2nd TTC Topical Workshop on « SRF Cryomodule Clean Room Assembly » Introduction and Goal of the Workshop O.Napoly TTC Chair 12 November 2014 TTC Topical Workshop on Clean Room Assembly

TTC Topical Workshop on Clean Room Assembly Workshop Goal The goal of this Topical Workshop is essentially to collect, compare and discuss the best practices on clean room equipment and procedures from various international laboratories on the diversity of low to high beta superconducting RF cryomodules, primarily in order to circumvent the so-called cavity gradient degradation after cryomodule assembly. Others outputs expected from this Workshop are: the ‘global’ Clean Room discuss clean room assembly vs. cost efficiency for large series spread the knowledge about the challenges and the practices of clean room assembly from the core of specialists (a workshop of < 30 participants) to the wider circle of SRF scientists (a workshop of > 70 participants). 12 November 2014 TTC Topical Workshop on Clean Room Assembly

TTC Topical Workshop on Clean Room Assembly Gradient Degradation From the original proposal (TTC @ IHEP, Dec. 2011) of cross-exchanging clean room assembly procedures, and the intermediate proposal to have these procedures evaluated by the TTC Technical Board (TTC @ JLab, Nov. 2012), to this Workshop, blessed by the Technical Board (TTC @ DESY, March 2014), , the general goal is to collect the knowledge of TTC labs about cavity degradation after cryomodule assembly observed in FLASH cryomodules SPIRAL2 first round of cryomodule tests (RF coupler cleaning ?) ILC ‘S1 Global’ cryomodule test at and others… Main questions: Types of cavity performance degradations: Eacc, Q0, or couplers Physical observations: field emission, early quench, multipacting, … Causes: contamination, displacement, venting, shocks, … In-situ diagnosics and repair: multi-mode RF power, high-power short pulse conditionning, plasma cleaning, … 12 November 2014 TTC Topical Workshop on Clean Room Assembly

TTC Topical Workshop on Clean Room Assembly Economics Economic impacts of gradient degradation : ‘XFEL-like’ β=1 projects: 2 MV loss is about 1% of cryomodule gap voltage  about 5 k€/MV For β<1 projects, gradient is ‘deadly’ because it drives particle velocity: ‘SPIRAL2-like’ projects: the cost of full repair or of one spare cryomodule ‘IFMIF-like’ or ‘SARAF-like’ projects: the cost of the full repair of the cryomodule. IFMIF string of 8 ½ wave resonator 12 November 2014 TTC Topical Workshop on Clean Room Assembly

TTC Topical Workshop on Clean Room Assembly TTC Priorities 2011-2014 Performances SCRF systems Applications Economics Last two recommendations : The cross-communication of Clean Room Procedures between TTC Institutes is still on the table Let is be an Open Workshop, bring your own goals and ideas 12 November 2014 TTC Topical Workshop on Clean Room Assembly

Gradient Variations in XFEL Cryomodules Maximal Gradients: VT (horizontal axis) vs. AMTF (vertical axis) gradients: (courtesy D. Kostin) 12 November 2014 TTC Topical Workshop on Clean Room Assembly

Gradient Variations in XFEL Cryomodules Usable gradients: VT (horizontal axis) vs. AMTF (vertical axis) gradients: (courtesy D. Kostin, including my revision) 12 November 2014 TTC Topical Workshop on Clean Room Assembly

Workshop Organisation Thank you all (~70 + Walid) for travelling and participating Thanks to Catherine Madec, Stéphane Berry and Sébastien Bousson for organizing the TTC Topical Workshop and putting together the scientific program Acknowledge Irfu’s support for : Berthelot auditorium Coffee breaks Lunch banquet Social dinner My dinner 12 November 2014 TTC Topical Workshop on Clean Room Assembly