Transcript JlabVisitReport_QWu_010617x

Jlab Visit Report
Dec. 19-20, 2016
Qiong Wu
LARP meeting
Jan 6, 2017
DQW #1
Status on Dec. 19 morning:
HOM
Beampipe
HOMpu
Pick-up
FPC
HOMfpc
• Cavity was BCPed last Friday, Dec. 16
• Cavity mounted on the standard frame with a slight angle to dry.
• The rinse after BCP was multiple cold DI water cycles + multiple hot water cycles
Visual inspection of bulk BCP finished surface
In general, the cavity appears
typical smooth and shiny inner
surface
Uneven band on
beampipe port
Uneven band on
beampipe port
•
One orange peel section observed
(inductive plate surface, antiPU side, next
to HOMfpc). This is the side ‘UP’ during
first iteration. Orange peel is due to local
air bubble forming and extra heating.
•
Both beam pipes had uneven band showing acid flow with
bubble. Bands appear in both beampipes, and both on FPC side.
This side is the ‘UP’ side of first BCP iteration.
FPC side
2HOM side
Mark due to
weld section
Smooth
Rough
2HOM side
FPC side
pit
pit
•
•
•
Pits on both center plates.
Center plates show very shiny tuner tab shapes.
Center plates are rougher on some regions (edge of the center plate on FPC side) than other.
Cavity in welding
machine
Rough final weld –
see through HOMpu
smooth final weld –
see through HOMfpc
•
smooth final weld –
see through HOMfpc
Final weld show roughness in some sections. Cannot tell the roughness.
Brown marks
White residual
white residual wiped
out with acetone
decoloration
•
•
Acid residual seen on PU port near flange (white). White mark in PU was superficial and can be
removed mostly with acetone.
Brown mark and decoloration were found in PU port near flange, and Rongli suggested this is due to
poor sealing of the braze joint at PU, so the braze material got into the Nb cavity surface.
Cavity activity during visit
 Thickness measurement on assigned locations for after BCP record. The average removals are:
i. FPC side inductive plate – 252um
ii. FPC side capacitive plate – 259um
iii. HOM side inductive plate – 174um
iv. HOM side capacitive plate – 176um
Other findings
 The iteration sequence as proposed for BCP is swapped in the actual process
 Rongli Geng recommended cover up the port opening during baking, to prevent braze material vapor go
in. I suggested HyeKyoung making similar Nb covers as Ilan and Rama did.

Insitu thickness gauge data transfer via Bluetooth did not give reliable numbers. Only 2 thickness gauge
data transferred from beginning to the end in the first iteration, the other two failed (one failed from
beginning, the other failed soon after beginning). The two gauges with complete data during first
iteration showed removal of 8 microns and 54 microns, which is different from what was manually
recorded.
DQW #2
Status on Dec. 19 morning:
• Cavity was final welded last week
• No leak check was done
• Cavity was put on a cart side ways
Visual inspection of final weld
Bump near HOMfpc
Bump near HOMfpc
• Weld started in the middle of the cavity along beampipe direction
• Bump found at weld (HOMfpc).
spatter between HOMpu
and HOM
spatter between HOMpu
and HOM
• Weld spatters found at weld (between HOMpu and HOM)
spatter between HOMpu
and HOM
spatter between HOMpu
and HOM
• Weld spatters found at weld (between HOMpu and HOM)
smooth rough weld –
view from beampipe
Sharp rough weld –
view from HOMfpc
• sharp weld prep edges and sharp welds inside the cavity
Cavity activity during visit
• Cavity was leak checked and no leak was found.
• Cavity was measured with all three copper HOM couplers prototypes from Niowave for frequency shift. The
frequency shift from all 3 couplers is 85 kHz. The simulation result is 68 kHz.
• Cavity had first three HOMs frequency recorded before BCP: 585MHz, 706MHz, and 962MHz. Recorded in the
frequency tracking file.
• Cavity was sent to get thickness measurement spot mark engraved.
•Other finings
1.The cavity has rougher weld compared to DQW #1.
2.The cavity had two scratches on the outside surface. The scratches are on HOM and HOMpu blending region. Might get those
during HOM coupler frequency measurements.