Treatments of Niobium A. Camacho*^, A.A. Rossi* and V. Palmieri*^, * - - PowerPoint PPT Presentation

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Treatments of Niobium A. Camacho*^, A.A. Rossi* and V. Palmieri*^, * - - PowerPoint PPT Presentation

Jun 29, 2023 201 likes •602 views

Athmospheric Surface Treatments of Niobium A. Camacho*^, A.A. Rossi* and V. Palmieri*^, * INFN Legnaro National Laboratories ^ University of Padua Samples or Cavities? Material Study or Cavity construction? Low research budget Large

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Athmospheric Surface Treatments of Niobium

  • A. Camacho*^, A.A. Rossi* and V. Palmieri*^,

* INFN – Legnaro National Laboratories ^ University of Padua

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Material Study or Cavity construction?

Samples or Cavities?

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Low research budget  Large amount of cavities

6 6 GHz GHz

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Resistive

Samples Real cavities

Inductive Hc1 Measurement Calorimetric methods RS Differential measurements Microstrip Resonators 6 GHz cavities 1,5 /1,3 GHz monocells 1,3 GHz 3-cell cavity 1,3 GHz 9-cell cavities

Pillbox cavities, etc

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SLIDE 5
  • No electron beam welding, neither for flanges
  • Obtained by spinning from Nb scraps
  • Short fabrication time
  • Fast and low cost BCP and EP treatments
  • Inexpensive Cryogenics
  • Quick RF Measurements

6 GHz CAVITY MINILAB

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6 Ghz Cavity Geometry

20 mm 36 mm

Seamless flanges [mm]

Flange Area = 7 cm2

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SLIDE 7
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Mini Mechanical Tumbling

SiC ZrO2 Al2O3 + SiO2

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Mini EP

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6 GHz CAVITY MINI-furnace

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6 GHz CAVITY MINI-Camera

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Ready for the RF measurement

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6 GHz CAVITY: MINI-Kapton gasket

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Quick RF Measurements

The insert has been conceived to even enter into a 450 lt Helium dewar INSERT DEWAR RF measuring system

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High Temperature Rapid Metathesis (Nitriding in Mushy State)

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The Homologous Temperature

1

T [K]

q =

Tm [K]

for Nb 2467 °C

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T [K]

q =

Tm [K]

0,98 0,9 1 2467 °C 2196 °C

Mushy State

0,96 2357 °C 2412 °C

Premelting

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6 Ghz @4,2K

1 2 3 4 5 6 10

7

10

8 PureNb NbN2 NbN2a NbN2b NbN3 NbN4 NbN5 NbN6 NbN8 NbN8Ox NbN9 NbN11 NbN12 NbN13 NbN13 3'' BCP NbN14

Q EPk(MV/m)

Bulk Nb

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  • Fast ( takes only few sec)
  • Cheap (Vacuum Technology Free)
  • Simple (No need of special expertise)

High Temperature Rapid Metathesis (Nitriding in Mushy State) The Process is:

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Pr Premelting emelting (also Surf Surface ace melting melting)

Even below its melting point (Tm),

quasi-liquid films can be

  • bserved on crystalline surfaces
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The thickness of the quasi-liquid film is T - dependent This effect is common for all crystalline materials

Pr Premelting emelting (also Surf Surface ace melting melting)

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Nb NbN

3 mm

Nb NbN

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 Nb5N6; N4N3 Over-Stoichiometric

 d-NbN 1-x;

 g-Nb4N3-x Under-Stoichiometric  a-Nb (N) (bcc solid solution)  Niobium

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Nb5N6; N4N3 d-NbN 1-x; h-NbN (hexagonal); d’-NbN (hexagonal); b-Nb2N (hexagonal); g-Nb4N3-x a-Nb (N) (bcc solid solution) Niobium

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Surface layers

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Temp emper eratu ture Ti Time me

Tm of Nb

3 3 – 30 sec 30 sec

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g-Nb N d-Nb N

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As the d-NbN  g-Nb4N3-x phase transformation is a

very fast, quasi-continuous

Transition,

it cannot be avoided by quenching

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The good layer is the most

external one

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1 2 3 4 5 6 10

7

10

8

PureNb NbN13 NbN13 - BCP 3' Q EPk (MV/m)

BCP 3’

BCP 3’ Pure Nb NbN

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1 2 3 4 5 10

6

10

7

10

8

PureNb NbN NbN He Annealing NbN N2 Annealing

Q EPk (MV/m)

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NbN @4,2K

T = 4,2 K

Bulk Nb

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High Temperatures for

Nb Purification

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 10

6

10

7

10

8

Nb 26 Nb 17 Nb 1 Nb 27 Nb 37 Nb 13 G Nb 111 Q EPk [MV/m]

IL - EP IL - EP Classical – EP Classical – EP Classical – EP Classical – EP

5 min at 2300°C

5 min at 2300°C

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SLIDE 37

Conclusions 1

  • 6 Ghz cavities allow a fast and

dense statistics

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Conclusions 2

  • No vacuum required!
  • 5min @ 2300°C seem to purify Nb
  • Nitriding performed atAtmospheric pressure
  • At 4,2 K the Q-value at low field increases of

even a factor 5