sc cavity design and manufacturing n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SC cavity design and manufacturing PowerPoint Presentation
Download Presentation
SC cavity design and manufacturing

Loading in 2 Seconds...

play fullscreen
1 / 18

SC cavity design and manufacturing - PowerPoint PPT Presentation


  • 136 Views
  • Uploaded on

SC cavity design and manufacturing. Material studies for SPL cavities at CERN Niobium raw material procurement. ARNAU IZQUIERDO, Gonzalo. Intro Niobium for superconducting cavities Production of high RRR niobium Niobium raw material procurement for SPL beta=1 cavities Shapes and Quantities

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'SC cavity design and manufacturing' - fletcher-jenkins


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
sc cavity design and manufacturing

SC cavity design and manufacturing

Material studies for SPL cavities at CERN

Niobium raw material procurement

ARNAU IZQUIERDO, Gonzalo

slide2

Intro

    • Niobium for superconducting cavities
    • Production of high RRR niobium
  • Niobium raw material procurement for SPL beta=1 cavities
    • Shapes and Quantities
    • Material specification
    • Order follow up and QC
    • Inspection and follow up at CERN
    • Alternative suppliers
  • Material studies of assemblies  see next presentation

G. Arnau Izquierdo EN/MME

intro
Intro
  • Use of Nb for superconducting cavities
    • High transition temperature Tc = 9,3 K and critical magnetic field Hc = 200 mT
    • Available in industrial shapes
    • Can be easily formed and machined, can be welded
  • Need of high purity ( high RRR) niobium
    • Reduce defects and impurities acting as normal conductive clusters
    • High thermal conductivity to keep T< Tc around normal conductive clusters and avoid propagation of normal conductive state (quench)  thermal stability
    • Impurities and lattice defects act as scatter centres that reduce both thermal and electrical conductivity at low temperature.
    • Measuring the RRR is a practical way to evaluate purity and low temperature thermal conductivity of a material

K (W/mK)

F.Koechlin, and B.Bonin

G. Arnau Izquierdo EN/MME

intro1
Intro
  • Production of high RRR niobium
    • Main impurity from the ore is Ta
    • Main impurities reducing RRR are interstitial elements O, N, C and H.
    • Key points:
    • Refining by several electron beam remeltings under high vacuum.
    • Clean handling during forge, hot and cold rolling.
    • Final annealing 1-2 h at 700-800 °C in good vacuum.

R. Grill et al. Plansee-Heraeus

G. Arnau Izquierdo EN/MME

shapes and quantities
Shapes and quantities
  • Price Inquiry (restricted by FI to member states)
  • Plansee /AT with Heraeus /DE as supplier for ingots and subcontractor for smaller tubes

G. Arnau Izquierdo EN/MME

material specification antecedents
Material Specification. Antecedents
  • Antecedents
    • DESY (W. Singer, D. Proch)
      • Technical Specification for Niobium Applied for the Fabrication of 1.3 GHz Superconducting cavities RRR 300
    • FERMILAB (P. Bauer, C. Antoine)
      • Technical Specification for High RRR Grade Niobium Sheet and Rod for use in Superconducting Cavities
    • International standards
      • No EN standards for niobium
      • SAE AMS7850, Columbium Sheet, Strip, Plate and Foil
      • ASTM, Standard Specification for Niobium and Niobium Alloy ...
        • B391-09 ... Ingots
        • B392-09 ... Bar, Rod, and Wire
        • B393-09 ... Strip, Shit, and Plate

The only standard dealing with a high RRR grade

G. Arnau Izquierdo EN/MME

material specification astm b393 09
Material Specification. ASTM B393-09
  • ASTM B393-09
    • The only standard dealing with a high RRR grade
    • UNS R04220, Type 5

G. Arnau Izquierdo EN/MME

material specification astm b393 091
Material Specification. ASTM B393-09

G. Arnau Izquierdo EN/MME

material specification cern tech specs
Material Specification. CERN Tech. Specs.
  • Two Material Technical Specifications for RRR>300 and RRR>40 issued for the Price Inquiry
  • General characteristics
    • Chemical composition
    • Microstructure
    • Mechanical properties
    • Electrical properties
    • Surface defects
    • Bulk defects
  • Manufacturing process
  • Dimensions and tolerances
  • Quality control
  • Packing

G. Arnau Izquierdo EN/MME

order follow up and qc
Order follow up and QC
  • Quality Control program defined in hte specification
    • A batch is defined as parts from the same melt, having followed the same forging and rolling and that have been annealed in the same charge

