Produc duction o n of INFN NFN TTC Meeting, East Lansing, 21 24 - - PowerPoint PPT Presentation

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Produc duction o n of INFN NFN TTC Meeting, East Lansing, 21 24 - - PowerPoint PPT Presentation

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Produc duction o n of INFN NFN TTC Meeting, East Lansing, 21 24 February 2017 medium me um be beta cavi vities s for ESS SS From the design to the Vertical Test of the cavity prototype integrated in the tank Paolo Michelato on

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SLIDE 1

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Produc duction o n of INFN NFN me medium um be beta cavi vities s for ESS SS

From the design to the Vertical Test of the cavity prototype integrated in the tank Paolo Michelato on behalf of the LASA group

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SLIDE 2

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity RF Parameters INFN Design

  • Design philosophy:
  • Boundaries fully

compatible to ESS requirement.

  • We design the cells!
  • Our goal:
  • To have large cell-to-cell

coupling factor, k>1.5%

  • Allowing for a slight

modest sacrifice on Epeak and R/Q

Parameters INFN design ESS spec. Riris (mm) 50 ≥47 Geometrical beta 0.67 0.67 Frequency (MHz) 704.42 704.42

  • Acc. length (m)

0.855 0.855 Cell to cell coupling k 1.55%↗(+26%) π-5π/6 mode sep.(MHz) 0.70↗(+30%) >0.45 G (Ω) 198.8 Optimum beta, βopt 0.705 0.705 Max R/Q at βopt (Ω) 374 ↘ (-6%) Eacc at βopt (MV/m) 16.7 16.7 Epeak/Eacc 2.55 ↗ (+7%) Epeak (MV/m) 42.6 < 45 Bpeak/Eacc(mT/MV/m) 4.95 ↗ (+3%) Q0 at nominal gradient >5×109 >5×109 Qext 7.8×105 5.9~8×105

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SLIDE 3

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity Mechanical Parameters INFN Design

Mechanical parameter

INFN Design Cavity wall thickness (mm) 4.5 Stiffening ring radius (mm) 70 Internal volume (l) 69 Cavity internal surface (m2) 1.8 Stiffness (kN/mm) 1.7 Tuning sensitivity KT (kHz/mm)

  • 210

Vacuum sensitivity KV for Kext ~ 21 kN/mm (Hz/mbar) 31 LFD coefficient KL for Kext ~ 21 kN/mm (Hz/(MV/m)2)

  • 1.7

Pressure test scenario:

  • Cavity fully constrained
  • Pressure in the tank

The maximum pressure difference allowable is

  • 2.60 bar for 50 MPa VM (worst scenario)
  • 3.64 bar for 70 MPa VM (best scenario)

Scenario:

  • Cavity with one free end
  • Increasing displacement on free end

The maximum displacement allowable is

  • 2.59 mm for 50 MPa VM (worst scenario)
  • 3.60 mm for 70 MPa VM (best scenario)
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SLIDE 4

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Frequency and length evolution

  • A key point in the cavity fabrication is the

estimation of the cavity frequency just after production and before any treatment, because at this frequency we need to produce the DB.

Effect ∆f [MHz] Cavity Frequency [MHz] Cavity @ 2K in vacuum

  • 704.42

Tuner pre-load

  • 0.2

704.22 Cavity @ 300K in vacuum

  • 1.03

703.19 Cavity @ 300K in air

  • 0.23

702.96 Cavity @ 300K in air before BCP (180 µm) +0.58 703.53

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SLIDE 5

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

DB fabrication

  • The DBs have been trimmed to proper length

(«frequency») taking into account also the step- and-recess needed for cavity assembly.

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SLIDE 6

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity Composition

  • Mechanical after welding
  • Based on relaxed tolerances from CEA, the cavity

length foreseen is 1259.4 ± 3 mm.

  • The MB001 length after welding was 1256.88 mm
  • Frequency
  • The expected frequency, as reported before, was

703.53 MHz.

  • The MB001 frequency after welding was

703.52 MHz

  • Field Flatness
  • After fabrication, FF ≈ 70 %
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SLIDE 7

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Surface treatments fully done at the industry (EZ)

