BE-KT Innovation DayOctopus Temperature Mapping System for

Cavity Diagnostics

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

Presentation Structure

1. Background : Cavity diagnostics for quench

2. Mainstream (Existing) systems

3. NEW- The Octopus Temp. Mapping system

4. Outlook & Summary

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao 2 of 8

BE-KT innovation day Octopus Temperature Mapping System

3 of 8

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 - 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

HNiobium bulkTc =9.2 K

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)

Superfluid He (2 K)

source: G. Ciovati, et al.,” Temperature mapping system for single cell cavities”, Fermilab, internal report (2005)

Field emission

Quench Loss distribution

Precursor

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao

BE-KT innovation day Octopus Temperature Mapping System

4 of 8

Mainstream systemsRotating Fixed

scan time slow fast

sensor few many

accuracy - better

flexibility x x

sour

ce: D

. Res

chke

et a

l.,

TH

P01

6, L

INA

C08

sour

ce: T

. Taj

ima,

L

A-U

R-0

9-02

723,

PA

C09

β↓β↑

sour

ce: J

. Kno

bloc

h et

. al,

Rev

. S

cien

tifi

c In

stru

. 65

(11)

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao

BE-KT innovation day Octopus Temperature Mapping System

5 of 8

Octopus Temperature Mapping SystemDesign 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 of 8

• 1/3 Octopus flexible polymide (Kapton) PCB

- sensor res. 20 (equator) ~ 34 mm

- pre carved space for second sound travel

- multiplexers IC

Octopus Temperature Mapping SystemPrototype

• Allen-Bradley sensor package - dedicated glass fiber holder - concealed manganin wires in stycast - stable pins on the sides - ~3000 (5 cell)

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao

H. Piel & R. Romijn, CERN/EF/RF 80-2 (1980)

BE-KT innovation day Octopus Temperature Mapping System

7 of 8

Octopus Temperature Mapping SystemPrototype

• 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

Resistors

MUX µc boards

1 cell 576 144 65 cell 2880 720 30

12 ribbon cables for a single cell

PC

Temp maps

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao

BE-KT innovation day Octopus Temperature Mapping System

8 of 8

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)!

Background Mainstream systems The Octopus T-map Outlook & Summary

03/06/2013 K.Liao