Successful test of MITICA cryo-pumps in Padua, Italy

16/03/2023 Varie

On 8th March 2023, Site Acceptance Tests of MITICA cryo-pumps were successfully completed at the Neutral Beam Test Facility – NBTF in Padua, Italy, under the supervision of ITER IO, Fusion for Energy, and the Consorzio RFX teams.

MITICA is the neutral beam prototype of the main ITER’s heating system that will launch extremely energetic neutral particles into the plasma to make it reach 150 million °C. The facility in Padua has the task to test and improve such a critical system before it is installed in ITER and allow scientists to familiarize with its operation.

The cryopump system is an important component of MITICA as it provides the vacuum conditions necessary during the neutral beam injector operation.

Manufactured by SDMS from Saint-Romans in France, under a contract with F4E, the cryo-pump system is composed of 2 pumping assemblies (8m long, 2.8m high and 0.45 m wide). Each assembly consists of a frame with 32 pumping sections, each one made of 7 hydroformed panels in aluminium alloy and stainless steel, where helium flows at 4K, in the cryo-pumps circuits, and at 80K, in the thermal radiation shield circuits.

  • One of the two MITICA cryo-pump assemblies
  • Preparing for Site Acceptance Test (SDMS company)
  • Details of MITICA cryo-pumps
  • Thermal radiation shields of MITICA cryo-pumps

“The site acceptance test successfully completed today on MITICA cryo-pumps is an important milestone, which has been possible thanks to an intense and positive collaboration with SDMS, ITER IO and F4E colleagues”, says Stefano Manfrin, RFX Responsible Officer .

Following the successful site acceptance test of MITICA cryo-pumps, the component will be placed in a safe storage to await for its on-site installation.

Some insights of MITICA Cryo-pumps

  • Two cryo-sorption pumps, with a total pumping inlet area of 38 m2, will be installed against the lateral walls of MITICA Beam Line Vessel.
  • The two cryo-pumps have a flat geometry and each has a length of 8 m, a height of 2.8 m and a depth of 0.45 m.
  • The cryo-pumps are based on adsorption pumping by charcoal coated cryo-panels (CP) operated between 4.6 K for hydrogen pumping and 400 K for pumps regeneration. These cryo-panels are surrounded by thermal radiation shield (TRS) operated between 80 K and 400 K aiming to protect the cryo-panels from the high heat loads due to thermal radiation.
  • Each cryo-pump is equipped with 32 pumping sections, each including three CP and four TRS. The cryo-pump frames support these pumping sections.
  • The cryo-panels are cooled by supercritical helium at 4 bar to between 4.6 and 6.6 K.
  • The thermal radiation shields are cooled to between 80 K and 90 K by a forced flow of pressurized helium at 1.8 MPa.
  • The high pumping speed per unit area needed to achieve the required pumping speed is realised by using a custom design open structure geometry of cryo-panels and radiation shields.
  • The two cryo-pumps will achieve a pumping speed of 4500 m3/s for hydrogen.
  • The cryo-pumps, composed of several hundred components, are the world’s largest cryo-sorption pumping device.

References:

“Overview of the design of the ITER heating neutral beam injectors”

R S Hemsworth, D Boilson, P Blatchford, M Dalla Palma, G Chitarin, H P L de Esch, F Geli, M Dremel, J Graceffa, D Marcuzzi, G Serianni, D Shah, M Singh, M Urbani and P Zaccaria