G. Arnau Izquierdo EN/MME

order follow up and qc1
Order follow up and QC
  • Order placed to Plansee /AT (procurement of ingots and production of smaller tubes subcontracted to Heraeus /DE)
    • Delivery schedule announced in the bid: 16–18 weeks (subject to prior sales!)
    • Order placed Aug 2010
    • Order confirmation Dec 2010
    • First sheets received Oct 2011
    • Last item received next week hopefully...
  • Five visits
    • Discussion of CERN results on qualification samples
    • Pushing up in view of continuous delays
    • Ensuring strict respect of QC program and traceability
  • Various reasons given along the + 1 year for the cumulating delays

G. Arnau Izquierdo EN/MME

order follow up and qc2
Order follow up and QC
  • Chemical composition
    • Effect on electrical and thermal conductivity. Most sensitive is RRR measurement
    • Specified:
      • Analysis of interstitials on final product because of risk of pick up during process
    • Obtained: OK

G. Arnau Izquierdo EN/MME

order follow up and qc3
Order follow up and QC

Cross-secton of qualification samples.

  • Microstructure
      • Homogeneous and fine, to avoid heterogeneous behaviour on forming (ie. orange peel on deep drawing, not so critical for spinning)
      • Very high purity makes difficult to master the cast grain size because of few nucleation sites
    • Specified
      • Completely recrystallized
      • Homogeneous grain size G  6 (45 µm), locally G  4 (90 µm)
    • Obtained

Not fully recrystalized.

Regions of coarse grains

QC on sheets delivered. Worst cases found by the firm and by CERN:

G. Arnau Izquierdo EN/MME

order follow up and qc4
Order follow up and QC
  • Mechanical properties
    • Annealed product is required for forming.
    • Specified
      • Max of hardness
      • Band of yield strength (Rp0,2)
      • Min of ultimate strength (Rm)
      • Min of ductility (A)
    • Obtained

Rm

Rp0,2

A

G. Arnau Izquierdo EN/MME

order follow up and qc5
Order follow up and QC
  • Electrical properties
    • High RRR is (indirectly) required for cavity performance
    • Specified
      • RRR  300 @ 4.2 K
    • Obtained
      • 297 – 396 @ 4.2 K (estimated from measurements @ 9.3 K)
    • RRR check at CERN
      • Cryostat four point setup of TE/MCS. Measure just above Tc (9.3 to 10 K)
      • Samples 2x2x100 mm3, etched in a mixture of HF, HNO3 and H3PO4, kept below 15 °C to limit H2 pick up.

Samples in the holder for chemical etching and etched

Sample holder of the RRR measurement setup at CERN/TE/MSC

G. Arnau Izquierdo EN/MME

inspection and follow up at cern
Inspection and follow up at CERN
  • Square sheets
    • Visual inspection, marking, cutting of two corners for witness and sampling
    • Tests in progress
      • Microstructure
      • Hardness
      • Tensile
      • RRR
      • Roughness
    • Anodising as a means of assisting visual inspection was tried and abandoned. Not easy, added handling is risky and no obvious enhancement of the surface inclusions.
  • Tubes
    • Dimensional control  deviations
    • Roughness

Anodising tests with different conditions on samples with metallic particlesembedded .

Square sheet anodised

G. Arnau Izquierdo EN/MME

alternative suppliers
Alternative suppliers
  • Alternative producers
    • Wah Chang /US
    • Tokyo Denkai /JP
    • Ningxia Group /CN, represented in Europe by Elite Material Solution /UK
  • Most propose only sheets
  • Prices are similar
  • A qualification sample from Ningxia has been tested satisfactory
    • RRR, microstructure, hardness, tensile test (on small specimen)

G. Arnau Izquierdo EN/MME

conclusions
Conclusions
  • All shapes and quantities required will be procured with satisfactory quality
  • Most firms have made the effort of qualifying for previous and ongoing Nb SC projects and are now mature for sheet production
  • Seamless tubes required specific development not completely mastered for tight tolerances
  • Keeping the schedule is a concern, at least with a relatively small order, not standard dimensions and a producer for which Nb is a very minor share of activity
  • Grain size G 6 is tight for sheets of 3.6 mm
  • RRR measurement is not a widespread in house technique amongst Nb producers
  • Anodising for visual inspection do not seems to be advantageous for as received sheet

G. Arnau Izquierdo EN/MME