Transcript Folie 1

Update on activities of investigations
for analysis of module cavity
degradation
Degradation and possible sources
Statistic of resonators
Analysis of log books
Analysis of hard ware
Status of RF tests on degraded resonators
Test results
Conclusions
Axel Matheisen, Denis Kostin, Detlef Reschke
TTC Meeting Beijing Dec 2011
Degradation
> Degradation between last Q(E) in vertical acceptance test and module
test
=> lot of handlings, treatment + assembly
> Degradation by
a) enhanced field emission with lower usable / maximum gradient
=> typically explained by particle contamination during handling or
improper venting condition
b) reduced quench gradient
=> ???
> In vertical acceptance tests degradation sometimes seen due to
a) field emission activation during first power rise (Q(E)-curve)
b) after quenches at high fields (>35 MV/m) by some MV/m
(cure by warming-up => indication by one older single-cell test)
c) after FE-processing ??
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 2
Handlings, treatments, assembly
> From vertical test to module test:
- cleanroom assembly of power coupler
- cleanroom connection of string
- partially exchange of flanges (e.g. HOM feedthroughs)
- HPR
- partially tank welding (cavity stays closed)
- several pumping and venting cycles
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 3
Statistics of Degraded Cavities
Module
Cavity
Pos
Preparation Gradient
drop
Module
Gradient
(MV/m)
3*
S32(X)
2
EP+BCP
8
19
3**
Z102(X)
6
EP
9
22
(X)
AC116
7
BCP flash
12
19
(X)
3***
AC118
5
BCP flash
7
23
AC148(X)
6
BCP flash
8
23
6
Z85
5
EP
12
22
Z92
6
EP
12
22
(Y)
8
Z101
1
EP
6
23
Z109
2
BCP+EP
8
22
Z108(Y)
3
EP
10
23
Z88(Y)
4
EP
4
28
Z104
8
EP
10
27
PXFEL1
Z100
7
EP
13
27
PXFEL2
Z133 *
3
BCP flash
11
16
PXFEL3
Z88 *
3
EP
12
18
AC127 *
6
EP
8
19
S1 global
Z108*
3
EP
12
20
CM1
Z89
1
EP
7
17
AC73
3
BCP flash
15
16
(Y): Field emission loaded
(X): No data of field emission available
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 4
* Recruited for analysis
Position of degraded Cavities
Position of Cavity in
modules
P1 P 2
No of cavities degraded @ 2
position
2
P3
P4
P5
P6
P7
P8
5
1
2
4
2
1
Statistic of position of resonators showing
reduced performance in modules
=> Position 3 + 6: ???
Remark: Leak check during string assembly after P4
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 5
Analysis of Logbooks for Z88, Z108, AC127, Z133
> Storage
Z108; Z88; AC127:
- non-standard storage (=> out of cleanroom) during cleanroom shut
down (in respect to the other cavities of Module S1 global and
PXFEL-modules)
- stored closed under vacuum
- cleaned manually (no US-cleaning due to assembled power coupler)
> Assembly procedures
Z133; AC127; Z88:
- No differences to other cavities in line found in assembly log book
in respect of
- particulates loading
- assembly times
- leakage found
- RGA
- Z108 ? People on place did not report on irregularities.
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 6
Analysis of hard ware
Vacuum
Accessories
DESY
Equipment
Leak rate
Z88
AC127
Z108
RGA
OK
OK
OK
P total before
Module
OK
OK
OK
Power coupler
cold part after
dismounting
Clean no sparks top no
oxidation
Clean no sparks top no
oxidation
Wait for analysis
HOM Antennas
after dismounting
OK no irregularity
OK no irregularity
Wait for analysis
Flanges gaskets
Ok no irregularity
Ultrasonic bath
Non homogeneity
top bottom; also in use
for cavities not showing
degradation
Non homogeneity
top bottom; also in use
for cavities not
showing degradation
Non homogeneity
top bottom; also in
use for cavities not
showing degradation
Flange cleaning*
manual cleaning due to
installed power couplers
for reentering cleanroom
manual cleaning due to
installed power
couplers for reentering
cleanroom
manual cleaning due
to installed power
couplers for
reentering cleanroom
*New test set up developed
not applied on these cavities yet
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 7
Status of RF tests on degraded cavities
#
Test mode
Antenna
type
HOM
installed
AC127 gradient
Z88 gradient
Z133 gradient
Eacc max
(Fe onset )
Eacc max
(Fe onset )
Eacc max
(Fe onset )
1
Vertical
HQ
No
27,6 (27)
30,4 (30)
27,3 (20,5)
2
Module
PC
Yes
19,2 (19)
18,5 (18)
16,2 (?)
3
CHECHIA
PC
Yes
20,4 (19)
19,9 (18)
----
4
CHECHIA
HQ
Yes
-----
12,8 (11)*
----
5
Vertical
HQ
Yes
19,7 (14)
-----
----
6
Vertical
HQ
No
17,7 (13)
-----
----
Mode
analysis
Remove tank
HD
No
??
----
----
----
----
Yes
Yes
Yes
T map
variable
No
wait
wait
wait
7
HQ = high Q antenna long pulse mode RF test
PC = power coupler operated with Klystron in pulse mode
Var= Variable antenna installed fro T map
* Limitation by HOM coupler
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 8
Q(E)-measurements of Z88
0.10
1.0E+11
0.09
0.08
0.07
Qo
0.06
0.05
1.0E+09
0.04
0.03
1.0E+08
radiation [mGY/min]
1.0E+10
0.02
0.01
0.00
1.0E+07
0
5
10
15
20
25
30
35
Z 88: Eacc [MV/m]
vertikal
Cechia
Modul
Xrays chechia
Xrays modul
HQ antenna >Cechia fe
HQ antenna Cechia
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 9
Q(E)-measurements of AC127
0.2
1.0E+11
0.18
0.16
Qo
0.14
0.12
1.0E+09
0.1
0.08
0.06
1.0E+08
0.04
0.02
0
1.0E+07
0
5
vertikal test
vertical test High Q antenna
vertical test fe High Q antenna
10
15
20
AC 127 : Eacc [MV/m]
Chechia test
Xray chechia
25
30
Modul test
Xrays modul
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 10
radiation [mGY/min]
1.0E+10
Conclusion
> Up to now:
NO proveable explanation for degradation w/o FE
> Vertical test with T-mapping and subsequent optical inspection of Z88,
Z108 + AC127 in preparation
Detlef Reschke| TTC Meeting Beijing Dec 2011 | Page 11