)
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System

7. Octopus Temperature Mapping System Prototype
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
Resistors
MUX
µc boards
1 cell
576
144 6
5 cell
2880
720 30
12 ribbon cables for a single cell
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System

8. BE-KT innovation day Octopus Temperature Mapping System
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)!
03/06/2013 K.Liao
BE-KT innovation day Octopus Temperature Mapping System