Thin films for Superconducting RF

Sabrina El Yacoubi — Thu, 27 Nov 2014 10:28:12 +0000

Thin films for Superconducting RF
by Sergio Calatroni (CERN)

Pb-coated photocatode plug, and global view of the 1.5-cell 1.3 GHz cavity used for testing. Image credit: CERN

The activity led by CERN in close collaboration with several other laboratories (CI-Lancaster, CEA, CNRS-IPNO, DESY, SINS) within the EuCARD Work Package 10.4 aims to address diverse topics in the thin film technology applied to SRF.

The analysis of the relative merits of several state of the art thin film coating technologies and the establishment of a network of SRF thin film test facilities were the first goal of this activity. The second goal was the establishment of state of the art Nb/Cu deposition on QWR cavities by sputtering techniques, including also the novel HIPIMS technique which has been demonstrated first on elliptical cavities. The third goal was the successful demonstration of the compatibility of arc-coated Pb photocathodes with the stringent requirements needed for achieving high surface fields, when used in conjunction with state of the art Nb superconducting cavities.

The several positive results obtained in this task have led to the establishment of two new tasks in EuCARD-2, which are devoted to the further development of innovative thin films (multilayers, HIPIMS, new materials) and of photocathode manufacturing processes.

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issue 6

Synergies for testing Superconducting RF cavities

Margarita Synanidi — Mon, 24 Nov 2014 14:20:01 +0000

Synergies for testing Superconducting RF cavities
by Detlef Reschke (DESY)

Fig 1, left: XFEL series cavity during incoming inspection at DESY. Image credit: DESY
Fig2, right: Vertical test inserts equipped with XFEL superconducting accelerator series cavities. Image credit: DESY.

Within the 36 month period of the CRISP project the main objective of WP4 is to upgrade and harmonize the SRF Accelerator Structures for ESS, ILC, LHC upgrade and the European XFEL. The activity supports an optimised surface treatment, the application of advanced test and preparation infrastructure as well as state-of-the-art diagnostics tools.

At CERN the SRF cavity test infrastructure is under upgrade to allow 2 Kelvin operation needed for the characterisation of a first cryomodule for the ESS and the CERN-SPL. The upgrade includes a new cryogenic transfer line between the cryoplant and RF test stand area with two horizontal cryomodule test places and four vertical RF test cryostats. Two of the vertical cryostats have been modified for 2K operation, which is necessary for the testing of the SPL cavities.

The industrial production of the series accelerator cavities for the European XFEL started successfully beginning of 2013. Until end October 2013, 164 series accelerator and ILC-HiGrade cavities for the European XFEL have been delivered to DESY. For many of the cavities that didn’t pass the tests an additional treatment applying a chemical surface removal (“Buffered Chemical Polishing BCP”) is under consideration. The development of advanced diagnostics like high resolution optical inspection and the experience of industrial cavity production and surface treatment will be extremely beneficial for any other European large scale SRF project such as ESS as well as for the preparation of the ILC.

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Thin films for Superconducting RF

Synergies for testing Superconducting RF cavities