  • Bulk & final BCP: 1:1:2
  • BCP1: 60 min, subdivided in 2 steps (20 min + 40 min).
  • BCP2: 90 min, cavity is turned upside down.
  • Heat treatment at 600 °C, 12 h
  • Final BCP (15 min)
  • Cavity weight monitoring for each treatment
  • For each BCP treatment, barrel and output acid temperature are

acquired, together with acid throughput

  • 6 thermocouple sensors (t1,…,t6) are placed on cavity surface,

continuously acquiring temperature during chemical etching

  • IR camera with standard emissivity dots monitoring during BCP
  • A Nb sample is placed inside cavity (through MC) for monitor etching

rate and RRR variation

  • Cavity thickness measurement with ultrasound gauge before and after

etching

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SLIDE 8

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

BCP treatment

STEP BCP1 A 20 min BCP1 B 40 min BCP2 90 min BULK BCP total Final BCP 15 min

Cavity weight change (g) 434 795 1685 2914 Cavity removed thick. (µm) 28 51 109 188 22 (expected) Cavity etching rate (µm/min) 1.4 1.3 1.2 Sample weight change (g) 1.53 3.08 4.15 1.20 Sample removed thick. (µm) 40 81 110 32 Sample etch. rate (µm/min) 2.0 2.0 1.2 2.10

Nb sample Acid throughput: 20 l/min

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SLIDE 9

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

BCP treatment

10 20 30 40 50 60 5 10 15 20 25 30 35 16:32:10 16:37:55 16:43:41 16:49:26 16:55:12

throughput (L/min) Temperature (°C)

BCP1 A: 20 min

t1 t2 t3 t4 t5 t6 T tank throughput T out

Nb sample t1 t3 t4 t5 t6 t2 Acid flow T out T tank

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SLIDE 10

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Annealing and dehydrogenation

1.E-07 1.E-06 1.E-05 1.E-04 100 200 300 400 500 600 700 500 1000 1500 2000 2500 3000 3500 4000 P (mbar) T (°C) Temperature Pressure 1.0E-11 1.0E-10 1.0E-9 1.0E-8 1.0E-7 1.0E-6 1.0E-5 500 1000 1500 2000 2500 3000 3500 4000 Pressure (Torr) Minutes H2 H2O N2 O2 CO2 TPressure

H2

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SLIDE 11

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Annealing and dehydrogenation

1.E-07 1.E-06 1.E-05 1.E-04 100 200 300 400 500 600 700 500 1000 1500 2000 2500 3000 3500 4000 P (mbar) T (°C) Temperature Pressure 1.0E-11 1.0E-10 1.0E-9 1.0E-8 1.0E-7 1.0E-6 1.0E-5 500 1000 1500 2000 2500 3000 3500 4000 Pressure (Torr) Minutes H2 H2O N2 O2 CO2 TPressure

H2

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SLIDE 12

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Treatments:

Iris Equator ratio

  • A simple model as well as a code are used to

analyze the Iris/equator removal ratio in each

  • BCP. A cross-check of calculated weight for the

estimated ratio and the measured weight shows good consistency.

  • Calculation shows the iris/equator removal ratio

ranges from 1.1 to 1.5.

BCP Weight meas (g) dFπ (kHz) Ave.remov (um) Fsens (kHz/um) Ir/Eq dReq (um) dRir (um) Weight estm (g) dW/ W 1A 434

  • 62

28

  • 2.2

1.5 22 34 409

  • 6%

1B 795

  • 155

51

  • 3.0

1.1 49 54 776

  • 3%

2 1685

  • 306

109

  • 2.8

1.2 99 119 1651

  • 2%
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SLIDE 13

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

RF Parameters after final tuning

  • Frequency at 300 K: 702.9 MHz
  • Field Flatness: > 97 %
  • HOM measurement

Fsim = 1740 MHz Simulation Measurement About 2.5 MHz lower than the one at 2K.

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SLIDE 14

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

LASA Installation of the naked cavity for cold test

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SLIDE 15

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity properties

  • Frequency @ 2K
  • Length @ room temperature
  • 1257.6 mm

704.213 MHz (as expected)

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SLIDE 16

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Power Rise @ 2K

100 W CW cryo power, i.e. 16,7 MV/m @ Q0 5e9

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SLIDE 17

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

MP and SEY

  • MP simulations with “FishPact” and “MultiPac” codes consistently show

that stable trajectories of 1st order two-point MP appear in a very small region near equator center, with Eacc in range from 7 to 14 MV/m and a maximum impact energy (Ef) around 30 eV at Eacc = 11 MV/m.

  • We do expect soft barriers if the initial SEY is higher.

10 15 20 25 30 35 5 6 7 8 9 10 11 12 13 14 15 Ef(eV) Eacc (MV/m)

Inner cell End cell

SEY for Nb End Cell Inner Cell

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SLIDE 18

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Radiation

Radiation due to multipacting is seen in the first cold test, but it was

  • conditioned. In fact, it disappered during the second test done just after

some minutes. The data are consistent with the simulation.

