1. DESY experiences on assembly procedures for cavity - and string assembly
Definition of work flow for string DESY
Example on critical operation
Analysis of data
Summary
TTC Topical Workshop on SRF Cryomodule Clean Room Assembly
CEA Saclay, 12th november 2014

2. DESY experiences on assembly procedures for cavity - and string assembly ---- Definition of work flow
Cavity String =
8 Super conducting resonators
(ready for installation)
8 beam connecting bellows
(cleaned and leak checked)
2 Gate valves
1 Beam position monitor (BPM )
1 superconducting quadrupole
(pre cleaned and pre aligned)
Step
item 1
BPM 2
BPM to Quadrupole 3
Gate valve 1 to BPM 4
quality control of BPM /gate valve assembly 5
Gate valve2 to cavity 1 6
Connect cavity 1 to cavity 2 by bellows connection 7
Connect cavity 2 to cavity 3 by bellows connection
8 to 12
Connect cavity 3 to cavity 4
(4-5;5-6;6-7;7-8 )
by bellows connection 13
adjust coupler distance 14
Leak check of sub string unit 15
Connect cavity 8 to quadrupole assembly 16
final leak check of string

3. DESY experiences on assembly procedures for cavity - and string assembly ---- Definition of work flow cont.
Power coupler is different station.
(no cross contamination)
Cavities come under vacuum for string assembly
(final leak check and RGA just before assembly)

4. DESY experiences on assembly procedures for cavity - and string assembly ---Example for critical operation
Most critical operation on cav or string assembly Opening / closing of flanges Particulates from slits or bore holes are hard to remove by cleaning for ISO 4
Nuts and bots bolts produce particulates when nuts are turned
Generalized work flow for critical assembly steps on cav and strings
Align cavity on rail and connect to TMP
perform RGA and leak check
Vent CAV to air pressure
Start Argon overlay /(Flushing)
Dismount flange connection
Remove 4 studs from flange
clean holes (<10 counts /sqft min)
Insert cleaned new studs
Remove remaining studs
remove all studs and flanges and open flange
Connect to next flange with Gas flushing overlay
Install 4 cleaned studs and close connection hand tight

5. DESY experiences on assembly procedures for cavity - and string assembly ---Example for critical operation cont. Y
Film 1

6. DESY experiences on assembly procedures for cavity - and string assembly ---Experiences from the past string assemblies at DESY
At DESY string assembly was prototyping
2 types of Helium vessels 2 types of gaskets
3 types of Quadruple and Beam Position Monitors
Several types of power coupler
Limited space in ISO 4 area
Assembly procedure and tools needed to be adjusted several times

7. DESY experiences on assembly procedures for cavity - and string assembly ---Analysis of data
TTC meeting at Milano, March 04, 2010
Eiji Kako (KEK, Japan)
D.Kostin (DESY Germany '

8. DESY experiences on assembly procedures for cavity - and string assembly ---Analysis of data cont.
TTC meeting at Milano, March 04, 2010 Eiji Kako (KEK, Japan) D.Kostin (DESY Germany)

9. DESY experiences on assembly procedures for cavity - and string assembly ---Analysis of data cont.
Eiji Kako (KEK, Japan)

10. DESY experiences on assembly procedures for cavity - and string assembly ---Summary
At DESY string assemblies are done on prototype modules
Some strings needed repair (Not met spec) Repairs were done successfully
(by exchange of cavities of complete sub strings)
In Module test degradation of cavities was seen after string assembly in resp. to vertical or horizontal test
Some degradations can be explained by field emission
Remark: At that time we had only 1 Xray detector (!) [cavity beam tube long side]
Some showed Quench without indication of field emission
Remark: this effect was also seen at KEK with complete different assembly sequence
Analysis of data recorded did not give explanations for degradation
(Degradation without field emission still not explained until now)
Remark: When major errors happened cav was exchanged immediately to spare one!
CAV with little degradation had lost of NC record in log book
Cavities showing strong degradation had no logbook entries (?)

11. DESY experiences on assembly procedures for cavity - and string assembly ---Summary Open questions
Do operators (Do they have a chance) to recognize the Non Conformance
while doing the job ?