1. 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

2. 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

3. TTC Topical Workshop on Clean Room Assembly
Gradient Degradation
From the original proposal IHEP, Dec. 2011) of cross-exchanging clean room assembly procedures, and the intermediate proposal to have these procedures evaluated by the TTC Technical Board JLab, Nov. 2012), to this Workshop, blessed by the Technical Board 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

4. 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

5. TTC Topical Workshop on Clean Room Assembly
TTC Priorities
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

6. 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

7. 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

8. 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