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SLIDE 19

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Radiation

1 10 100 1000 10000 100000 500 1000 1500 2000 2500 3000 3500

counts Energy (keV)

X ray spectrum @21.5MV/m

0.0E+0 5.0E+1 1.0E+2 1.5E+2 2.0E+2 2.5E+2 19:40:48 20:09:36 20:38:24 21:07:12 21:36:00 22:04:48 22:33:36

uSv/h

time

∼10 MV/m Conditioning attempt 20-22 MV/m (quench field)

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SLIDE 20

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

HOM

  • The monopole mode close to 5th machine line
  • Directly measured at 2K, F = 1741.8 MHz

(>19 MHz from machine line at 1761.05 MHz)

  • Close to expected value, <1 MHz to

simulation at 1742.4 MHz.

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SLIDE 21

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Tolerances

Qext sensitivity to fabrication errors

  • Selected values in the following table are based
  • n practical mechanical tolerances in cavity

fabrication process.

Mechanical Dimention Qext variation Etching effect in beam pipe (A) 68 + 0.15 mm 7.8E5 - 0.12E5 EndCell distance to coupler port (B) 35 ± 0.1 mm 7.8E5 ± 0.05E5 Antenna tip to cavity axis (C) 60.26 ± 0.1 mm 7.8E5 ± 0.06E5 Coulper port blended edge radius (D) 7 ± 1 mm 7.8E5 ∓ 0.07E5 Inner conductor of antenna distance to EndCell iris (E) 85 ± 0.1 mm 7.8E5 ± 0.03E5

A B C D E

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SLIDE 22

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity integration

  • After successful cold test the

cavity was integrated in the He tank

  • Frequency change: 35 kHz
  • Pressure test: done
  • New Final BCP: 15 min, 20 µm
  • Successful cold test done at

LASA last week

  • Next step: installation in the

medium beta cryomodule demonstator at CEA

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SLIDE 23

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Cavity with tank cold test preparation at LASA

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SLIDE 24

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

Power Rise @ 2K

100 W CW cryo power, i.e. 16,7 MV/m @ Q0 5e9

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SLIDE 25

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

ESS cavity box and transportation

A single prototype built

  • Four soft supports no foam
  • 3 transports: OK
  • Further analyses:
  • g-shock reducing factor > 8
  • Residual oscillations < 7 Hz
  • Dumping τ0 about 0.25 s
  • Safe values resulted
  • Highest accelerations registered

during box lifting to the truck vane: +0.71 g (X) +0.85 g (Y) +1.15 g (Z)

  • Travelling was smooth, peaks

are always well below previous values

  • Driver driving “style” might be

judged as reasonably safe and quiet

  • Up to 0.2 g sustained acceleration, 0.4 g sustained

deceleration (besides peaks and single events)

  • Up to 0.4 g sustained lateral acceleration
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SLIDE 26

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

The (near) future

  • Successful cold test of the cavity prototype at LASA last week
  • Next step: installation in the medium beta cryomodule

demonstrator at CEA

Series cavities:

  • Niobium call for tender: issued
  • Two identical lots. Higher throughput
  • Nb scanning: DESY (through ESS)
  • Cavity call for tender: final stage
  • Complete cavity production at the industry: cavities will be delivered

ready for the cold test, already integrated in the He tank.

  • Vertical Test: DESY
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SLIDE 27

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

ESS quality control: SCHEME

ESS PDR, INFN-

NCR

Cavity production data

Managing System Quality Control

INFN Industry

INFN Managing system Database (parameter analysis)

INFN Experts Check

DESY

(Cold RF test)

Q0 vs. Eacc

CEA

STRING ASSEMBLY

CAVITY with TANK CAVITY with TANK MODULE

ESS

ESS

(approval)

NCR

Documents for full equipped cavity acceptance (for string assembly)

NCR

Laura Monaco, INFN LASA

NCR NCR

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SLIDE 28

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

The Acceptance Levels for the ESS Series Production

ESS PDR, INFN-

Level Cavity status Needed documents If Level reached One

“Naked” cavity after mechanical fabrication Mechanical, RF, vacuum, visual documents Proceed to Level Two

Two

Cavity before He-tank integration Mechanical, RF, vacuum, Treatment documents & tank documents Proceed to Level Three

Three

Accessory assembly, last surface treatments, outer inspection document Treatment, vacuum, RF, transfer measurements documents Integrated cavity ready to be cold RF tested

Four

Cavity cold tested Documents relative to cold test results and in/out checks Cavity can be sent to CEA for string assembly

Five

Cavity accepted for string assembly Documents with incoming inspection at CEA Cavity final approval

Laura Monaco, INFN LASA

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SLIDE 29

TTC Meeting, East Lansing, 21 – 24 February 2017

Paolo Michelato

The end