Supratech Facility: cavities and modules preparation

Context:

The facility includes equipment and technical area for the development, the preparation, assembling and testing SRF cavity, accelerating cryomodules equipped with the cryogenic cold box and housing SRF cavities fully dressed with their ancillaries (e.g. power coupler, magnetic shielding, cold tuning system, pumping systems, instrumentation). The cold tests are performed at liquid helium temperature in the range 1.7 K- 4.2K. The RF instrumentation and RF power sources allow to perform both low (up to 200 W) and high RF power (from 80 kW to MW peak power) tests at two main frequencies: 352 MHz and 704 MHz.

Technical means

Chemical etching facility

Goal:

Chemical etching of the RF surface of the cavity for removal damaged layer and/or possible surface contamination

Features:
  • Operational since 2009
  • Acid mixture: Phosphoric, Nitric and Hydrofluoric (2.4:1:1)
  • Volume of acid : 180 L
  • Average etching rate: 0.5 µm/minute
  • Chiller to maintain cavity temperature between 15 and 20°C
  • Typical etching depth: between 10 and 250 µm
  • Maximal Niobium concentration in acid 50 g/l
  • On average 10 cavity processing per year
Characterization and quality control:
  • Ultrasonic probe (local depth measurement)
  • Roughness meter
  • Optical microscope (ₓ1000)
  • Bright Field, Dark Field, Polarized light
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Weighing of a cavity

Nature

Ultrasonic cleaning

Fjords

Cavity preparation

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BCP etching

Nature

Rinsing with ultra-pure water

Fjords

Surface morphology prior to BCP etching (ₓ200)

Fjords

Surface morphology state after 100 µm BCP etching (ₓ200)

High Pressure Water Rinsing (HPWR) System

Goal:

Reduce field emission and increase accelerating fields. High pressure water rinsing is currently a standard process for SRF cavities used during the preparation prior to cold tests. It allows efficient removal of potential metallic and dielectric dust particles (field emitters) from the cavity RF surface.

Features:
  • Ultra-pure water (18.2 MΩ⋅cm) flow rate: 100 l/h
  • HPWR system: Pressure: 100 Bar, Flow rate: 400l/h
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High Pressure Water Rinsing (HPWR) System

Clean room dedicated to SRF cavity preparation and cryomodules assembling

Goal:

Final SRF cavity preparation and assembling

Features:
  • Total area: 85 m2, ISO4 area: 45 m2
  • Controlled ambient temperature and humidity
  • Filtered N2 and He gases (for leak tests and particle counting)
  • Versatile handling carts for cavities of various shapes and dimensions (elliptical, Spoke, QWR)
  • Particles Counter (Range: 0.3 µm-25 µm)
  • Deionized water tank: 1500L (about 4h00 of HPWR process)
  • 1 Leak detectors
  • 200L Ultrasonic bath operating at a power of 10 kW/l (dimensions 100x50x50)
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Clean room in operation since 2007

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Assembling of Spiral2 QWR

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Assembling of Spiral2 cryomodule

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Assembling of cavity for power coupler conditioning

Field of Expertise and Relevant Infrastructure or equipment at IPN Orsay (Accelerators Division)

Field of Expertise Relevant Infrastructure or equipment
  • Design, fabrication and operation of Accelerating cryomodules including low level RF, and high power RF components
  • Design softwares and numerical simulation codes (RF, Mechanical, thermal design)
  • 3D code for multipacting simulation
  • Treatment and preparation of SRF cavities
  • BCP facility
  • Clean Room with HPWR
  • Low temperature baking facilities
  • High vacuum, High temperature (500 °C-1400°C) heat treatment of SRF cavities
  • Nitrogen and Argon doping
  • Vacuum furnace
  • Material and surface Characterization
  • Optical microscope
  • Roughness meter (contact)
  • SEM at CSNSM
  • Confocal microscope
  • Cryogenic tests
  • Helium liquefier: Liquefaction rate: 70 l.h-1
  • Pumping system for sub-atmospheric operation of cryomodules and vertical cryostat
  • Vertical acceptance Tests of SRF Cavities at cryogenic temperatures
  • Low Temperature Vertical Tests Stands of SRF Cavities at low and high RF power and operating at different frequencies (88 MHz, 352 MHz, 704 MHz, 1300 MHz, 3-6 GHz) with a dedicated
  • High power RF Tests of cryomodules (e.g. horizontal cryostat housing fully equipped cavity, with LHe Tank, Magnetic Shielding, Power Coupler, Cold Tuning System and cryogenic instrumentation)
  • High RF power test stand at 704 MHz
  • High RF power test stand at 352 MHz
  • High RF power test facilities for Main coupler conditioning
  • Cryogenic instrumentation
  • Calibration facility for cryogenic thermometers
  • Test stands for RF and DC characterization of samples
  • Electrical resistivity, thermal conductivity, Kapitza resistance, heat transfer TE011 cavity (RF properties of materials)

Recent developments

High energy section of the SPIRAL2 superconducting LINAC
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  • Fourteen 88MHz QWR, β=0.12 SRF cavities successfully tested
  • High energy section β=0.12 superconducting linac consisting of seven cryomodules CMB1 to CMB7. The 7 crymodules housing each, two QWR fully equipped (power coupler, cold tuning system, magnetic shielding, and cryogenic instrumentation) were assembled, completed, successfully tested, shipped to Ganil and installed.
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Spiral2 cryomodule B

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SPIRAL 2 superconducting linac during installation at GANIL

Location

IPN - Orsay (France)

Service

This technical platform provides the expertise and manpower to perform the work and training,

Contact

For further information, please email fouaidy@ipno.in2p3.fr